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Sample records for fluorescent liquid penetrant

  1. Standard practice for fluorescent liquid penetrant testing using the Solvent-Removable process

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice covers procedures for fluorescent penetrant examination utilizing the solvent-removable process. It is a nondestructive testing method for detecting discontinuities that are open to the surface, such as cracks, seams, laps, cold shuts, laminations, isolated porosity, through leaks, or lack of fusion and is applicable to in-process, final, and maintenance examination. It can be effectively used in the examination of nonporous, metallic materials, both ferrous and nonferrous, and of nonmetallic materials such as glazed or fully densified ceramics and certain nonporous plastics and glass. 1.2 This practice also provides a reference: 1.2.1 By which a fluorescent penetrant examination solvent-removable process recommended or required by individual organizations can be reviewed to ascertain its applicability and completeness. 1.2.2 For use in the preparation of process specifications dealing with the fluorescent solvent-removable liquid penetrant examination of materials and parts. Agreement by th...

  2. Standard practice for fluorescent liquid penetrant testing using the hydrophilic Post-Emulsification process

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice covers procedures for fluorescent penetrant examination utilizing the hydrophilic post-emulsification process. It is a nondestructive testing method for detecting discontinuities that are open to the surface such as cracks, seams, laps, cold shuts, laminations, isolated porosity, through leaks, or lack of fusion and is applicable to in-process, final, and maintenance examination. It can be effectively used in the examination of nonporous, metallic materials, both ferrous and nonferrous, and of nonmetallic materials such as glazed or fully densified ceramics and certain nonporous plastics and glass. 1.2 This practice also provides a reference: 1.2.1 By which a fluorescent penetrant examination hydrophilic post-emulsification process recommended or required by individual organizations can be reviewed to ascertain their applicability and completeness. 1.2.2 For use in the preparation of process specifications dealing with the fluorescent penetrant examination of materials and parts using the hy...

  3. Standard practice for fluorescent liquid penetrant testing using the Water-Washable process

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice covers procedures for water-washable fluorescent penetrant examination of materials. It is a nondestructive testing method for detecting discontinuities that are open to the surface such as cracks, seams, laps, cold shuts, laminations, isolated porosity, through leaks, or lack of porosity and is applicable to in-process, final, and maintenance examination. It can be effectively used in the examination of nonporous, metallic materials, both ferrous and nonferrous, and of nonmetallic materials such as glazed or fully densified ceramics and certain nonporous plastics and glass. 1.2 This practice also provides a reference: 1.2.1 By which a fluorescent penetrant examination method using the water-washable process recommended or required by individual organizations can be reviewed to ascertain its applicability and completeness. 1.2.2 For use in the preparation of process specifications dealing with the water-washable fluorescent penetrant examination of materials and parts. Agreement by the purch...

  4. FAA Fluorescent Penetrant Laboratory Inspections

    Energy Technology Data Exchange (ETDEWEB)

    WINDES,CONNOR L.; MOORE,DAVID G.

    2000-08-02

    The Federal Aviation Administration Airworthiness Assurance NDI Validation Center currently assesses the capability of various non-destructive inspection (NDI) methods used for analyzing aircraft components. The focus of one such exercise is to evaluate the sensitivity of fluorescent liquid penetrant inspection. A baseline procedure using the water-washable fluorescent penetrant method defines a foundation for comparing the brightness of low cycle fatigue cracks in titanium test panels. The analysis of deviations in the baseline procedure will determine an acceptable range of operation for the steps in the inspection process. The data also gives insight into the depth of each crack and which step(s) of the inspection process most affect penetrant sensitivities. A set of six low cycle fatigue cracks produced in 6.35-mm thick Ti-6Al-4V specimens was used to conduct the experiments to produce sensitivity data. The results will document the consistency of the crack readings and compare previous experiments to find the best parameters for water-washable penetrant.

  5. FAA Fluorescent Penetrant Activities - An Update

    Energy Technology Data Exchange (ETDEWEB)

    Moore, D.G.

    1998-10-20

    The Federal Aviation Administration's Airworthiness Assurance NDI Validation Center (AANC) is currently characterizing low cycle fatigue specimens that will support the needs of penetrant manufacturers, commercial airline industry and the Federal Aviation Administration. The main focus of this characterization is to maintain and enhance the evaluation of penetrant inspection materials and apply resources to support the aircraft community needs. This paper discusses efforts to-date to document the Wright Laboratory penetrant evaluation process and characterize penetrant brightness readings in the initial set of sample calibration panels using Type 1 penetrant.

  6. Effect of Liquid Penetrant Sensitivity on Probability of Detection

    Science.gov (United States)

    Parker, Bradford H.

    2008-01-01

    The objective of the task is to investigate the effect of liquid penetrant sensitivity level on probability of crack detection (POD). NASA-STD-5009 currently requires the use of only sensitivity level 4 liquid penetrants. This requirement is based on the fact that the data generated in the NTIAC Nondestructive Evaluation (NDE) Capabilities Data Book was produced using only sensitivity level 4 penetrants. Many NDE contractors supporting NASA Centers routinely use sensitivity level 3 penetrants. Because of the new NASA-STD-5009 requirement, these contractors will have to either shift to sensitivity level 4 penetrants or perform formal POD demonstration tests to qualify their existing process.

  7. BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES

    Energy Technology Data Exchange (ETDEWEB)

    Farquar, G; Leif, R

    2009-07-15

    Biocompatible polymers with hydrolyzable chemical bonds have been used to produce safe, non-toxic fluorescent microspheres for material penetration studies. The selection of polymeric materials depends on both biocompatibility and processability, with tailored fluorescent properties depending on specific applications. Microspheres are composed of USFDA-approved biodegradable polymers and non-toxic fluorophores and are therefore suitable for tests where human exposure is possible. Micropheres were produced which contain unique fluorophores to enable discrimination from background aerosol particles. Characteristics that affect dispersion and adhesion can be modified depending on use. Several different microsphere preparation methods are possible, including the use of a vibrating orifice aerosol generator (VOAG), a Sono-Tek atomizer, an emulsion technique, and inkjet printhead. Applications for the fluorescent microspheres include challenges for biodefense system testing, calibrants for biofluorescence sensors, and particles for air dispersion model validation studies.

  8. Standard practice for liquid penetrant examination for general industry

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This practice covers procedures for penetrant examination of materials. Penetrant testing is a nondestructive testing method for detecting discontinuities that are open to the surface such as cracks, seams, laps, cold shuts, shrinkage, laminations, through leaks, or lack of fusion and is applicable to in-process, final, and maintenance testing. It can be effectively used in the examination of nonporous, metallic materials, ferrous and nonferrous metals, and of nonmetallic materials such as nonporous glazed or fully densified ceramics, as well as certain nonporous plastics, and glass. 1.2 This practice also provides a reference: 1.2.1 By which a liquid penetrant examination process recommended or required by individual organizations can be reviewed to ascertain its applicability and completeness. 1.2.2 For use in the preparation of process specifications and procedures dealing with the liquid penetrant testing of parts and materials. Agreement by the customer requesting penetrant inspection is strongly rec...

  9. Effect of Liquid Penetrant Sensitivity on Probability of Detection

    Science.gov (United States)

    Parker, Bradford H.

    2011-01-01

    The objective of the task is to investigate the effect of liquid penetrant sensitivity level on probability of detection (POD) of cracks in various metals. NASA-STD-5009 currently requires the use of only sensitivity level 4 liquid penetrants for NASA Standard Level inspections. This requirement is based on the fact that the data used to establish the reliably detectable flaw sizes penetrant inspection was from studies performed in the 1970s using penetrant deemed to be equivalent only to modern day sensitivity level 4 penetrants. However, many NDE contractors supporting NASA Centers routinely use sensitivity level 3 penetrants. Because of the new NASA-STD-5009 requirement, these contractors will have to either shift to sensitivity level 4 penetrants or perform formal POD demonstration tests to qualify their existing process. We propose a study to compare the POD generated for two penetrant manufactures, Sherwin and Magnaflux, and for the two most common penetrant inspection methods, water washable and post emulsifiable, hydrophilic. NDE vendors local to GSFC will be employed. A total of six inspectors will inspect a set of crack panels with a broad range of fatigue crack sizes. Each inspector will perform eight inspections of the panel set using the combination of methods and sensitivity levels described above. At least one inspector will also perform multiple inspections using a fixed technique to investigate repeatability. The hit/miss data sets will be evaluated using both the NASA generated DOEPOD software and the MIL-STD-1823 software.

  10. BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES

    Energy Technology Data Exchange (ETDEWEB)

    farquar, G; Leif, R

    2008-09-12

    Biocompatible polymers with hydrolyzable chemical bonds are being used to produce safe, non-toxic fluorescent microspheres for material penetration studies. The selection of polymeric materials depends on both biocompatibility and processability, with tailored fluorescent properties depending on specific applications. Microspheres are composed of USFDA-approved biodegradable polymers and non-toxic fluorophores and are therefore suitable for tests where human exposure is possible. Micropheres are being produced which contain unique fluorophores to enable discrimination from background aerosol particles. Characteristics that affect dispersion and adhesion can be modified depending on use. Several different microsphere preparation methods are possible, including the use of a vibrating orifice aerosol generator (VOAG), a Sono-Tek atomizer, an emulsion technique, and inkjet printhead. The advantages and disadvantages of each method will be presented and discussed in greater detail along with fluorescent and charge properties of the aerosols. Applications for the fluorescent microspheres include challenges for biodefense system testing, calibrants for biofluorescence sensors, and particles for air dispersion model validation studies.

  11. Penetrating behavior of eutectic liquid during Al/Cu contact reactive brazing

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The behavior of eutectic liquid penetrating into the Al base during Al/Cu contact reactive brazing process was studied. Analysis results show that the eutectic liquid prefers to expand along the grain boundary in the depth direction. Meanwhile, dissolution of solid Al and Cu into the eutectic liquid promotes the eutectic reaction and the continuously formed eutectic liquid leads to the reactive penetrating.

  12. Dynamics of a solid sphere bouncing on or penetrating through a liquid-air interface

    Science.gov (United States)

    Kim, Seong Jin; Jung, Sunghwan; Lee, Sungyon

    2014-11-01

    In this study, we investigate the dynamics of a solid particle moving from liquid to air through a liquid-air interface. The experimental setup consists of an air-piston system that shoots a solid particle into water towards the free surface from below. Experimental results indicate that the particle either penetrates or bounces back depending on the particle size, impact speed, and surface tension. In particular, the particle needs to overcome the resistive interfacial forces in order to penetrate through the liquid-air interface. This transition from bouncing to penetration regimes is captured theoretically by conducting a simple force balance and is further compared with experiments.

  13. Unsteady penetration of a target by a liquid jet.

    Science.gov (United States)

    Uth, Tobias; Deshpande, Vikram S

    2013-12-10

    It is widely acknowledged that ceramic armor experiences an unsteady penetration response: an impacting projectile may erode on the surface of a ceramic target without substantial penetration for a significant amount of time and then suddenly start to penetrate the target. Although known for more than four decades, this phenomenon, commonly referred to as dwell, remains largely unexplained. Here, we use scaled analog experiments with a low-speed water jet and a soft, translucent target material to investigate dwell. The transient target response, in terms of depth of penetration and impact force, is captured using a high-speed camera in combination with a piezoelectric force sensor. We observe the phenomenon of dwell using a soft (noncracking) target material. The results show that the penetration rate increases when the flow of the impacting water jet is reversed due to the deformation of the jet-target interface--this reversal is also associated with an increase in the force exerted by the jet on the target. Creep penetration experiments with a constant indentation force did not show an increase in the penetration rate, confirming that flow reversal is the cause of the unsteady penetration rate. Our results suggest that dwell can occur in a ductile noncracking target due to flow reversal. This phenomenon of flow reversal is rather widespread and present in a wide range of impact situations, including water-jet cutting, needleless injection, and deposit removal via a fluid jet.

  14. Real-time monitoring of the penetration of amphiphilic acrylate copolymer in leather using a fluorescent copolymer as tracer.

    Science.gov (United States)

    Du, Jin-Xia; Shi, Lu; Peng, Bi-Yu

    2015-12-01

    A fluorescent tracer, poly (acrylic-co-stearyl acrylate-co-3-acryloyl fluorescein) [poly (AA-co-SA-co-Ac-Flu)], used for real-time monitoring the penetration of amphiphilic acrylate copolymer, poly (acrylic-co-stearyl acrylate) [poly (AA-co-SA)], in leather was synthesized by radical polymerization of acrylic, stearyl acrylate and fluorescent monomer, 3-acryloyl fluorescein (Ac-Flu). The structure, molecular weight, introduced fluorescent group content and fluorescent characteristics of the fluorescent tracer and target copolymer, amphiphilic acrylate copolymer, were also characterized. The results show that the tracer presents the similar structural characteristics to the target and enough fluorescence intensity with 1.68 wt % of the fluorescent monomer introduced amount. The vertical section of the leather treated with the target copolymer mixing with 7% of the tracer exhibits evident fluorescence, and the change of fluorescence intensity along with the vertical section with treating time increasing can reflect the penetration depth of the target copolymer. The introduction of the fluorescent group in polymer structure through copolymerization with a limited amount of fluorescent monomer, Ac-Flu, is an effective way to make a tracer to monitor the penetration of the target in leather, which provides a new thought for the penetration research of syntans such as vinyl copolymer materials in leather manufacture.

  15. A model on liquid penetration into soft material with application to needle-free jet injection.

    Science.gov (United States)

    Chen, Kai; Zhou, Hua; Li, Ji; Cheng, Gary J

    2010-10-01

    A mathematical model has been presented for a high speed liquid jet penetration into soft solid by a needle-free injection system. The model consists of a cylindrical column formed by the initial jet penetration and an expansion sphere due to continuous deposition of the liquid. By solving the equations of energy conservation and volume conservation, the penetration depth and the radius of the expansion sphere can be predicted. As an example, the calculation results were presented for a typical needle-free injection system into which a silicon rubber was injected into. The calculation results were compared with the experimental results.

  16. Spatial Filter Based Bessel-Like Beam for Improved Penetration Depth Imaging in Fluorescence Microscopy

    Science.gov (United States)

    Purnapatra, Subhajit B.; Bera, Sampa; Mondal, Partha Pratim

    2012-01-01

    Monitoring and visualizing specimens at a large penetration depth is a challenge. At depths of hundreds of microns, several physical effects (such as, scattering, PSF distortion and noise) deteriorate the image quality and prohibit a detailed study of key biological phenomena. In this study, we use a Bessel-like beam in-conjugation with an orthogonal detection system to achieve depth imaging. A Bessel-like penetrating diffractionless beam is generated by engineering the back-aperture of the excitation objective. The proposed excitation scheme allows continuous scanning by simply translating the detection PSF. This type of imaging system is beneficial for obtaining depth information from any desired specimen layer, including nano-particle tracking in thick tissue. As demonstrated by imaging the fluorescent polymer-tagged-CaCO3 particles and yeast cells in a tissue-like gel-matrix, the system offers a penetration depth that extends up to 650 µm. This achievement will advance the field of fluorescence imaging and deep nano-particle tracking. PMID:23012646

  17. Capillary Drop Penetration Method to Characterize the Liquid Wetting of Powders.

    Science.gov (United States)

    Liu, Zhanjie; Wang, Yifan; Muzzio, Fernando J; Callegari, Gerardo; Drazer, German

    2017-01-10

    We present a method to characterize the wettability of powders, based on the penetration dynamics of a sessile drop deposited on a slightly compressed powder bed. First, we show that a direct comparison of the wetting properties of different liquids is possible without having to solve the three-dimensional liquid penetration problem, by considering the appropriate dimensionless variables. We show that the contact area between the sessile drop and the powder bed remains constant during most of the penetration process and demonstrate that as a result, the evolution of the dimensionless penetration volume is given by a universal function of the dimensionless time, with no dimensionless parameters. Then, using a reference liquid that completely wets the powder, it is possible to obtain an effective contact angle for a test liquid of interest, independent of other properties of the powder bed, such as permeability and a characteristic pore size. We apply the proposed method to estimate the contact angle of water with different powder blends, by using silicone oil as the reference liquid. Finally, to highlight the potential of the proposed method to characterize pharmaceutical powders, we consider a blend of lactose, acetaminophen, and a small amount of lubricant (magnesium stearate). The proposed method adequately captures a significant decrease in hydrophilicity that results from exposing the blend to excessive mixing, a well-known effect in the pharmaceutical industry.

  18. Using liquid droplet penetration experiments to determine wetting properties of powders

    Science.gov (United States)

    Callegari, Gerardo; Liu, Zhanjie; Wang, Yifan; Muzzio, Fernando; Drazer, German

    2016-11-01

    We show that the spontaneous penetration of droplets on a powder bed provides a simple way to characterize the wetting properties of a test liquid. Specifically, we demonstrate that calculating the appropriate dimensionless penetrating volume and time, and performing supplementary experiments with a reference liquid, it is possible to obtain the contact angle between the test liquid and the powder. Interestingly, the proposed analysis lets us calculate the contact angle without having to compute the solution to the 3D penetration problem. This approach is valid when the contact area between the droplet and the powder bed remains constant, which is a good approximation in many powder systems. We first test the validity of our approach by studying droplets of different sizes and show that the non-dimensional penetration curves are independent of the initial volume and contact radius of the drops, as predicted. We then use a reference liquid (silicone oil) to measure the contact angle of water on three powder systems with increasing number of pharmaceutical components and different processing conditions known to affect blend wettability. We show that the proposed method is able to capture the overlubrication of the blend, a well-known effect in pharmaceutical manufacturing.

  19. Visualization of the Nucleolus in Living Cells with Cell-Penetrating Fluorescent Peptides.

    Science.gov (United States)

    Martin, Robert M; Herce, Henry D; Ludwig, Anne K; Cardoso, M Cristina

    2016-01-01

    The nucleolus is the hallmark of nuclear compartmentalization and has been shown to exert multiple roles in cellular metabolism besides its main function as the place of ribosomal RNA synthesis and assembly of ribosomes. The nucleolus plays also a major role in nuclear organization as the largest compartment within the nucleus. The prominent structure of the nucleolus can be detected using contrast light microscopy providing an approximate localization of the nucleolus, but this approach does not allow to determine accurately the three-dimensional structure of the nucleolus in cells and tissues. Immunofluorescence staining with antibodies specific to nucleolar proteins albeit very useful is time consuming, normally antibodies recognize their epitopes only within a small range of species and is applicable only in fixed cells. Here, we present a simple method to selectively and accurately label this ubiquitous subnuclear compartment in living cells of a large range of species using a fluorescently labeled cell-penetrating peptide.

  20. Fluorescence self-quenching of tetraphenylporphyrin in liquid medium

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Mihir [Integrated Science Education and Research Centre, Siksha-Bhavana, Visva-Bharati, Santiniketan 731235 (India); Nath, Sukhendu [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Hajra, Alakananda [Department of Chemistry, Siksha-Bhavana, Visva-Bharati, Santiniketan 731235 (India); Sinha, Subrata, E-mail: subratasinha67@rediffmail.com [Integrated Science Education and Research Centre, Siksha-Bhavana, Visva-Bharati, Santiniketan 731235 (India)

    2013-09-15

    Self-quenching of the fluorescence emission of tetraphenylporphyrin at high concentrations in toluene at the ambient temperature (300 K) is discussed in detail based on steady state and time-resolved fluorescence measurements. The fluorescence self-quenching is mainly attributed to re-absorption effect and the Förster type resonance energy transfer process (homotransfer). The re-absorption effect is found to deform the fluorescence emission spectra significantly in energy positions as well as relative intensities of different peaks at high concentrations. Nearly ideal fluorescence emission spectra are observed at a concentration ∼10{sup −7} mol/L. Moreover, there is an apparent enhancement of the fluorescence lifetime value of tetraphenylporphyrin in toluene at high concentrations, especially on the blue side of the fluorescence emission spectra. To the best knowledge of the authors, this is the first detail report on the fluorescence self-quenching of porphyrins in liquid medium. This finding carries great importance in view of the widespread research on porphyrins in the fields of solar light harvesting, artificial photosynthesis, photodynamic therapy, etc. -- Highlights: • The effect of concentration on the fluorescence emission spectra of tetraphenylporphyrin (TPhP) in toluene at 300 K is investigated by using steady state and time-resolved fluorescence techniques. • Both re-absorption effect and the Förster type resonance energy transfer are found to be responsible for the observed fluorescence self-quenching at high concentrations. • These investigations are extremely important in view of the extensive applications of porphyrins in the fabrication of molecular electronic devices, especially for solar and artificial photosynthetic devices, where highly concentrated porphyrins are often used for efficient light harvesting.

  1. Prediction of Melting Penetration of Armco Iron by Liquid Uranium Using MPS_LER

    Science.gov (United States)

    Mustari, A. P. A.; Iksal; Sumiati; Syeilendra; Irwanto, Dwi; Aprianti, N. A.

    2017-01-01

    Given the nuclear reactor severe accident, molten uranium may relocate and contact with iron based structural material which could result in melting of iron based material. According to binary phase diagram, contact between Fe and U may include eutectic phenomenon where melting temperature of the material drop sharply. Information of melting penetration rate of iron based material by uranium is important for melting relocation investigation during severe accident. MPS_LER has been developed and validated to simulate eutectic phenomena of Fe-U system. In the present study, the MPS_LER was used to predict melting penetration of Armco Iron by liquid uranium that has not been experimentally recorded. The present results show MPS_LER’s prediction on melting penetration rate of Fe-U system at high temperature.

  2. Highly compressible fluorescent particles for pressure sensing in liquids

    Science.gov (United States)

    Cellini, F.; Peterson, S. D.; Porfiri, M.

    2017-05-01

    Pressure sensing in liquids is important for engineering applications ranging from industrial processing to naval architecture. Here, we propose a pressure sensor based on highly compressible polydimethylsiloxane foam particles embedding fluorescent Nile Red molecules. The particles display pressure sensitivities as low as 0.0018 kPa-1, which are on the same order of magnitude of sensitivities reported in commercial pressure-sensitive paints for air flows. We envision the application of the proposed sensor in particle image velocimetry toward an improved understanding of flow kinetics in liquids.

  3. Fluorescence decay-time constants in organic liquid scintillators.

    Science.gov (United States)

    Marrodán Undagoitia, T; von Feilitzsch, F; Oberauer, L; Potzel, W; Ulrich, A; Winter, J; Wurm, M

    2009-04-01

    The fluorescence decay-time constants have been measured for several scintillator mixtures based on phenyl-o-xylylethane (PXE) and linear alkylbenzene (LAB) solvents. The resulting values are of relevance for the physics performance of the proposed large-volume liquid scintillator detector Low Energy Neutrino Astronomy (LENA). In particular, the impact of the measured values to the search for proton decay via p-->K(+)nu is evaluated in this work.

  4. Rapid and Reliable Detection of Antimicrobial Peptide Penetration into Gram-Negative Bacteria Based on Fluorescence Quenching▿

    OpenAIRE

    Benincasa, Monica; Pacor, Sabrina; Gennaro, Renato; Scocchi, Marco

    2009-01-01

    In this paper, we describe a rapid flow cytometry method to identify antimicrobial peptides that are internalized into bacterial cells and differentiate them from those that are membrane active. The method was applied to fluorescently labeled Bac71-35 and polymyxin B, whose mechanisms of action are, respectively, based on cell penetration and on membrane binding and permeabilization. Identification of peptides with the former mechanism is of considerable interest for the intracellular deliver...

  5. Rapid and Reliable Detection of Antimicrobial Peptide Penetration into Gram-Negative Bacteria Based on Fluorescence Quenching▿

    Science.gov (United States)

    Benincasa, Monica; Pacor, Sabrina; Gennaro, Renato; Scocchi, Marco

    2009-01-01

    In this paper, we describe a rapid flow cytometry method to identify antimicrobial peptides that are internalized into bacterial cells and differentiate them from those that are membrane active. The method was applied to fluorescently labeled Bac71-35 and polymyxin B, whose mechanisms of action are, respectively, based on cell penetration and on membrane binding and permeabilization. Identification of peptides with the former mechanism is of considerable interest for the intracellular delivery of membrane-impermeant drugs. PMID:19470515

  6. Predicting drug penetration across the blood-brain barrier: comparison of micellar liquid chromatography and immobilized artificial membrane liquid chromatography.

    Science.gov (United States)

    De Vrieze, Mike; Lynen, Frédéric; Chen, Kai; Szucs, Roman; Sandra, Pat

    2013-07-01

    Several in vitro methods have been tested for their ability to predict drug penetration across the blood-brain barrier (BBB) into the central nervous system (CNS). In this article, the performance of a variety of micellar liquid chromatographic (MLC) methods and immobilized artificial membrane (IAM) liquid chromatographic approaches were compared for a set of 45 solutes. MLC measurements were performed on a C18 column with sodium dodecyl sulfate (SDS), polyoxyethylene (23) lauryl ether (Brij35), or sodium deoxycholate (SDC) as surfactant in the micellar mobile phase. IAM liquid chromatography measurements were performed with Dulbecco's phosphate-buffered saline (DPBS) and methanol as organic modifier in the mobile phase. The corresponding retention and computed descriptor data for each solute were used for construction of models to predict transport across the blood-brain barrier (log BB). All data were correlated with experimental log BB values and the relative performance of the models was studied. SDS-based models proved most suitable for prediction of log BB values, followed closely by a simplified IAM method, in which it could be observed that extrapolation of retention data to 0% modifier in the mobile phase was unnecessary.

  7. Ground penetrating radar detection of subsnow liquid overflow on ice-covered lakes in interior Alaska

    Directory of Open Access Journals (Sweden)

    A. Gusmeroli

    2012-07-01

    Full Text Available Lakes are abundant throughout the pan-Arctic region. For many of these lakes ice cover lasts for up to two thirds of the year. This frozen cover allows human access to these lakes, which are therefore used for many subsistence and recreational activities, including water harvesting, fishing, and skiing. Safe access to these lakes may be compromised, however, when, after significant snowfall, the weight of the snow acts on the ice and causes liquid water to spill through weak spots and overflow at the snow-ice interface. Since visual detection of subsnow liquid overflow (SLO is almost impossible our understanding on SLO processes is still very limited and geophysical methods that allow SLO detection are desirable. In this study we demonstrate that a commercially available, lightweight 1GHz, ground penetrating radar system can detect and map extent and intensity of SLO. Radar returns from wet snow-ice interfaces are at least twice as much in strength than returns from dry snow-ice interface. The presence of SLO also affects the quality of radar returns from the base of the lake ice. During dry conditions we were able to profile ice thickness of up to 1 m, conversely, we did not retrieve any ice-water returns in areas affected by SLO.

  8. Boiling crisis controlled by capillary pumping and viscous friction: Liquid penetration length and dry spot diameter

    Science.gov (United States)

    Kim, Hyungdae; Ahn, Ho Seon; Kwak, Ho Jae; Kim, Moo Hwan; Kim, Dong Eok

    2016-12-01

    A boiling crisis, or critical heat flux (CHF), is a condition that determines the upper bound on removable thermal energy at a boiling surface. In such situations, the liquid cannot wet the surface because a vapor film completely covers it. CHF is enhanced on micro-structured surfaces when under boiling conditions. CHF values were measured for surfaces with rectangular microchannel geometries of various channel widths, (10-30 μm) and generally increased in value as channel widths decreased. However, the CHF value for the 5-μm channel-width surface was found to be lower than the wider channel-width surfaces. This observation contradicts models based on vapor recoil and classical instability mechanisms. Hence, we present a fluid-dynamics model that considers capillary pumping and viscous friction. With a focus on the spatial distribution of the liquid penetration region and the local dry spot under a large vapor bubble, this model can accurately predict the CHF variation associated with different channel widths.

  9. In Situ Measurement of Airway Surface Liquid [K+] Using a Ratioable K+-sensitive Fluorescent Dye*

    OpenAIRE

    Namkung, Wan; Song, Yuanlin; Mills, Aaron D.; Padmawar, Prashant; Finkbeiner, Walter E.; Verkman, A. S.

    2009-01-01

    The airway surface liquid (ASL) is the thin fluid layer lining airway surface epithelial cells, whose volume and composition are tightly regulated and may be abnormal in cystic fibrosis (CF). We synthesized a two-color fluorescent dextran to measure ASL [K+], TAC-Lime-dextran-TMR, consisting of a green-fluorescing triazacryptand K+ ionophore-Bodipy conjugate, coupled to dextran, together with a red fluorescing tetramethylrhodamine reference chromophore. TAC-Lime-dextran-TMR fluorescence was K...

  10. Determination of multiple phytohormones in fruits by high-performance liquid chromatography with fluorescence detection using dispersive liquid-liquid microextraction followed by precolumn fluorescent labeling.

    Science.gov (United States)

    Li, Guoliang; Lu, Shuaimin; Wu, Hongliang; Chen, Guang; Liu, Shucheng; Kong, Xiaojian; Kong, Weiheng; You, Jinmao

    2015-01-01

    Plant hormone determination in food matrices has attracted more and more attention because of their potential risks to human health. However, analytical methods for the analysis of multiple plant hormones remain poorly investigated. In the present study, a convenient, selective, and ultrasensitive high-performance liquid chromatography method for the simultaneous determination of multiple classes of plant hormones has been developed successfully using dispersive liquid-liquid microextraction followed by precolumn fluorescent labeling. Eight plant hormones in fruits including jasmonic acid, 12-oxo-phytodienoic acid, indole-3-acetic acid, 3-indolybutyric acid, 3-indolepropionic acid, gibberellin A3 , 1-naphthylacetic acid, and 2-naphthaleneacetic acid were analyzed by this method. The conditions employed for dispersive liquid-liquid microextraction were optimized systematically. The linearity for all plant hormones was found to be >0.9993 (R(2) values). This method offered low detection limits of 0.19-0.44 ng/mL (at a signal-to-noise ratio of 3), and method accuracies were in the range of 92.32-103.10%. The proposed method was applied to determine plant hormones in five kinds of food samples, and this method can achieve a short analysis time, low threshold levels of detection, and a high specificity for the analysis of targeted plant hormones present at trace level concentrations in complex matrices.

  11. Optical absorption and fluorescence studies on imidazolium ionic liquids comprising the bis(trifluoromethanesulphonyl)imide anion

    Indian Academy of Sciences (India)

    Aniruddha Paul; Anunay Samanta

    2006-07-01

    Optical absorption and fluorescence behaviour of two rigorously purified imidazolium ionic liquids, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide are studied in the neat condition and in solution. Non-negligible absorption in the UV region with a long tail extending into the visible region is the main feature of the absorption. Excitation wavelength-dependent two-component fluorescence characterizes the emission behaviour of these liquids. That ion association gives rise to the long absorption tail and shifting fluorescence maximum, which appears to be common to most of the imidazolium ionic liquids, is evident from the effect of the conventional solvents.

  12. Model for the dynamics of liquid penetration into porous structures and its detection with the help of changes in ultrasonic attenuation

    OpenAIRE

    Daun, Matias

    2007-01-01

    The dynamics of liquid penetration into porous networks is important for many processes during the production and printing of paper. One commercially available device to measure liquid penetration indirectly uses the change of ultrasonic attenuation when a specimen is brought into contact with liquid. In order to interpret results obtained by this device the generation and detection of ultra-sound are modelled as functions of the Sender and the Receiver, their material properties, their diame...

  13. Synthesis of fluorescent C24-ceramide: evidence for acyl chain length dependent differences in penetration of exogenous NBD-ceramides into human skin.

    Science.gov (United States)

    Novotný, Jakub; Pospechová, Katerina; Hrabálek, Alexandr; Cáp, Robert; Vávrová, Katerina

    2009-12-15

    Topical skin lipid supplementation may provide opportunities for controlling ceramide (Cer) deficiency in skin diseases such as atopic dermatitis or psoriasis. Here we describe the synthesis of a long-chain 7-nitrobenzo[c][1,2,5]oxadiazol-4-yl (NBD)-labeled Cer and its different penetration through human skin compared to widely used short-chain fluorescent Cer tools.

  14. Fluorescence action spectra of algae and bean leaves at room and at liquid nitrogen temperatures

    NARCIS (Netherlands)

    Goedheer, J.C.

    1965-01-01

    Fluorescence action spectra were determined, both at room temperature and at liquid nitrogen temperature, with various blue-green, red and green algae, and greening bean leaves. The action spectra of algae were established with samples of low light absorption as well as dense samples. Fluorescence

  15. The fluorescence and dynamics properties in phenoxy-phthalocyanines liquid

    Science.gov (United States)

    Yao, Cheng-Bao; Yan, Xiao-Yan; Tan, Ming-Yue; Li, Jin; Sun, Wen-Jun; Yang, Shou-Bin

    2015-06-01

    We investigated the one/two-photon fluorescence and excited state dynamics properties of two synthesized phenoxy-phthalocyanines (Pc1 and Pc2) using mild reaction coordination method. The results show that the fast decay component in the time-resolved fluorescence technique dynamics comes from the intramolecular vibrational relaxation, the slower ones from the internal conversion. Furthermore, in comparison with one-photon fluorescence spectra, the red shift of two-photon fluorescence spectra can be explained by the reabsorption effect of molecules. The samples are expected to be a potential candidate for optical applications and photodynamic therapy.

  16. Material Factors in Relation to Development Time in Liquid-Penetrant Inspection. Part 1. Material Factors

    Directory of Open Access Journals (Sweden)

    Irek P.

    2016-06-01

    Full Text Available In technical publications and European Standards the development time (i.e. time of getting out of penetrant from a discontinuity to the material surface in penetration testing is specified within the range of 10-30 minutes. In practice, however, it is seen , that it is closely connected

  17. Application of the penetration theory for gas - Liquid mass transfer without liquid bulk : Differences with system with a bulk

    NARCIS (Netherlands)

    van Elk, E. P.; Knaap, M. C.; Versteeg, G. F.

    2007-01-01

    Frequently applied micro models for gas-liquid mass transfer all assume the presence of a liquid bulk. However, some systems are characterized by the absence of a liquid bulk, a very thin layer of liquid flows over a solid surface. An example of such a process is absorption in a column equipped with

  18. Liquid Fuel Emulsion Jet-in-Crossflow Penetration and Dispersion Under High Pressure Conditions

    Science.gov (United States)

    Gomez, Guillermo Andres

    The current work focuses on the jet-in-crossflow penetration and dispersion behavior of water-in-oil emulsions in a high pressure environment. Both fuel injection strategies of using a water-in-oil emulsion and a jet-in-crossflow have demonstrated unique benefits in improving gas turbine performance from an emissions and efficiency standpoint. A jet-in-crossflow is very practical for use in gas turbine engines, rocket propulsion, and aircraft engines since it utilizes already available crossflow air to atomize fuel. Injecting water into a combustion chamber in the form of a water-in-oil emulsion allows for pollutant emissions reduction while reducing efficiency loses that may result from using a separate water or steam injection circuit. Dispersion effects on oil droplets are expected, therefore investigating the distribution of both oil and water droplets in the crossflow is an objective in this work. Understanding the synchronization and injection behavior of the two strategies is of key interest due to their combined benefits. A water-to-oil ratio and an ambient pressure parameter are developed for emulsion jet-in-crossflow trajectories. To this end, a total of 24 emulsion jet-in-crossflow tests were performed with varying ambient pressures of 2-8 atm and momentum flux ratios of 50, 85, and 120. Sobel edge filtering was applied to each averaged image obtained from a high speed video of each test case. Averaged and filtered images were used to resolve top and bottom edges of the trajectory in addition to the overall peak intensity up to 40 mm downstream of the injection point. An optimized correlation was established and found to differ from literature based correlations obtained under atmospheric pressure conditions. Overall it was found that additional parameters were not necessary for the top edge and peak intensity correlations, but a need for a unique emulsion bottom edge and width trajectory correlation was recognized. In addition to investigating emulsion

  19. Fluorescence quenching of coumarin 153 by hydroxyl-functionalized room temperature ionic liquids

    Science.gov (United States)

    Li, Shuang; Yu, Anchi; Lu, Rong

    2016-08-01

    Steady-state absorption and fluorescence as well as time-resolved fluorescence of coumarin 151 (C151) and coumarin 153 (C153) were measured in hydroxyl-functionalized ionic liquids ([HOEmim][BF4] and [HOEmim][N(CN)2]) and in nonhydroxyl-functionalized ionic liquids ([Emim][BF4] and [Emim][N(CN)2]). Both the steady-state fluorescence and time-resolved fluorescence observations reveal that hydroxyl-functionalized ionic liquid quenches the fluorescence of C153 while the nonhydroxyl-functionalized ionic liquid does not. We also measured the time-resolved fluorescence anisotropy of C151 and C153 in both [HOEmim][BF4] and [Emim][BF4]. It is found that the ratio of the rotational relaxation lifetime of C153 in [HOEmim][BF4] with respect to that in [Emim][BF4] is about 15% larger than that of C151 in [HOEmim][BF4] with respect to that in [Emim][BF4], indicating extra interaction between C153 and [HOEmim][BF4] exists except the effect of the viscosity of ionic liquid.

  20. Fluorescence Spectrum and Decay Measurement for Hsil VS Normal Cytology Differentiation in Liquid Pap Smear Supernatant

    Science.gov (United States)

    Vaitkuviene, A.; Gegzna, V.; Juodkazis, S.; Jursenas, S.; Miasojedovas, S.; Kurtinaitiene, R.; Rimiene, J.; Vaitkus, J.

    2009-06-01

    Cervical smear material contains endo and exocervical cells, mucus and inflammative, immune cells in cases of pathology. Just not destroyed keratinocytes lay on the glass for microscopy. Liquid cytology supernatant apart other diagnostics could be used for photodiagnostic. The spectroscopic parameters suitable for Normal and HSIL cytology groups supernatant differentiation are demonstrated. The dried liquid PAP supernatant fractions—sediment and liquid were investigated. Excitation and emission matrices (EEM), supernatant fluorescence decay measured under 280 nm diode short pulse excitation and fluorescence spectroscopy by excitation with 355 nm laser light were analyzed. The differences between Normal and HSIL groups were statistically proven in the certain spectral regions. Fluorescence decay peculiarities show spectral regions consisting of few fluorophores. Obtained results on fluorescence differences in Normal and HSIL groups' supernatant shows the potency of photodiagnosis application in cervical screening.

  1. Assay of tolnaftate in human skin samples after in vitro penetration studies using high performance liquid chromatography.

    Science.gov (United States)

    Kezutyte, Toma; Kornysova, Olga; Maruska, Audrius; Briedis, Vitalis

    2010-01-01

    Abstract: Tolnaftate, an antifungal of thiocarbamate class, is used topically in 1% formulations. Its penetration into skin layers is a prerequisite for tolnaftate action against dermatophytes. The aim of this work was to optimize and validate a simple, rapid, accurate and reproducible procedure for tolnaftate assay in human skin samples and to apply this procedure for in vitro tolnaftate penetration studies. High performance liquid chromatography (HPLC) method with UV detection was used to validate tolnaftate assay for linearity, specificity, accuracy, precision, limit of quantitation, limit of detection, drug extraction recovery and stability in skin extracts. In vitro tolnaftate penetration studies were carried out using flow-through diffusion cells, mounted with human skin. Epidermis and dermis, separated by heat-separation method, were extracted using ultrasonication in methanol. Linear range of the analytical procedure was within 0.6-100 pg/mL. The assay was specific, accurate (within-day and between-day recovery values were 98.2-104.2% and 98.7-101.4%, respectively) and precise (within-day and between-day imprecision was = 3.8%). Mean extraction recoveries of tolnaftate from epidermis and dermis were satisfactory and reaching 90%. In vitro skin penetration studies revealed that after application of 1% (w/w) tolnaftate solution in polyethylene glycol 400 for 24 hours, the mean amount of tolnaftate penetrating into the epidermis and dermis was 2.60 +/- 0.28 microg/cm2 and 0.92 +/- 0.12 microg/cm2, respectively. A validated reliable HPLC method could be recommended for biopharmaceutical evaluation of tolnaftate preparations and studies of pharmacokinetics in human skin after in vitro penetration studies.

  2. Fluorescence derivatization of clarithromycin for high performance liquid chromatographic determination with fluorescence detection

    OpenAIRE

    Boonleang, J.

    2007-01-01

    Clarithromycin (CAM) is a semisynthetic macrolide antibiotic whose chemical structure has no suitable chromophore for highly sensitive and accurate direct determination. The aim of this study was toderivatize CAM with fluorescence-labeling compounds capable of enhancing the sensitivity of CAM determination. Two fluorescence-labeling compounds were used in this study, 9-fluorenylmethyloxycarbonylchloride (FMOC-Cl) and 1-naphthylisocyanate (NIC), both of which gave the fluorescent derivatives o...

  3. Surfactant for dye-penetrant inspection is insensitive to liquid oxygen

    Science.gov (United States)

    1966-01-01

    LOX insensitive solvent is blended into a mixture of commercially available surfactants to clean metal surfaces which are to be investigated by the dye-penetrant method. The surfactant mixture is applied before and after application of the dye.

  4. A dual functional fluorescent probe for glioma imaging mediated by blood-brain barrier penetration and glioma cell targeting.

    Science.gov (United States)

    Ma, Hongwei; Gao, Zhiyong; Yu, Panfeng; Shen, Shun; Liu, Yongmei; Xu, Bainan

    2014-06-20

    Glioma is a huge threat for human being because it was hard to be completely removed owing to both the infiltrating growth of glioma cells and integrity of blood brain barrier. Thus effectively imaging the glioma cells may pave a way for surgical removing of glioma. In this study, a fluorescent probe, Cy3, was anchored onto the terminal of AS1411, a glioma cell targeting aptamer, and then TGN, a BBB targeting peptide, was conjugated with Cy3-AS1411 through a PEG linker. The production, named AsT, was characterized by gel electrophoresis, (1)H NMR and FTIR. In vitro cellular uptake and glioma spheroid uptake demonstrated the AsT could not only be uptaken by both glioma and endothelial cells, but also penetrate through endothelial cell monolayer and uptake by glioma spheroids. In vivo, AsT could effectively target to glioma with high intensity. In conclusion, AsT could be used as an effective glioma imaging probe.

  5. Light propagation and fluorescence quantum yields in liquid scintillators

    Science.gov (United States)

    Buck, C.; Gramlich, B.; Wagner, S.

    2015-09-01

    For the simulation of the scintillation and Cherenkov light propagation in large liquid scintillator detectors a detailed knowledge about the absorption and emission spectra of the scintillator molecules is mandatory. Furthermore reemission probabilities and quantum yields of the scintillator components influence the light propagation inside the liquid. Absorption and emission properties are presented for liquid scintillators using 2,5-Diphenyloxazole (PPO) and 4-bis-(2-Methylstyryl)benzene (bis-MSB) as primary and secondary wavelength shifter. New measurements of the quantum yields for various aromatic molecules are shown.

  6. Light propagation and fluorescence quantum yields in liquid scintillators

    CERN Document Server

    Buck, C; Wagner, S

    2015-01-01

    For the simulation of the scintillation and Cherenkov light propagation in large liquid scintillator detectors a detailed knowledge about the absorption and emission spectra of the scintillator molecules is mandatory. Furthermore reemission probabilities and quantum yields of the scintillator components influence the light propagation inside the liquid. Absorption and emission properties are presented for liquid scintillators using 2,5-Diphenyloxazole (PPO) and 4-bis-(2-Methylstyryl)benzene (bis-MSB) as primary and secondary wavelength shifter. New measurements of the quantum yields for various aromatic molecules are shown.

  7. Application of Single Molecule Fluorescence Microscopy to Characterize the Penetration of a Large Amphiphilic Molecule in the Stratum Corneum of Human Skin

    Directory of Open Access Journals (Sweden)

    Pierre Volz

    2015-03-01

    Full Text Available We report here on the application of laser-based single molecule total internal reflection fluorescence microscopy (TIRFM to study the penetration of molecules through the skin. Penetration of topically applied drug molecules is often observed to be limited by the size of the respective drug. However, the molecular mechanisms which govern the penetration of molecules through the outermost layer of the skin are still largely unknown. As a model compound we have chosen a larger amphiphilic molecule (fluorescent dye ATTO-Oxa12 with a molecular weight >700 Da that was applied to excised human skin. ATTO-Oxa12 penetrated through the stratum corneum (SC into the viable epidermis as revealed by TIRFM of cryosections. Single particle tracking of ATTO-Oxa12 within SC sheets obtained by tape stripping allowed us to gain information on the localization as well as the lateral diffusion dynamics of these molecules. ATTO-Oxa12 appeared to be highly confined in the SC lipid region between (intercellular space or close to the envelope of the corneocytes. Three main distinct confinement sizes of 52 ± 6, 118 ± 4, and 205 ± 5 nm were determined. We conclude that for this amphiphilic model compound several pathways through the skin exist.

  8. Application of single molecule fluorescence microscopy to characterize the penetration of a large amphiphilic molecule in the stratum corneum of human skin.

    Science.gov (United States)

    Volz, Pierre; Boreham, Alexander; Wolf, Alexander; Kim, Tai-Yang; Balke, Jens; Frombach, Janna; Hadam, Sabrina; Afraz, Zahra; Rancan, Fiorenza; Blume-Peytavi, Ulrike; Vogt, Annika; Alexiev, Ulrike

    2015-03-27

    We report here on the application of laser-based single molecule total internal reflection fluorescence microscopy (TIRFM) to study the penetration of molecules through the skin. Penetration of topically applied drug molecules is often observed to be limited by the size of the respective drug. However, the molecular mechanisms which govern the penetration of molecules through the outermost layer of the skin are still largely unknown. As a model compound we have chosen a larger amphiphilic molecule (fluorescent dye ATTO-Oxa12) with a molecular weight >700 Da that was applied to excised human skin. ATTO-Oxa12 penetrated through the stratum corneum (SC) into the viable epidermis as revealed by TIRFM of cryosections. Single particle tracking of ATTO-Oxa12 within SC sheets obtained by tape stripping allowed us to gain information on the localization as well as the lateral diffusion dynamics of these molecules. ATTO-Oxa12 appeared to be highly confined in the SC lipid region between (intercellular space) or close to the envelope of the corneocytes. Three main distinct confinement sizes of 52 ± 6, 118 ± 4, and 205 ± 5 nm were determined. We conclude that for this amphiphilic model compound several pathways through the skin exist.

  9. A Spectrometric Setup for Synchronous Total Internal Reflection Fluorescence Measurement at the Solid/Liquid Interface

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A spectrometric setup to perform total internal reflection fluorescence (TIRF) and synchronous TIRF measurements at solid/liquid interfaces is presented. The combination of TIRF and synchronous fluorescence was proposed to analyze simultaneously different components at interfaces. The TIRF excitation, emission and synchronous spectra of a water-soluble porphyrin were obtained from water/glass interface using this setup without the existence of a surfactant.

  10. Analysis of liquid penetration in paper structures by advanced imaging techniques

    Science.gov (United States)

    Arthur, Beth Ann

    Ink penetration in paper is influenced by the structure of the interfiber and intrafiber void spaces and the surface characteristics of the fibers. This dissertation describes new techniques to determine the influence of the fiber surfaces and the cell wall internal structure on ink spreading and penetration. The location and penetration of ink is demonstrated by optical, scanning electron, confocal laser scanning, and transmission electron (TEM) microscopy methods. Ink penetration, as determined by each of these methods, is compared. The hemicelluloses of the fiber's internal void surfaces can be determined by immunochemical labeling in conjunction with TEM imaging. It is demonstrated through the use of primary monoclonal antibodies with specificity for hemicelluloses with a secondary colloidal gold marker. This technique provides a way to visualize the location of hemicelluloses inside the cell wall and on the surfaces of nanopores. Combining paper structure with fluid spreading and wicking models can identify the influence of fiber surfaces and the cell wall on drop absorption. Ink spreading coefficients for such modeling are determined through a series of designed experiments (DoE) and comparisons to a theoretical sessile drop. Application: Microscopic techniques used to determine biological and physical locations in plants on a fibrous level also can be used to study ink diffusion, water uptake, and other characteristics of fibrous material. Key Words: Immunolableing of hemicelluloses, DoE, drop spread modeling, ink diffusion.

  11. 3-D simulation of plunging jet penetration into a denser liquid pool by the RD-MPS method

    Energy Technology Data Exchange (ETDEWEB)

    Park, Shane, E-mail: shane@knfc.co.kr [Technology and Engineering Division, KEPCO Nuclear Fuel, 242 Daeduk-daero 989beon-gil, Yuseong, Daejeon 34057 (Korea, Republic of); Park, Hyun Sun [Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, 77 Cheongnam-ro, Nam-gu, Pohang 37673, Gyeongbuk (Korea, Republic of); Jang, Byeong Il; Kim, Hong Ju [Technology and Engineering Division, KEPCO Nuclear Fuel, 242 Daeduk-daero 989beon-gil, Yuseong, Daejeon 34057 (Korea, Republic of)

    2016-04-01

    We used the rigid body dynamics coupled moving particle semi-implicit (RD-MPS) method (Park and Jeun, 2011) to simulate a plunging liquid jet penetrating into a denser liquid pool in two and three dimensions. Our improved algorithm revisited the simulation by Ikeda et al. (2001) that simulated special fuel–coolant interactions (FCI) during severe accidents in nuclear power plants when a coolant water jet was forcedly injected into a melt pool. The simulation results suggested that the coupled model improved the stability of simulation on dynamic interactions of multi-phase incompressible fluids. Phenomenologically, the 3-D simulation for the plunging water jet in a confined geometry showed better agreement with experimental results than the 2-D simulation did.

  12. Fluorescence derivatization of clarithromycin for high performance liquid chromatographic determination with fluorescence detection

    Directory of Open Access Journals (Sweden)

    Boonleang, J.

    2007-03-01

    Full Text Available Clarithromycin (CAM is a semisynthetic macrolide antibiotic whose chemical structure has no suitable chromophore for highly sensitive and accurate direct determination. The aim of this study was toderivatize CAM with fluorescence-labeling compounds capable of enhancing the sensitivity of CAM determination. Two fluorescence-labeling compounds were used in this study, 9-fluorenylmethyloxycarbonylchloride (FMOC-Cl and 1-naphthylisocyanate (NIC, both of which gave the fluorescent derivatives of CAM with approximately the same fluorescence intensity. The derivatization reactions in the concentration rangestudied (0.1-2.4 μg/ml were reproducible with coefficient of variation of less than 6.01% and the fluorescence responses were linearly proportional to CAM concentration with r2 of greater than 0.99. The reaction of CAM with FMOC-Cl optimally occurred in a solvent mixture of acetonitrile and phosphate buffer pH 7.5(4:1 volume ratio at 40oC for 40 min. The optimum derivatization reaction of CAM with NIC took place in acetonitrile with triethylamine as catalyst at 30oC for 60 min. It was mild and quantitative giving CAM-NICfluorescent derivative, which is more stable at room temperature than CAM-FMOC derivative. This derivatization should, therefore, be more applicable for highly sensitive CAM determination especially for thestudy involving the analysis of several samples.

  13. Polarized fluorescence measurements of orientational order in a uniaxial liquid crystal

    DEFF Research Database (Denmark)

    Chapoy, L. Lawrence; DuPré, Donald B.

    1979-01-01

    The second and fourth orientational order parameters and , have been measured throughout the liquid crystalline phase of p-methoxybenzylidene-p[prime]-n-butylaniline (MBBA) using small quantities of a fluorescent probe. Complications of rotational Brownian motion and the intramolecular transfer...... of excitation energy were considered in the analysis. The results are in agreement with previous Raman measurements on the doped liquid crystal. The Journal of Chemical Physics is copyrighted by The American Institute of Physics....

  14. Breakup of metal jets penetrating a volatile liquid. Final report, October 1, 1991--February 28, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, J.P.

    1995-07-01

    In a loss of coolant accident, the core may become uncovered, causing the fuel pins to melt. The molten fuel would pour onto the plenum and collect on the reactor pressure vessel (RPV) lower head. The RPV internal structure includes one or more perforated plates in the lower plenum which would divide the molten fuel into small diameter streams or jets, which would break up as they penetrate the coolant in the lower plenum. The breakup of these jets would occur in two phases, each dominated by a distinct fragmentation mechanism. As a fuel jet first penetrates the coolant, a stagnation flow develops at its leading edge, causing the column to spread radially and eject molten fuel into the coolant. The jet fluid in the column is fragmented by pressure fluctuations due to the jet/ambient fluid relative motion, so that a steady jet is reduced to a field of falling drops below a critical depth called the breakup length. The present work includes analyses yielding simple correlations for jet breakup length and jet leading edge penetration.

  15. Ultrasound-assisted dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-fluorescence detection for sensitive determination of biogenic amines in rice wine samples.

    Science.gov (United States)

    Huang, Ke-Jing; Wei, Cai-Yun; Liu, Wei-Li; Xie, Wan-Zhen; Zhang, Jun-Feng; Wang, Wei

    2009-09-18

    Ultrasound-assisted dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography-fluorescence detection was used for the extraction and determination of three biogenic amines including octopamine, tyramine and phenethylamine in rice wine samples. Fluorescence probe 2,6-dimethyl-4-quinolinecarboxylic acid N-hydroxysuccinimide ester was applied for derivatization of biogenic amines. Acetonitrile and 1-octanol were used as disperser solvent and extraction solvent, respectively. Extraction conditions including the type of extraction solvent, the volume of extraction solvent, ultrasonication time and centrifuging time were optimized. After extraction and centrifuging, analyte was injected rapidly into high-performance liquid chromatography and then detected with fluorescence. The calibration graph of the proposed method was linear in the range of 5-500 microg mL(-1) (octopamine and tyramine) and 0.025-2.5 microg mL(-1) (phenethylamine). The relative standard deviations were 2.4-3.2% (n=6) and the limits of detection were in the range of 0.02-5 ng mL(-1). The method was applied to analyze the rice wine samples and spiked recoveries in the range of 95.42-104.56% were obtained. The results showed that ultrasound-assisted dispersive liquid-liquid microextraction was a very simple, rapid, sensitive and efficient analytical method for the determination of trace amount of biogenic amines.

  16. Transdermal penetration of topically applied fluorescent dyes with and without the influence of Water Filtered Infrared-A-Radiation

    OpenAIRE

    Grone, Diego

    2010-01-01

    Optical methods were used to investigate the influence of water filtered infrared A radiation (wIRA) on the dermatopharmacokinetics of topically applied substances. The penetration profiles of the hydrophilic dye fluoresceine and the lipophilic dye curcumin in a standard o/w emulsion were determined by tape stripping, in combination with spectroscopic measurements. Additionally, the penetration was investigated in vivo by laser scanning microscopy. Three different protocols (mode A-C) were us...

  17. Stable Dispersed MoS2 Nanosheets in Liquid Lubricant with Enhanced Rate of Penetration for Directional Well

    Directory of Open Access Journals (Sweden)

    Fuwei Lu

    2016-01-01

    Full Text Available MoS2 nanosheets of approx. 100 nm were synthesized by a reverse microemulsion route firstly, then were annealed under nitrogen atmosphere, and were finally modified with 1-dodecanethiol. The prepared MoS2 nanosheets were characterized by XRD, TEM, FTIR, and so forth. Experimental results show that MoS2 nanosheets with the typical layer structure can be easily dispersed in oil lubricant for rate of penetration (ROP increasing in directional well. The ROP of directional well with the prepared liquid lubricant was 52.9% higher than that of the similar directional wells at least, and the drilling velocity was increased 20% while the total proportion of lubricant in drilling fluid was 1.5%.

  18. Ionic liquids for improving the extraction of NSAIDs in water samples using dispersive liquid-liquid microextraction by high performance liquid chromatography-diode array-fluorescence detection.

    Science.gov (United States)

    Toledo-Neira, Carla; Álvarez-Lueje, Alejandro

    2015-03-01

    A rapid, sensitive and efficient analytical method based on the use of ionic liquids for determination of non-steroidal anti-inflammatory drugs (NSAIDs) in water samples was developed. High-performance liquid chromatography equipped with a diode array and fluorescence detector was used for quantification of ketoprofen, ibuprofen and diclofenac in tap and river water samples. This new method relies on the use of two ionic liquids with multiple functionalities: one functions as an extraction solvent (1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), and the other changes the polarity in the aqueous medium (1-butyl-3-methylimidazolium tetrafluoroborate, ([BMIM][BF4]). Factors such as the type and volume of the ILs and dispersive solvent, sample volume, and centrifugation time were investigated and optimized. The optimized method exhibited good precision, with relative standard deviation values between 2% and 3%, for the three NSAIDs. Limits of detection achieved for all of the analytes were between 17 and 95 ng mL(-1), and the recoveries ranged from 89% to 103%. Furthermore, the enrichment factors ranged from 49 to 57. The proposed method was successfully applied to the analysis of NSAIDs in tap and river water samples.

  19. A new method for measuring concentration of a fluorescent tracer in bubbly gas-liquid flows

    Science.gov (United States)

    Moghaddas, J. S.; Trägårdh, C.; Kovacs, T.; Östergren, K.

    2002-06-01

    A new experimental model, the two-tracer method (TTM), based on the planar laser-induced fluorescence technique (PLIF), is presented for the measurement of the local concentration of a fluorescent tracer in the liquid phase of a bubbly two-phase system. Light scattering and shading effects due to the bubbles were compensated for using the new model. The TTM results were found to give more accurate predictions of the local concentration than the normal PLIF method in a bubbly two-phase system.

  20. Measurement of Flow Velocity and Inference of Liquid Viscosity in a Microfluidic Channel by Fluorescence Photobleaching

    DEFF Research Database (Denmark)

    Carroll, Nick J.; Jensen, Kaare Hartvig; Parsa, Shima

    2014-01-01

    We present a simple, noninvasive method for simultaneous measurement of flow velocity and inference of liquid viscosity in a microfluidic channel. We track the dynamics of a sharp front of photobleached fluorescent dye using a confocal microscope and measure the intensity at a single point...... downstream of the initial front position. We fit an exact solution of the advection diffusion equation to the fluorescence intensity recovery curve to determine the average flow velocity and the diffusion coefficient of the tracer dye. The dye diffusivity is correlated to solute concentration to infer...

  1. Experimental evaluation and modeling of liquid jet penetration to estimate droplet size in a three-phase riser reactor

    Institute of Scientific and Technical Information of China (English)

    Ali Akbar Jamali; Shahrokh Shahhosseini; Yaghoub Behjat

    2016-01-01

    In this work, the effects of injecting an evaporating liquid jet into solid–gas flow are experimentally investigated. A new model (SHED model) and a supplementary model (spray model) have also been proposed to investigate some flow-field characteristics in three-phase fluidized bed with the mean relative error 4.3%between model and measured results. Some experiments were conducted to study the influences of flow-field parameters such as liquid volumetric flow rate, injection velocity, jet angle and gas superficial velocity as well as solid mass flux on the jet penetration depth (JPD). In addition, independent variables were experimentally employed to propose two empirical correlations for JPD by using multiple regression method and spray cone angle (SCA) by using dimensional analysis technique. The mean relative errors between the JPD and SCA correlations versus ex-perimental data were 7.5%and 3.9%, respectively. In addition, in order to identify the variable effect, a parametric study was carried out. Applying the proposed model can avoid direct use of expensive devices to measure JPD and to predict droplet size.

  2. Ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction for the separation and determination of estrogens in water samples by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Zhang, Rui; Wang, Chuanliu; Yue, Qiaohong; Zhou, Tiecheng; Li, Na; Zhang, Hanqi; Hao, Xiaoke

    2014-11-01

    An ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction method was proposed for the extraction and concentration of 17-α-estradiol, 17-β-estradiol-benzoate, and quinestrol in environmental water samples by high-performance liquid chromatography with fluorescence detection. 1-Hexyl-3-methylimidazolium tetrafluoroborate was applied as foaming agent in the foam flotation process and dispersive solvent in microextraction. The introduction of the ion-pairing and salting-out agent NH4 PF6 was beneficial to the improvement of recoveries for the hydrophobic ionic liquid phase and analytes. Parameters of the proposed method including concentration of 1-hexyl-3-methylimidazolium tetrafluoroborate, flow rate of carrier gas, floatation time, types and concentration of ionic liquids, salt concentration in samples, extraction time, and centrifugation time were evaluated. The recoveries were between 98 and 105% with relative standard deviations lower than 7% for lake water and well water samples. The isolation of the target compounds from the water was found to be efficient, and the enrichment factors ranged from 4445 to 4632. This developing method is free of volatile organic solvents compared with regular extraction. Based on the unique properties of ionic liquids, the application of foam floatation, and dispersive liquid-liquid microextraction was widened.

  3. Functional properties of fluorescent poly(amidoamine) dendrimers in nematic liquid crystalline media

    Science.gov (United States)

    Grabchev, Ivo; Sali, Seher; Chovelon, Jean-Marc

    2006-05-01

    The effectiveness of poly(amidoamine) dendrimers from zero generation as a fluorescent guest for liquid crystal displays of the 'guest-host' type is discussed on the basis of their absorption and fluorescent properties. It has been shown that the dendrimers at concentration of 0.3 wt% do not destabilize the orientation of the liquid crystal matrix. The orientation order parameters SA and SF depends on the nature of the substituent at C-4 position of the 1,8-naphthalimide. The effect that poly(amidoamine) dendrimers have upon the phase transition temperature and the electro-optical properties of the LC/dendrimer mixtures has been also presented. All investigations reported have been carried out in surface stabilized display cells.

  4. Serum Protein Profile Study of Clinical Samples Using High Performance Liquid Chromatography-Laser Induced Fluorescence

    DEFF Research Database (Denmark)

    Karemore, Gopal Raghunath; Ukendt, Sujatha; Rai, Lavanya

    2009-01-01

    The serum protein profiles of normal subjects, patients diagnosed with cervical cancer, and oral cancer were recorded using High Performance Liquid Chromatography combined with Laser Induced Fluorescence detection (HPLC-LIF). Serum protein profiles of the above three classes were tested for estab......The serum protein profiles of normal subjects, patients diagnosed with cervical cancer, and oral cancer were recorded using High Performance Liquid Chromatography combined with Laser Induced Fluorescence detection (HPLC-LIF). Serum protein profiles of the above three classes were tested...... for establishing the ability of HPLC-LIF protein profiling technique for discrimination, using hard clustering and Fuzzy clustering methods. The clustering algorithms have quite successfully classified the profiles as belonging to normal, cancer of cervix, and oral cancer conditions....

  5. Fluorescence spectroscopic analysis of the interaction of papain with ionic liquids.

    Science.gov (United States)

    Fan, Yunchang; Yan, Jinlong; Zhang, Sheli; Li, Junhai; Chen, Dong; Duan, Peigao

    2012-10-01

    The interaction between papain and two typical ionic liquids (ILs), 1-octyl-3-methylimidazolium chloride ([C(8)mim]Cl) and 1-butyl-3-methylimidazolium chloride ([C(4)mim]Cl), was investigated by using fluorescence spectroscopy technique at a pH value of 7.4. The results suggested that ILs could quench the intrinsic fluorescence of papain probably via a static quenching mechanism. The binding constants were determined by employing the fluorescence quenching method. They were very small compared with that of volatile organic solvents, indicating that only very weak interaction between ILs and papain existed. The Gibbs free energy change (∆G), enthalpy change (∆H), and entropy change (∆S) during the interaction of papain and ILs were estimated. Negative values of these parameters indicated that the interaction between ILs and papain was a spontaneous process, also implying that hydrogen bonding and van der Waals forces played important roles in the interaction processes.

  6. Determination of eight fluoroquinolones in groundwater samples with ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction prior to high-performance liquid chromatography and fluorescence detection.

    Science.gov (United States)

    Vázquez, M M Parrilla; Vázquez, P Parrilla; Galera, M Martínez; García, M D Gil

    2012-10-20

    An ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction (US-IL-DLLME) procedure was developed for the extraction of eight fluoroquinolones (marbofloxacin, norfloxacin, ciprofloxacin, lomefloxacin, danofloxacin, enrofloxacin, oxolinic acid and nalidixic acid) in groundwater, using high-performance liquid chromatography with fluorescence detection (HPLC-FD). The ultrasound-assisted process was applied to accelerate the formation of the fine cloudy solution using a small volume of disperser solvent (0.4 mL of methanol), which increased the extraction efficiency and reduced the equilibrium time. For the DLLME procedure, the IL 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)MIM] [PF(6)]) and methanol (MeOH) were used as extraction and disperser solvent, respectively. By comparing [C(8)MIM] [PF(6)] with 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM] [PF(6)]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)MIM] [PF(6)]) as extraction solvents, it was observed that when using [C(8)MIM] [PF(6)] the cloudy solution was formed more readily than when using [C(6)MIM] [PF(6)] or [C(4)MIM] [PF(6)]. The factors affecting the extraction efficiency, such as the type and volume of ionic liquid, type and volume of disperser solvent, cooling in ice-water, sonication time, centrifuging time, sample pH and ionic strength, were optimised. A slight increase in the recoveries of fluoroquinolones was observed when an ice-water bath extraction step was included in the analytical procedure (85-107%) compared to those obtained without this step (83-96%). Under the optimum conditions, linearity of the method was observed over the range 10-300 ng L(-1) with correlation coefficient >0.9981. The proposed method has been found to have excellent sensitivity with limit of detection between 0.8 and 13 ng L(-1) and precision with relative standard deviation values between 4.8 and 9.4% (RSD, n=5). Good enrichment factors (122-205) and recoveries (85

  7. Quantitative determination of paralytic shellfish poisoning toxins in shellfish using prechromatography oxidation and liquid chromatography with fluorescence detection: interlaboratory study

    NARCIS (Netherlands)

    Lawrence, J.F.; Niedzwiadek, B.; Menard, C.; Wezenbeek, P.

    2004-01-01

    An interlaboratory study was conducted for the determination of paralytic shellfish poisoning (PSP) toxins in shellfish. The method used liquid chromatography with fluorescence detection after prechromatographic oxidation of the toxins with hydrogen peroxide and periodate. The PSP toxins studied

  8. Microstructure-Enhanced Liquid–Liquid Extraction in a Real-Time Fluorescence Detection Microfluidic Chip

    Directory of Open Access Journals (Sweden)

    Penghui Xiong

    2016-03-01

    Full Text Available Microfluidic system is widely employed in the detection of environmental contaminants and biological specimens. One of the critical issues which limits the applications of microfluidic chips is the limit of detection of trace specimens. Liquid–liquid extraction is of great importance in the preprocessing in microfluidic devices. In this paper, we developed a real-time fluorescence detection microfluidic chip combined with a microstructure-enhanced liquid–liquid laminar extraction technique, which concentrated the trace compound and realized real-time monitoring. Auxiliary microstructures integrated in the microfluidic chip were applied to increase the extraction efficiency, which was proved by the FEM (finite element method simulation as well. A common fluorescence probe, Rhodamine 6G (Rh6g, was used in the experiment to demonstrate the performance of the microfluidic system. It revealed that the liquid–liquid laminar extraction combined with auxiliary microstructures of a cross shape was an effective method for enrichment. The efficiency of microstructure-enhanced liquid–liquid extraction was increased by 350% compared to the traditional laminar flow extraction.

  9. Effects of imidazolium room temperature ionic liquids on the fluorescent properties of norfloxacin.

    Science.gov (United States)

    Zou, Yujie; Wang, Huili; Wang, Wenwei; Ma, Meiping; Wang, Ping; Wang, Chengjun; Wang, Xuedong

    2012-01-01

    The effects of 12 imidazolium room temperature ionic liquids (RTILs), including [C(n)mim]BF4, [C(n)mim]PF6, and [C(n)mim]Br (n = 4, 6, 8, 10), on the fluorescent properties of norfloxacin were examined. The fluorescence intensity of norfloxacin at 0.1 mg/L in methanol significantly increased with the addition of [C(n)mim]BF4 and [C(n)mim]PF6 into the solvent at 0.1-15.0%. The sensitizing effect may result from the higher viscosity of the RTILs-methanol mixture solvent than that of the methanol itself. However, the quenching effect on fluorescence of norfloxacin was observed in [C(n)mim]Br-methanol solvent. The fluorescence intensities of norfloxacin decreased with an increase in the alkyl chain length of the alkyl substituents of the imidazolium ring of RTILs. The main interaction between the RTILs and norfloxacin is not by hydrogen bonding. The fact, that some RTILs can significantly sensitize fluorescence of norfloxacin, indicates that RTILs could be a group of promising solvents for development of sensitive spectrofluorimetric methods for determination of norfloxacin at ultra-trace levels in environmental samples. Copyright © 2011 John Wiley & Sons, Ltd.

  10. Penetration of short fluorescence-labeled peptides into the nucleus in HeLa cells and in vitro specific interaction of the peptides with deoxyribooligonucleotides and DNA.

    Science.gov (United States)

    Fedoreyeva, L I; Kireev, I I; Khavinson, V Kh; Vanyushin, B F

    2011-11-01

    Marked fluorescence in cytoplasm, nucleus, and nucleolus was observed in HeLa cells after incubation with each of several fluorescein isothiocyanate-labeled peptides (epithalon, Ala-Glu-Asp-Gly; pinealon, Glu-Asp-Arg; testagen, Lys-Glu-Asp-Gly). This means that short biologically active peptides are able to penetrate into an animal cell and its nucleus and, in principle they may interact with various components of cytoplasm and nucleus including DNA and RNA. It was established that various initial (intact) peptides differently affect the fluorescence of the 5,6-carboxyfluorescein-labeled deoxyribooligonucleotides and DNA-ethidium bromide complexes. The Stern-Volmer constants characterizing the degree of fluorescence quenching of various single- and double-stranded fluorescence-labeled deoxyribooligonucleotides with short peptides used were different depending on the peptide primary structures. This indicates the specific interaction between short biologically active peptides and nucleic acid structures. On binding to them, the peptides discriminate between different nucleotide sequences and recognize even their cytosine methylation status. Judging from corresponding constants of the fluorescence quenching, the epithalon, pinealon, and bronchogen (Ala-Glu-Asp-Leu) bind preferentially with deoxyribooligonucleotides containing CNG sequence (CNG sites are targets for cytosine DNA methylation in eukaryotes). Epithalon, testagen, and pinealon seem to preferentially bind with CAG- but bronchogen with CTG-containing sequences. The site-specific interactions of peptides with DNA can control epigenetically the cell genetic functions, and they seem to play an important role in regulation of gene activity even at the earliest stages of life origin and in evolution.

  11. Simultaneous determination of airborne carbamates in workplace by high performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Li, Hong-Ping; Li, Jen-Hou; Li, Gwo-Chen; Jen, Jen-Fon

    2004-06-17

    A high performance liquid chromatography with fluorescence (HPLC-F) detector was examined to simultaneous determination of airborne carbamates in the workplace of manufactory. The OVS-2 air sampling tube filled with glass fiber filter or quartz fiber and combined filter/XAD-2 were evaluated to collect nine commonly used carbamates (Carbofuran, Isoprocarb, Methomyl, Metolcarb, Thiodicarb, Carbaryl, Oxamyl, Methiocarb, and Prpoxur) from the air of manufactory in high humidity country. After being extracted with acetonitrile from sampling tubes, the carbamates were determined by high performance liquid chromatography with fluorescence detection posterior to on-line derivatization. The collection of carbamates and the recovery of extraction from glass wool fiber in several concentration levels, and from quartz filter were evaluated. The storage stability of carbamates was also tested. Results indicated that the HPLC-fluorescence method offers satisfactory resolution and sensitivity in carbamate analysis. With the glass fiber filter and combined filter/XAD-2, the Carbofuran, Isoprocarb, Methomyl, Metolcarb, and Thiodicarb were stable for a 28-day storage test, Carbaryl and Oxamyl for 14 days, and Methiocarb and Prpoxur for 7 days. All of these pesticides were with detection limit of 3mugm(-3). It is suited for environmental monitoring. The airborne carbamates in different areas of the manufactory were measured.

  12. Low cost methodology for estrogens monitoring in water samples using dispersive liquid-liquid microextraction and HPLC with fluorescence detection.

    Science.gov (United States)

    Lima, Diana L D; Silva, Carla Patrícia; Otero, Marta; Esteves, Valdemar I

    2013-10-15

    A new low cost methodology for estrogens' analysis in water samples was developed in this work. Based on dispersive liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection, the developed method is fast, cheap, easy-to-use, uses low volumes of organic solvents and has the possibility of a large number of samples to be extracted in parallel. Under optimum conditions (sample volume: 8 mL; extraction solvent: 200 μL of chlorobenzene; dispersive solvent: 2000 μL of acetone), the enrichment factor and extraction recoveries were 145 and 72% for 17β-estradiol (E2) and 178 and 89% for 17α-ethinylestradiol (EE2), respectively. Limits of detection of 2.0 ng L(-1) for E2 and 6.5 ng L(-1) for EE2 were achieved, allowing the detection and quantification of these compounds in surface and waste water samples with concentrations from 12 to 32 ng L(-1) for E2 and from 11 to 18 ng L(-1) for EE2. Also, recovery tests were performed to evaluate possible matrix effects. Recoveries between 98% and 106% were obtained using humic acids (HA) to simulate the effect of organic matter, and between 86% and 120% in real water samples.

  13. Liquid chromatographic determination of beta-cyclodextrin derivatives based on fluorescence enhancement after inclusion complexation.

    Science.gov (United States)

    Reeuwijk, H J; Irth, H; Tjaden, U R; Merkus, F W; van der Greef, J

    1993-04-21

    A liquid chromatographic method using fluorescence detection for the determination of beta-cyclodextrin (beta CD) and its derivatives is presented. The chromatographic system is based on size-exclusion chromatography with the addition of the fluorophoric compound 1-naphthol to the mobile phase. Detection is based on fluorescence enhancement caused by the formation of inclusion complexes. By incorporating 10(-4) M 1-naphthol in the mobile phase, detection limits of 90, 27, 370 and 37 pmol were obtained for beta CD, hydroxypropyl-beta CD, trimethyl-beta CD and dimethyl-beta CD, respectively. The method was applied to the determination of dimethyl-beta CD in urine: the minimum detectable concentration was 0.2 microgram/ml after preconcentration of 10 ml of urine.

  14. Rapid determination of ampicillin in bovine milk by liquid chromatography with fluorescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Ang, C.Y.W.; Luo, Wenhong [National Center for Toxicological Research, Jefferson, AR (United States)

    1997-01-01

    A rapid and sensitive liquid chromatographic (LC) method was developed for the determination of ampicillin residues in raw bovine milk, processed skim milk, and pasteurized, homogenized whole milk with vitamin D. Milk samples were deproteinized with trichloroacetic acid (TCA) and acetonictrile. After centrifugation, the clear supernatant was reacted with formaldehyde and TCA under heat. The major fluorescent derivative of ampicillin was then determined by reversed-phase LC with fluorescence detection. Average recoveries of ampicillin fortified at 5, 10, and 20 ppb (ng/mL) were all >85% with coefficients of variation <10%. Limits of detection ranged from 0.31 to 0.51 ppb and limits of quantitation, from 0.66 to 1.2 ppb. After appropriate validation, this method should be suitable for rapid analysis of milk for ampicillin residues at the tolerance level of 10 ppb. 16 refs., 4 figs., 3 tabs.

  15. Ionic liquid as a mobile phase additive in high-performance liquid chromatography for the simultaneous determination of eleven fluorescent whitening agents in paper materials.

    Science.gov (United States)

    Wang, Qing; Chen, Xianbo; Qiu, Bin; Zhou, Liang; Zhang, Hui; Xie, Juan; Luo, Yan; Wang, Bin

    2016-04-01

    In the present study, 11 4,4'-diaminostilbene-2,2'-disulfonic acid based fluorescent whitening agents with different numbers of sulfonic acid groups were separated by using an ionic liquid as a mobile phase additive in high-performance liquid chromatography with fluorescence detection. The effects of ionic liquid concentration, pH of mobile phase B, and composition of mobile phase A on the separation of fluorescent whitening agents were systematically investigated. The ionic liquid tetrabutylammonium tetrafluoroborate is superior to tetrabutylammomnium bromide for the separation of the fluorescent whitening agents. The optimal separation conditions were an ionic liquid concentration at 8 mM and the pH of mobile phase B at 8.5 with methanol as mobile phase A. The established method exhibited low limits of detection (0.04-0.07 ng/mL) and wide linearity ranges (0.30-20 ng/mL) with high linear correlation coefficients from 0.9994 to 0.9998. The optimized procedure was applied to analyze target analytes in paper samples with satisfactory results. Eleven target analytes were quantified, and the recoveries of spiked paper samples were in the range of 85-105% with the relative standard deviations from 2.1 to 5.1%. The obtained results indicated that the method was efficient for detection of 11 fluorescent whitening agents.

  16. Rapid determination of succinylcholine in human plasma by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Lagerwerf, A J; Vanlinthout, L E; Vree, T B

    1991-10-04

    A high-performance liquid chromatographic method with fluorometric detection has been developed for the determination of succinylcholine in human plasma. Succinylcholine shows fluorescence at 282 nm with an excitation at 257 nm. The assay is sensitive, reproducible and linear for concentrations ranging from 100 ng/ml to 100 micrograms/ml of succinylcholine. In a pilot study the plasma concentration-time curve showed a triphasic elimination, with half-lives of 0.4, 1.2 and 8 min, respectively. In a clinical setting, drugs commonly administered during anaesthesia did not interfere with the assay. This method provides a simple and time-saving alternative to existing methods.

  17. Evaluation of sphingomyelin, cholester, and phosphatidylcholine-based immobilized artificial membrane liquid chromatography to predict drug penetration across the blood-brain barrier.

    Science.gov (United States)

    De Vrieze, Mike; Verzele, Dieter; Szucs, Roman; Sandra, Pat; Lynen, Frédéric

    2014-10-01

    Over the past decades, several in vitro methods have been tested for their ability to predict drug penetration across the blood-brain barrier. So far, in high-performance liquid chromatography, most attention has been paid to micellar liquid chromatography and immobilized artificial membrane (IAM) LC. IAMLC has been described as a viable approach, since the stationary phase emulates the lipid environment of a cell membrane. However, research in IAMLC has almost exclusively been limited to phosphatidylcholine (PC)-based stationary phases, even though PC is only one of the lipids present in cell membranes. In this article, sphingomyelin and cholester stationary phases have been tested for the first time towards their ability to predict drug penetration across the blood-brain barrier. Upon comparison with the PC stationary phase, the sphingomyelin- and cholester-based columns depict similar predictive performance. Combining data from the different stationary phases did not lead to improvements of the models.

  18. Fluorescence resonance-energy-transfer in systems of Rhodamine 6G with ionic liquid showing emissions by excitation at wide wavelength areas.

    Science.gov (United States)

    Izawa, Hironori; Wakizono, Satoshi; Kadokawa, Jun-ichi

    2010-09-14

    Fluorescence resonance-energy-transfer occurred in a solution of Rhodamine 6G in an ionic liquid by excitation at wide wavelength areas owing to specific fluorescent behavior of the ionic liquid to show emissions at each excitation wavelength, which was also observed in the guar gum/ionic liquid gel material containing Rhodamine 6G.

  19. Genetic Screening for Bacterial Mutants in Liquid Growth Media By Fluorescence-Activated Cell Sorting

    Science.gov (United States)

    Abuaita, Basel H.; Withey, Jeffrey H.

    2010-01-01

    Many bacterial pathogens have defined in vitro virulence inducing conditions in liquid media which lead to production of virulence factors important during an infection. Identifying mutants that no longer respond to virulence inducing conditions will increase our understanding of bacterial pathogenesis. However, traditional genetic screens require growth on solid media. Bacteria in a single colony are in every phase of the growth curve, which complicates the analysis and make screens for growth phase-specific mutants problematic. Here, we utilize fluorescence-activated cell sorting in conjunction with random transposon mutagenesis to isolate bacteria grown in liquid media that are defective in virulence activation. This method permits analysis of an entire bacterial population in real time and selection of individual bacterial mutants with the desired gene expression profile at any time point after induction. We have used this method to identify Vibrio cholerae mutants defective in virulence induction. PMID:21094189

  20. Mapping Liquid-liquid protein phase separation using ultra-fast-scanning fluorescence correlation spectroscopy

    Science.gov (United States)

    Wei, Ming-Tzo; Elbaum-Garfinkle, Shana; Arnold, Craig B.; Priestley, Rodney D.; Brangwynne, Clifford P.

    Intrinsically disordered proteins (IDPs) are an understudied class of proteins that play important roles in a wide variety of biological processes in cells. We've previously shown that the C. elegans IDP LAF-1 phase separates into P granule-like droplets in vitro. However, the physics of the condensed phase remains poorly understood. Here, we use a novel technique, ultra-fast-scanning fluorescence correlation spectroscopy, to study the nano-scale rheological properties of LAF-1 droplets. Ultra-fast-scanning FCS uses a tunable acoustic gradient index of refraction (TAG) lens with an oil immersion objective to control axial movement of the focal point over a length of several micrometers at frequencies of 70kHz. Using ultra-fast-scanning FCS allows for the accurate determination of molecular concentrations and their diffusion coefficient, when the particle is passing through an excitation volume. Our work reveals an asymmetric LAF-1 phase diagram, and demonstrates that LAF-1 droplets are purely viscous phases which are highly tunable by salt concentration.

  1. Quantitative fluorescence spectroscopy and flow cytometry analyses of cell-penetrating peptides internalization pathways: optimization, pitfalls, comparison with mass spectrometry quantification

    Science.gov (United States)

    Illien, Françoise; Rodriguez, Nicolas; Amoura, Mehdi; Joliot, Alain; Pallerla, Manjula; Cribier, Sophie; Burlina, Fabienne; Sagan, Sandrine

    2016-11-01

    The mechanism of cell-penetrating peptides entry into cells is unclear, preventing the development of more efficient vectors for biotechnological or therapeutic purposes. Here, we developed a protocol relying on fluorometry to distinguish endocytosis from direct membrane translocation, using Penetratin, TAT and R9. The quantities of internalized CPPs measured by fluorometry in cell lysates converge with those obtained by our previously reported mass spectrometry quantification method. By contrast, flow cytometry quantification faces several limitations due to fluorescence quenching processes that depend on the cell line and occur at peptide/cell ratio >6.108 for CF-Penetratin. The analysis of cellular internalization of a doubly labeled fluorescent and biotinylated Penetratin analogue by the two independent techniques, fluorometry and mass spectrometry, gave consistent results at the quantitative and qualitative levels. Both techniques revealed the use of two alternative translocation and endocytosis pathways, whose relative efficacy depends on cell-surface sugars and peptide concentration. We confirmed that Penetratin translocates at low concentration and uses endocytosis at high μM concentrations. We further demonstrate that the hydrophobic/hydrophilic nature of the N-terminal extremity impacts on the internalization efficiency of CPPs. We expect these results and the associated protocols to help unraveling the translocation pathway to the cytosol of cells.

  2. Determination of aflatoxin B1 in cereals by homogeneous liquid-liquid extraction coupled to high performance liquid chromatography-fluorescence detection.

    Science.gov (United States)

    Sheijooni-Fumani, Neda; Hassan, Jalal; Yousefi, Seyed R

    2011-06-01

    A simple and rapid method based on homogeneous liquid-liquid extraction coupled to HPLC with fluorescence detection was developed for the determination of aflatoxin B1 (AFB1) in the rice and grain samples after post-column derivatization. The proposed method eliminated the use of immunoaffinity columns for clean-up in the determination of AFB1. The parameters affecting recovery and preconcentration such as type and volume of organic solvent, volume ratio of water/methanol, concentration of phase separator reagent and extraction time were optimized. Under the optimized conditions, the calibration graph was linear in the concentration range of 0.01-1.0 ng/g with the detection limit of 0.003 ng/g. This method was successfully applied for the analysis of AFB1 in different cereal samples.

  3. Polarized fluorescent emission in uniaxial liquid crystals. The effect of intramolecular energy transfer and rotational Brownian motion on measurements of the orientational distribution function

    DEFF Research Database (Denmark)

    Chapoy, Larry Lawrence; DuPré, Donald B.

    1978-01-01

    An expression is derived for the anisotropic fluorescent emission in uniaxial liquid crystals where fluorescent sites governed by an initial nonrandom distribution of orientations are subject to rotational Brownian motion. The possibility of nonparallelism of absorption and emission oscillators...

  4. Rapid determination of trace thiabendazole in apple juice utilizing dispersive liquid-liquid microextraction combined with fluorescence spectrophotometry.

    Science.gov (United States)

    Li, Wei; Wang, Yuning; Huang, Limin; Wu, Ting; Hu, Huilian; Du, Yiping

    2015-09-01

    Food safety has become a large concern and prompts an urgent need for the development of rapid, simple and sensitive analytical methods that can monitor pesticide residues in foods. This study aimed to provide a method for quantitative determination of trace thiabendazole in apple juice. Due to its high sensitivity and selectivity, fluorescence spectrophotometry was utilized as a front end to dispersive liquid-liquid microextraction (DLLME). The experimental parameters that influenced the extraction were systematically investigated. Under optimum conditions, the whole procedure, including DLLME and analysis of one sample, was carried out within 5 min, and linearity was found in the 5-50 µg/L range with a correlation coefficient (r) of 0.9987. The limit of detection value was 2.2 µg/L. Good reproducibility was achieved based with a less than 4.5% relative standard deviation (RSD) for five replicates at different sample concentrations. This method was shown to be suitable for rapid and sensitive quantification of thiabendazole in apple juice.

  5. Determination of lead in environmental waters with dispersive liquid-liquid microextraction prior to atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Qingxiang, E-mail: zhouqx@cup.edu.cn [School of Chemistry and Environmental Sciences, Henan Normal University, Henan Key Laboratory for Environmental Pollution Control, Key Laboratory for Yellow River and Huaihe River Water Environment and Pollution Control, Ministry of Education, Xinxiang 453007 (China); State Laboratory of Petroleum Resource and Prospecting, College of Geosciences, China University of Petroleum Beijing, Beijing 102249 (China); Zhao, Na [State Laboratory of Petroleum Resource and Prospecting, College of Geosciences, China University of Petroleum Beijing, Beijing 102249 (China); Xie, Guohong [College of Resources and Environment, Henan Institute of Science and Technology, Xinxiang 453003 (China)

    2011-05-15

    This paper established a new, rapid and sensitive method for the determination of lead in water samples preconcentrated by dispersive liquid-liquid microextraction (DLLME) prior to atomic fluorescence spectrometry. Dithizone was used as the chelating agent. In the DLLME procedure, lead formed lead-dithizone complex and migrated into the carbon tetrachloride micro-droplets. Important factors that would affect the extraction efficiency had been investigated including the kind and volume of extraction solvent and dispersive solvent, sample pH, the amount of chelating agent, extraction time and centrifugation time. The results showed that the coexisting ions containing in water samples had no obvious negative effect on the determination of lead. The experimental results indicated that the proposed method had a good linear range of 0.01-100 ng mL{sup -1} (r{sup 2} = 0.9990). The precision was 2.12% (RSD, n = 7) and the detection limit was 0.95 ng L{sup -1}. Proposed method was validated with four real environmental samples and the results indicated that the proposed method was excellent for the future use and satisfied spiked recoveries were in the range of 92.9-97.4%.

  6. Single-Photon Source for Quantum Information Based on Single Dye Molecule Fluorescence in Liquid Crystal Host

    Energy Technology Data Exchange (ETDEWEB)

    Lukishova, S.G.; Knox, R.P.; Freivald, P.; McNamara, A.; Boyd, R.W.; Stroud, Jr., C.R.; Schmid, A.W.; Marshall, K.L.

    2006-08-18

    This paper describes a new application for liquid crystals: quantum information technology. A deterministically polarized single-photon source that efficiently produces photons exhibiting antibunching is a pivotal hardware element in absolutely secure quantum communication. Planar-aligned nematic liquid crystal hosts deterministically align the single dye molecules which produce deterministically polarized single (antibunched) photons. In addition, 1-D photonic bandgap cholesteric liquid crystals will increase single-photon source efficiency. The experiments and challenges in the observation of deterministically polarized fluorescence from single dye molecules in planar-aligned glassy nematic-liquid-crystal oligomer as well as photon antibunching in glassy cholesteric oligomer are described for the first time.

  7. In situ measurement of airway surface liquid [K+] using a ratioable K+-sensitive fluorescent dye.

    Science.gov (United States)

    Namkung, Wan; Song, Yuanlin; Mills, Aaron D; Padmawar, Prashant; Finkbeiner, Walter E; Verkman, A S

    2009-06-05

    The airway surface liquid (ASL) is the thin fluid layer lining airway surface epithelial cells, whose volume and composition are tightly regulated and may be abnormal in cystic fibrosis (CF). We synthesized a two-color fluorescent dextran to measure ASL [K(+)], TAC-Lime-dextran-TMR, consisting of a green-fluorescing triazacryptand K(+) ionophore-Bodipy conjugate, coupled to dextran, together with a red fluorescing tetramethylrhodamine reference chromophore. TAC-Lime-dextran-TMR fluorescence was K(+)-selective, increasing >4-fold with increasing [K(+)] from 0 to 40 mm. In well differentiated human airway epithelial cells, ASL [K(+)] was 20.8 +/- 0.3 mm and decreased by inhibition of the Na(+)/K(+) pump (ouabain), ENaC (amiloride), CF transmembrane conductance regulator (CFTR(inh)-172), or K(+) channels (TEA or XE991). ASL [K(+)] was increased by forskolin but not affected by Na(+)/K(+)/2Cl(-) cotransporter inhibition (bumetanide). Functional and expression studies indicated the involvement of [K(+)] channels KCNQ1, KCNQ3, and KCNQ5 as determinants of ASL [K(+)]. [K(+)] in CF cultures was similar to that in non-CF cultures, suggesting that abnormal ASL [K(+)] is not a factor in CF lung disease. In intact airways, ASL [K(+)] was also well above extracellular [K(+)]: 22 +/- 1 mm in pig trachea ex vivo and 16 +/- 1 mm in mouse trachea in vivo. Our results provide the first noninvasive measurements of [K(+)] in the ASL and indicate the involvement of apical and basolateral membrane ion transporters in maintaining a high ASL [K(+)].

  8. Diffusion-controlled intergranular penetration and embrittlement of copper by liquid bismuth between 300 and 600 Celsius degrees; Penetration intergranulaire fragilisante du cuivre par le bismuth liquide: identification de la cinetique et du mecanisme de type diffusionnel entre 300 et 600 deg

    Energy Technology Data Exchange (ETDEWEB)

    Laporte, V

    2005-02-15

    Hybrid reactors are a new concept for energy production and nuclear waste treatment. Among other requirements, structural materials have to withstand liquid metal embrittlement. This thesis aimed therefore to identify the controlling mechanism for the intergranular embrittlement of copper in contact with liquid bismuth. Scanning electron microscopy, Auger electron spectroscopy, X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy have been used to analyze fracture surfaces of both copper polycrystals and a copper bicrystal (symmetric tilt boundary 50 degrees <100>). These analyses reveal both parabolic intergranular penetration kinetics and a maximal intergranular bismuth concentration that is less than two monolayers equivalent. These two results allow us to identify grain boundary diffusion as the controlling mechanism for the intergranular penetration of copper by liquid bismuth between 300 and 600 Celsius degrees, showing the absence of perfect grain boundary wetting. (author)

  9. Detection of airborne Legionella while showering using liquid impingement and fluorescent in situ hybridization (FISH).

    Science.gov (United States)

    Deloge-Abarkan, Magali; Ha, Thi-Lan; Robine, Enric; Zmirou-Navier, Denis; Mathieu, Laurence

    2007-01-01

    Aerosols of water contaminated with Legionella bacteria constitute the only mode of exposure for humans. However, the prevention strategy against this pathogenic bacteria risk is managed through the survey of water contamination. No relationship linked the Legionella bacteria water concentration and their airborne abundance. Therefore, new approaches in the field of the metrological aspects of Legionella bioaerosols are required. This study was aimed at testing the main principles for bioaerosol collection (solid impaction, liquid impingement and filtration) and the in situ hybridization (FISH) method, both in laboratory and field assays, with the intention of applying such methodologies for airborne Legionella bacteria detection while showering. An aerosolization chamber was developed to generate controlled and reproducible L. pneumophila aerosols. This tool allowed the identification of the liquid impingement method as the most appropriate one for collecting airborne Legionella bacteria. The culturable fraction of airborne L. pneumophila recovered with the liquid impingement principle was 4 and 700 times higher compared to the impaction and filtration techniques, respectively. Moreover, the concentrations of airborne L. pneumophila in the impinger fluid were on average 7.0 x 10(5) FISH-cells m(-3) air with the fluorescent in situ hybridization (FISH) method versus 9.0 x 10(4) CFU m(-3) air with the culture method. These results, recorded under well-controlled conditions, were confirmed during the field experiments performed on aerosols generated by hot water showers in health institutions. This new approach may provide a more accurate characterization of aerobiocontamination by Legionella bacteria.

  10. [Determination of four phenolic endocrine disruptors in environmental water samples by high performance liquid chromatography-fluorescence detection using dispersive liquid-liquid microextraction coupled with derivatization].

    Science.gov (United States)

    Wang, Xiaoyan; Qi, Weimei; Zhao, Xian'en; Lü, Tao; Wang, Xiya; Zheng, Longfang; Yan, Yehao; You, Jinmao

    2014-06-01

    To achieve accurate, fast and sensitive detection of phenolic endocrine disruptors in small volume of environmental water samples, a method of dispersive liquid-liquid microextraction (DLLME) coupled with fluorescent derivatization was developed for the determination of bisphenol A, nonylphenol, octylphenol and 4-tert-octylphenol in environmental water samples by high performance liquid chromatography-fluorescence detection (HPLC-FLD). The DLLME and derivatization conditions were investigated, and the optimized DLLME conditions for small volume of environmental water samples (pH 4.0) at room temperature were as follows: 70 microL chloroform as extraction solvent, 400 microL acetonitrile as dispersing solvent, vortex mixing for 3 min, and then high-speed centrifugation for 2 min. Using 2-[2-(7H-dibenzo [a, g] carbazol-7-yl)-ethoxy] ethyl chloroformate (DBCEC-Cl) as precolumn derivatization reagent, the stable derivatives of the four phenolic endocrine disruptors were obtained in pH 10.5 Na2CO3-NaHCO3 buffer/acetonitrile at 50 degrees C for 3 min, and then separated within 10 min by HPLC-FLD. The limits of detection (LODs) were in the range of 0.9-1.6 ng/L, and the limits of quantification (LOQs) were in the range of 3.8-7.1 ng/L. This method had perfect linearity, precision and recovery results, and showed obvious advantages and practicality comparing to the previously reported methods. It is a convenient and validated method for the routine analysis of phenolic endocrine disruptors in waste water of paper mill, lake water, domestic wastewater, tap water, etc.

  11. One-pot synthesis of fluorescent carbon nanoribbons, nanoparticles, and graphene by the exfoliation of graphite in ionic liquids.

    Science.gov (United States)

    Lu, Jiong; Yang, Jia-xiang; Wang, Junzhong; Lim, Ailian; Wang, Shuai; Loh, Kian Ping

    2009-08-25

    In this work we demonstrate a facile means to generate fluorescent carbon nanoribbons, nanoparticles, and graphene from graphite electrode using ionic liquid-assisted electrochemical exfoliation. A time-dependence study of products exfoliated from the graphite anode allows the reconstruction of the exfoliation mechanism based on the interplay of anodic oxidation and anion intercalation. We have developed strategies to control the distribution of the exfoliated products. In addition, the fluorescence of these carbon nanomaterials can be tuned from the visible to ultraviolet region by controlling the water content in the ionic liquid electrolyte.

  12. Automated dispersive liquid-liquid microextraction coupled to high performance liquid chromatography - cold vapour atomic fluorescence spectroscopy for the determination of mercury species in natural water samples.

    Science.gov (United States)

    Liu, Yao-Min; Zhang, Feng-Ping; Jiao, Bao-Yu; Rao, Jin-Yu; Leng, Geng

    2017-04-14

    An automated, home-constructed, and low cost dispersive liquid-liquid microextraction (DLLME) device that directly coupled to a high performance liquid chromatography (HPLC) - cold vapour atomic fluorescence spectroscopy (CVAFS) system was designed and developed for the determination of trace concentrations of methylmercury (MeHg(+)), ethylmercury (EtHg(+)) and inorganic mercury (Hg(2+)) in natural waters. With a simple, miniaturized and efficient automated DLLME system, nanogram amounts of these mercury species were extracted from natural water samples and injected into a hyphenated HPLC-CVAFS for quantification. The complete analytical procedure, including chelation, extraction, phase separation, collection and injection of the extracts, as well as HPLC-CVAFS quantification, was automated. Key parameters, such as the type and volume of the chelation, extraction and dispersive solvent, aspiration speed, sample pH, salt effect and matrix effect, were thoroughly investigated. Under the optimum conditions, linear range was 10-1200ngL(-1) for EtHg(+) and 5-450ngL(-1) for MeHg(+) and Hg(2+). Limits of detection were 3.0ngL(-1) for EtHg(+) and 1.5ngL(-1) for MeHg(+) and Hg(2+). Reproducibility and recoveries were assessed by spiking three natural water samples with different Hg concentrations, giving recoveries from 88.4-96.1%, and relative standard deviations <5.1%.

  13. Selective identification and quantification of saccharin by liquid chromatography and fluorescence detection.

    Science.gov (United States)

    Bruno, Sergio N F; Cardoso, Carlos R; Maciel, Márcia Mosca A; Vokac, Lidmila; da Silva Junior, Ademário I

    2014-09-15

    High-pressure liquid chromatography with ultra-violet detection (HPLC-UV) is one of the most commonly used methods to identify and quantify saccharin in non-alcoholic beverages. However, due to the wide variety of interfering UV spectra in saccharin-containing beverage matrices, the same method cannot be used to measure this analyte accurately. We have developed a new, highly effective method to identify and quantify saccharin using HPLC with fluorescence detection (HPLC-FLD). The excitation wavelength (250 nm) and emission wavelength (440 nm) chosen increased selectivity for all matrices and ensured few changes were required in the mobile phase or other parameters. The presence of saccharin in non-diet beverages - a fraud commonly used to replace more expensive sucrose - was confirmed by comparing coincident peaks as well as the emission spectra of standards and samples.

  14. Determination of aristolochic acids by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Wang, Yinan; Chan, Wan

    2014-06-25

    Nephrotoxic and carcinogenic aristolochic acids (AAs) are naturally occurring nitrophenanthrene carboxylic acids in the herbal genus Aristolochia. The misuse of AA-containing herbs in preparing slimming drugs has caused hundred of cases of kidney disease in Belgium women in a slimming regime in the early 1990s. Accumulating evidence also suggested that prolong dietary intake of AA-contaminated food is one of the major causes to the Balkan endemic nephropathy that was first observed in the late 1950s. Therefore, analytical methods of high sensitivity are extremely important for safeguarding human exposure to AA-containing herbal medicines, herbal remedies, and food composites. In this paper, we describe the development of a new high-performance liquid chromatography coupled fluorescence detector (HPLC-FLD) method for the sensitive determination of AAs. The method makes use of a novel cysteine-induced denitration reaction that "turns on" the fluorescence of AAs for fluorometric detections. Our results showed that the combination of cysteine-induced denitration and HPLC-FLD analysis allows for sensitive quantification of AA-I and AA-II at detection limits of 27.1 and 25.4 ng/g, respectively. The method was validated and has been successfully applied in quantifying AAs in Chinese herbal medicines.

  15. Automatic analyzer for highly polar carboxylic acids based on fluorescence derivatization-liquid chromatography.

    Science.gov (United States)

    Todoroki, Kenichiro; Nakano, Tatsuki; Ishii, Yasuhiro; Goto, Kanoko; Tomita, Ryoko; Fujioka, Toshihiro; Min, Jun Zhe; Inoue, Koichi; Toyo'oka, Toshimasa

    2015-03-01

    A sensitive, versatile, and reproducible automatic analyzer for highly polar carboxylic acids based on a fluorescence derivatization-liquid chromatography (LC) method was developed. In this method, carboxylic acids were automatically and fluorescently derivatized with 4-(N,N-dimethylaminosulfonyl)-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ) in the presence of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride by adopting a pretreatment program installed in an LC autosampler. All of the DBD-PZ-carboxylic acid derivatives were separated on the ODS column within 30 min by gradient elution. The peak of DBD-PZ did not interfere with the separation and the quantification of all the acids with the exception of lactic acid. From the LC-MS/MS analysis, we confirmed that lactic acid was converted to an oxytriazinyl derivative, which was further modified with a dimethoxy triazine group of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM). We detected this oxytriazinyl derivative to quantify lactic acid. The detection limits (signal-to-noise ratio = 3) for the examined acids ranged from 0.19 to 1.1 µm, which correspond to 95-550 fmol per injection. The intra- and inter-day precisions of typical, highly polar carboxylic acids were all carboxylic acids in various samples, which included fruit juices, red wine and media from cultured tumor cells.

  16. Microwave assisted one-step green synthesis of fluorescent carbon nanoparticles from ionic liquids and their application as novel fluorescence probe for quercetin determination

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Deli; Yuan, Danhua [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China); He, Hua, E-mail: dochehua@163.com [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China); Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, China Pharmaceutical University, Nanjing 210009 (China); Gao, Mengmeng [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China)

    2013-08-15

    In this study, a new sensitive and convenient method for the determination of quercetin based on the fluorescence quenching of fluorescent carbon nanoparticles (CNPs) was developed. The CNPs derived from ionic liquids were prepared using a green and rapid microwave-assisted synthetic approach for the first time. The one-step green preparation process is simple and effective, neither a strong acid solvent nor surface modification reagent is needed, which makes this approach very suitable for large-scale production. The prepared CNPs were characterized by high-resolution transmission electron microscopy, Fourier transform infrared spectrometry, elemental analysis and spectrofluorometry. In NH{sub 3}–NH{sub 4}Cl buffer solution (pH 9.47), the fluorescence signals of CNPs decreased obviously with increase of the quercetin concentration. The effect of other coexisting foreign substances on the intensity of CNPs showed a low interference response. Under the optimum conditions, the fluorescence intensity presented a linear response versus quercetin concentration according to the Stern–Volmer equation with an excellent 0.9989 correlation coefficient. The linearity ranged from 2.87×10{sup −6} to 31.57×10{sup −6} mol L{sup −1} with the detection limit (3σ) of 9.88×10{sup −8} mol L{sup −1}. The recovery of this method was in the range of 93.3–105.1%. Therefore, the CNPs could to be a promising candidate as a fluorescence probe for the detection of trace levels of quercetin due to their advantages in low-cost production, low cytotoxicity, strong fluorescence and excellent biocompatibility. -- Highlights: ► Fluorescent CNPs were synthesized with microwave pyrolysis approach. ► Ionic liquids were used as sources of carbon and nitrogen for the first time. ► The formation and functionalization of CNPs were accomplished simultaneously. ► CNPs were used as fluorescent probes for the determination of quercetin. ► A sensitive and convenient method based

  17. Determination of three ultraviolet filters in sunscreen formulations and from skin penetration studies by high-performance liquid chromatography

    Directory of Open Access Journals (Sweden)

    Fernanda Maria Pinto Vilela

    2011-01-01

    Full Text Available An analytical procedure to quantify 3-benzophenone, octylmethoxycinnamate and octylsalicylate was validated and employed to assess these ultraviolet filters in sunscreen formulations and from skin penetration studies. The effect of the vehicle on the skin retention of these filters was investigated. HPLC and extraction procedure were found to be reliable when obtaining data for the sunscreen formulations and for evaluation skin penetration. The results demonstrated that a cream gel generated higher epidermal concentrations of these filters than a lotion or cream-based formulation. Additionally, when comparing the skin retentions of each filter using the same formulation, 3-benzophenone showed the highest skin retention.

  18. Ratiometric Optical Temperature Sensor Using Two Fluorescent Dyes Dissolved in an Ionic Liquid Encapsulated by Parylene Film

    Directory of Open Access Journals (Sweden)

    Isao Shimoyama

    2013-03-01

    Full Text Available A temperature sensor that uses temperature-sensitive fluorescent dyes is developed. The droplet sensor has a diameter of 40 µm and uses 1 g/L of Rhodamine B (RhB and 0.5 g/L of Rhodamine 110 (Rh110, which are fluorescent dyes that are dissolved in an ionic liquid (1-ethyl-3-methylimidazolium ethyl sulfate to function as temperature indicators. This ionic liquid is encapsulated using vacuum Parylene film deposition (which is known as the Parylene-on-liquid-deposition (PoLD method. The droplet is sealed by the chemically stable and impermeable Parylene film, which prevents the dye from interacting with the molecules in the solution and keeps the volume and concentration of the fluorescent material fixed. The two fluorescent dyes enable the temperature to be measured ratiometrically such that the droplet sensor can be used in various applications, such as the wireless temperature measurement of microregions. The sensor can measure the temperature of such microregions with an accuracy of 1.9 °C, a precision of 3.7 °C, and a fluorescence intensity change sensitivity of 1.0%/K. The sensor can measure temperatures at different sensor depths in water, ranging from 0 to 850 µm. The droplet sensor is fabricated using microelectromechanical system (MEMS technology and is highly applicable to lab-on-a-chip devices.

  19. Ratiometric optical temperature sensor using two fluorescent dyes dissolved in an ionic liquid encapsulated by Parylene film.

    Science.gov (United States)

    Kan, Tetsuo; Aoki, Hironori; Binh-Khiem, Nguyen; Matsumoto, Kiyoshi; Shimoyama, Isao

    2013-03-27

    A temperature sensor that uses temperature-sensitive fluorescent dyes is developed. The droplet sensor has a diameter of 40 µm and uses 1 g/L of Rhodamine B (RhB) and 0.5 g/L of Rhodamine 110 (Rh110), which are fluorescent dyes that are dissolved in an ionic liquid (1-ethyl-3-methylimidazolium ethyl sulfate) to function as temperature indicators. This ionic liquid is encapsulated using vacuum Parylene film deposition (which is known as the Parylene-on-liquid-deposition (PoLD) method). The droplet is sealed by the chemically stable and impermeable Parylene film, which prevents the dye from interacting with the molecules in the solution and keeps the volume and concentration of the fluorescent material fixed. The two fluorescent dyes enable the temperature to be measured ratiometrically such that the droplet sensor can be used in various applications, such as the wireless temperature measurement of microregions. The sensor can measure the temperature of such microregions with an accuracy of 1.9 °C, a precision of 3.7 °C, and a fluorescence intensity change sensitivity of 1.0%/K. The sensor can measure temperatures at different sensor depths in water, ranging from 0 to 850 µm. The droplet sensor is fabricated using microelectromechanical system (MEMS) technology and is highly applicable to lab-on-a-chip devices.

  20. Simple, rapid, and sensitive liquid chromatography-fluorescence method for the quantification of tranexamic acid in blood

    NARCIS (Netherlands)

    J.F. Huertas-Perez; M. Heger; H. Dekker; H. Krabbe; J. Lankelma; F. Ariese

    2007-01-01

    Tranexamic acid (TA) is a synthetic antifibrinolytic agent that is being considered as a candidate adjuvant drug for site-specific pharmaco-laser therapy of port wine stains. For drug utility studies, a high-performance liquid chromatography (HPLC)-fluorescence method was developed for the quantific

  1. Effect of Host Medium on the Fluorescence Emission Intensity of Rhodamine B in Liquid and Solid Phase

    Science.gov (United States)

    Fikry, M.; Omar, M. M.; Ismail, Lotfi Z.

    2011-06-01

    In this work, we study the effect of concentration, host medium, PH, ions complex and phase states on the fluorescence emission from the laser dye, Rhodamine B, pumping by UV laser as exited source. The polymethylmethacrylate PMMA used as host medium in case of solid phase samples while, ethanol and Tetrahydrofuran (THF) are used in case of liquid one. The Laser Induced Fluorescence (LIF) technique was used to study the fluorescence properties of the both cases liquid and thin film solid-state samples. In addition, the Dual Thermal Lens (DTL) technique was used to study the quantum yield of these samples. The maximum fluorescence emission observed at concentration of Rhodamine B C=3×10-4M. At this concentration of Rhodamine B, the type of solvent and polarity of the medium affect on the fluorescence emission intensity of Rhodamine B with. The measurements revile that, the behavior of both phases state was analogous and Rhodamine B/PMMA thin film sample by ratio of 4:1 and thickness 0.12 mm is the best photostability sample and its quantum yield about ≈ 0.82. Also, the fluorescence emission intensity of Rhodamine B was quenched by complex formation of Co, Al, Cu and iodide ions with Rhodamine B due to the increase of the charge density of the ions.

  2. Ionic liquid-based zinc oxide nanofluid for vortex assisted liquid liquid microextraction of inorganic mercury in environmental waters prior to cold vapor atomic fluorescence spectroscopic detection.

    Science.gov (United States)

    Amde, Meseret; Liu, Jing-Fu; Tan, Zhi-Qiang; Bekana, Deribachew

    2016-01-01

    Zinc oxide nanofluid (ZnO-NF) based vortex assisted liquid liquid microextraction (ZnO-NF VA-LLME) was developed and employed in extraction of inorganic mercury (Hg(2+)) in environmental water samples, followed by cold vapor atomic fluorescence spectrometry (CV-AFS). Unlike other dispersive liquid liquid microextraction techniques, ZnO-NF VA-LLME is free of volatile organic solvents and dispersive solvent consumption. Analytical signals were obtained without back-extraction from the ZnO-NF phase prior to CV-AFS determination. Some essential parameters of the ZnO-NF VA-LLME and cold vapor generation such as composition and volume of the nanofluid, vortexing time, pH of the sample solution, amount of the chelating agent, ionic strength and matrix interferences have been studied. Under optimal conditions, efficient extraction of 1ng/mL of Hg(2+) in 10mL of sample solution was achieved using 50μL of ZnO-NF. The enrichment factor before dilution, detection limits and limits of quantification of the method were about 190, 0.019 and 0.064ng/mL, respectively. The intra and inter days relative standard deviations (n=8) were found to be 4.6% and 7.8%, respectively, at 1ng/mL spiking level. The accuracy of the current method was also evaluated by the analysis of certified reference materials, and the measured Hg(2+) concentration of GBW08603 (9.6ng/mL) and GBW(E)080392 (8.9ng/mL) agreed well with their certified value (10ng/mL). The method was applied to the analysis of Hg(2+) in effluent, influent, lake and river water samples, with recoveries in the range of 79.8-92.8% and 83.6-106.1% at 1ng/mL and 5ng/mL spiking levels, respectively. Overall, ZnO-NF VA-LLME is fast, simple, cost-effective and environmentally friendly and it can be employed for efficient enrichment of the analyte from various water samples.

  3. Visualization of Structured Packing with Laser Induced Fluorescence Technique:Two-Dimensional Measurement of Liquid Concentration Distribution

    Institute of Scientific and Technical Information of China (English)

    刘伯潭; 申言同; 张会书; 刘春江; 唐忠利; 袁希钢

    2016-01-01

    A method of using laser induced fluorescence(LIF)technique was applied to two-dimensional meas-urement of the liquid concentration distribution in the 250Y structured packing sheet. The experimental structured packing sheet was made of perspex so that the laser could pass through it. The visualization of the distribution of the liquid concentration in the structured packing sheet was realized. The calibration of the thickness and liquid concentration was carried out firstly and the regression formulaI=kcd was acquired, in which concentrationc and the liquid film thicknessd were both considered. Then the liquid feed of uniform tracer(rhodamine)concentration entered the perspex structured packing from the top under different spraying densities. The corresponding thickness of liquid film on the packing was calculated. Finally, tracer(rhodamine)with a high concentration was injected only at one fixed point of the structured packing under different spraying densities of the liquid. With the known liquid film thickness, the concentration distribution of the tracer can be calculated inside the structured packing sheet.

  4. Determination of nitrofuran metabolites in shrimp by high performance liquid chromatography with fluorescence detection and liquid chromatography-tandem mass spectrometry using a new derivatization reagent.

    Science.gov (United States)

    Du, Na-Na; Chen, Ming-Ming; Sheng, Liang-Quan; Chen, Shui-Sheng; Xu, Hua-Jie; Liu, Zhao-Di; Song, Chong-Fu; Qiao, Rui

    2014-01-31

    A high performance liquid chromatography with fluorescence detection (HPLC-FLD) method for the simultaneous determination of total nitrofuran metabolite residues (furazolidone, furaltadone, nitrofurantoin, and nitrofurazone) in shrimp was developed. The method involves the acid hydrolysis of protein-bound metabolites, followed by the derivatization of the freed metabolites with the new fluorescent derivatization reagent 2-hydroxy-1-naphthaldehyde (HN) and subsequent liquid-liquid extraction (LLE). Separation is achieved on a YMC-Pack Polymer C18 column under alkaline conditions, and the high fluorescence intensity of the derivatives at an emission wavelength Em=463nm (Ex=395nm) enables, for the first time, their simultaneous determination in shrimp at concentrations as low as 1μg/kg by HPLC-FLD. The method was validated using blank shrimp fortified with all four metabolites at 0.5, 1.0 and 2.0μg/kg. Recoveries were >87% with relative standard deviations of HPLC-FLD were in very good agreement with those obtained by LC-MS/MS analysis.

  5. Quantitation of aflatoxins in walnut kernels by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Kabak, Bulent

    2014-01-01

    A total of 85 walnut samples collected between October 2012 and April 2013 in different provinces of Turkey were analysed for the presence of aflatoxins (AFs). The method involved methanol-water extraction, clean-up with immunoaffinity columns and a sensitive high-performance liquid chromatography coupled with fluorescence detection after post-column derivatisation. The method was validated for selectivity, linearity, trueness, precision, limit of detection and limit of quantification (LOQ), which met the performance criteria as set by EC regulation No. 401/2006. LOQs were 0.07, 0.04, 0.09 and 0.05 µg kg(-1) for AFB1, AFB2, AFG1 and AFG2, respectively. AFs were present in 9.4% of walnut samples (8/85) at total AFs levels ranging from 0.09 to 15.4 µg kg(-1). Only one of eight walnut samples exceeded the European Union limit of 2 and 4 µg kg(-1) for AFB1 and total AFs, respectively.

  6. Multiresidue determination of quinolone antibacterials in eggs of laying hens by liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Hassouan, M K; Ballesteros, O; Taoufiki, J; Vílchez, J L; Cabrera-Aguilera, M; Navalón, A

    2007-06-01

    An analytical method for the simultaneous determination of seven quinolones (ciprofloxacin, enrofloxacin, danofloxacin, difloxacin, flumequine, oxolinic acid and sarafloxacin) in egg samples of laying hens was developed. Their use is totally prohibited in animals from which eggs are produced for human consumption. Protein precipitation was achieved by addition of acetonitrile and ammonia, removal of acetonitrile with dichloromethane, the quinolones remaining in the basic aqueous extract. The aqueous extract was analysed by liquid chromatography with fluorescence detection (LC-FD). The mobile phase was composed of acetonitrile and 10 mM citrate buffer solution of pH 4.5, with an initial composition of acetonitrile-water (12:88, v/v) and using linear gradient elution. Norfloxacin was used as an internal standard. The limits of detection found were 4-12 ng g(-1). These values were lower than the maximum residue limits (MRLs) established by the European Union for these compounds in different tissues of eggs-producing animals.

  7. Inclusion complex formation of ionic liquids with 4-sulfonatocalixarenes studied by competitive binding of berberine alkaloid fluorescent probe

    Science.gov (United States)

    Miskolczy, Zsombor; Biczók, László

    2009-07-01

    A clinically important natural isoquinoline alkaloid, berberine, was used as a fluorescent probe to study the encapsulation of 1-alkyl-3-methylimidazolium (C nMIm +) type ionic liquids in 4-sulfonato-substituted calix[4]arene (SCX4) and calix[6]arene (SCX6) at pH 2. Addition of ionic liquids to the aqueous solution of berberine-SCXn inclusion complexes brought about considerable fluorescence intensity diminution due to the extrusion of berberine from the macrocycle into the aqueous phase by the competitive inclusion of C nMIm + cation. The lengthening of the aliphatic side chain of the imidazolium moiety diminished the equilibrium constant of complexation with SCX4, but enhanced the stability of SCX6 complexes. Larger binding strength was found for SCX4.

  8. Fluorescent assay of total serum cholesterol, with use of gas-liquid chromatography to study saponification efficiency.

    Science.gov (United States)

    Majeski, E J; Seltzer, E J; Carter, P L; Howlett, D R; Stuart, J D

    1977-11-01

    We describe a fluorescent determination of total cholesterol in serum for which the accuracy and precision are comparable to that for the method of Abell-Kendall, a method of generally accepted accuracy. By the use of quality reagents and the rigorous exclusion of water, the strong fluorophor that develops on reacting concentrated sulfuric acid with cholesterol can be used to quantitatively determine the total cholesterol in serum. We used gas-liquid chromatography to monitor the extent of saponification of the cholesterol esters, because we found them to have fluorescent efficiencies that differed from that of free cholesterol. Sodium methoxide in methanol/methylene chloride (1/3 by vol) was shown by gas-liquid chromatography to very effectively saponify the cholesterol esters in serum.

  9. Rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Yang, Xiao; Diao, Chun-Peng; Sun, Ai-Ling; Liu, Ren-Min

    2014-10-01

    A method for the rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection was proposed in this paper. A simple apparatus consisting of a test tube and a cut-glass dropper was designed and applied to collect the floating extraction drop in liquid-liquid microextraction when low-density organic solvent was used as the extraction solvent. Solidification and melting steps that were tedious but necessary once the low-density organic solvent used as extraction solvent could be avoided by using this apparatus. Bisphenol A was selected as model pollutant and vortex-assisted liquid-liquid microextraction was employed to investigate the usefulness of the apparatus. High-performance liquid chromatography with fluorescence detection was selected as the analytical tool for the detection of bisphenol A. The linear dynamic range was from 0.10 to 100 μg/L for bisphenol A, with good squared regression coefficient (r(2) = 0.9990). The relative standard deviation (n = 7) was 4.7% and the limit of detection was 0.02 μg/L. The proposed method had been applied to the determination of bisphenol A in natural water samples and was shown to be economical, fast, and convenient.

  10. Correlative fluorescence and scanning transmission electron microscopy of quantum dot-labeled proteins on whole cells in liquid.

    Science.gov (United States)

    Peckys, Diana B; Bandmann, Vera; de Jonge, Niels

    2014-01-01

    Correlative fluorescence microscopy combined with scanning transmission electron microscopy (STEM) of cells fully immersed in liquid is a new methodology with many application areas. Proteins, in live cells immobilized on microchips, are labeled with fluorescent quantum dot nanoparticles. In this protocol, the epidermal growth factor receptor (EGFR) is labeled. The cells are fixed after a selected labeling time, for example, 5 min as needed to form EGFR dimers. The microchip with cells is then imaged with fluorescence microscopy. Thereafter, STEM can be accomplished in two ways. The microchip with the labeled cells and one microchip with a spacer are assembled into a special microfluidic device and imaged with dedicated high-voltage STEM. Alternatively, thin edges of cells can be studied with environmental scanning electron microscopy with a STEM detector, by placing a microchip with cells in a cooled wet environment.

  11. Determination of Polycyclic Aromatic Hydrocarbons in Automobile Exhaust by Means of High-Performance Liquid Chromatography with Fluorescence Detection

    DEFF Research Database (Denmark)

    Nielsen, Tom

    1979-01-01

    A chromatographic method has been developed and applied to the determination of polycyclic aromatic hydrocarbons (PAHs) in particulate matter in automobile exhaust, in petrols, and in crankcase oils. The PAHs were purified from other organic compounds by thin-layer chromatography, separated by high......-performance liquid chromatography, and measured by means of on-line fluorescence detection. The identities of the PAHs were verified by comparing the emission spectra obtained by a stop-flow technique with those of standard PAHs...

  12. Measurements of high energy neutrons penetrated through iron shields using the Self-TOF detector and an NE213 organic liquid scintillator

    CERN Document Server

    Sasaki, M; Nunomiya, T; Nakamura, T; Fukumura, A; Takada, M

    2002-01-01

    Neutron energy spectra penetrated through iron shields were measured using the Self-TOF detector and an NE213 organic liquid scintillator which have been newly developed by our group at the Heavy-Ion Medical Accelerator in Chiba (HIMAC) of National Institute of Radiological Sciences (NIRS), Japan. Neutrons were generated by bombarding 400 MeV/nucleon C ion on a thick (stopping-length) copper target. The neutron spectra in the energy range from 20 to 800 MeV were obtained through the FORIST unfolding code with their response functions and compared with the MCNPX calculations combined with the LA150 cross section library. The neutron fluence measured by the NE213 detector was simulated by the track length estimator in the MCNPX, and evaluated the contribution of the room-scattered neutrons. The calculations are in fairly good agreement with the measurements. Neutron fluence attenuation lengths were obtained from the experimental results and the calculation.

  13. Occurrence of aflatoxins in peanuts and peanut products determined by liquid chromatography with fluorescence detection

    Directory of Open Access Journals (Sweden)

    Stojanovska-Dimzoska Biljana

    2013-01-01

    Full Text Available Liquid chromatography with fluorescence detection using immunoaffinity column clean-up was a method described for determination of aflatoxins (AFB1, AFB2, AFG1 and AFG2 in peanuts and peanut based products. The validation of the procedure was performed. Good coefficient of correlation was found for all aflatoxins in the range of 0.9993-0.9999. Limit of detection (LOD and limit of quantification (LOQ ranged from 0.003-0.005 mg/kg and 0.009-0.023 mg/kg, respectively, which was acceptable. The mean recovery for total aflatoxins was 88.21%. The method also showed acceptable precision values in the range of 0.171-2.626% at proposed concentration levels for all four aflatoxins. RSDR values (within laboratory reproducibility calculated from the results showed good correlation between two analysts for all aflatoxins and they ranged from 4.93-11.87%. The developed method was applied for the determination of aflatoxins in 27 samples of peanuts and peanut based products. The results showed that 21 peanut samples (77.7% were below LOD of the method. Three samples had positive results over the MRL. There was one extreme value recorded for the total aflatoxins in peanut (289.2 mg/kg and two peanut based products, peanut snack and peanut, with total content of aflatoxins being 16.3 mg/kg and 8.0 mg/kg, respectively. The obtained results demonstrated that the procedure was suitable for the de­termination of aflatoxins in peanuts and peanut based products and it could be implemented for the routine analysis.

  14. High performance liquid chromatography--atomic fluorescence spectrometric determination of arsenic species in beer samples

    Energy Technology Data Exchange (ETDEWEB)

    Melo Coelho, N.M.; Parrilla, Carmen; Cervera, M.L.; Pastor, A.; Guardia, M. de la

    2003-04-10

    A method has been developed for the direct determination of As(III), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and As(V) in beers by hydride generation--atomic fluorescence spectrometry after separation of arsenic species by high performance liquid chromatography. Compounds were separated by anion-exchange chromatography with isocratic elution using KH{sub 2}PO{sub 4}/K{sub 2}HPO{sub 4} as mobile phase with elution times of 1.67, 2.08, 6.52 and 10.72 min for As(III), DMA, MMA and As(V), respectively. Parameters affecting the hydride generation of all arsenic species were studied and the best conditions were established as a reaction coil of 150 cm, for a sample injected volume of 100 {mu}l, a 4.0% (m/v) solution of sodium tetrahydroborate and 2.0 mol l{sup -1} hydrochloric acid with flow rates of 2.7 and 1.7 ml min{sup -1}, respectively and a flow rate of 500 ml min{sup -1} for the argon carrier gas. Under the best experimental conditions, the detection limit was found to be 0.12, 0.20, 0.27 and 0.39 {mu}g l{sup -1} for As(III), DMA, MMA and As(V), respectively. The relative standard deviation for eight independent determinations varied from 3.9 till 8.9% for species considered at a concentration level of 10.0 {mu}g l{sup -1}. Recovery and comparative studies evidenced that the method is suitable for the accurate determination of arsenic species in water and beer samples.

  15. Organic Liquids-Responsive β-Cyclodextrin-Functionalized Graphene-Based Fluorescence Probe: Label-Free Selective Detection of Tetrahydrofuran

    Directory of Open Access Journals (Sweden)

    Huawen Hu

    2014-06-01

    Full Text Available In this study, a label-free graphene-based fluorescence probe used for detection of volatile organic liquids was fabricated by a simple, efficient and low-cost method. To fabricate the probe, a bio-based β-cyclodextrin (β-CD was firstly grafted on reduced graphene surfaces effectively and uniformly, as evidenced by various characterization techniques such as Ultraviolet/Visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The subsequent inclusion of Rhodamine B (RhB into the inner cavities of the β-CD grafted on the graphene surfaces was achieved easily by a solution mixing method, which yielded the graphene-based fluorescent switch-on probe. In addition, the gradual and controllable quenching of RhB by Fluorescence Resonance Energy Transfer from RhB to graphene during the process of stepwise accommodation of the RhB molecules into the β-CD-functionalized graphene was investigated in depth. A wide range of organic solvents was examined using the as-fabricated fluorescence probe, which revealed the highest sensitivity to tetrahydrofuran with the detection limit of about 1.7 μg/mL. Some insight into the mechanism of the different responsive behaviors of the fluorescence sensor to the examined targets was also described.

  16. A novel pre-column fluorescent derivatization method for the sensitive determination of aristolochic acids in medicinal herbs by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Guo, Lin; Yue, Hao; Cai, Zongwei

    2010-09-21

    Aristolochic acids (AAs) are a family of structurally related nitrophenanthrene carboxylic acids existing in Aristolochia, Bragantia, and Asarum species. AAs have been proven to have nephrotoxic and carcinogenic toxicity. In this study, a novel pre-column fluorescence derivatization procedure followed by high-performance liquid chromatography-fluorescence detection (HPLC-FLD) is developed for the analysis of AAs in medicinal herbs. The nitro group in the phenanthrene ring of AAs was removed by NaBH(4) in water-THF (2:1, v/v), resulting in the corresponding aristolic acids. The analysis of AAs in medicinal herbs was based of the sensitive fluorescence detection of aristolic acids after the chemical derivatization. Because the produced aristolic acids are highly fluorescent the limit of detection (LOD) of AAI and AAII were lowered to 0.06 and 0.04 ng/mL, respectively, which is at least an order of magnitude lower than those in the reported HPLC and LC-MS methods. Good linearity with correlation coefficients higher than 0.997 were obtained for AAI and AII in the calibration ranges of 0.2-800 ng/mL. The derivatization conditions such as reaction temperature, time and the amount of NaBH(4) were optimized. The developed method provided satisfactory intra-day and inter-day precisions with RSDs less than 1.4% and 3.8%, respectively. The relative analytical error was less than 7% for the analysis of AAI and AAII in spiked matrix samples.

  17. Penetration equations

    Energy Technology Data Exchange (ETDEWEB)

    Young, C.W. [Applied Research Associates, Inc., Albuquerque, NM (United States)

    1997-10-01

    In 1967, Sandia National Laboratories published empirical equations to predict penetration into natural earth materials and concrete. Since that time there have been several small changes to the basic equations, and several more additions to the overall technique for predicting penetration into soil, rock, concrete, ice, and frozen soil. The most recent update to the equations was published in 1988, and since that time there have been changes in the equations to better match the expanding data base, especially in concrete penetration. This is a standalone report documenting the latest version of the Young/Sandia penetration equations and related analytical techniques to predict penetration into natural earth materials and concrete. 11 refs., 6 tabs.

  18. Validation of a high-performance liquid chromatography/fluorescence detection method for the simultaneous quantification of fifteen polycyclic aromatic hydrocarbons

    DEFF Research Database (Denmark)

    Hansen, Åse Marie; Olsen, I L; Holst, E

    1991-01-01

    A high-performance liquid chromatography/fluorescence method using multiple wavelength shift for simultaneous quantification of different PAH compounds was developed. The new method was superior to the methods of DONG and GREENBERG [J. Liquid Chromatogr. 11, 1887-1905 (1988)] and WISE et al...

  19. Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system.

    Science.gov (United States)

    Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

    2013-06-15

    The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid-liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system.

  20. A sensitive fluorescence reagent for the determination of aldehydes from alcoholic beverage using high-performance liquid chromatography with fluorescence detection and mass spectrometric identification

    Energy Technology Data Exchange (ETDEWEB)

    You Jinmao [Northwest Plateau Institute of Biology, Chinese Academy of Sciences, Xining 810001 (China)], E-mail: Jmyou6304@163.com; Yan Tao; Zhao Huaixin [Key Laboratory of Life-Organic Analysis, College of Chemistry Science, Qufu Normal University, Qufu Shandong 273165 (China); Sun Zhiwei; Xia Lian; Suo Yourui; Li Yulin [Northwest Plateau Institute of Biology, Chinese Academy of Sciences, Xining 810001 (China)

    2009-03-16

    A pre-column derivatization method for the sensitive determination of aldehydes using the tagging reagent 2-[2-(7H-dibenzo[a,g] carbazol-7-yl)-ethoxy] ethyl carbonylhydrazine (DBCEEC) followed by high-performance liquid chromatography with fluorescence detection and APCI-MS identification has been developed. The chromophore of fluoren-9-methoxy-carbonylhydrazine (Fmoc-hydrazine) reagent was replaced by 2-[2-(7H-dibenzo[a,g] carbazol-7-yl)-ethoxy] ethyl functional group, which resulted in a sensitive fluorescence tagging reagent DBCEEC. DBCEEC could easily and quickly labeled aldehydes. The maximum excitation (300 nm) and emission (400 nm) wavelengths did not essentially change for all the aldehyde derivatives. Derivatives were sufficiently stable to be efficiently analyzed by high-performance liquid chromatography. The derivatives showed an intense protonated molecular ion corresponding m/z [M + (CH{sub 2}){sub n}]{sup +} in positive-ion mode (M: molecular weight of DBCEEC, n: corresponding aldehyde carbon atom numbers). The collision-induced dissociation of protonated molecular ion formed fragment ions at m/z 294.6, m/z 338.6 and m/z 356.5. Studies on derivatization demonstrated excellent derivative yields in the presence of trichloroacetic acid (TCA) catalyst. Maximal yields close to 100% were observed with a 10 to 15-fold molar reagent excess. Separation of the derivatized aldehydes had been optimized on ZORBAX Eclipse XDB-C{sub 8} column with aqueous acetonitrile as mobile phase in conjunction with a binary gradient elution. Excellent linear responses were observed at the concentration range of 0.01-10 nmol mL{sup -1} with coefficients of >0.9991. Detection limits obtained by the analysis of a derivatized standard containing 0.01 nmol mL{sup -1} of each aldehyde, were from 0.2 to 1.78 nmol L{sup -1} (at a signal-to-noise ratio of 3)

  1. A sensitive fluorescence reagent for the determination of aldehydes from alcoholic beverage using high-performance liquid chromatography with fluorescence detection and mass spectrometric identification.

    Science.gov (United States)

    You, Jinmao; Yan, Tao; Zhao, Huaixin; Sun, Zhiwei; Xia, Lian; Suo, Yourui; Li, Yulin

    2009-03-16

    A pre-column derivatization method for the sensitive determination of aldehydes using the tagging reagent 2-[2-(7H-dibenzo[a,g] carbazol-7-yl)-ethoxy] ethyl carbonylhydrazine (DBCEEC) followed by high-performance liquid chromatography with fluorescence detection and APCI-MS identification has been developed. The chromophore of fluoren-9-methoxy-carbonylhydrazine (Fmoc-hydrazine) reagent was replaced by 2-[2-(7H-dibenzo[a,g] carbazol-7-yl)-ethoxy] ethyl functional group, which resulted in a sensitive fluorescence tagging reagent DBCEEC. DBCEEC could easily and quickly labeled aldehydes. The maximum excitation (300nm) and emission (400nm) wavelengths did not essentially change for all the aldehyde derivatives. Derivatives were sufficiently stable to be efficiently analyzed by high-performance liquid chromatography. The derivatives showed an intense protonated molecular ion corresponding m/z [M+(CH(2))(n)](+) in positive-ion mode (M: molecular weight of DBCEEC, n: corresponding aldehyde carbon atom numbers). The collision-induced dissociation of protonated molecular ion formed fragment ions at m/z 294.6, m/z 338.6 and m/z 356.5. Studies on derivatization demonstrated excellent derivative yields in the presence of trichloroacetic acid (TCA) catalyst. Maximal yields close to 100% were observed with a 10 to 15-fold molar reagent excess. Separation of the derivatized aldehydes had been optimized on ZORBAX Eclipse XDB-C(8) column with aqueous acetonitrile as mobile phase in conjunction with a binary gradient elution. Excellent linear responses were observed at the concentration range of 0.01-10nmolmL(-1) with coefficients of >0.9991. Detection limits obtained by the analysis of a derivatized standard containing 0.01nmolmL(-1) of each aldehyde, were from 0.2 to 1.78nmolL(-1) (at a signal-to-noise ratio of 3).

  2. Rapid determination of polycyclic aromatic hydrocarbons in rainwater by liquid-liquid microextraction and LC with core-shell particles column and fluorescence detection.

    Science.gov (United States)

    Vinci, Giuliana; Antonelli, Marta L; Preti, Raffaella

    2013-02-01

    Liquid-liquid microextraction coupled to LC with fluorescence detection for the determination of Environmental Protection Agency's 16 priority pollutant polycyclic aromatic hydrocarbons in rainwater has been developed. The optimization of the extraction method has involved several parameters, including the comparison between an ultrasonic bath and a magnetic stirrer as extractant apparatus, the choice of the extractant solvent, and the optimization of the extraction time. Liquid-liquid microextraction gave good results in terms of recoveries (from 73.6 to 102.8% in rainwater) and repeatability, with a very simple procedure and low solvent consumption. The reported chromatographic method uses a Core-Shell technology column, with particle size system rather than the more expensive ultrahigh performance LC (UHPLC). An average decrease of 59% in run time and 75% in eluent consumption has been obtained, compared to classical HPLC methods, keeping good separation, sensitivity, and repeatability. The proposed conditions were successfully applied to the determinations of polycyclic aromatic hydrocarbons in genuine rainwater samples.

  3. Excited state dynamics of 9,9'-bianthryl in room temperature ionic liquids as revealed by picosecond time-resolved fluorescence study

    Indian Academy of Sciences (India)

    Dinesh Chandra Khara; Aniruddha Paul; Kotni Santhosh; Anunay Samanta

    2009-05-01

    Picosecond time-resolved fluorescence measurements have been carried out on 9,9'-bianthryl in three imidazolium ionic liquids to probe the excited state dynamics. In the early time-scale, the fluorescence spectra of bianthryl have been found to consist of emission from both locally excited (LE) and charge transfer (CT) states. The LE → CT relaxation time, as estimated from the decay of the fluorescence intensity of the LE emission, is found to vary between 230 and 390 ps, while the average solvent relaxation time, as estimated from the analysis of time-dependent fluorescence Stokes shift, is found to vary between 620 ps and 1840 ps, depending on the viscosity of the ionic liquids. The results confirm that while in conventional less viscous solvents the CT formation kinetics of bianthryl occurs simultaneously with the solvation dynamics, in ionic liquids the two processes mostly occur in different time scales.

  4. Simultaneous determination of 11 fluorescent whitening agents in food-contact paper and board by ion-pairing high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Jiang, Dingguo; Chen, Lisong; Fu, Wusheng; Qiu, Hanquan

    2015-02-01

    4,4'-Diaminostilbene-2,2'-disulfonic acid based fluorescent whitening agents (DSD-FWAs) are prohibited in food-contact paper and board in many countries. In this work, a reliable high-performance liquid chromatography method was developed for the simultaneous determination of 11 common DSD-FWAs in paper material. Sample preparation and extraction as well as chromatographic separation of multicomponent DSD-FWAs were successfully optimized. DSD-FWAs in prepared samples were ultrasonically extracted with acetonitrile/water/triethylamine (40:60:1, v/v/v), separated on the C(18) column with the mobile phase containing tetrabutylammonium bromide, and then detected by a fluorescence detector. The limits of detection were 0.12-0.24 mg/kg, and the calibration curves showed the linear correlation (R(2) ≥ 0.9994) within the range of 8.0-100 ng/mL, which was equivalent to the range of 0.80-10 mg/kg in the sample. The average recoveries and the RSDs were 81-106% and 2-9% at two fortification levels (1.0 and 5.0 mg/kg) in paper bowls, respectively. The successful determination of 11 DSD-FWAs in food-contact paper and board obtained from local markets indicated that the newly developed method was rapid, accurate, and highly selective.

  5. Sensitive determination of specific radioactivity of positron emission tomography radiopharmaceuticals by radio high-performance liquid chromatography with fluorescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Nakao, Ryuji [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan)], E-mail: nakaor@nirs.go.jp; Furutsuka, Kenji [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Sumitomo Accelerator Service, Tokyo 141-8686 (Japan); Yamaguchi, Masatoshi [Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka 814-0180 (Japan); Suzuki, Kazutoshi [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan)

    2008-10-15

    A sensitive quality control method is often required in positron emission tomography (PET) radiopharmaceutical analysis due to the high specific radioactivity of synthetic products. The applicability of a radio high-performance liquid chromatography (HPLC) method with fluorescence detection was evaluated for a wide variety of PET radiopharmaceuticals. In 29 different radiopharmaceuticals studied, 20 compounds exhibited native fluorescence. These properties enabled sensitive determination of their chemical masses by direct fluorimetric detection after separation by HPLC. For some substances, detection limits were below nanograms per milliliter level, at least 40 times better than current UV absorbance detection. Sufficient reproducibility and linearity were obtained for the analysis of pharmaceutical fluid. Post-column fluorimetric derivatization was also established for the quantitative determination of FDG and ClDG in [{sup 18}F]FDG samples. These methods could be applied successfully to the analysis of PET radiopharmaceuticals with ultra-high specific radioactivity.

  6. Ultraviolet-Visible (UV-Vis) and Fluorescence Spectroscopic Investigation of the Interactions of Ionic Liquids and Catalase.

    Science.gov (United States)

    Dong, Xing; Fan, Yunchang; Yang, Peng; Kong, Jichuan; Li, Dandan; Miao, Juan; Hua, Shaofeng; Hu, Chaobing

    2016-11-01

    The inhibitory effects of nine ionic liquids (ILs) on the catalase activity were investigated using fluorescence, absorption ultraviolet-visible spectroscopy. The interactions of ILs and catalase on the molecular level were studied. The experimental results indicated that ILs could inhibit the catalase activity and their inhibitory abilities depended on their chemical structures. Fluorescence experiments showed that hydrogen bonding played an important role in the interaction process. The inhibitory abilities of ILs on catalase activity could be simply described by their hydrophobicity and hydrogen bonding abilities. Unexpected less inhibitory effects of trifluoromethanesulfonate (TfO(-)) might be ascribed to its larger size, which makes it difficult to go through the substrate channel of catalase to the active site. © The Author(s) 2016.

  7. Fluorescence anisotropy of diphenylhexatriene and its cationic Trimethylamino derivative in liquid dipalmitoylphosphatidylcholine liposomes: opposing responses to isoflurane

    Directory of Open Access Journals (Sweden)

    Nelson Steven C

    2012-03-01

    Full Text Available Abstract Background The mechanism of action of volatile general anesthetics has not yet been resolved. In order to identify the effects of isoflurane on the membrane, we measured the steady-state anisotropy of two fluorescent probes that reside at different depths. Incorporation of anesthetic was confirmed by shifting of the main phase transition temperature. Results In liquid crystalline dipalmitoylphosphatidylcholine liposomes, isoflurane (7-25 mM in the bath increases trimethylammonium-diphenylhexatriene fluorescence anisotropy by ~0.02 units and decreases diphenylhexatriene anisotropy by the same amount. Conclusions The anisotropy data suggest that isoflurane decreases non-axial dye mobility in the headgroup region, while increasing it in the tail region. We propose that these results reflect changes in the lateral pressure profile of the membrane.

  8. Determination of oxolinic acid, danofloxacin, ciprofloxacin, and enrofloxacin in porcine and bovine meat by micellar liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Terrado-Campos, David; Tayeb-Cherif, Khaled; Peris-Vicente, Juan; Carda-Broch, Samuel; Esteve-Romero, Josep

    2017-04-15

    A method was developed for the determination of oxolinic acid, danofloxacin, ciprofloxacin and enrofloxacin by micellar liquid chromatography - fluorescence detection in commercial porcine and bovine meat. The samples were ultrasonicated in a micellar solution, free of organic solvent, to extract the analytes, and the supernatant was directly injected. The quinolones were resolved in 0.9998), trueness (89.3-105.1%), precision (<8.3%), decision limit (<12% over the maximum residue limit), detection capability (<21% over the maximum residue limit), ruggedness (<5.6%) and stability. The procedure was rapid, eco-friendly, safe and easy-to-handle.

  9. Rapid determination of silver in nanobased liquid dietary supplements using a portable X-ray fluorescence analyzer.

    Science.gov (United States)

    Sánchez-Pomales, Germarie; Mudalige, Thilak K; Lim, Jin-Hee; Linder, Sean W

    2013-07-31

    This paper reports a rapid and straightforward method for the quantitation of total Ag content in nanobased commercially available liquid dietary supplements using a portable X-ray fluorescence (pXRF) analyzer. Figures of merits were evaluated by analyzing a series of AgNO3 standards. This method was shown to have a detection limit of 3 ppm, a quantitation limit of 10 ppm, and a broad linear range from the detection limit to 10000 ppm (1%). Accurate detection and quantitation of Ag content in well-characterized Ag nanoparticle samples and in nanobased liquid dietary supplements were achieved with good correlation (i.e., percentage difference average values under 15%) between the total Ag concentration obtained by the pXRF analyzer and by inductively coupled plasma mass spectrometry (ICP-MS). Furthermore, accurate quantitation of Ag in the presence of high concentrations of potential spectral interferences was also demonstrated.

  10. Fluorescent derivatization combined with aqueous solvent-based dispersive liquid-liquid microextraction for determination of butyrobetaine, l-carnitine and acetyl-l-carnitine in human plasma.

    Science.gov (United States)

    Chen, Yi-Ching; Tsai, Chia-Ju; Feng, Chia-Hsien

    2016-09-16

    A novel aqueous solvent-based dispersive liquid-liquid microextraction (AS-DLLME) method was combined with narrow-bore liquid chromatography and fluorescence detection for the determination of hydrophilic compounds. A remover (non-polar solvent) and extractant (aqueous solution) were introduced into the derivatization system (acetonitrile) to obtain a water-in-oil emulsion state that increased the mass transfer of analytes. As a proof of concept, three quaternary ammonium substances, including butyrobetaine, l-carnitine and acetyl-l-carnitine, were also used as analytes and determined in pharmaceuticals, personal care products, food and human plasma. The analytes were derivatized with 4-bromomethylbiphenyl for fluorescence detection and improved retention in the column. The linear response was 10-2000nM for l-carnitine and acetyl-l-carnitine with a good determination coefficient (r(2)>0.998) in the standard solution. The detection limit for l-carnitine and acetyl-l-carnitine was 4.5 fmol. The method was also successfully applied to a 1μL sample of human plasma. In the linearity calculations for determining butyrobetaine, l-carnitine and acetyl-l-carnitine in human plasma, the determination coefficients ranged from 0.996 to 0.999. Linear regression exhibited good reproducibility and a relative standard deviation better than 7.50% for the slope and 9.06% for the intercept. To characterize highly hydrophilic compounds in various samples, the proposed method provides good sensitivity for a small sample volume with a low consumption of toxic solvents.

  11. A simple and specific high performance liquid chromatography method for the assay of a series of novel dermal penetration enhancers.

    Science.gov (United States)

    Michniak, B B; Seyda, K L

    1993-02-01

    Synopsis A series of clofibric acid amides has been synthesized and previously reported by the authors as possessing enhancer activity in vitro in athymic nude mouse skin against model drugs, hydrocortisone-21-acetate and beta-methasone-17-valerate. An assay was required for each of these enhancers however, which would be specific for each compound and would also separate model drugs and their metabolite peaks. This study reports reverse phase high performance liquid chromatography assays for clofibric acid amide and seven derivatives (Ia-Ig). All enhancers showed maximum absorption at 232 nm, betamethasone (BM) and its valerate (BMV) at 238 nm, and hydrocortisone (HC) and its acetate (HCA) at 242 nm. Practical units of detection for the amides were 0.46-2.8 mug ml(-1) and peaks were sharp and well-separated from steroid peaks in three vehicles - methanol alone. Franz diffusion cell receptor phase samples (isotonic phosphate buffer), and full-thickness athymic nude mouse skin extracts in methanol. Mobile phases consisted of various proportions of acetonitrile and water, some with 2-propanol. The octyl amide for example, with mobile phase CH(3)CN: H(2)O (85:15) at 1 ml min(-1) had a retention time (t(R)) of 7.9 mins. Under the same conditions, retention times for the steroids were HC, t(R)= 3.3 mins; HCA, t(R)= 4.3 mins; BM, t(R)= 3.4 mins; BMV, t(R)= 4.6 mins. Résumé Les auteurs avaient démontré dans un article précédent le pouvoir accélérateur de pénétration dermique in vitro d'une gamme d'amides d'acide clofibrique sur la peau de souris sans poils, et sans thymus avec des médicaments types tels que l'acetate 21 d'hydrocortisone et le valerate 17 de beta-metasone. Il a cependant été requis, pour chacun de ces accélérateurs, un test spécifique pour chaque composition, permettant de séparer chaque médicament et les pics des métabolites. Cette étude décrit des tests par chromatographie liquide à haute performance en phase inverse pour l

  12. The impalement of water drops impinging onto hydrophobic/superhydrophobic graphite surfaces: the role of dynamic pressure, hammer pressure and liquid penetration time

    Science.gov (United States)

    Pittoni, Paola G.; Lin, Ya-Chi; Lin, Shi-Yow

    2014-05-01

    Droplet impingement experiments at low Weber numbers were conducted by digitizing silhouettes of impacting water drops onto unlike graphite substrates, typified by different advancing water contact angles (θa): 140 and 160°. The relaxation of wetting diameter, dynamic contact angle, and drop shapes were measured. The purpose was to carefully investigate the phenomenology and possible causes of the failure of the superhydrophobicity. During impact and spreading phases, all the drops impinging onto both graphite substrates showed a similar behavior. Then, after an initial free recoil, drops impinging at lower impact velocities onto graphite substrates characterized by θa = 140° clearly exhibited time intervals in which the wetting diameter appeared to be almost constant. The duration of this pinned phase was observed decreasing with increasing the impact height and almost completely disappearing for drops impinging at higher impact velocities. This behavior has never been reported before, and, contrariwise, water droplets impinging at lower impact velocities onto hydrophobic and superhydrophobic surfaces have been generally observed more freely retracting, and ultimately rebounding, compared to drops impacting at higher velocities. In the present study, this latter behavior was recorded just for drops impinging onto graphite surfaces characterized by θa = 160°. A theoretical description of the experimental results was proposed, specifically investigating the role of dynamic pressure, hammer pressure and liquid penetration time during the impact, spreading and recoil stages.

  13. X-ray fluorescence analysis of trace metal ions following a preconcentration of metal-diethyldithiocarbamate complexes by homogeneous liquid-liquid extraction

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Atsushi; Igarashi, Shukuro; Ueki, Yasuo [Ibaraki Univ., Hitachi (Japan). Faculty of Engineering; Yamaguchi, Hitoshi [National Research Inst. for Metals, Ibaraki (Japan)

    2000-11-01

    A homogeneous liquid-liquid extraction method for 36 metal ions with diethyldithiocarbamate was studied. As a result, 11 metal ions were extracted as metal-chelates. Under the experimental conditions, the maximum concentration factor was 500 (i.e., 0.1 mL of sedimented liquid phase was produced from 50 mL of aqueous phase). Moreover, the proposed method was utilized as a preconcentration method for X-ray fluorescence analysis of these metals. The recovery of each metal was ca. 97-100%. All calibration curves were linear over the range of 5.0 x 10{sup -7} mol L{sup -1} to 1.0 x 10{sup -5} mol L{sup -1}. The detection limits were at the 10{sup -8} mol L{sup -1} levels and the relative standard deviations were below 5% (5 determinations). When the proposed method was used for the determination of contaminants in a synthetic sample (Al-based alloy model) and of components in an Au-Pd alloy, the results were satisfactory. (orig.)

  14. Determination of quinolone residues in shrimp using liquid chromatography with fluorescence detection and residue confirmation by mass spectrometry.

    Science.gov (United States)

    Karbiwnyk, Christine M; Carr, Lori E; Turnipseed, Sherri B; Andersen, Wendy C; Miller, Keith E

    2007-07-23

    The quinolones, oxolinic acid (OXO), flumequine (FLU), and nalidixic acid (NAL), are antibacterial drugs effective against gram-negative bacteria. Quinolones are used in both human and veterinary medicine, but are currently not approved by the U.S. Food and Drug Administration for use in food fish. A liquid chromatography-fluorescence (LC-FL) method was developed to determine OXO, FLU, and NAL residues in shrimp. An additional liquid chromatography-mass spectrometry (LC-MS(n)) method was created to confirm these residues using the same sample extract. Samples were prepared with a simple ethyl acetate extraction followed by solvent exchange into 0.2% formic acid and cleaned-up with hexane. Reverse phase chromatography was used to separate the three compounds in both procedures. For the LC-FL determinative method, fluorescence emission was monitored at 369 nm with excitation at 327 nm. With electrospray ionization, the three most abundant ions from the MS3 product ion spectrum were used to identify OXO, FLU, and NAL in the confirmation procedure. Shrimp samples fortified at levels ranging from 7.5 to 100 ng g(-1) were used to validate both methods.

  15. Determination of 11 quinolones in bovine milk using immunoaffinity stir bar sorptive microextraction and liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Yao, Kai; Zhang, Wei; Yang, Linyan; Gong, Jianfang; Li, Liuan; Jin, Tianming; Li, Cun

    2015-10-15

    A sensitive, selective and reproducible immunoaffinity stir bar sorptive microextraction (SBSME) coupled with liquid chromatography-fluorescence method for determination of 11 quinolones (QNs) in bovine milk was developed and validated. It is first report of a broad-specificity monoclonal antibody to QNs that has been immobilized to glass bar for preparation of a re-usable immunoaffinity stir bar. Analytes were extracted by placing stir bar in milk and shaking on a rotary shaker for 30min at 30rpm, followed by liquid chromatography and fluorescence detection. The newly developed method has limits of detection for each QN from 0.05 to 0.1ng/g with intra-day and inter-day precision ranging from 3.2 to 11.9% and from 5.2 to 12.5%, respectively. This allowed us to quantitatively analyze drugs in bovine milk with the advantage of significantly simplified sample preparation. The proposed method was successfully applied to the bovine milk samples analyses with QNs, demonstrating its rare application in animal food safety analysis.

  16. Determination and characterization of phytochelatins by liquid chromatography coupled with on line chemical vapour generation and atomic fluorescence spectrometric detection.

    Science.gov (United States)

    Bramanti, Emilia; Toncelli, Daniel; Morelli, Elisabetta; Lampugnani, Leonardo; Zamboni, Roberto; Miller, Keith E; Zemetra, Joseph; D'Ulivo, Alessandro

    2006-11-10

    Liquid chromatography (LC) coupled on line with UV/visible diode array detector (DAD) and cold vapour generation atomic fluorescence spectrometry (CVGAFS) has been developed for the speciation, determination and characterization of phytochelatins (PCs). The method is based on a bidimensional approach, e.g. on the analysis of synthetic PC solutions (apo-PCs and Cd(2+)-complexed PCs) (i) by size exclusion chromatography coupled to UV diode array detector (SEC-DAD); (ii) by the derivatization of PC -SH groups in SEC fractions by p-hydroxymercurybenzoate (PHMB) and the indirect detection of PC-PHMB complexes by reversed phase liquid chromatography coupled to atomic fluorescence detector (RPLC-CVGAFS). MALDI-TOF/MS (matrix assisted laser desorption ionization time of flight mass spectrometry) analysis of underivatized synthetic PC samples was performed in order have a qualitative information of their composition. Quantitative analysis of synthetic PC solutions has been performed on the basis of peak area of PC-PHMB complexes of the mercury specific chromatogram and calibration curve of standard solution of glutathione (GSH) complexed to PHMB (GS-PHMB). The limit of quantitation (LOQ) in terms of GS-PHMB complex was 90 nM (CV 5%) with an injection volume of 35 microL, corresponding to 3.2 pmol (0.97 ng) of GSH. The method has been applied to analysis of extracts of cell cultures from Phaeodactylum tricornutum grown in Cd-containing nutrient solutions, analysed by SEC-DAD-CVGAFS and RPLC-DAD-CVGAFS.

  17. Liquid chromatographic determination with fluorescence detection of B{sub 6} vitamers and riboflavin in milk and pharmaceuticals

    Energy Technology Data Exchange (ETDEWEB)

    Gatti, R. [Dipartimento di Scienze Farmaceutiche, Universita di Bologna, Via Belmeloro 6, 40126 Bologna (Italy)]. E-mail: rita.gatti2@unibo.it; Gioia, M.G. [Dipartimento di Scienze Farmaceutiche, Universita di Bologna, Via Belmeloro 6, 40126 Bologna (Italy)

    2005-05-04

    A simple, reliable and selective high performance liquid chromatographic method with fluorescence detection at different programmed wavelengths has been developed for the simultaneous analysis of B{sub 6} vitamers (pyridoxal 5'-phosphate, 4-pyridoxic acid, pyridoxal, pyridoxine and pyridoxamine) and Vitamin B{sub 2} in commercial vitaminized milk and in woman milk. The chromatographic separations were performed on a reversed phase octyl column by using a mobile phase consisting of sodium pentanesulfonate in 1% acetic acid-methanol-tetrahydrofuran under gradient elution conditions. The fluorescence intensity of pyridoxal 5'-phosphate was enhanced by post-column photochemical conversion, giving significantly different fluorescence spectra by a on-line photoreactor switched OFF and ON under irradiation at 254 nm. In addition, a simple and rapid method in isocratic conditions without the need of photochemical conversion was proposed for the analysis of Vitamin B{sub 6} and Vitamin B{sub 2} in pharmaceuticals. Linearity, precision, recovery, selectivity and sensitivity were found satisfactory for each analysed compound. Quantitation limits ranged from 26 to 240 fmol.

  18. Determination of ubiquinone in blood by high-performance liquid chromatography with post-column fluorescence derivatization using 2-cyanoacetamide.

    Science.gov (United States)

    Nohara, Yukio; Suzuki, Junko; Kubo, Hiroaki

    2011-11-01

    It was shown that ubiquinone (CoQ(10)) and ubiquinol (CoQ(10)H(2)) produce fluorescence products under alkaline conditions when reacted with 2-cyanoacetamide. The reaction mixture from CoQ(10) gave fluorescence with excitation and emission maximum wavelengths at 442 nm and 549 nm, respectively. This reaction was considered to proceed via Craven's reaction. Moreover, 2-cyanoacetamide was shown to be a useful reagent for high-performance liquid chromatography (HPLC) with post-column fluorescence derivatization of CoQ(10) and CoQ(10)H(2) in blood. CoQ(10) showed a linear response in the range of 0.32-1276 ng, and the detection limit (S/N = 3) was 0.16 ng. Moreover, the sample pretreatment by deproteinization and extraction of CoQ(10) and CoQ(10)H(2) from plasma using 1-propanol with potassium formate was effective for excellent separation of CoQ(10) and CoQ(10)H(2) from other fluorescent substances in the blood. This simple and rapid pretreatment was considered to minimize the oxidation of CoQ(10)H(2). On the other hand, CoQ(10) and CoQ(10)H(2) in plasma samples obtained by finger prick were detected, as in venous blood obtained by venipuncture. Our method involving the simple and rapid collection of plasma by finger prick and sample pretreatment is thought to be applicable for the determination of CoQ(10)H(2)/total CoQ(10) ratio as a biomarker of oxidative stress.

  19. A simple, sensitive determination of ganciclovir in infant plasma by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Yoshida, Terumitsu; Takahashi, Ryohei; Imai, Koichi; Uchida, Hiroshi; Arai, Yasutoshi; Oh-ishi, Tsutomu

    2010-03-01

    This study developed a simple and sensitive method using reversed-phase high-performance liquid chromatography (HPLC) for ganciclovir (GCV) plasma concentrations in cytomegalovirus infectious infants with hearing loss. The method involves a simple protein precipitation procedure that uses no solid-phase or liquid-liquid extraction. The HPLC separation was carried out on a Cadenza CD-C(18) column (3 microm, 4.6 mm x 150 mm) with phosphate buffer (pH 2.5, 25 mM) containing 1% methanol-acetonitrile mixture (4:3, v/v) as a mobile phase at a 0.7 mL/min flow rate. GCV was detected using a fluorescence detection (lambdaex/em: 265/380 nm). The quantification limit was 0.025 microg/mL for 100 microL of plasma sample at which good intra- and inter-assay coefficient of variation values (< 4.96%) and recoveries (94.9-96.5%) were established.

  20. Fluorescence depolarization and contact angle investigation of dynamic and static interfacial tension of liquid crystal display materials.

    Science.gov (United States)

    Quintella, Cristina M; Lima, Angelo M V; Gonçalves, Cristiane C; Watanabe, Yuji N; Mammana, Alaide P; Schreiner, Marcos A; Pepe, Iuri; Pizzo, Angela A

    2003-06-01

    Interfacial interactions control two processes empirically known to be critical for molecular anchoring in twisted nematic liquid crystal displays technology (TN-LCDs): surface treatment and filling procedure. Static and dynamical interfacial tensions (Gamma(SL)) between liquids and several substrates with similar roughness were observed respectively by contact angle (theta(c)) of sessile drops and by fluorescence depolarization of thin liquid films flowing at high velocity. Gamma(SL) decreased when glass was coated with tin dioxide and increased with polyvinyl alcohol (PVA) deposition. Drops were circular for all substrates except rubbed PVA, where they flowed spontaneously along the rubbing direction, reaching an oblong form that had theta(c) parallel and perpendicular to the rubbing direction respectively greater and smaller than theta(c) for non-rubbed PVA. This is attributed to polar group alignment generating an asymmetric Gamma(SL) distribution with nanometric preferential direction, inducing a capillary-like flow. Polarization and anisotropy maps for high-velocity flow parallel to the PVA rubbing direction showed an increase in the net alignment of molecular domains and a widening of the region where it occurred. This is attributed to preferential anchoring in the downstream direction, instead of in several directions, as for non-rubbed PVA. This explains why filling direction is crucial for TN-LCDs homogeneous behavior.

  1. Redistribution of fluorescent molecules at the solid/liquid interface with total internal reflection illumination.

    Science.gov (United States)

    Wei, Lin; Ye, Zhongju; Luo, Wenjuan; Chen, Bo; Xiao, Lehui

    2016-08-01

    Many intriguing physical and chemical processes commonly take place at the solid/liquid interface. Total internal reflection illumination, together with single molecule spectroscopy, provides a robust platform for the selective exploration of kinetic processes close the interface. With these techniques, it was observed that the distribution of Rhodamine B molecules close to a solid/liquid interface could be regulated in a photo-induced route. The laser-induced repulsion force at this interface is enough to compromise the Brownian diffusion of single molecules in a range of several hundred nanometers normal to the solid/liquid interface. This observation is fundamentally and practically interesting because moderate laser intensity is enough to initiate this repulsion effect. Therefore, it might display extensive applications in the development of photo-modulation technique with high throughput capability.

  2. Porphyrin synthesized from cashew nut shell liquid as part of a novel superparamagnetic fluorescence nanosystem

    Science.gov (United States)

    Clemente, C. S.; Ribeiro, V. G. P.; Sousa, J. E. A.; Maia, F. J. N.; Barreto, A. C. H.; Andrade, N. F.; Denardin, J. C.; Mele, G.; Carbone, L.; Mazzetto, S. E.; Fechine, P. B. A.

    2013-06-01

    Magnetic Fe3O4 nanoparticles with average size approximately 11 nm were first oleic acid coated to interact with the meso-porphyrin derivative from CNSL. This procedure produced a novel superparamagnetic fluorescent nanosystem (SFN) linked by van der Waals interactions. This system was characterized by transmission electron microscope, infrared spectroscopy, thermogravimetric analysis, magnetic measurements, UV-Vis absorption, and fluorescence emission measurements. These results showed that SFN has good thermal stability, excellent magnetization, and nanosized dimensions ( 13 nm). It exhibited emission peaks at 668 and 725 nm with a maximum emission at 467 nm of excitation wavelength. The type of interaction between porphyrin and magnetic nanoparticles allowed to obtain a material with interesting optical properties which might be used as an imaging agent for contrast in cells as well as heterogeneous photocatalysis.

  3. Fluorescence-based remote irradiation sensor in liquid-filled hollow-core photonic crystal fiber

    Science.gov (United States)

    Zeltner, R.; Bykov, D. S.; Xie, S.; Euser, T. G.; Russell, P. St. J.

    2016-06-01

    We report an irradiation sensor based on a fluorescent "flying particle" that is optically trapped and propelled inside the core of a water-filled hollow-core photonic crystal fiber. When the moving particle passes through an irradiated region, its emitted fluorescence is captured by guided modes of the fiber core and so can be monitored using a filtered photodiode placed at the fiber end. The particle speed and position can be precisely monitored using in-fiber Doppler velocimetry, allowing the irradiation profile to be measured to a spatial resolution of ˜10 μm. The spectral response can be readily adjusted by appropriate choice of particle material. Using dye-doped polystyrene particles, we demonstrate detection of green (532 nm) and ultraviolet (340 nm) light.

  4. Porphyrin synthesized from cashew nut shell liquid as part of a novel superparamagnetic fluorescence nanosystem

    Energy Technology Data Exchange (ETDEWEB)

    Clemente, C. S.; Ribeiro, V. G. P.; Sousa, J. E. A.; Maia, F. J. N.; Barreto, A. C. H. [Universidade Federal do Ceara, Laboratorio de Produtos e Tecnologia em Processos (LPT) (Brazil); Andrade, N. F. [Universidade Federal do Ceara, Departamento de Fisica (Brazil); Denardin, J. C. [Universidad de Santiago de Chile (USACH), Departamento de Fisica (Chile); Mele, G. [Universita del Salento, Dipartimento di Ingegneria dell' Innovazione (Italy); Carbone, L. [NNL, Istituto Nanoscienze UOS Lecce (Italy); Mazzetto, S. E. [Universidade Federal do Ceara, Laboratorio de Produtos e Tecnologia em Processos (LPT) (Brazil); Fechine, P. B. A., E-mail: fechine@ufc.br [Universidade Federal do Ceara (UFC), Grupo de Quimica de Materiais Avancados (GQMAT), Departamento de Quimica Analitica e Fisico-Quimica (Brazil)

    2013-06-15

    Magnetic Fe{sub 3}O{sub 4} nanoparticles with average size approximately 11 nm were first oleic acid coated to interact with the meso-porphyrin derivative from CNSL. This procedure produced a novel superparamagnetic fluorescent nanosystem (SFN) linked by van der Waals interactions. This system was characterized by transmission electron microscope, infrared spectroscopy, thermogravimetric analysis, magnetic measurements, UV-Vis absorption, and fluorescence emission measurements. These results showed that SFN has good thermal stability, excellent magnetization, and nanosized dimensions ({approx}13 nm). It exhibited emission peaks at 668 and 725 nm with a maximum emission at 467 nm of excitation wavelength. The type of interaction between porphyrin and magnetic nanoparticles allowed to obtain a material with interesting optical properties which might be used as an imaging agent for contrast in cells as well as heterogeneous photocatalysis.

  5. Quantitative determination of Closantel residues in milk by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Stoev, G; Dakova, T; Michailova, A

    1999-06-18

    A HPLC method with fluorescence detection for quantitative determination of Closantel residues in milk has been developed and validated. The proposed cleaning procedure with acetonitrile and acetone extraction, and solid-phase clean-up with Florisil enables concentrations of Closantel below 50 micrograms/l to be determined. The method was shown to be sufficient, precise, accurate, selective and rugged. The method was applied in the regular monitoring of Closantel residues in milk and of the pharmacokinetic behavior of Closantel in sheep.

  6. A comparative evaluation of different ionic liquids for arsenic species separation and determination in wine varietals by liquid chromatography - hydride generation atomic fluorescence spectrometry.

    Science.gov (United States)

    Castro Grijalba, Alexander; Fiorentini, Emiliano F; Martinez, Luis D; Wuilloud, Rodolfo G

    2016-09-02

    The application of different ionic liquids (ILs) as modifiers for chromatographic separation and determination of arsenite [As(III)], arsenate [As(V)], dimethylarsonic acid (DMA) and monomethylarsonic acid (MMA) species in wine samples, by reversed-phase high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry detection (RP-HPLC-HG-AFS) was studied in this work. Several factors influencing the chromatographic separation of the As species, such as pH of the mobile phase, buffer solution concentration, buffer type, IL concentration and length of alkyl groups in ILs were evaluated. The complete separation of As species was achieved using a C18 column in isocratic mode with a mobile phase composed of 0.5% (v/v) 1-octyl-3-methylimidazolium chloride ([C8mim]Cl) and 5% (v/v) methanol at pH 8.5. A multivariate methodology was used to optimize the variables involved in AFS detection of As species after they were separated by HPLC. The ILs showed remarkable performance for the separation of As species, which was obtained within 18min with a resolution higher than 0.83. The limits of detection for As(III), As(V), MMA and DMA were 0.81, 0.89, 0.62 and 1.00μg As L(-1). The proposed method was applied for As speciation analysis in white and red wine samples originated from different grape varieties.

  7. Characterization of the external and internal flow structure of an aerated-liquid injector using X-ray radiography and fluorescence

    Science.gov (United States)

    Peltier, Scott J.; Lin, Kuo-Cheng; Carter, Campbell D.; Kastengren, Alan L.

    2017-09-01

    In the present study, the internal flowfield of aerated-liquid fuel injectors is examined through X-ray radiography and X-ray fluorescence. An inside- out injector, consisting of a perforated aerating tube within an annular liquid stream, sprays into a quiescent environment at a fixed mass flow rate of water and nitrogen gas. The liquid is doped with bromine (in the form of NaBr) to create an X-ray fluorescence signal. This allows for reasonable absorption and fluorescence signals, and one or both diagnostics can be used to track the liquid distribution. The injector housing is fabricated from beryllium (Be), which allows the internal flowfield to be examined (as Be has relatively low X-ray attenuation coefficient). Two injector geometries are compared, illustrating the effects of aerating orifice size and location on the flow evolution. Time-averaged equivalent pathlength and line-of-sight averaged density ρ( y) reveal the formation of the two-phase mixture, showing that the liquid film thickness along the injector walls is a function of the aerating tube geometry, though only upstream of the nozzle. These differences in gas and liquid distribution (between injectors with different aerating tube designs) are suppressed as the mixture traverses the nozzle contraction. The averaged liquid velocity (computed from the density and liquid mass flow rate) reveals a similar trend. This suggests that at least for the current configurations, the plume width, liquid mass distribution, and averaged liquid velocity for the time-averaged external spray are insensitive to the aerating tube geometry.

  8. Respirator Testing Using Virus Aerosol: Comparison between Viability Penetration and Physical Penetration.

    Science.gov (United States)

    Zuo, Zhili; Kuehn, Thomas H; Pui, David Y H

    2015-07-01

    Viability, fluorescence (particle volume), photometric, viral RNA, and particle number penetration of MS2 bacteriophage through filter media used in three different models of respirators were compared to better understand the correlation between viability and physical penetration. Although viability and viral RNA penetration were better represented by particle volume penetration than particle number penetration, they were several-fold lower than photometric penetration, which was partially due to the difference in virus survival between upstream and downstream aerosol samples. Results suggest that the current NIOSH photometer-based test method can be used as a quick means to roughly differentiate respirators with different performance against virus aerosols.

  9. Determination of low molecular weight thiols using monobromobimane fluorescent labeling and high-performance liquid chromatography

    Science.gov (United States)

    Fahey, Robert C.; Newton, Gerald L.

    1988-01-01

    Methods are described for the preparation and high-performance liquid chromatography (HPLC) analysis of monobromobimane derivatives of low molecular weight thiols in extracts of biological samples. Typical problems encountered in the development and application of these methods are discussed. Analysis of mung bean extract is used as an example.

  10. Serum protein profile study of normal and cervical cancer subjects by high performance liquid chromatography with laser-induced fluorescence.

    Science.gov (United States)

    Sujatha; Rai, Lavanya; Kumar, Pratap; Mahato, Krishna K; Kartha, Vasudevan B; Santhosh, Chidangil

    2008-01-01

    High performance liquid chromatography with high sensitivity laser-induced fluorescence detection is used to study the protein profiles of serum samples from healthy volunteers and cervical cancer subjects. The protein profiles are subjected to principal component analysis (PCA). PCA shows that the large number of chromatograms of a given class of serum samples--say normal/malignant--can be expressed in terms of a small number of factors (principal components). Three parameters--scores of the factors, squared residuals, and Mahalanobis distance--are derived from PCA. The parameters are observed to have a narrow range for protein profiles of standard calibration sets formed from groups of clinically confirmed normal/malignant classes. Limit tests using match/no match of the parameters of any test sample with parameters derived for the standard calibration sets give very good discrimination between malignant and normal samples with high sensitivity (approximately 100%) aand specificity (approximately 94%).

  11. Feasibility study of total reflection X-ray fluorescence analysis using a liquid metal jet X-ray tube

    Energy Technology Data Exchange (ETDEWEB)

    Maderitsch, A.; Smolek, S. [Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Wien (Austria); Wobrauschek, P., E-mail: wobi@ati.ac.at [Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Wien (Austria); Streli, C. [Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Wien (Austria); Takman, P. [Excillum AB, Finlandsgatan 14, 164 74 Kista (Sweden)

    2014-09-01

    Total reflection X-ray spectroscopy (TXRF) is a powerful analytical technique for qualitative and quantitative analysis of trace and ultratrace elements in a sample with lower limits of detection (LLDs) of pg/g to ng/g in concentration and absolute high fg levels are attainable. Several X-ray sources, from low power (few W), 18 kW rotating anodes to synchrotron radiation, are in use for the excitation and lead accordingly to their photon flux delivered on the sample the detection limits specified. Not only the power, but also the brilliance and focal shape are of importance for TXRF. A microfocus of 50–100 μm spot size or the line focus of diffraction tubes is best suited. Excillum developed a new approach in the design of a source: the liquid metal jet anode. In this paper the results achieved with this source are described. A versatile TXRF spectrometer with vacuum chamber designed at Atominstitut was used for the experiments. A multilayer monochromator selecting the intensive Ga-Kα radiation was taken and the beam was collimated by 50 μm slits. Excellent results regarding geometric beam stability, high fluorescence intensities and low background were achieved leading to detection limits in the high fg range for Ni. A 100 mm{sup 2} silicon drift detector (SDD) collimated to 80 mm{sup 2} was used to collect the fluorescence radiation. The results from measurements on single element samples are presented. - Highlights: • Using a new X-ray source for TXRF • Liquid metal jet X-ray source from Excillum • Offers improvements for lab based TXRF spectrometers • Can also be important for related techniques.

  12. Efficient analysis of selected estrogens using fabric phase sorptive extraction and high performance liquid chromatography-fluorescence detection.

    Science.gov (United States)

    Kumar, Rajesh; Gaurav; Heena; Malik, Ashok Kumar; Kabir, Abuzar; Furton, Kenneth G

    2014-09-12

    A simple, fast and sensitive analytical method using fabric phase sorptive extraction (FPSE) followed by high performance liquid chromatography with fluorescence detection (HPLC-FLD) has been developed for efficient quantification of biologically important molecules e.g., 17α-ethynylestradiol (EE2), β-estradiol (E2) and bisphenol A (BPA). FPSE is a new sorptive extraction technique that integrates the advantages of permeable sol-gel derived hybrid organic-inorganic sorbents with flexible and permeable fabric substrates, resulting in a highly efficient and sensitive extraction media that can be introduced directly into any kind of fluidic matrix. Various factors affecting the performance of FPSE technique were optimized. The chromatographic separation was carried using mobile phase acetonitrile/methanol/water (30:15:55; v/v) at a flow rate 1.0mL/min on C18 column with fluorescence detection (λex=280nm and λem=310nm). The calibration curves of the target analytes were prepared with good correlation coefficient values (R(2)>0.992). Limit of detection (LOD) values range from 20 to 42pg/mL. The developed method was applied successfully for the analysis of estrogen molecules in urine and various kinds of aqueous samples.

  13. [Study on fluorescence labeling and determination of polypeptide (PC2~PC6) by high performance liquid chromatography].

    Science.gov (United States)

    Li, Jing-xi; Gao, Li-jie; Cao, Wei; Zheng, Li; Chen, Jun-hui; Xu, Xiu-li; Wang, Xiao-ru

    2014-12-01

    This study was based on the thiol groups (-SH) of PC2~PC6, which could be reacted with the Monobromobimane (mBBr), in order to get polypeptide derivatives with fluorescent signal. A new method was developed for measuring the Polypeptides by high performance liquid chromatography with fluorescence detector, then the chromatographic conditions of HPLC was optimized; meawhile the reaction proportion of PCs and mBBr was identified by Trap-MS. The results showed that, the reaction proportion of PCs and mBBr was 1:1, the polypeptide derivatives had good stability; the five compounds separation was better, and the peak time focused on the 16.6~22.0 min; the linear correlation coefficient of PC2, PC3, PC4, PC5 and PC6 was >0.9991, and the limits of quantification were 0.3, 0.05, 0.3, 0.5 and 0.8 mg · L(-1) respectively, the recovery rate was 83.0%-102.0%; the method was reproducible, RSD<2%, this method for measuring the peptide compounds was rapid and accurate.

  14. Determination of Fluorescent Whitening Agents in Paper Materials by Ion-Pair Reversed-Phase High-Performance Liquid Chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong Soo; Kim, Keon [Korea Univ., Seoul (Korea, Republic of); Kim, Do Hwan [Daegu Univ., Gyeongsan (Korea, Republic of)

    2012-12-15

    A simple method was developed for the analysis of seven stilbene-type fluorescent whitening agents (FWAs) in paper materials by ion-pair reversed-phase high-performance liquid chromatography with fluorescence detection. These stilbene-type FWAs included two disulfonate, two tetrasulfonate, and three hexasulfonate compounds. After optimization of chromatographic conditions, the FWAs were satisfactorily separated using a reversed-phase column (RP-18) with the following isocratic mobile phase: methanol-water (60:40) containing 17.5 mM TBABr and 10 mM citrate buffer (pH = 7.0). The calibration plot was linear in the range from 5 to 500 ng/mL for two disulfo-FWAs and from 1 to 500 ng/mL for the other five FWAs. Precision levels of the calibration curve as indicated by RSD of response factors were 1.2 and 8.1%. Limits of quantitation (LOQ) ranged from 1.2 to 11 ng/mL.

  15. Fluorescence detection of tramadol in healthy Chinese volunteers by high-performance liquid chromatography and bioequivalence assessment

    Directory of Open Access Journals (Sweden)

    Zhou X

    2015-02-01

    Full Text Available Xiao Zhou, Ji Liu Department of Anesthesia, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, People’s Republic of China Abstract: This study developed a revised high-performance liquid chromatography fluorescence method to determine plasma tramadol concentration, and thereby to examine the bioequivalence of two tramadol formulations among healthy male Chinese volunteers. The study used a double-blind, randomized, 2×2 crossover-design principle. Calculated pharmacokinetic parameters for both formulations were consistent with previous reports. According to the observation of vital signs and laboratory measurement, no subjects had any adverse reactions. The geometric mean ratios (90% confidence interval of the test drug/reference drug for tramadol were 100.2% (95.3%–103.4% for the area under the plasma concentration–time curve (AUC from time zero to the last measurable concentration, 99.6% (94.2%–102.7% for the AUC from administration to infinite time, and 100.8% (93.1%–106.4% for maximum concentration. For the 90% confidence intervals of the test/reference AUC ratio and maximum concentration ratio of tramadol, both were in the acceptance range for bioequivalence. According to the two preparations by pharmacokinetic parameter statistics, the half-life, mean residence time, and clearance values showed no significant statistical differences. Therefore, the conclusion of this study was that the two tramadol formulations (tablets and capsules were bioequivalent. Keywords: tramadol hydrochloride, in vitro release, pharmacokinetic, bioequivalence, fluorescence detector

  16. A liquid core waveguide fluorescence detector for multicapillary electrophoresis applied to DNA sequencing in a 91-capillary array.

    Science.gov (United States)

    Hanning, A; Westberg, J; Roeraade, J

    2000-09-01

    A new laser-induced fluorescence (LIF) detector for multicapillary electrophoresis is presented. The detection principle is based on waveguiding of the emitted fluorescence from the point of illumination to the capillary ends by total internal reflection (TIR) and imaging of the capillary ends. The capillaries themselves thus act as liquid core waveguides (LCWs). At the illumination point, the capillaries are arranged in a planar array, which allows clean and efficient illumination with a line-focused laser beam. The capillary ends are rearranged into a small, densely packed two-dimensional array, which is imaged end-on with high light collection efficiency and excellent image quality. Wavelength dispersion is obtained with a single prism. Intercapillary optical crosstalk is less than 0.5%, and rejection of stray light is very efficient. The detector is applied to four-color DNA sequencing by gel electrophoresis in a 91-capillary array, with simple fluorescein and rhodamine dyes as fluorophores. Since the imaged two-dimensional array is so compact, the detector has a high potential for very large-scale multiplexing.

  17. Selective Determination of tetrabromobisphenol A by liquid chromatography following intramolecular excimer-forming fluorescence derivatization with pyrene-labeling reagent

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, H.; Tsunetomo, S.; Todoroki, K.; Nohta, H.; Yamaguchi, M. [Fukuoka Univ. (Japan); Hayama, T. [Foundation for Kyushu Environmental and Occupational Health, Kurume (Japan); Kuroki, H. [Daiichi College of Pharmaceutical Sciences, Fukuoka (Japan)

    2004-09-15

    A large number of compounds have been used as flame-retardants to protect different products from catching fire, and one of the most widely used flameretardants is tetrabromobisphenol A (TBBPA). Trace amounts of TBBPA have been determined by gas chromatography (GC) with electron-capture detection or GC-mass spectrometry (MS) as reviewed in. Only a few liquid chromatographic (LC) methods have been reported. Recently, we developed highly selective and sensitive determination methods for polyamines and dicarboxylic acids based on intramolecular excimer-forming fluorescence derivatization using pyrene reagents. By the derivatization, the resulting polypyrene-labeled derivatives of polyamines and dicarboxylic acids provided intramolecular excimer fluorescence at the wavelength region of 440 - 520 nm, which was shifted markedly to the higher emission wavelengths as compared to the wavelengths of the pyrene reagent itself and monopyrene-labeled concomitants (360 - 420 nm). This chemistry allowed to selectively analyzing poly-functional compounds even in the complex samples containing monofunctional compounds. More recently, we have found that 4-(1-pyrene)butanoyl chloride (PBC) reacts with not only polyamines, but also phenol compounds such as bisphenols, and the obtained PBC derivatives form strong intramolecular excimers. The aim of this work was to develop an intramolecular excimer-forming derivatization method for fluorimetric determination of halogenated-bisphenols including TBBPA following their derivatization with PBC. The new method allows a highly sensitive and selective determination of tetrabromobisphenol A.

  18. Quantification of β-carotene, retinol, retinyl acetate and retinyl palmitate in enriched fruit juices using dispersive liquid-liquid microextraction coupled to liquid chromatography with fluorescence detection and atmospheric pressure chemical ionization-mass spectrometry.

    Science.gov (United States)

    Viñas, Pilar; Bravo-Bravo, María; López-García, Ignacio; Hernández-Córdoba, Manuel

    2013-02-01

    A detailed optimization of dispersive liquid-liquid microextraction (DLLME) was carried out for developing liquid chromatographic (HPLC) techniques, using both fluorescence and atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection, for the simultaneous analysis of preforms of vitamin A: retinol (R), retinyl acetate (RA), retinyl palmitate (RP) and β-carotene (β-C). The HPLC analyses were carried out using a mobile phase composed of methanol and water, with gradient elution. The APCI-MS and fluorescence spectra permitted the correct identification of compounds in the analyzed samples. Parameters affecting DLLME were optimized using 2 mL of methanol (disperser solvent) containing 150 μL carbon tetrachloride (extraction solvent). The precision ranged from 6% to 8% (RSD) and the limits of detection were between 0.03 and 1.4 ng mL(-1), depending on the compound. The enrichment factor values were in the 21-44 range. Juice samples were analyzed without saponification and no matrix effect was found when using fluorescence detection, so calibration was possible with aqueous standards. However, a matrix effect appeared with APCI-MS, in which case it was necessary to apply matrix-matched calibration. There was great variability in the forms of vitamin A present in the juices, the most abundant ester being retinyl acetate (0.04 to 3.4 μg mL(-1)), followed by the amount of retinol (0.01 to 0.16 μg mL(-1)), while retinyl palmitate was not detected, except in the milk-containing juice, in which RP was the main form. The representative carotenoid β-carotene was present in the orange, peach, mango and multifruit juices in high amounts. The method was validated using two certified reference materials.

  19. Optimization of fluorescence detection for polyaromatic hydrocarbon determination by using high performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Marriott, P.J.; Carpenter, P.D.; Brady, P.H.; McCormick, M.J.; Griffiths, A.J.; Hatvani, T.S.G.; Rasdell, S.G. (Royal Melbourne Inst. of Tech., Victoria (Australia))

    1993-01-01

    Polyaromatic hydrocarbon determination is often one of the requirements in site evaluations and chemical audit studies, particularly where the site usage is to change from industrial to recreational or domestic housing. It is also a general parameter included in air particulate studies and water quality evaluations in the urban environment, where PAHs accumulate as a result of vehicle and industrial emissions. The procedures needed for the optimization of programmable fluorescence detectors have been investigated. The authors found that wavelength programs had to be developed from data obtained from the particular detector for which the program was to be used--programs reported in the literature or developed from data obtained on other instruments gave substantially lower sensitivities. The wavelength program they developed was a compromise between: chromatographic separation, abundance and relative sensitivity of each PAH; the ease with which a timed event could be included in the elution profile and; the relative importance of each PAH to the analyst. The success of programmable fluorescence detection was dependant on the reproducibility with which the detector was able to reset specified wavelengths, with corresponding detector response variability of up to 20% for one new detector.

  20. High-performance liquid chromatography with fluorescence detection for the rapid analysis of pheophytins and pyropheophytins in virgin olive oil.

    Science.gov (United States)

    Li, Xueqi; Woodman, Michael; Wang, Selina C

    2015-08-01

    Pheophytins and pyropheophytin are degradation products of chlorophyll pigments, and their ratios can be used as a sensitive indicator of stress during the manufacturing and storage of olive oil. They increase over time depending on the storage condition and if the oil is exposed to heat treatments during the refining process. The traditional analysis method includes solvent- and time-consuming steps of solid-phase extraction followed by analysis by high-performance liquid chromatography with ultraviolet detection. We developed an improved dilute/fluorescence method where multi-step sample preparation was replaced by a simple isopropanol dilution before the high-performance liquid chromatography injection. A quaternary solvent gradient method was used to include a fourth strong solvent wash on a quaternary gradient pump, which avoided the need to premix any solvents and greatly reduced the oil residues on the column from previous analysis. This new method not only reduces analysis cost and time but shows reliability, repeatability, and improved sensitivity, especially important for low-level samples.

  1. Determination of alkylphenol and alkylphenolethoxylates in biota by liquid chromatography with detection by tandem mass spectrometry and fluorescence spectroscopy

    Science.gov (United States)

    Schmitz-Afonso, I.; Loyo-Rosales, J.E.; de la Paz Aviles, M.; Rattner, B.A.; Rice, C.P.

    2003-01-01

    A quantitative method for the simultaneous determination of octylphenol, nonylphenol and the corresponding ethoxylates (1 to 5) in biota is presented. Extraction methods were developed for egg and fish matrices based on accelerated solvent extraction followed by a solid-phase extraction cleanup, using octadecylsilica or aminopropyl cartridges. Identification and quantitation were accomplished by liquid chromatography-electrospray tandem mass spectrometry (LC-MS-MS) and compared to the traditional liquid chromatography with fluorescence spectroscopy detection. LC-MS-MS provides high sensitivity and specificity required for these complex matrices and an accurate quantitation with the use of 13C-labeled internal standards. Quantitation limits by LC-MS-MS ranged from 4 to 12 ng/g in eggs, and from 6 to 22 ng/g in fish samples. These methods were successfully applied to osprey eggs from the Chesapeake Bay and fish from the Great Lakes area. Total levels found in osprey egg samples were up to 18 ng/g wet mass and as high as 8.2 ug/g wet mass in the fish samples.

  2. Comparison of High Performance Liquid Chromatography with Fluorescence Detector and with Tandem Mass Spectrometry methods for detection and quantification of Ochratoxin A in green and roasted coffee beans

    Directory of Open Access Journals (Sweden)

    Raquel Duarte da Costa Cunha Bandeira

    2013-12-01

    Full Text Available Two analytical methods for the determination and confirmation of ochratoxin A (OTA in green and roasted coffee samples were compared. Sample extraction and clean-up were based on liquid-liquid phase extraction and immunoaffinity column. The detection of OTA was carried out with the high performance liquid chromatography (HPLC combined either with fluorescence detection (FLD, or positive electrospray ionization (ESI+ coupled with tandem mass spectrometry (MS-MS. The results obtained with the LC-ESI-MS/MS were specific and more sensitive, with the advantages in terms of unambiguous analyte identification, when compared with the HPLC-FLD.

  3. Simultaneous analysis of aflatoxins B1, B2, G1, G2, M1 and ochratoxin A in breast milk by high-performance liquid chromatography/fluorescence after liquid-liquid extraction with low temperature purification (LLE-LTP).

    Science.gov (United States)

    Andrade, Patricia Diniz; Gomes da Silva, Julyane Laine; Caldas, Eloisa Dutra

    2013-08-23

    The aims of this study were to optimize and validate a methodology for the simultaneous analysis of aflatoxins B1, B2, G1, G2, M1 (AFB1, AFB2, AFG1, AFG2, AFM1) and ochratoxin A (OTA) in breast milk, and to analyze these mycotoxins in samples obtained from human milk banks in the Federal District, Brazil. The optimized analytical method was based on liquid-liquid extraction with low temperature purification (3.25mL of acidified acetonitrile+0.75mL of ethyl acetate), followed by analysis by high-performance liquid chromatography with fluorescence detector (HPLC/FLD) and a photochemical post-column reactor. Limits of quantification (LOQ) ranged from 0.005 to 0.03ng/mL, recoveries from 73 to 99.5%, and relative standard deviations (RSD) from 1.8 to 17.3%. The LLE-LTP extraction method was shown to be simple and cost-effective, since no columns were needed for clean-up. Only 2 of the 224 breast milk samples analyzed were positive for the mycotoxins, both samples containing AFB2 at the LOQ level (0.005ng/mL). The identity of the mycotoxin detected was confirmed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). This result indicates that infants who are fed with breast milk from the milk banks are not at risk from aflatoxin and ochratoxin exposure.

  4. High Efficiency Pulse Acetone Liquid Raman Laser Using DCM Fluorescent Dye as the Enhancement Medium

    Institute of Scientific and Technical Information of China (English)

    CHENG Andrew Yuk-Sun; YANG Jing-Guo; CHAN Mau-Hing

    2006-01-01

    Pumped by a frequency-doubled Nd:YAG laser, 10-Hz repetition rate, 320-mJ pump energy, and 5.1-ns pulse width, a liquid Raman laser using acetone as the Raman shifting medium has been established. The residual pump laser pulse and the generated Stokes pulse are directed to a DCM dye cell for energy enhancement of the Stokes pulse. The Raman laser system is capable to produce a laser pulse at wavelength 630 nm, with single pulse energy of 120 mJ, peak power of 70 MW and an average power of 1200 mW. The energy conversion efficiency is 37.5%, or equivalently a quantum efficiency of 44.5%.

  5. Co marker determination in rumen liquid sample by energy dispersive X-ray fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Eduardo de; Nascimento Filho, Virgilio F.; Massoni, Paulo R. [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de Instrumentacao Nuclear (LIN)]. E-mail: edualm@usp.br; Leite, Laudi C.; Lanna, Dante P.D. [Escola Superior de Agricultura ' Luiz de Queiroz' (ESALQ/USP), Piracicaba, SP (Brazil). Dept. de Zootecnia. Lab. de Anatomia e Fisiologia Animal (LAFA)]. E-mail: lcleite@ciagri.usp.br

    2007-07-01

    The Co element is used in nutritional studies as marker. This paper describes an analytical methodology for Co determination in rumen liquid sample using energy dispersive X-ray spectrometry (EDXRF). 200 {mu}L of the sample were dried at 60 deg C on 6.35 {mu}m Mylar film. Ga was used as internal standard. The excitation was carried out utilizing Mo target X-ray tube (Zr filter) at 30 kV / 20 mA. The acquisition time was 200 s. The accuracy of this methodology was assessed through standard addition method, the recovery obtained was 98.7 % for Co. The detection limit was 0.15 mg / L for this element. (author)

  6. Simultaneous determination of six triterpenic acids in some Chinese medicinal herbs using ultrasound-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Wu, Hongliang; Li, Guoliang; Liu, Shucheng; Liu, Di; Chen, Guang; Hu, Na; Suo, Yourui; You, Jinmao

    2015-03-25

    A novel analytical method was developed for simultaneous determination of six triterpenic acids using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) follow by high-performance liquid chromatography (HPLC) with fluorescence detection. Six triterpenic acids (ursolic acid, oleanolic acid, betulinic acid, maslinic acid, betulonic acid and corosolic acid) were extracted by UA-DLLME using chloroform and acetone as the extraction and disperser solvents, respectively. After the extraction and nitrogen flushing, the extracts were rapidly derivatized with 2-(12,13-dihydro-7H-dibenzo[a,g]carbazol-7-yl)ethyl4-methylbenzenesulfonate. The main experimental parameters affecting extraction efficiency and derivatization yield were investigated and optimized by response surface methodology (RSM) combined with Box-Behnken design (BBD). The limits of detection (LODs) and the limits of quantification (LOQs) were in the range of 0.95-1.36 ng mL(-1) and 3.17-4.55 ng mL(-1), respectively. Under the optimum conditions, the method has been successfully applied for the analysis of triterpenic acids in six different traditional Chinese medicinal herbs.

  7. Antimony speciation analysis in sediment reference materials using high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Potin-Gautier, M. [Laboratoire de Chimie Analytique, BioInorganique et Environnement LCABIE (UMR CNRS 3054), Universite de Pau et des pays de l' Adour, 64000 Pau (France); Pannier, F. [Laboratoire de Chimie Analytique, BioInorganique et Environnement LCABIE (UMR CNRS 3054), Universite de Pau et des pays de l' Adour, 64000 Pau (France)]. E-mail: Florence.pannier@univ-pau.fr; Quiroz, W. [Laboratoire de Chimie Analytique, BioInorganique et Environnement LCABIE (UMR CNRS 3054), Universite de Pau et des pays de l' Adour, 64000 Pau (France); Laboratorio de Quimica Analitica y Ambiental, Instituto de Quimica, Pontificia Universidad catolica de Valparaiso (Chile); Pinochet, H. [Laboratorio de Quimica Analitica y Ambiental, Instituto de Quimica, Pontificia Universidad catolica de Valparaiso (Chile); Gregori, I. de [Laboratorio de Quimica Analitica y Ambiental, Instituto de Quimica, Pontificia Universidad catolica de Valparaiso (Chile)

    2005-11-30

    This work presents the development of suitable methodologies for determination of the speciation of antimony in sediment reference samples. Liquid chromatography with a post-column photo-oxidation step and hydride generation atomic fluorescence spectrometry as detection system is applied to the separation and determination of Sb(III), Sb(V) and trimethylantimony species. Post-column decomposition and hydride generation steps were studied for sensitive detection with the AFS detector. This method was applied to investigate the conditions under which speciation analysis of antimony in sediment samples can be carried out. Stability studies of Sb species during the extraction processes of solid matrices, using different reagents solutions, were performed. Results demonstrate that for the extraction yield and the stability of Sb species in different marine sediment extracts, citric acid in ascorbic acid medium was the best extracting solution for antimony speciation analysis in this matrix (between 55% and 65% of total Sb was recovered from CRMs, Sb(III) being the predominant species). The developed method allows the separation of the three compounds within 6 min with detection limits of 30 ng g{sup -1} for Sb(III) and TMSbCl2 and 40 ng g{sup -1} for Sb(V) in sediment samples.

  8. Fluorescence detection of tramadol in healthy Chinese volunteers by high-performance liquid chromatography and bioequivalence assessment.

    Science.gov (United States)

    Zhou, Xiao; Liu, Ji

    2015-01-01

    This study developed a revised high-performance liquid chromatography fluorescence method to determine plasma tramadol concentration, and thereby to examine the bioequivalence of two tramadol formulations among healthy male Chinese volunteers. The study used a double-blind, randomized, 2×2 crossover-design principle. Calculated pharmacokinetic parameters for both formulations were consistent with previous reports. According to the observation of vital signs and laboratory measurement, no subjects had any adverse reactions. The geometric mean ratios (90% confidence interval) of the test drug/reference drug for tramadol were 100.2% (95.3%-103.4%) for the area under the plasma concentration-time curve (AUC) from time zero to the last measurable concentration, 99.6% (94.2%-102.7%) for the AUC from administration to infinite time, and 100.8% (93.1%-106.4%) for maximum concentration. For the 90% confidence intervals of the test/reference AUC ratio and maximum concentration ratio of tramadol, both were in the acceptance range for bioequivalence. According to the two preparations by pharmacokinetic parameter statistics, the half-life, mean residence time, and clearance values showed no significant statistical differences. Therefore, the conclusion of this study was that the two tramadol formulations (tablets and capsules) were bioequivalent.

  9. High-throughput isolation of giant viruses in liquid medium using automated flow cytometry and fluorescence staining.

    Directory of Open Access Journals (Sweden)

    Jacques Yaacoub Bou Khalil

    2016-01-01

    Full Text Available The isolation of giant viruses using amoeba co-culture is tedious and fastidious. Recently, the procedure was successfully associated with a method that detects amoebal lysis on agar plates. However, the procedure remains time-consuming and is limited to protozoa growing on agar. We present here advances for the isolation of giant viruses. A high-throughput automated method based on flow cytometry and fluorescent staining was used to detect the presence of giant viruses in liquid medium. Development was carried out with the Acanthamoeba polyphaga strain widely used in past and current co-culture experiments. The proof of concept was validated with virus suspensions: artificially contaminated samples but also environmental samples from which viruses were previously isolated. After validating the technique, and fortuitously isolating a new Mimivirus, we automated the technique on 96-well plates and tested it on clinical and environmental samples using other protozoa. This allowed us to detect more than ten strains of previously known species of giant viruses and 7 new strains of a new virus lineage. This automated high-throughput method demonstrated significant time saving, and higher sensitivity than older techniques. It thus creates the means to isolate giant viruses at high speed.

  10. Determination of Ochratoxin A in Wheat and Maize by Solid Bar Microextraction with Liquid Chromatography and Fluorescence Detection.

    Science.gov (United States)

    Al-Hadithi, Nabil; Kössler, Philip; Karlovsky, Petr

    2015-08-05

    Solid bar microextraction (SBME), followed by liquid chromatography with fluorescence detection (HPLC-FLD), for the quantification of ochratoxin A in wheat and maize was developed. Ground wheat and maize grains were extracted with acetonitrile-water-acetic acid (79:20:1, v/v/v), followed by defatting with cyclohexane, and subjected to SBME-LC-FLD analysis. SBME devices were constructed by packing 2 mg sorbent (C18) into porous polypropylene micro-tubes (2.5 cm length, 600 μm i.d., and 0.2 μm pore size). SBME devices were conditioned with methanol and placed into 5 mL stirred sample solutions for 70 min. After extraction, OTA was desorbed into 200 μL of methanol for 15 min, the solution was removed in vacuum, the residue was dissolved in 50 μL of methanol-water (1:1, v/v) and ochratoxin A content was determined by HPLC-FLD. Under optimized extraction conditions, the limit of detection of 0.9 μg·kg(-1) and 2.5 μg·kg(-1) and the precision of 3.4% and 5.0% over a concentration range of 1 to 100 μg·kg(-1) in wheat and maize flour, respectively, were obtained.

  11. High-Throughput Isolation of Giant Viruses in Liquid Medium Using Automated Flow Cytometry and Fluorescence Staining

    Science.gov (United States)

    Khalil, Jacques Y. B.; Robert, Stephane; Reteno, Dorine G.; Andreani, Julien; Raoult, Didier; La Scola, Bernard

    2016-01-01

    The isolation of giant viruses using amoeba co-culture is tedious and fastidious. Recently, the procedure was successfully associated with a method that detects amoebal lysis on agar plates. However, the procedure remains time-consuming and is limited to protozoa growing on agar. We present here advances for the isolation of giant viruses. A high-throughput automated method based on flow cytometry and fluorescent staining was used to detect the presence of giant viruses in liquid medium. Development was carried out with the Acanthamoeba polyphaga strain widely used in past and current co-culture experiments. The proof of concept was validated with virus suspensions: artificially contaminated samples but also environmental samples from which viruses were previously isolated. After validating the technique, and fortuitously isolating a new Mimivirus, we automated the technique on 96-well plates and tested it on clinical and environmental samples using other protozoa. This allowed us to detect more than 10 strains of previously known species of giant viruses and seven new strains of a new virus lineage. This automated high-throughput method demonstrated significant time saving, and higher sensitivity than older techniques. It thus creates the means to isolate giant viruses at high speed. PMID:26858703

  12. Reversed-phase liquid chromatography coupled on-line to estrogen receptor bioaffinity detection based on fluorescence polarization.

    Science.gov (United States)

    Reinen, Jelle; Kool, Jeroen; Vermeulen, Nico P E

    2008-04-01

    We describe the development and validation of a high-resolution screening (HRS) platform which couples gradient reversed-phase high-performance liquid chromatography (RP-HPLC) on-line to estrogen receptor alpha (ERalpha) affinity detection using fluorescence polarization (FP). FP, which allows detection at high wavelengths, limits the occurrence of interference from the autofluorescence of test compounds in the bioassay. A fluorescein-labeled estradiol derivative (E2-F) was synthesized and a binding assay was optimized in platereader format. After subsequent optimization in flow-injection analysis (FIA) mode, the optimized parameters were translated to the on-line HRS bioassay. Proof of principle was demonstrated by separating a mixture of five compounds known to be estrogenic (17beta-estradiol, 17alpha-ethinylestradiol and the phytoestrogens coumestrol, coumarol and zearalenone), followed by post-column bioaffinity screening of the individual affinities for ERalpha. Using the HRS-based FP setup, we were able to screen affinities of off-line-generated metabolites of zearalenone for ERalpha. It is concluded that the on-line FP-based bioassay can be used to screen for the affinity of compounds without the disturbing occurrence of autofluorescence.

  13. Determination of alpha-methyldopa in human plasma by validated high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Róna, K; Ary, K; Gachályi, B; Klebovich, I

    1996-04-12

    A sensitive reversed-phase gradient elution high-performance liquid chromatographic method with fluorescence detection has been developed for the determination of alpha-methyldopa (AMD) in human plasma. Separation of the investigated compound and the 3,4-dihydroxyphenylalanine (DOPA) internal standard was achieved on a Nucleosil 7 C18 column with a 5 mM heptanesulphonic acid sodium salt containing 0.05 M potassium dihydrogenphosphate (pH 3.2)-acetonitrile mobile phase. The composition of the mobile phase was changed according to a linear gradient time program. Detection was performed at 270 nm fluorimetric excitation and 320 nm emission. The compounds were isolated from plasma by Bond-Elut C18 solid-phase extraction. The limit of quantitation was found to be 10 ng/ml plasma. The assay was validated with respect to accuracy, precision and system suitability. All validated parameters were found to be within the 20% required limits. On the basis of the sensitivity, linearity and validation parameters the developed analytical method was found to be suitable for application in a bioequivalency study.

  14. New sample treatment for determination of linear alkylbenzene sulfonate (LAS) in agricultural soils by liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Nimer, M; Ballesteros, O; Navalón, A; Crovetto, G; Verge, C; López, I; Berna, J L; Vílchez, J L

    2007-03-01

    A new sample-treatment procedure has been developed for determination of total linear alkylbenzene sulfonate (LAS), i.e. homologues and isomers, in agricultural soil. The procedure involves two steps, ultrasound-assisted extraction of LAS from the samples with methanol then clean-up of the methanolic extracts and preconcentration of the LAS by solid-phase extraction on two adsorbent cartridges (SAX and C18). The ultrasound-assisted procedure reduces extraction time (10 min in contrast with 6-12 h for conventional Soxhlet extraction) and requires only small volumes of organic solvent. The effect of different variables interacting in the ultrasound-assisted extraction process was studied. Finally, separation and quantification of the homologues and isomers of LAS was performed by liquid chromatography with fluorescence detection (LC-FD). 2-Octylbenzenesulfonic acid sodium salt (Na-2ØC8-LAS) was used as internal standard. The proposed method was satisfactorily used for determination of LAS in agricultural soil samples from the fertile plain of Granada (Spain).

  15. Serum protein profile study of clinical samples using high performance liquid chromatography-laser induced fluorescence: case of cervical and oral cancers

    Science.gov (United States)

    Karemore, Gopal; Sujatha, .; Rai, Lavanya; Pai, Keerthilatha M.; Kartha, V. B.; Santhosh C., .

    2009-02-01

    The serum protein profiles of normal subjects, patients diagnosed with cervical cancer, and oral cancer were recorded using High Performance Liquid Chromatography combined with Laser Induced Fluorescence detection (HPLC-LIF). Serum protein profiles of the above three classes were tested for establishing the ability of HPLC-LIF protein profiling technique for discrimination, using hard clustering and Fuzzy clustering methods. The clustering algorithms have quite successfully classified the profiles as belonging to normal, cancer of cervix, and oral cancer conditions.

  16. A new direct laser photo-induced fluorescence method coupled on-line with liquid chromatographic separation for the simultaneous determination of anilides pesticides.

    Science.gov (United States)

    Mbaye, O M A; Maroto, A; Gaye-Seye, M D; Stephan, L; Deschamps, L; Aaron, J J; Giamarchi, P

    2015-01-01

    A new direct laser photo-induced fluorescence high performance liquid chromatography (DL-PIF-HPLC) method is developed for the simultaneous determination of three anilide pesticides, namely carboxin, monalide and propanil. DL-PIF-HPLC uses a tunable Nd:YAG-OPO laser to obtain fluorescent photoproduct(s) and to simultaneously analyze their fluorescence in a short acquisition time with an intensified CCD camera, which improves the selectivity (by choosing the suitable excitation wavelength), increases the sensitivity (due to the high energy of the laser beam) and reduces the time of analysis, relative to the classical PIF methods. However, one of the main drawbacks of PIF methods is the presence of interferences with other compounds, such as other pesticides from the same group yielding similar fluorescent photoproducts, which reduces their selectivity. The analytical interest of DL-PIF-HPLC to avoid these interferences is demonstrated. The DL-PIF spectra, chromatographic conditions and analytical performances of DL-PIF-HPLC are presented for the simultaneous determination of three anilide pesticides. The calibration curves are linear over one order of magnitude and the limits of detection are in the ng mL(-1) range. The new DL-PIF-HPLC system has the advantage to combine the performances of both techniques, DL-PIF and liquid chromatography, and to improve the analysis selectivity.

  17. Determination of Gonyautoxin-4 in Echinoderms and Gastropod Matrices by Conversion to Neosaxitoxin Using 2-Mercaptoethanol and Post-Column Oxidation Liquid Chromatography with Fluorescence Detection.

    Science.gov (United States)

    Silva, Marisa; Rey, Verónica; Botana, Ana; Vasconcelos, Vitor; Botana, Luis

    2015-12-30

    Paralytic Shellfish Toxin blooms are common worldwide, which makes their monitoring crucial in the prevention of poisoning incidents. These toxins can be monitored by a variety of techniques, including mouse bioassay, receptor binding assay, and liquid chromatography with either mass spectrometric or pre- or post-column fluorescence detection. The post-column oxidation liquid chromatography with fluorescence detection method, used routinely in our laboratory, has been shown to be a reliable method for monitoring paralytic shellfish toxins in mussel, scallop, oyster and clam species. However, due to its high sensitivity to naturally fluorescent matrix interferences, when working with unconventional matrices, there may be problems in identifying toxins because of naturally fluorescent interferences that co-elute with the toxin peaks. This can lead to erroneous identification. In this study, in order to overcome this challenge in echinoderm and gastropod matrices, we optimized the conversion of Gonyautoxins 1 and 4 to Neosaxitoxin with 2-mercaptoethanol. We present a new and less time-consuming method with a good recovery (82.2%, RSD 1.1%, n = 3), requiring only a single reaction step.

  18. Determination of S-carboxymethyl-L-cysteine and some of its metabolites in urine and serum by high-performance liquid chromatography using fluorescent pre-column labelling.

    Science.gov (United States)

    Staffeldt, B; Brockmöller, J; Roots, I

    1991-11-15

    Pre-column labelling techniques are described for the determination of S-carboxymethyl-L-cysteine (CMC) and its metabolites in urine and plasma samples by high-performance liquid chromatography (HPLC) without prior extraction. All substances containing an amino group were converted into fluorescent fluorenylmethyl derivatives with 9-fluorenylmethyloxycarbonyl chloride (FMOC). Deaminated or N-acetylated carbocysteine metabolites were coupled with 1-pyrenyldiazomethane (PDAM) to give fluorescent PDAM esters. Similar results were obtained with the two commercially available and stable diazomethane derivatives PDAM and 9-anthryldiazomethane (ADAM). Following double derivatization with PDAM and FMOC, in a single chromatographic run with two fluorescence detectors connected in series, amines and amino(carboxylic) acids could be detected by their FMOC residues and, simultaneously, carboxylic acids were detected as fluorescent PDAM esters. The (R) and (S) enantiomers of the sulphoxides of CMC, of methylcysteine and of N-acetyl CMC were separated, although the reversed-phase HPLC system did not contain a chiral additive or stationary phase designed for the separation of enantiomers. The methods do not include liquid extraction steps and can therefore be performed either manually or automatically using an HPLC autosampler. These methods were used for the investigation of a disputed pharmacogenetic polymorphism of S-oxidation of CMC in humans, which until now has most often been studied using paper chromatography. The described techniques were applied to the determination of CMC and its metabolites in human urine and plasma samples.

  19. Determination of mesotrione residues and metabolites in crops, soil, and water by liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Alferness, Philip; Wiebe, Lawrence

    2002-07-03

    A method for the determination of residues of mesotrione and two metabolites in a variety of environmental matrixes has been developed. Mesotrione, a new selective herbicide for use in corn, is 2-(4-methylsulfonyl-2-nitrobenzoyl)-1,3-cyclohexanedione. The metabolite 4-methylsulfonyl-2-nitrobenzoic acid (MNBA) is determined with the parent compound in crops, whereas two metabolites, 2-amino-4-methylsulfonyl-benzoic acid (AMBA) and MNBA are determined with parent in soil and water. Crop samples are macerated with an acetonitrile/water mixture, and an aliquot is evaporated and acidified then centrifuged. Soil is shaken with an ammonium hydroxide solution, and an aliquot is acidified then centrifuged. For water analysis, an aliquot is acidified. Crop and soil extracts, and water, are cleaned up using reverse-phase high-performance liquid chromatography (RPHPLC) with mesotrione and MNBA isolated using a fraction collector. During this clean up, AMBA is determined in soil and water samples using fluorescence detection. The collected mesotrione and MNBA fractions are converted into AMBA via oxidation followed by reduction in the case of mesotrione, or by reduction alone in the case of MNBA. Both fractions are analyzed by RPHPLC with fluorescence detection using an AMBA external reference standard. The method was tested on corn grain, fodder, and forage, as well as on sugar cane. The limits of quantitation (LOQ) for each analyte are 0.01 mg/kg for crops, 0.005 mg/kg for soil, and 0.10 microg/L for water. Method fortification recoveries from all crop commodities averaged 79% (CV = 7%, n = 37 and 82% (CV = 5%, n = 37) for mesotrione and MNBA, respectively. Soil was fortified at 0.005 and 0.05 mg/kg. Recoveries were 79% (CV = 4%, n = 12), 96% (CV = 2%, n = 12), and 89% (CV = 2%, n = 12) for mesotrione, MNBA, and AMBA, respectively. Groundwater, drinking water, seawater, and river water were fortified at 0.1 and 1.0 microg/L. Recoveries for all waters were 80% (CV = 7%, n = 51

  20. [Determination of seven biothiols in rice by high performance liquid chromatography-fluorescence detection with pre-column derivatization].

    Science.gov (United States)

    Zhou, Rong; Cao, Zhaoyun; Mou, Renxiang; Li, Zhengxiang; Chen, Mingxue

    2015-01-01

    A high performance liquid chromatographic method with fluorescence detection and precolumn derivatization (HPLC-FLD) has been developed for the determination of seven biothiols including Cys, GSH, and phytochelatins (PCs: PC2, PC3, PC4, PC5 and PC6) in rice. The samples were ultrasonically extracted with 0.1% trifluoroacetic acid (TFA) containing 6. 3 mmol/L diethylenetriaminepentaacetic acid (DTPA), and then the seven biothiols were derivatized with monobromobimane (mBrB) as derivatization agent in 4-(2-hydroxyethyl)-1-piperazine propanesulfonic acid (HEPPS) buffer solution (pH 8.0). The separation was performed on an Agilent Eclipse Plus C18 column (50 mm x 4.6 mm, 5 microm) with gradient elution of 0.1% TFA solution (the pH value was adjusted to 2.5 with hydrochloric acid) and acetonitrile as mobile phases at a flow rate of 0.8 mL/min. The detection was performed at 380 nm for excitation and 470 nm for emission. The calibration curves of the seven biothiols showed good linearity in the concentration range of 0.7-100.0 mg/L with the correlation coefficients (r2) > or = 0.9991. The limits of detection were 0.03-0.20 mg/L. The recoveries of standard addition were in the range of 89.26%-99.42% with the relative standard deviations (RSDs, n = 6) of 2.05%-5.87%. The method is sensitive, accurate, reproducible and suitable for the simultaneous determination of Cys, GSH, PC2, PC3, PC4, PC5 and PC6 in rice.

  1. Migration of bisphenol A from polycarbonate baby bottles purchased in the Spanish market by liquid chromatography and fluorescence detection.

    Science.gov (United States)

    Santillana, M I; Ruiz, E; Nieto, M T; Bustos, J; Maia, J; Sendón, R; Sánchez, J J

    2011-11-01

    During the last decade the safety of bisphenol A (BPA) monomer in polycarbonate baby bottles has drawn the attention of both the public and the scientific community. This paper presents the results of BPA migration from polycarbonate baby bottles bought in the Spanish market, into simulant B (3% acetic acid), 50% ethanol and into real food (reconstituted infant formula). Furthermore, it was also the objective of this study to assess the suitability of 50% ethanol as a simulant for infant formula. BPA was analysed by a multi-analyte liquid chromatography method with fluorescence detection and mass spectrometry confirmation. The method was in-house validated and accredited by the national accreditation body. The validation results for this analyte in the previous mentioned matrices were: LOD = 0.004-0.007 mg kg(-1); LOQ (validated) = 0.03 mg kg(-1); RSD% = 3.4-5.8; and recovery = 106.6-118.2%. A collection of 72 different baby bottle samples from 12 different brands were analysed. Baby bottle material was identified by FTIR. The migration test conditions used were those recommended for baby bottles in the Guidelines on testing conditions for articles in contact with foodstuffs (with a focus on kitchenware), prepared by the European network of laboratories for food-contact materials. In most of the migration assays the results were below the LOD. In four of the commercial brands there was detectable migration into the simulant 50% ethanol and BPA was detected in only two samples of infant formula (0.01 mg kg(-1)). Migration results obtained were in compliance with European Union regulations.

  2. Determination of selective serotonin reuptake inhibitors in plasma and urine by micellar liquid chromatography coupled to fluorescence detection.

    Science.gov (United States)

    Agrawal, Nitasha; Esteve-Romero, Josep; Bose, Devasish; Dubey, Neeti Prakesh; Peris-Vicente, Juan; Carda-Broch, Samuel

    2014-08-15

    Citalopram, paroxetine and fluoxetine are selective serotonin reuptake inhibitor (SSRIs) currently used in the treatment of psychiatric disorders. We present an analytical method using micellar liquid chromatography to quantify these three drugs in pharmaceutical formulations, plasma and urine. The resolution was performed using a mobile phase of 0.075 M SDS - 6% (v/v) butanol buffered at pH 7 running through a C18 column under isocratic mode at 1 mL/min at 25°C. The analytes were eluted in less than 20 min. The fluorescence detection was programmed at the maximum excitation (236, 295 and 230 nm) and emission (310, 350 and 305 nm) wavelengths for citalopram, paroxetine and fluoxetine, respectively. The experimental procedure was expedited to 1/5 dilution of the sample in the micellar mobile phase and filtration, thus avoiding clean-up and extraction steps. An aliquot of 20 μL was injected after 80 min of preparation, to obtain maximum sensitivity. The method was validated according to the guidelines of the Food and Drug Administration (FDA) in terms of calibration range (20-500 ng/mL; r(2)>0.999), sensitivity, accuracy (91.3-103.2%), precision (<9.3%), and robustness (<6.1%). The suitability of the method was successfully evaluated by analyzing plasma and urine samples from patients treated with SSRIs and checking the content of the active principle in tablets. Thus, the method can be applied to pharmacokinetics studies and in forensic cases, as well as in quality control of commercial pharmaceutical formulations.

  3. Analysis of Levodopa Content in Commercial Mucuna pruriens Products Using High-Performance Liquid Chromatography with Fluorescence Detection.

    Science.gov (United States)

    Soumyanath, Amala; Denne, Tanya; Hiller, Amie; Ramachandran, Shaila; Shinto, Lynne

    2017-09-18

    Mucuna pruriens (MP) seeds contain levodopa (up to 2% by weight) and have been used in traditional Indian medicine to treat an illness named "Kampavata," now understood to be Parkinson's disease (PD). Studies have shown MP to be beneficial, and even superior, to levodopa alone in treating PD symptoms. Commercial products containing MP are readily available from online and retail sources to patients and physicians. Products often contain extracts of MP seeds, with significantly higher levodopa content than the seeds. However, MP products have limited regulatory controls with respect to quality and content of active ingredient. The aim of this study was to apply a quantitative method to determine levodopa content in readily available MP products that might be used by patients or in research studies. Levodopa present in six commercial MP products was quantified by solvent extraction followed by reversed-phase high-performance liquid chromatography (HPLC) coupled to fluorescence detection (FD). Certificates of analysis (COA) were obtained, from manufacturers of MP products, to assess the existence and implementation of specifications for levodopa content. HPLC-FD analysis revealed that the levodopa content of the six commercial MP products varied from 6% to 141% of individual label claims. No product contained levodopa within normal pharmacopeial limits of 90%-110% label claim. The maximum daily dose of levodopa delivered by the products varied from 14.4 to 720 mg/day. COAs were inconsistent in specifications for and verification of levodopa content. The commercial products tested varied widely in levodopa content, sometimes deviating widely from the label claim. These deficiencies could impact efficacy and safety of MP products used by PD patients and compromise the results of scientific studies on MP products. The HPLC-FD method described in this study could be utilized by both manufacturers and scientific researchers to verify levodopa content of MP products.

  4. Determination of bisphenol A, 4-octylphenol, and 4-nonylphenol in soft drinks and dairy products by ultrasound-assisted dispersive liquid-liquid microextraction combined with derivatization and high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Lv, Tao; Zhao, Xian-En; Zhu, Shuyun; Qu, Fei; Song, Cuihua; You, Jinmao; Suo, Yourui

    2014-10-01

    A novel hyphenated method based on ultrasound-assisted dispersive liquid-liquid microextraction coupled to precolumn derivatization has been established for the simultaneous determination of bisphenol A, 4-octylphenol, and 4-nonylphenol by high-performance liquid chromatography with fluorescence detection. Different parameters that influence microextraction and derivatization have been optimized. The quantitative linear range of analytes is 5.0-400.0 ng/L, and the correlation coefficients are more than 0.9998. Limits of detection for soft drinks and dairy products have been obtained in the range of 0.5-1.2 ng/kg and 0.01-0.04 μg/kg, respectively. Relative standard deviations of intra- and inter-day precision for retention time and peak area are in the range of 0.47-2.31 and 2.76-8.79%, respectively. Accuracy is satisfactory in the range of 81.5-118.7%. Relative standard deviations of repeatability are in the range of 0.35-1.43 and 2.36-4.75% for retention time and peak area, respectively. Enrichment factors for bisphenol A, 4-octylphenol, and 4-nonylphenol are 170.5, 240.3, and 283.2, respectively. The results of recovery and matrix effect are in the range of 82.7-114.9 and 92.0-109.0%, respectively. The proposed method has been applied to the determination of bisphenol A, 4-octylphenol, and 4-nonylphenol in soft drinks and dairy products with much higher sensitivity than many other methods.

  5. Terbium-doped gadolinium oxide nanoparticles prepared by laser ablation in liquid for use as a fluorescence and magnetic resonance imaging dual-modal contrast agent.

    Science.gov (United States)

    Chen, Fei; Chen, Min; Yang, Chuan; Liu, Jun; Luo, Ningqi; Yang, Guowei; Chen, Dihu; Li, Li

    2015-01-14

    Dual-modal lanthanide-doped gadolinium nanoparticles (NPs), which exhibit an excellent magnetic resonance imaging (MRI) spatial resolution and high fluorescence imaging (FI) sensitivity, have attracted tremendous attention in biotechnology and nanomedicine applications. In this paper, terbium (Tb) ion doped gadolinium oxide (Gd2O3:Tb) NPs with varied Tb concentrations were synthesized by a laser ablation in liquid (LAL) method. The characterization of the structure, morphology, and composition shows that these NPs are spherical with excellent crystallinity. The effects of Tb ion concentration on the visible green fluorescence and longitudinal relaxivity were investigated, indicating that the fluorescence properties were significantly influenced by the Tb ion concentration, but all samples were still efficient T1-weighted contrast agents. Furthermore, the optimum Tb doping concentration was determined to be 1%. The cell viability, cellular fluorescence imaging and in vivo MRI of this dual-modal nano-probe were studied, with the results revealing that the Gd2O3:Tb NPs did not have a significant cytotoxic effect, making them good candidates for use as a dual-modal contrast agent for MRI and fluorescence imaging.

  6. Modulation of the excited state intramolecular electron transfer reaction and dual fluorescence of crystal violet lactone in room temperature ionic liquids.

    Science.gov (United States)

    Santhosh, Kotni; Samanta, Anunay

    2010-07-22

    The influence of polarity, viscosity, and hydrogen bond donating ability of the medium on the fluorescence behavior of crystal violet lactone (CVL), which undergoes excited state electron transfer reaction and exhibits dual fluorescence from two different electronic states, termed as CT(A) and CT(B), has been studied in six different room temperature ionic liquids (ILs) using steady state and time-resolved emission techniques. It is shown that the excited state CT(A) --> CT(B) transformation and dual fluorescence of CVL can be controlled by appropriate choice of the ILs. While dual fluorescence of CVL is clearly observed in pyrrolidinium IL, the molecule exhibits a single fluorescence band in ammonium IL. While the second emission from the CT(B) state can barely be seen in 1,3-dialkylimidazolium ILs, dual fluorescence is quite prominent in 1-butyl-2,3-dimethylimidazolium IL, [bmMim][Tf(2)N]. These contrasting results have been explained taking into account the hydrogen bonding interactions of the 1,3-dialkylimidazolium ions (mediated through the C(2)-hydrogen) with CVL and the viscosity of the ILs. The excited state CT(A) --> CT(B) reaction kinetics has been studied in IL by monitoring the time-evolution of the CT(B) emission in [bmMim][Tf(2)N]. The solvation dynamics in this IL has been studied by following the dynamic fluorescence Stokes shift of C153, which is used as a probe molecule. A comparison of the excited state reaction time and solvation time suggests that the rate of the CT(A) --> CT(B) reaction in moderately viscous ILs is primarily dictated by the rate of solvation. Very little or negligible excitation wavelength dependence of the emission behavior of CVL can be observed in these ILs.

  7. STED microscopy detects and quantifies liquid phase separation in lipid membranes using a new far-red emitting fluorescent phosphoglycerolipid analogue.

    Science.gov (United States)

    Honigmann, Alf; Mueller, Veronika; Hell, Stefan W; Eggeling, Christian

    2013-01-01

    We have developed a bright, photostable, and far-red emitting fluorescent phosphoglycerolipid analogue to probe diffusion characteristics of lipids in membranes. The lipid analogue consists of a saturated (C18) phosphoethanolamine and a hydrophilic far-red emitting fluorescent dye (KK114) that is tethered to the head group by a long polyethylenglycol linker. In contrast to reported far-red emitting fluorescent lipid analogues, this one partitions predominantly into liquid ordered domains of phase-separated ternary bilayers. We performed fluorescence correlation spectroscopy with a super-resolution STED microscope (STED-FCS) to measure the lateral diffusion of the new lipid analogue in the liquid ordered (Lo) and disordered (Ld) phase. On a mica support, we observed micrometer large phases and found that the lipid analogue diffuses freely on all tested spatial scales (40-250 nm) in both the Ld and Lo phase with diffusion coefficients of 1.8 microm2 s(-1) and 0.7 microm2 s(-1) respectively. This indicates that the tight molecular packing of the Lo phase mainly slows down the diffusion rather than causing anomalous sub-diffusion. The same ternary mixture deposited on acid-cleaned glass forms Lo nanodomains of analogue into the nano-domains, where diffusion is slowed down. Our results suggest that STED-FCS in combination with a Lo-partitioning fluorescent lipid analogue can directly probe the presence of Lo nano-domains, which in the future should allow the study of potential lipid rafts in live-cell membranes.

  8. Experimental Study on Penetration Properties of High Velocity Fragment into Safety Liquid Cabin%高速破片侵彻防护液舱试验研究

    Institute of Scientific and Technical Information of China (English)

    沈晓乐; 朱锡; 侯海量; 陈长海

    2011-01-01

    为研究水下接触爆炸产生的高速破片在水中的侵彻特性,针对3.3 g立方体破片进行了水下弹道试验,结果表明:破片的侵彻阻力系数受形状的影响较大,撞击隔板时产生压缩波使破片产生墩粗和侵蚀,造成破片迎流面积的增加和质量的下降,从而使破片在速度较高时侵彻深度反而下降。%In order to study penetration properties of high velocity fragment produced by underwater contact explosion, underwater ballistic experiments of 3.3 g cubic fragment was carried out, the results show that resistance coefficient of fragment is significantly influenced by the fragment shape. When the fragment crash on the steel plate, it will bring about great compress wave which makes fragment generate mushrooming and erosion, so the incident flow area increases and the weight decreases, consequently the underwater penetration ability of the fragments decrease with the increasing of velocity.

  9. Chemometric processing of second-order liquid chromatographic data with UV-vis and fluorescence detection. A comparison of multivariate curve resolution and parallel factor analysis 2.

    Science.gov (United States)

    Bortolato, Santiago A; Olivieri, Alejandro C

    2014-09-01

    Second-order liquid chromatographic data with multivariate spectral (UV-vis or fluorescence) detection usually show changes in elution time profiles from sample to sample, causing a loss of trilinearity in the data. In order to analyze them with an appropriate model, the latter should permit a given component to have different time profiles in different samples. Two popular models in this regard are multivariate curve resolution-alternating least-squares (MCR-ALS) and parallel factor analysis 2 (PARAFAC2). The conditions to be fulfilled for successful application of the latter model are discussed on the basis of simple chromatographic concepts. An exhaustive analysis of the multivariate calibration models is carried out, employing both simulated and experimental chromatographic data sets. The latter involve the quantitation of benzimidazolic and carbamate pesticides in fruit and juice samples using liquid chromatography with diode array detection, and of polycyclic aromatic hydrocarbons in water samples, in both cases in the presence of potential interferents using liquid chromatography with fluorescence spectral detection, thereby achieving the second-order advantage. The overall results seem to favor MCR-ALS over PARAFAC2, especially in the presence of potential interferents.

  10. Validated ion pair liquid chromatography/fluorescence detection method for assessing the variability of the loratadine metabolism occurring in bioequivalence studies.

    Science.gov (United States)

    Sora, Daniela Iuliana; Udrescu, Stefan; David, Victor; Medvedovici, Andrei

    2007-10-01

    Inter- and intra-individual variability of the loratadine (LOR) metabolism in Caucasian subjects was assessed during a bioequivalence study for two pharmaceutical formulations (solid oral dosage forms) containing 10 mg of the active substance. The analytical data were obtained by applying a reliable, low-cost and sensitive ion pair liquid chromatography/fluorescence (IPLC/FLD) method for determination of both loratadine and descarboethoxyloratadine (DCL) in human plasma samples. The sample preparation procedure is based on liquid-liquid extraction of the target analytes from alkalinized plasma using diethyl-ether. The separation of the analytes and 8-chloroazatadine as internal standard (IS) was achieved through an isocratic ion pair (IP) elution on a Purospher((R)) STAR RP-18 column. The mobile phase containing sodium dodecyl sulfate (SDS) as ion pairing agent was pumped at a flow rate of 1 mL/min. Fluorescence detection (FLD) was achieved at 280 nm (excitation) and 440 nm (emission) wavelengths. The increased sensitivity of the method is also based on a large sample injected volume (250 microL). Linear response was found over the 0.5-20 ng/mL concentration interval for both target compounds. Low limits of quantification (LLOQ) around 0.3 ng/mL were found for LOR and DCL. Method validation is presented.

  11. Optimizing high-performance liquid chromatography method with fluorescence detection for quantification of tamoxifen and two metabolites in human plasma: application to a clinical study.

    Science.gov (United States)

    Zhu, Yu-Bing; Zhang, Qian; Zou, Jian-Jun; Yu, Cui-Xia; Xiao, Da-Wei

    2008-01-22

    We set an improved high-performance liquid chromatography method with fluorescence detection HPLC-FLU assay with more sensitivity and precision for the quantification of tamoxifen and two metabolites: 4-hydroxytamoxifen and N-desmethyltamoxifen. The compounds and internal standard, mexiletine, were separated with an Agilent Extend C18 column set at 65 degrees C and a mobile phase of methanol-1% triethylamine aqueous solution (pH 11; 82:18, v/v). The detection system utilized offline ultraviolet irradiation to convert the analytes to their respective photocyclisation products, followed by fluorescence detection (lambda ex=260 nm and lambda em=375 nm). The limits of quantification for tamoxifen, N-desmethyltamoxifen and 4-hydroxytamoxifen in plasma were improved to 0.5, 0.5 and 0.1 ng/ml, respectively. And the retention times for tamoxifen, N-desmethyltamoxifen and 4-hydroxytamoxifen were minimized to 11, 10 and 3.9 min, respectively. A single stage liquid-liquid extraction method for determination of these triphenylethylene drugs in plasma was developed, with high extraction efficiency and rapid sample treatment for target compounds. The method has been validated for use in a clinical bioavailability research of tamoxifen.

  12. Development and validation of a novel derivatization method for the determination of lactate in urine and saliva by liquid chromatography with UV and fluorescence detection.

    Science.gov (United States)

    Pellegrini, Davide; Onor, Massimo; Degano, Ilaria; Bramanti, Emilia

    2014-12-01

    We developed a novel and straightforward derivatization method for the determination of lactate by reversed phase high-performance liquid chromatography (RP-HPLC) with fluorescence and UV detection in biological matrices as urine and saliva. The derivatization of lactate was achieved employing 9-chloromethyl anthracene (9-CMA) as fluorescence reagent, which has never been previously used to obtain a lactate derivative. Lactate reacts with 9-CMA with high selectivity in a very short time, without requiring extraction procedures from the aqueous solution, and the reaction reaches 70% completion in 30 min. The ester derivative obtained can be easily determined by RP-HPLC with fluorescence detection at 410 nm (λ ex=365 nm) and UV detection at 365 nm. The method was also optimized in order to allow for the simultaneous determination of lactate and creatinine for the application to urine samples. The lactate calibration curve was linear in the investigated range 2 × 10(-4)-3 × 10(-2)mM and the limit of detection, calculated as three times the standard deviation of the blank divided by the calibration curve slope, was 50 nM for both fluorescence and UV detection. Intra-day and inter-day repeatability were lower than 5% and 6%, respectively. The method proposed was successfully applied to the analysis of urine and saliva samples.

  13. Application of thin-layer chromatography with fluorescence scanning densitometry for analysing saturates in heavy liquids derived from co-pyrolysis of biomass and plastics

    Energy Technology Data Exchange (ETDEWEB)

    Cebolla, V.L. [Consejo Superior de Investigaciones Cientificas (CSIC), Instituto de Carboquimica, Zaragoza (Spain); Matt, M. [Institute of Chemistry and Chemical Technology, Krasnoyarsk (Russian Federation). Siberian Branch of Russian Academy of Sciences; Membrado, L. [Universite de Metz, Saint-Avold (FR). Laboratoire de Chimie et Applications] [and others

    2002-01-01

    Two alternative methods, based on Thin-Layer Chromatography (TLC) with Fluorescence Scanning Densitometry have been developed for characterization of heavy liquids from copyrolysis of different kinds of biomass and plastics in autoclaves under inert atmosphere. A conventional TLC system, which includes a vertical developing tank, and a High Performance TLC (HPTLC) system, with a horizontal developing chamber and the use of HPTLC plates, have been used. The analytical method involves in both cases the measurement of two chromatograms per sample: the first, on a silica gel berberine-impregnated plate, for detection of saturates using the phenomenon of berberine-induced fluorescence; and the second, on a silica gel plate, for detection of aromatic-polars and polars, by native fluorescence. Although the HPTLC system is more sensitive and faster, both techniques represent an improvement with regard to current methods for analyzing these kinds of products. However their application depends on the particular solubility of each sample and on its slope of the fluorescent response-sample load regression. (orig.)

  14. NADH-fluorescence scattering correction for absolute concentration determination in a liquid tissue phantom using a novel multispectral magnetic-resonance-imaging-compatible needle probe

    Science.gov (United States)

    Braun, Frank; Schalk, Robert; Heintz, Annabell; Feike, Patrick; Firmowski, Sebastian; Beuermann, Thomas; Methner, Frank-Jürgen; Kränzlin, Bettina; Gretz, Norbert; Rädle, Matthias

    2017-07-01

    In this report, a quantitative nicotinamide adenine dinucleotide hydrate (NADH) fluorescence measurement algorithm in a liquid tissue phantom using a fiber-optic needle probe is presented. To determine the absolute concentrations of NADH in this phantom, the fluorescence emission spectra at 465 nm were corrected using diffuse reflectance spectroscopy between 600 nm and 940 nm. The patented autoclavable Nitinol needle probe enables the acquisition of multispectral backscattering measurements of ultraviolet, visible, near-infrared and fluorescence spectra. As a phantom, a suspension of calcium carbonate (Calcilit) and water with physiological NADH concentrations between 0 mmol l-1 and 2.0 mmol l-1 were used to mimic human tissue. The light scattering characteristics were adjusted to match the backscattering attributes of human skin by modifying the concentration of Calcilit. To correct the scattering effects caused by the matrices of the samples, an algorithm based on the backscattered remission spectrum was employed to compensate the influence of multiscattering on the optical pathway through the dispersed phase. The monitored backscattered visible light was used to correct the fluorescence spectra and thereby to determine the true NADH concentrations at unknown Calcilit concentrations. Despite the simplicity of the presented algorithm, the root-mean-square error of prediction (RMSEP) was 0.093 mmol l-1.

  15. Simultaneous determination of p-arsanilic acid and roxarsone in feed by liquid chromatography-hydride generation online coupled with atomic fluorescence spectrometry.

    Science.gov (United States)

    Liu, Jianjing; Yu, Hongxia; Song, Haibin; Qiu, Jing; Sun, Fengmei; Li, Ping; Yang, Shuming

    2008-08-01

    A novel, simple and sensitive liquid chromatography-hydride generation online coupled with atomic fluorescence spectrometry (LC-HG-AFS) method was developed for simultaneous determination of p-arsanilic acid (p-ASA) and roxarsone in feed. 20% Methanol aqueous was used as extraction reagent, after preprocessing samples by ultrasonic oscillation, then injected into the chromatography Waters symmetry shield RP18 analytical column (150mm x 4.6mm, 5 microm), finally detected by an atomic fluorescence spectrometer. The calibration curves of analyses were linear over a range of concentrations (0.2-4mg L-1 and the correlation coefficients were higher than 0.9990. The limits of detection were 0.2 mg L-1. The method has been validated by linearity, precision and recovery. p-ASA and roxarsone in feed can be successfully and simultaneously determined using the developed method without a tedious pretreatment procedure.

  16. Sensitive and background-free determination of thiols from wastewater samples by MOF-5 extraction coupled with high-performance liquid chromatography with fluorescence detection using a novel fluorescence probe of carbazole-9-ethyl-2-maleimide.

    Science.gov (United States)

    Lv, Zhengxian; Sun, Zhiwei; Song, Cuihua; Lu, Shuaimin; Chen, Guang; You, Jinmao

    2016-12-01

    A sensitive and background-free pre-column derivatization method for the determination of thiol compounds using metal-organic framework material (MOF-5) as dispersive solid-phase extraction (DSPE) adsorbent followed by high-performance liquid chromatography fluorescence detection (HPLC-FLD) has been developed. In this paper, a novel labeling reagent, carbazole-9-ethyl-2-maleimide(CAEM), was synthesized and reacted with thiols at 40°C for 10min in the presence of PBS buffer (0.02mol/L, pH 7.5). Interestingly, CAEM itself had no fluorescence, while its derivatives exhibited intense fluorescence with an excitation maximum at λex 274nm and an emission maximum at λem 363nm, which greatly reduced the background interference and improved the sensitivity of the method. Furthermore, the MOF-5 was prepared and used as DSPE adsorbent for the selective adsorption of thiols from wastewater sample. Under the optimized experimental conditions, an excellent linearity for all analytes over their concentration ranges of 0.01-1.0μmol/L (R(2)>0.9986)were obtained with the limit of detection (LOD) ranging from 8 to 17.1pmol/L for nine tested thiols. The feasibility of this method for the determination of thiols in wastewater samples had been evaluated and satisfactory average recoveries (n=3) were achieved with the range of 86.6-98.5%.

  17. Feasibility for direct rapid energy dispersive X-ray fluorescence (EDXRF) and scattering analysis of complex matrix liquids by partial least squares.

    Science.gov (United States)

    Angeyo, K H; Gari, S; Mustapha, A O; Mangala, J M

    2012-11-01

    The greatest challenge to material characterization by XRF technique is encountered in direct trace analysis of complex matrices. We exploited partial least squares (PLS) in conjunction with energy dispersive X-ray fluorescence and scattering (EDXRFS) spectrometry to rapidly (200 s) analyze lubricating oils. The PLS-EDXRFS method affords non-invasive quality assurance (QA) analysis of complex matrix liquids as it gave optimistic results for both heavy- and low-Z metal additives. Scatter peaks may further be used for QA characterization via the light elements.

  18. A study of the time-resolved fluorescence spectrum and red edge effect of ANF in a room-temperature ionic liquid.

    Science.gov (United States)

    Hu, Zhonghan; Margulis, Claudio J

    2006-06-15

    In a recent article, we have analyzed using molecular dynamics simulations the steady-state red edge effect (REE) observed by Samanta and co-workers when the fluorescent probe 2-amino-7-nitrofluorene (ANF) is photoexcited at different wavelengths in 1-butyl-3-methylimidazolium ([BMIM+]) hexafluorophosphate ([PF6-]). In this letter, we predict the time- and wavelength-dependent emission spectra of ANF in the same ionic solvent. From the analysis of our simulated data, we are able to derive an approximate time scale for reorganization of the solvent around the solute probe. The effect that slow varying local liquid environments have on the overall time-dependent signal is also discussed.

  19. Determination of AJ-3941, a possible agent for the treatment of cerebrovascular disorders, in plasma and brain by means of high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Kurono, M; Yoshida, K; Naruto, S

    1992-07-01

    A sensitive and selective high-performance liquid chromatographic method with fluorescence detection is described for the determination of AJ-3941 (I), a possible agent for the treatment of cerebrovascular disorders, in plasma and brain tissue. A simple hexane extraction was used for plasma, and for brain homogenate the hexane extract was further purified by solid-phase extraction. The determination limit was ca. 3 ng/ml for both plasma (0.5 ml) and 10% (w/v) brain homogenate (1 ml). The method was applied to the determination of I in plasma and brain samples of experimental animals.

  20. Determination of closantel residues in plasma and tissues by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Stoev, G

    1998-06-12

    The influence of the pH of the mobile phase with some modifiers on the chromatographic behavior and fluorescence properties of closantel have been investigated. At acidic pH values (2-6), the benzamide moiety of the closantel forms a six-membered ring by hydrogen bonding and possesses a native fluorescence. Using the fluorescence emission of closantel at lambda(ex) = 335 nm, lambda(em) = 510 nm, and pH 2.5 of the mobile phase, a linear calibration curve was estimated over a concentration range of about two orders of magnitude with a correlation coefficient larger than 0.992. The limit of the fluorescence detection was 10 microg/kg. This value was at least 10 times lower than that using UV detection. The method was applied to the determination of closantel in plasma and tissue samples, purified by a solid-phase extraction with C18 cartridges.

  1. Connecting Effective Immune Response, Fluorescent Granzyme B-like Peptide, Specific Peptide Binding Patterns, Patients with Cancer and Viral Infection, in Remission, Clinical Significance, and Liquid Biopsy.

    Science.gov (United States)

    Lo, Wai Chun Jennifer; Luther, Donald Gene

    2016-11-01

    Functional cytotoxic-T-lymphocytes (CTL) with granzyme B play an important role in an effective immune response to tumor growth and infection progression. Tumor cells and platelets in peripheral whole blood smears of cancer patients have shown the presence of innate binding targets for GP1R, a fluorescent synthetic Granzyme B-like peptide. It is not known if similar GP1R-binding targets and specific binding patterns are detectable in peripheral blood of patients with viral infection. It is also not known if a specific binding pattern may be associated with an effective immune response to indicate a favorable prognosis. We reviewed the GP1R-binding patterns in the peripheral blood smears of 5 patients in remission at the time of sampling (3 with cancer and 2 with flu-like symptoms) and a negative control. We show with fluoroscopic images that there are: 1) fluorescent GP1R-binding targets mostly in the cytoplasmic areas of nucleated cells in patients with breast and lung cancer who have longer survival, 2) intense fluorescent deposits mostly in the nuclear areas of segmented neutrophils in patients recovered from severe to mild flu-like symptoms, 3) discernible fluorescent deposits in the cytoplasmic areas of small lymphocyte-like elements and overall intense fluorescent stain in large cells in the patient with advanced pancreatic cancer who had shorter survival, 4) GP1R-binding targets in numerous platelet-like elements in all 5 patients. The control sample did not show similar binding patterns. The potential association between specific GP1R-binding patterns in peripheral blood samples and prognostic significance, and its use as liquid biopsy are discussed.

  2. Development, validation, and application of a method for selected avermectin determination in rural waters using high performance liquid chromatography and fluorescence detection.

    Science.gov (United States)

    Lemos, Maria Augusta Travassos; Matos, Camila Alves; de Resende, Michele Fabri; Prado, Rachel Bardy; Donagemma, Raquel Andrade; Netto, Annibal Duarte Pereira

    2016-11-01

    Avermectins (AVM) are macrocyclic lactones used in livestock and agriculture. A quantitative method of high performance liquid chromatography with fluorescence detection for the determination of eprinomectin, abamectin, doramectin and ivermectin in rural water samples was developed and validated. The method was employed to study samples collected in the Pito Aceso River microbasin, located in the Bom Jardim municipality, Rio de Janeiro State, Brazil. Samples were extracted by solid phase extraction using a polymeric stationary phase, the eluted fraction was re-concentrated under a gentle N2 flow and derivatized to allow AVM determination using liquid chromatography with fluorescence detection. The excitation and emission wavelengths of the derivatives were 365 and 470nm, respectively, and a total chromatographic run of 12min was achieved. Very low limits of quantification (22-58ngL(-1)) were found after re-concentration using N2. Recovery values varied from 85.7% to 119.2% with standard deviations between 1.2% and 10.2%. The validated method was applied in the determination of AVM in 15 water samples collected in the Pito Aceso River microbasin, but most of them were free of AVM or showed only trace levels of these compounds, except for a sample that contained doramectin (9.11µgL(-1)). The method is suitable for routine analysis with satisfactory recovery, sensitivity, and selectivity.

  3. High-performance liquid chromatographic determination of anti- hypertensive drugs on dried blood spots using a fluorescence detector--method development and validation.

    Science.gov (United States)

    Rao, R Nageswara; Bompelli, Sravan; Maurya, Pawan K

    2011-11-01

    A selective and sensitive high-performance liquid chromatography method with fluorescence detection for simultaneous determination of irbesartan, losartan and valsartan on dried blood spots (DBS) has been developed and validated. It involves solvent extraction of a punch of DBS followed by reversed-phase liquid chromatography on a Lichrospher(®) 100 RP-18e column. Fluorescence detection was performed at 259 and 385 nm as excitation and emission wavelengths, respectively. The detection limits of irbesartan, losartan and valsartan were 1.8, 3.6 and 1.8 ng/mL respectively. The mean recoveries of irbesartan, losartan and valsartan were 98.68, 98.42 and 97.81%, respectively. The mean inter-day and intra-day precisions of irbesartan, losartan and valsartan were 2.07 and 1.34%, 1.42 and 1.48%, and 3.20 and 2.15% respectively. The proposed method was simple and rapid. Design of experiments was used to evaluate the robustness of the method.

  4. Synthesis and Characterisation of Photo-Cross-Linkable Liquid Crystalline Poly(n-[n′-flurobenzoylstyryloxy]alkylmethacrylates and Their Fluorescence Lifetime Properties

    Directory of Open Access Journals (Sweden)

    G. Kumar

    2013-01-01

    Full Text Available This paper reports a study on photo-cross-linkable polymer containing pendant chalcone moiety exhibiting liquid crystalline as well as fluorescence lifetime properties in detail. The photoresponsive polymers were prepared, and their structure has been characterized by 1H-NMR, 13C-NMR, and UV-Visible spectroscopy. The photo-cross-linking behavior of polymers has been studied by UV-Visible and fluorescence spectroscopy. UV spectral studies revealed that the polymers follow 2π+2π cyclo addition reactions when they undergo photo-cross-linking under the influence of UV-light. Number and weight average molecular weight of the polymers were determined by Gel Permeation Chromatography (GPC and polydispersity index value near to 1.5. The thermal and thermooxidative stability of the polymers were determined by Thermogravimetric Analysis (TGA. Thermal transitions were studied by DSC, and presence of mesophases was identified at 147 and 126∘C by hot stage polarized light optical microscopy (HPOM. Fluorescence lifetime measurements using the time-correlated single photon counting (TCSPC method reveal that the average lifetime values decrease from 5.94 ns to 5.32 ns on UV-irradiation were discussed in detail.

  5. Comparison of fluorescence reagents for simultaneous determination of hydroxylated phenylalanine and nitrated tyrosine by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Iwasaki, Yusuke; Mochizuki, Keisuke; Nakano, Yuki; Maruya, Natsumi; Goto, Masato; Maruyama, Yosuke; Ito, Rie; Saito, Koichi; Nakazawa, Hiroyuki

    2012-01-01

    Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are well-known and important contributors to oxidative and nitrosative stress in several diseases. Hydroxylated phenylalanine and nitrated tyrosine products appear to be particularly susceptible targets of oxidative and nitrosative stress. We compared fluorescence reagents for their potential use in the analysis of hydroxylated phenylalanine and nitrated tyrosine products with a high-sensitivity and high-specificity HPLC-UV-FL technique. The analytes were extracted from serum via solid-phase extraction on Waters Oasis MCX cartridges. Chromatographic separation was achieved on an ODS column (Capcell Pak MG II; 150 × 2.0 mm) using a gradient mobile phase consisting of 20 mm sodium phosphate buffer (adjusted to pH 3.0) and acetonitrile. The method quantification limit for 4-nitrophenylalanine, m-tyrosine, and 3-nitrotyrosine was 0.1 μm. The relative standard deviation of the precision and accuracy was acceptable at the spiked concentration of 0.1 μm for 4-nitrophenylalanine, m-tyrosine and 3-nitrotyrosine. The method could be used for the in vitro analysis of serum samples.

  6. Novel analytical procedure using a combination of hollow fiber supported liquid membrane and dispersive liquid-liquid microextraction for the determination of aflatoxins in soybean juice by high performance liquid chromatography - Fluorescence detector.

    Science.gov (United States)

    Simão, Vanessa; Merib, Josias; Dias, Adriana N; Carasek, Eduardo

    2016-04-01

    This study describes a combination between hollow fiber membrane and dispersive liquid-liquid microextraction for determination of aflatoxins in soybean juice by HPLC. The main advantage of this approach is the use of non-chlorinated solvent and small amounts of organic solvents. The optimum extraction conditions were 1-octanol as immobilized solvent; toluene and acetone at 1:5 ratio as extraction and disperser solvents (100 μL), NaCl at 2% of the sample volume and extraction time of 60 min. The optimal condition for the liquid desorption was 150 μL acetonitrile:water (50:50 v/v) and desorption time of 20 min. The linear range varied from 0.03 to 21 μg L(-1), with R(2) coefficients ranging from 0.9940 to 0.9995. The limits of detection and quantification ranged from 0.01 μg L(-1) to 0.03 μg L(-1) and from 0.03 μg L(-1) to 0.1 μg L(-1), respectively. Recovery tests ranged from 72% to 117% and accuracy between 12% and 18%.

  7. Bioanalysis of captopril : Two sensitive high-performance liquid chromatographic methods with pre- or postcolumn fluorescent labeling

    NARCIS (Netherlands)

    Kok, R.J; Visser, Jan; Moolenaar, Frits; de Zeeuw, D; Meijer, D.K F

    1997-01-01

    This study describes the development and comparison of two HPLC methods for the analysis of the antihypertensive drug captopril. The first method is based on a precolumn derivatization of captopril with the fluorescent label monobromobimane (MBB). The second method is based on a postcolumn reaction

  8. Optimization of two methods for the analysis of hydrogen peroxide: high performance liquid chromatography with fluorescence detection and high performance liquid chromatography with electrochemical detection in direct current mode.

    Science.gov (United States)

    Tarvin, Megan; McCord, Bruce; Mount, Kelly; Sherlach, Katy; Miller, Mark L

    2010-11-26

    Two complementary methods were optimized for the separation and detection of trace levels of hydrogen peroxide. The first method utilized reversed-phase high-performance liquid chromatography with fluorescence detection (HPLC-FD). With this approach, hydrogen peroxide was detected based upon its participation in the hemin-catalyzed oxidation of p-hydroxyphenylacetic acid to yield the fluorescent dimer. The second method utilized high performance liquid chromatography with electrochemical detection (HPLC-ED). With this approach, hydrogen peroxide was detected based upon its oxidation at a gold working electrode at an applied potential of 400 mV vs. hydrogen reference electrode (Pd/H(2)). Both methods were linear across the range of 15-300 μM, and the electrochemical method was linear across a wider range of 7.4-15,000 μM. The limit of detection for hydrogen peroxide was 6 μM by HPLC/FD, and 0.6 μM by HPLC/ED. A series of organic peroxides and inorganic ions were evaluated for their potential to interfere with the detection of hydrogen peroxide. Studies investigating the recovery of hydrogen peroxide with three different extraction protocols were also performed. Post-blast debris from the detonation of a mixture of concentrated hydrogen peroxide with nitromethane was analyzed on both systems. Hydrogen peroxide residues were successfully detected on this post-blast debris.

  9. Fluorescence response of 4-(N,N'-dimethylamino)benzonitrile in room temperature ionic liquids: observation of photobleaching under mild excitation condition and multiphoton confocal microscopic study of the fluorescence recovery dynamics.

    Science.gov (United States)

    Santhosh, Kotni; Banerjee, Sanghamitra; Rangaraj, Nandini; Samanta, Anunay

    2010-02-11

    The fluorescence behavior of 4-(N,N'-dimethylamino) benzonitrile has been studied in room temperature ionic liquids (ILs) as a function of temperature, excitation wavelength, and exposure time. Dual emission from the locally excited (LE) and intramolecular charge transfer (ICT) states of the molecule has been observed and the relative intensities of the two emission bands and the peak position of the ICT emission are found consistent with the viscosity and polarity of the ILs. Temperature dependence study reveals a blue shift of the ICT emission peak with lowering of temperature indicating that under this condition the emission occurs from incompletely solvated state of the molecule. The observed excitation wavelength dependence of the emission behavior has been attributed to the microheterogeneity of the media. Exposure of the solution to the exciting radiation under very mild condition is found to influence the relative intensities of the two emission bands; an enhancement of the LE emission accompanied by a slight decrease of the ICT emission is observed. The emission intensities, however, return almost to their original values when the exposed solution is kept in the dark. The observation has been attributed to photoreaction of the exposed molecules and the recovery to replenishment of phototransformed molecules by the surrounding unexposed molecules. Fluorescence recovery after photobleaching has been studied by multiphoton confocal fluorescence microscopic technique to obtain insight into the recovery dynamics. The diffusion coefficient estimated from this study is found to be lower than that predicted by the Stokes-Einstein equation by a factor of nearly 7 indicating the microheterogeneous nature of the ILs.

  10. Determination of flumequine and oxolinic acid in sediments and soils by microwave-assisted extraction and liquid chromatography-fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Prat, M.D. [Departament de Quimica Analitica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona (Spain)]. E-mail: mdprat@ub.edu; Ramil, D. [Departament de Quimica Analitica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona (Spain); Compano, R. [Departament de Quimica Analitica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona (Spain); Hernandez-Arteseros, J.A. [Departament de Quimica Analitica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona (Spain); Granados, M. [Departament de Quimica Analitica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona (Spain)

    2006-05-17

    A method is reported for the determination of the quinolones oxolinic acid and flumequine in aquatic sediments and agricultural soils. The analytes are extracted by liquid-liquid partitioning between a sample homogenated in an aqueous buffer solution and dichloromethane. Microwave-assisted extraction (MAE) was tested to improve the speed and efficiency of the extraction process. The parameters affecting the efficiency of MAE, such as irradiation time and temperature, were studied. The clean-up consists of back-extraction in 1 M sodium hydroxide. The determination is carried out by reversed phase liquid chromatography on an octyl silica-based column and fluorimetric detection. The optimised method was applied to the analysis of two sediments and one agricultural soil spiked with the analytes. The absolute recovery rates for the whole process range from 79% to 94% (RSD 3-7%), and detection limits are in the low {mu}g kg{sup -1} level.

  11. Simple and sensitive high performance liquid chromatography method with fluorescence detection for therapeutic drug monitoring of topiramate.

    Science.gov (United States)

    Milosheska, Daniela; Vovk, Tomaž; Grabnar, Iztok; Roškar, Robert

    2015-01-01

    A simple, sensitive, accurate, precise and inexpensive HPLC method with fluorescence detection, suitable for routine therapeutic drug monitoring (TDM) of an antiepileptic drug topiramate, was developed and validated. The determination of plasma topiramate concentration was carried out after precolumn derivatization, using 4-chloro-7-nitrobenzofurazan as a fluorescent labeling agent and bendroflumethiazide as an internal standard. The standard calibration curve was linear over the concentration range of 0.01-24 μg/mL (r² > 0.9998). The intra- and inter-day accuracies expressed as bias were from 1.4 to 9.9% and from 1.9 to 10.2%, respectively. The intra- and inter-day precisions were below 7.9% and 2.7%, respectively. The validated method was applied for the measurement of plasma topiramate concentrations in patients with epilepsy. The reported method is appropriate for TDM of topiramate as well as for pharmacokinetic and bioequivalence studies.

  12. High sensitivity analysis of water-soluble, cyanine dye labeled proteins by high-performance liquid chromatography with fluorescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Qiao Xiaoqiang [CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Wang Li [State Key Laboratory of Fine Chemicals, Dalian University of Technology, 158 Zhongshan Road, Dalian 116012 (China); Ma Junfeng [CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Deng Qiliang; Liang Zhen [CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China); Zhang Lihua, E-mail: lihuazhang@dicp.ac.cn [CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China); Peng Xiaojun [State Key Laboratory of Fine Chemicals, Dalian University of Technology, 158 Zhongshan Road, Dalian 116012 (China); Zhang Yukui [CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China)

    2009-04-27

    A water-soluble sulfo-3H-indocyanine dye, the active N-hydroxysuccinimide ester of 3H-Indolium,1-[(4-carboxyphenyl)methyl]-2-[3-[1-[(4-carboxyphenyl)methyl] -1,3-dihydro-3,3-dimethyl-5-sulfo-2H-indol-2-ylidene]-1-propenyl] -3,3-dimethyl-5-sulfo-(9CI) (sb-cy3-NHS), containing two p-carboxybenzyl groups on nitrogen atoms, previously developed by our laboratory, was for the first time used for protein derivatization, followed by HPLC separation and fluorescence detection. With bovine serum albumin (BSA) as a model protein, effects of various experimental conditions, including denaturant concentration, reaction time and temperature, the pH value of buffer, and the molar ratio of fluorescence reagent to protein, on protein derivatization efficiency were systematically investigated. Under the optimal conditions, the limit of detection (LOD) for derivatized BSA was decreased to 12.8 nM, about 100-fold lower than that by UV and fluorescence detection with commercial fluorescein isothiocyanate (FITC) as labeling reagent. For HPLC analysis, an on-column excess fluorescence reagent depletion technique was developed based on the hydrophilicity of sb-cy3-NHS, which could avoid the interference on the analysis of target compounds. In addition, sb-cy3-NHS was applied for the derivatization of a three-protein mixture and egg white proteins. Compared to the results labeled by FITC, more proteins with low concentrations could be labeled by sb-cy3-NHS, resulting in improved detection sensitivity for protein analysis. All these results demonstrated that sb-cy3-NHS might be promising in detecting low abundance proteins, especially in the quantitative analysis of proteins.

  13. Analysis of electrophoretic soil humic acids fractions by reversed-phase high performance liquid chromatography with on-line absorbance and fluorescence detection.

    Science.gov (United States)

    Trubetskoj, Oleg A; Richard, Claire; Guyot, Ghislain; Voyard, Guillaume; Trubetskaya, Olga E

    2012-06-22

    A combination of reversed-phase high performance liquid chromatography (RP HPLC) with on-line absorbance and fluorescence detection was used for analysis of chernozem soil humic acids (HAs) and their fractions A, B and C+D with different electrophoretic mobility (EM) and molecular size (MS). Samples were injected onto the column at the identical volume and absorbance. All chromatograms exhibit the resolution of seven peaks. The estimation of relative recovery of HAs and fractions from the reverse-phase column has been done. High MS fraction A, which possesses the low EM, is essentially more hydrophobic (73% of the fraction amount remained adsorbed on the column) and aliphatic than medium MS and EM fraction B (33% of the fraction amount remained adsorbed on the column). The most hydrophilic and aromatic properties belong to low MS fraction C+D, which possess the highest EM and practically was not adsorbed on the column. The hydrophobicity of the bulk HAs lies within the range of fractions hydrophobicity. The absorption spectra of bulk HAs, electrophoretic fractions A, B, C+D and corresponding RP HPLC peaks were featureless but had differences in the values of absorbance ratio at 300 and 400 nm (A3/A4). For fractions A and B this ratio gradually decreased from peak 1 to 7 (from 3.05 to 2.80 and 3.00 to 2.40, respectively). This trend was less pronounced in HAs and practically absent in fraction C+D, where ratio A3/A4 varied within a small range. The strong relationship between fluorescence properties, EM, MS, polarity and aliphaticity/aromaticity of HAs fractions was found. Humic and protein-like fluorescence had different polarity nature. The protein-like fluorescence is located in humic material which irreversibly adsorbed on the reverse-phase column and not subjected to RP HPLC characterization. The humic-like fluorescence at Ex/Em 270/450 nm is mostly located in the hydrophilic peak of low MS fraction C+D. Taking into account that high MS fraction A consisted

  14. On-line enrichment and determination of polycyclic aromatic hydrocarbons in atmospheric particulates using high performance liquid chromatography with fluorescence as detector

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Seven polycyclic aromatic hydrocarbons (PAHs) in atmospheric particulates were determinated by high performance liquid chromatography (HPLC) with fluorescence detector using direction injection and an on-line enrichment trap column. The method simplified the sample pretreatment, saved time and increased the efficiency. With the on-line trap column, PAHs were separated availably even underground injecting 1.0 ml sample with relatively high column efficiency. The recoveries of the seven PAHs were from 85% to 120% for spiked atmospheric particulate sample. The limit of detection was 15.3-39.6 ng/L (S/N=3.3). There were good linear correlations between the peak areas and concentrations of the seven kinds of PAHs in the range of 1-50 ng/ml with the correlation coefficients over 0.9970. Furthermore, it also indicated that the method is available to determine PAHs in atmospheric particulates well.

  15. Ergot alkaloids in rye flour determined by solid-phase cation-exchange and high-pressure liquid chromatography with fluorescence detection

    DEFF Research Database (Denmark)

    Storm, Ida Marie Lindhardt Drejer; Rasmussen, Peter Have; Strobel, B.W.

    2008-01-01

    Ergot alkaloids are mycotoxins that are undesirable contaminants of cereal products, particularly rye. A method was developed employing clean-up by cation-exchange solid-phase extraction, separation by high-performance liquid chromatography under alkaline conditions and fluorescence detection....... It is capable of separating and quantifying both C8-isomers of ergocornine, alpha-ergocryptine, ergocristine, ergonovine, and ergotamine. The average recovery was 61% +/- 10% with limits of detection from 0.2 to 1.1 mu g kg(-1). Twenty-four unknown rye flour samples from Danish mills contained on average 46 mu...... g kg(-1) with a maximum content of 234 mu g kg(-1). The most common ergot alkaloids were ergotamine and alpha-ergocryptine including their C8-isomers. A total of 54% of the ergot alkaloids were detected as C(8)-S isomers....

  16. Analysis of oligomer proanthocyanidins in different barley genotypes using high-performance liquid chromatography-fluorescence detection-mass spectrometry and near-infrared methodologies.

    Science.gov (United States)

    Verardo, Vito; Cevoli, Chiara; Pasini, Federica; Gómez-Caravaca, Ana María; Marconi, Emanuele; Fabbri, Angelo; Caboni, Maria Fiorenza

    2015-04-29

    Proanthocyanidins are a class of polyphenols present in many foodstuffs (i.e., tea, cocoa, berries, etc.) that may reduce the risk of several chronic diseases. Barley, with sorghum, rice, and wheat, are the only cereals that contain these compounds. Because of that, two barley genotypes, named waxy and non-waxy, were analyzed by normal-phase high-performance liquid chromatography-fluorescence detection-mass spectrometry (NP-HPLC-FLD-MS). Total proanthocyanidin content ranged between 293.2 and 652.6 μg/g of flour. Waxy samples reported the highest content (p determination coefficients (R(2)) ranging from 0.92 to 0.97, in test set validation. Because of that, this study highlights that NIR spectroscopy technology with multivariate calibration analysis could be successfully applied as a rapid method to determine proanthocyanidin content in barley.

  17. Aptamer-affinity column clean-up coupled with ultra high performance liquid chromatography and fluorescence detection for the rapid determination of ochratoxin A in ginger powder.

    Science.gov (United States)

    Yang, Xihui; Kong, Weijun; Hu, Yichen; Yang, Meihua; Huang, Luqi; Zhao, Ming; Ouyang, Zhen

    2014-04-01

    Aptamers are single-stranded oligonucleotides with high affinity and specificity and are widely used in targets separation and enrichment. Here, an aptamer-affinity column (AAC) was firstly prepared in-house through a covalent immobilization strategy. Then, ochratoxin A (OTA) in ginger powder was absorbed and enriched using the new aptamer-based clean-up technology for the first time, and was further analyzed by ultra high performance liquid chromatography with fluorescence detection. After optimization, the average recoveries for blank samples spiked with OTA at 5, 15, and 45 μg/kg ranged from 85.36 to 96.83%. Furthermore, the AAC exhibited a similar accuracy as an immunoaffinity column to clean up OTA in ginger powder. Above all, it exhibited better reusability, twice that of the immunoaffinity column, had lower toxicity and cost, and took less time. Of 25 contaminated ginger powder samples, OTA contamination levels ranged from 1.51 to 4.31 μg/kg, which were lower than the European Union (EU) regulatory limits. All the positive samples were further confirmed by ultra-fast LC with MS/MS. In conclusion, the method of clean-up based on the AAC coupled to ultra-HPLC with fluorescence detection was rapid, specific, and sensitive for the quantitative analysis of OTA in a complex matrix.

  18. Determination of ASP3258, a novel phosphodiesterase type 4 inhibitor, in rat plasma by high-performance liquid chromatography with fluorescence detection and its application to pharmacokinetic study.

    Science.gov (United States)

    Ohtsu, Yoshiaki; Takanuki, Fumiyo; Fukunaga, Yasuhisa; Noguchi, Kiyoshi

    2015-02-01

    The potent phosphodiesterase 4 inhibitor ASP3258 contains a carboxylic acid moiety and a naphthyridine ring and is a novel therapeutic agent for asthma and chronic obstructive pulmonary disease. To support the drug development of ASP3258, we developed and validated a simple method for its determination in rat plasma. Following the addition of the analog AS1406604-00 as an internal standard, plasma samples were processed using C18 -bonded solid-phase extraction cartridges under acidic conditions and injected into a high-performance liquid chromatography system with fluorescence detection. Chromatographic separation was achieved on a Shiseido Capcell Pak C18 UG120 column (3.0 × 150 mm, 5 µm) with a mobile phase consisting of acetonitrile-0.5% acetic acid (50:50, v/v). HPLC eluent was monitored with a fluorescence detector set at a wavelength of 315 nm for excitation and 365 nm for emission. The calibration curve was linear over a range of 2.5-250 ng/mL. Validation data demonstrated that the method is selective, sensitive and accurate. In addition, the present method was successfully applied to rat plasma samples from a pharmacokinetic study.

  19. A very simple high-performance liquid chromatographic method with fluorescence detection for the determination of gemifloxacin in human breast milk.

    Science.gov (United States)

    Sagirli, Olcay; Demirci, Seda; Önal, Armağan

    2015-12-01

    A high-performance liquid chromatographic method with fluorescence detection was developed and validated for the determination of gemifloxacin in human breast milk. The proposed method allows the determination of gemifloxacin in breast milk samples without complex sample preparation. The samples were mixed with a mobile phase and filtered with a 0.45 µm polytetrafluoroethylene filter before analysis. Chromatographic separation was carried out on a C18 column (150 × 4.6 mm, 5 µm I.D.) using methanol:50 mM ortho-phosphoric acid solution (40:60) as the mobile phase with a 1.0 mL/min flow rate. Quantitation was performed using fluorescence detection with an excitation wavelength at 272 nm and an emission wavelength at 395 nm. The linear range was found to be 0.1-2.5 µg/mL. The method was applied successfully for the determination of gemifloxacin in breast milk obtained from a breastfeeding mother after oral administration of a single tablet that included 320 mg gemifloxacin per gemifloxacin tablet.

  20. Magnetic nanoparticles solid phase extraction for determination of ochratoxin A in cereals using high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Mashhadizadeh, Mohammad Hossein; Amoli-Diva, Mitra; Pourghazi, Kamyar

    2013-12-13

    A new, simple, fast, and environmental friendly sample preconcentration technique based on the modified Fe3O4 nanoparticles has been developed for extraction, and determination of ochratoxin A (OTA). Magnetic nanoparticles were coated with 3-(trimethoxysilyl)-1-propanethiol and modified by ethylene glycol bis-mercaptoacetate. Transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectrometry were used to characterize the adsorbents and the main parameters affecting the extraction and desorption efficiencies, such as pH of sample solution, sample volume, desorption conditions, extraction and desorption times, salt addition, and co-existing interferences have been investigated and established. Under optimal conditions, OTA was extracted and analyzed using high performance liquid chromatography with fluorescence detection. The mobile phase consists of acetonitrile:water:acetic acid (99:99:2, v/v/v) and fluorescence detection was performed with excitation and emission wavelengths at 333 and 477nm, respectively. An enrichment factor of 24 was achieved for OTA with relative standard deviation of <7%. The proposed method was applied to twenty samples of cereals (rice, wheat, and corn). The limits of detection of 0.06, 0.03, and 0.05ngmL(-1) and limits of quantitation of 0.19, 0.11, and 0.15ngmL(-1), were found for rice, wheat, and corn samples, respectively. The recoveries of OTA for spiked samples were ranged from 87 to 93%.

  1. A novel liquid chromatographic method with fluorescence detection for quantitation of tadalafil and dapoxetine hydrochloride in pharmaceutical dosage form and human plasma

    Institute of Scientific and Technical Information of China (English)

    MAHA Hegazy; AMIRA Kessiba; MOHAMED Abdelkawy; AHMED EMAD El Gindy

    2015-01-01

    Tadalafil( TAD)and dapoxetine HCl( DAP)are recently co-formulated and both show native fluo-rescence. Therefore,a novel,accurate,specific and sensitive reversed-phase high performance liquid chroma-tographic method with fluorescence detection was developed and validated for their separation and quantitation in dosage form and human plasma using avanafil as an internal standard( IS). Separation was achieved using isocratic elution within 7. 0 min on C18 column and acetonitrile-0. 15% triethylamine( 40∶60,v/v;pH 4)as a mobile phase. The flow rate was 1. 0 mL/min and the detection was time-programmed at 330,410 and 370 nm for TAD,DAP and IS,respectively,after excitation at 236 nm. The linear ranges from 0. 01 to 30. 00 μg/mL for each drug with the limits of detection of 4. 20 and 7. 20 ng/mL for TAD and DAP,respectively. The method was validated in accordance to the International Conference on Harmonization( ICH)guidelines and was successful-ly applied to spiked human plasma with mean recoveries of 98. 17% and 98. 83% for TAD and DAP respectively.

  2. Highly sensitive and selective high-performance liquid chromatography method for bioequivalence study of cefpodoxime proxetil in rabbit plasma via fluorescence labeling of its active metabolite.

    Science.gov (United States)

    Ahmed, Sameh; Abdel-Wadood, Hanaa M; Mohamed, Niveen A

    2013-09-01

    Cefpodoxime proxetil (CFP), a broad-spectrum third-generation cephalosporin, has been used most widely in the treatment of respiratory and urinary tract infections. For bioequivalence study of CFP in rabbit plasma, it was necessary to develop a highly sensitive and selective high-performance liquid chromatographic (HPLC) method with fluorescence (FL) detection. The pre-column labeling of cefpodoxime acid (CFA) (active metabolite) with an efficient benzofurazan type fluorogenic reagent, 4-N,N-dimethyl aminosulfonyl-7-fluoro-2,1,3-benzoxadiazole (DBD-F) was carried out in the present study in 100mM borate buffer (pH=8.5) at 50°C for 15min. The obtained fluorescent products were separated on C18 column with an isocratic elution of the mobile phase, which consists of 10mM phosphate buffer (pH=3.5)/CH3CN (70:30, v/v). The fluorescent product (DBD-CFA) was detected fluorimetrically at 556nm with an excitation wavelength of 430nm. Cefotaxime sodium was used as internal standard. The method was validated according to the requirements of US-FDA guidelines. The correlation coefficient of 0.999 was obtained in the concentration ranges of 10-1000ngmL(-1). The limits of detection and quantification (S/N=3) were 3 and 10ngmL(-1), respectively. Plasma CFA levels were successfully determined in rabbit with satisfactory precision and accuracy. The proposed HPLC-FL method was successfully applied to study bioequivalence in rabbits for two formulations of different brands contained CFP (prodrug) in a randomized, two-way, single-dose, crossover study and all pharmacokinetic parameters for the two formulations were assessed.

  3. Determination of marker pteridins and biopterin reduced forms, tetrahydrobiopterin and dihydrobiopterin, in human urine, using a post-column photoinduced fluorescence liquid chromatographic derivatization method

    Energy Technology Data Exchange (ETDEWEB)

    Canada-Canada, Florentina, E-mail: floricanada@gmail.com [Department of Analytical Chemistry, University of Extremadura, 06071 Badajoz (Spain); Espinosa-Mansilla, Anunciacion; Munoz de la Pena, Arsenio; Mancha de Llanos, Alicia [Department of Analytical Chemistry, University of Extremadura, 06071 Badajoz (Spain)

    2009-08-19

    A liquid chromatographic method for the simultaneous analysis of marker pteridins and biopterin reduced forms, in urine samples is proposed. A Zorbax Eclipse XDB-C18 column was used for the chromatographic separation, using a 98/2 (v/v), citrate buffer (pH 5.5)-acetonitrile mobile phase, in isocratic mode. A post-column photoderivatization was carried out with an on-line photoreactor, located between a diode array detector (DAD) and a fast scanning fluorescence detector (FSFD). Neopterin (NEO), biopterin (BIO), pterin (PT) and dihydrobiopterin (BH2) were determined by measuring native fluorescence, using the photoreactor in OFF-mode, and tetrahydrobiopterin (BH4) was determined by measuring of the induced fluorescence of the generated photoproducts, using the photoreactor in ON-mode. In addition, Creatinine (CREA), as a reference of metabolites excrection in urine, was simultaneously determined using the DAD detector. Detection limits were 0.2, 13.0, 0.3, 0.3 and 3.5 ng mL{sup -1}, for NEO, BH2, BIO, PT and BH4, respectively, and 0.4 {mu}g mL{sup -1} for CREA. Ratio values for NEO/CREA, PT/CREA, BH4/CREA, BH2/CREA, NEO/BIO and BIO{sub total}/CREA, in urine samples, of healthy children and adults, phenylketonuric children and infected mononucleosis children, are reported. A comparative study, about the mean values obtained for each of the compounds, by the present procedure and by the classical iodine oxidation method (Fukushimas method), has been performed, in urine samples belonging to healthy volunteers. The values obtained were BH4/CREA: 0.41, BH2/CREA: 0.31 and BIO{sub total}/CREA: 0.73, by the proposed method, and BH4/CREA: 0.35, BH2/CREA: 0.20 and BIO{sub total}/CREA: 0.48, by iodine oxidation method.

  4. Investigation of Real-Time Two-Dimensional Visualization of Fuel Spray Liquid/Vapor Distribution via Exciplex Fluorescence.

    Science.gov (United States)

    1987-08-30

    computer * In- house software I g I 06-10-72-12 15 [Gaussian mode]. The intensity distribution was observed and analyzed by capturing the frontal and...points of the exciplex coff ,ponents ar,.’ the 4uel at one atr,:soreire. and therety to reduce the ttendenc’y of the componeritz t:, e~:~ C;4eertia!l...fluorescence position. The cuvette is slow, and only a fraction of the M* initially formed chamber was heated with flowing house air, which had

  5. Dispersive liquid-liquid microextraction using diethyldithiocarbamate as a chelating agent and the dried-spot technique for the determination of Fe, Co, Ni, Cu, Zn, Se and Pb by energy-dispersive X-ray fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Kocot, Karina; Zawisza, Beata; Sitko, Rafal, E-mail: rafal.sitko@us.edu.pl

    2012-07-15

    Dispersive liquid-liquid microextraction (DLLME) using sodium diethyldithiocarbamate (DDTC) as a chelating agent was investigated for the simultaneous determination of iron, cobalt, nickel, copper, zinc, selenium and lead ions in water samples. The procedure was performed using 5 mL of the sample, 100 {mu}L of a 0.5% solution of DDTC, 30 {mu}L of carbon tetrachloride (extraction phase) and 500 {mu}L of methanol (disperser solvent). The experiments showed that Fe, Co, Ni, Cu, Zn and Pb can be simultaneously extracted at a pH of 5 and that Se can be extracted at a pH of 2-3. The results were compared with those obtained using ammonium pyrrolidine dithiocarbamate as a chelating agent. For all analytes, a linear range was observed up to 0.4 {mu}g mL{sup -1}. If Fe and Zn are present in concentrations 10 times higher than those of the other analytes, then the linearity is observed up to 0.2 {mu}g mL{sup -1}. In the present study, the organic phase that contained preconcentrated elements was deposited onto a Millipore filter and measured using energy-dispersive X-ray fluorescence spectrometry. The obtained detection limits were 2.9, 1.5, 2.0, 2.3, 2.5, 2.0 and 3.9 ng mL{sup -1} for Fe, Co, Ni, Cu, Zn, Se and Pb, respectively. This combination of DLLME and the dried-spot technique is promising for multielement analyses using other spectroscopy techniques, such as laser ablation-inductively coupled plasma-mass spectrometry, laser-induced breakdown spectroscopy or total-reflection X-ray fluorescence spectrometry. - Highlights: Black-Right-Pointing-Pointer Multielement trace analysis using dried-spot technique and dispersive liquid-liquid microextraction. Black-Right-Pointing-Pointer Possibility of combination of LPME with EDXRF, LIBS or LA-ICP-MS. Black-Right-Pointing-Pointer Comparison of APDC and DDTC as chelating agents.

  6. Automated In-Injector Derivatization Combined with High-Performance Liquid Chromatography-Fluorescence Detection for the Determination of Semicarbazide in Fish and Bread Samples.

    Science.gov (United States)

    Wang, Yinan; Chan, Wan

    2016-04-06

    Semicarbazide (1) is a widespread genotoxic food contaminant originating as a metabolic byproduct of the antibiotic nitrofurazone used in fish farming or as a thermal degradation product of the common flour additive azodicarbonamide. The goal of this study is to develop a simple and sensitive high-performance liquid chromatography coupled with fluorescence detection (HPLC-FLD) method for the detection of compound 1 in food products. In comparison to existing methods for the determination of compound 1, the reported method combining online precolumn derivatization and HPLC-FLD is less labor-intensive, produces higher sample throughput, and does not require the use of expensive analytical instruments. After validation of accuracy and precision, this method was applied to determine the amount of compound 1 in fish and bread samples. Comparative studies using an established liquid chromatography coupled with tandem mass spectrometry method did not yield systematically different results, indicating that the developed HPLC-FLD method is accurate and suitable for the determination of compound 1 in fish and bread samples.

  7. Planar Sauter Mean Diameter measurements in liquid centered swirl coaxial injector using Laser Induced Fluorescence, Mie scattering and laser diffraction techniques

    Science.gov (United States)

    Kannaiyan, Kamalakannan; Banda, Manoj Venkata Krishna; Vaidyanathan, Aravind

    2016-06-01

    An experimental technique is carried out to demonstrate the measurement of planar Sauter Mean Diameter (SMD or D32) distribution in a liquid centered swirl coaxial injector (LCSC) using simultaneous measurements of Mie scattering, Planar Laser-Induced Fluorescence (PLIF) and Laser diffraction technique (LDT). Here water is used as the test fluid with addition of optimized quantities of the organic dye (Rhodamine 6 g) for PLIF measurements. Experiments are carried out at three experimental conditions with momentum flux ratios of 6.25, 12.14, and 19.95 respectively. Experiments are carried out to study the effect of dye concentration in LDT. LDT (line of sight) is corrected for multiple scattering effects. The SMD distribution obtained from Liquid Sheet Drop Sizing (LSDS) technique is calibrated using LDT (Malvern particle analyzer) that utilizes the principle of diffraction; the results obtained from both the methods are compared and analyzed using the respective histograms. The variations in the distribution of droplet diameter along the axial and radial locations in the spray field are also studied in detail.

  8. Penetration Testing of the OPRA Regolith Penetrator

    Science.gov (United States)

    El Shafie, A.; Kegege, O.; Barrows, S.; Roe, L.; Ulrich, R.

    2008-03-01

    Our work focuses on the mechanical design and penetration forces for the Optical Probe for Regolith Analysis. This is a spike-shaped probe delivered to a planet, asteroid, or cometary body by a lander to provide IR spectroscopy of the subsurface.

  9. Dispersive liquid-liquid microextraction using diethyldithiocarbamate as a chelating agent and the dried-spot technique for the determination of Fe, Co, Ni, Cu, Zn, Se and Pb by energy-dispersive X-ray fluorescence spectrometry

    Science.gov (United States)

    Kocot, Karina; Zawisza, Beata; Sitko, Rafal

    2012-07-01

    Dispersive liquid-liquid microextraction (DLLME) using sodium diethyldithiocarbamate (DDTC) as a chelating agent was investigated for the simultaneous determination of iron, cobalt, nickel, copper, zinc, selenium and lead ions in water samples. The procedure was performed using 5 mL of the sample, 100 μL of a 0.5% solution of DDTC, 30 μL of carbon tetrachloride (extraction phase) and 500 μL of methanol (disperser solvent). The experiments showed that Fe, Co, Ni, Cu, Zn and Pb can be simultaneously extracted at a pH of 5 and that Se can be extracted at a pH of 2-3. The results were compared with those obtained using ammonium pyrrolidine dithiocarbamate as a chelating agent. For all analytes, a linear range was observed up to 0.4 μg mL- 1. If Fe and Zn are present in concentrations 10 times higher than those of the other analytes, then the linearity is observed up to 0.2 μg mL- 1. In the present study, the organic phase that contained preconcentrated elements was deposited onto a Millipore filter and measured using energy-dispersive X-ray fluorescence spectrometry. The obtained detection limits were 2.9, 1.5, 2.0, 2.3, 2.5, 2.0 and 3.9 ng mL- 1 for Fe, Co, Ni, Cu, Zn, Se and Pb, respectively. This combination of DLLME and the dried-spot technique is promising for multielement analyses using other spectroscopy techniques, such as laser ablation-inductively coupled plasma-mass spectrometry, laser-induced breakdown spectroscopy or total-reflection X-ray fluorescence spectrometry.

  10. Akon - A Penetrator for Europa

    Science.gov (United States)

    Jones, Geraint

    2016-04-01

    Jupiter's moon Europa is one of the most intriguing objects in our Solar System. This 2000km-wide body has a geologically young solid water ice crust that is believed to cover a global ocean of liquid water. The presence of this ocean, together with a source of heating through tidal forces, make Europa a conceivable location for extraterrestrial life. The science case for exploring all aspects of this icy world is compelling. NASA has selected the Europa Mission (formerly Europa Clipper) to study Europa in detail in the 2020s through multiple flybys, and ESA's JUICE mission will perform two flybys of the body in the 2030s. The US agency has extended to the European Space Agency an invitation to provide a contribution to their mission. European scientists interested in Europa science and exploration are currently organizing themselves, in the framework of a coordinated Europa M5 Inititative to study concurrently the main options for this ESA contribution, from a simple addition of individual instruments to the NASA spacecraft, to a lander to investigate Europa's surface in situ. A high speed lander - a penetrator - is by far the most promising technology to achieve this latter option within the anticipated mass constraints, and studies of such a hard lander, many funded by ESA, are now at an advanced level. An international team to formally propose an Europa penetrator to ESA in response to the anticipated ESA M5 call is growing. The working title of this proposal is Akon (Άκων), named after the highly accurate javelin gifted to Europa by Zeus in ancient Greek mythology. We present plans for the Akon penetrator, which would impact Europa's surface at several hundred metres per second, and travel up to several metres into the moon's subsurface. To achieve this, the penetrator would be delivered to the surface by a dedicated descent module, to be destroyed on impact following release of the penetrator above the surface. It is planned that the instruments to be

  11. Follicular penetration and targeting.

    Science.gov (United States)

    Lademann, Jürgen; Otberg, Nina; Jacobi, Ute; Hoffman, Robert M; Blume-Peytavi, Ulrike

    2005-12-01

    In the past, intercellular penetration was assumed to be the most important penetration pathway of topically applied substances. First hints that follicular penetration needs to be taken into consideration were confirmed by recent investigations, presented during the workshop "Follicular Penetration and Targeting" at the 4th Intercontinental Meeting of Hair Research Societies", in Berlin 2004. Hair follicles represent an efficient reservoir for the penetration of topically applied substances with subsequent targeting of distinct cell populations, e.g., nestin-expressing follicular bulge cells. The volume of this reservoir can be determined by differential stripping technology. The follicular penetration processes are significantly influenced by the state of the follicular infundibulum; recent experimental investigations could demonstrate that it is essential to distinguish between open and closed hair follicles. Topically applied substances can only penetrate into open hair follicle. Knowledge of follicular penetration is of high clinical relevance for functional targeting of distinct follicular regions. Human hair follicles show a hair-cycle-dependent variation of the dense neuronal and vascular network. Moreover, during hair follicle cycling with initiation of anagen, newly formed vessels occur. Thus, the potential of nestin-expressing hair follicle stem cells to form neurons and blood vessels was investigated.

  12. Quantitative analysis of closantel and rafoxanide in bovine and ovine muscles by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Yeung, Hoi-Sze; Ching, Wing-Hong; Lai, Shirley Sau-Ling; Lee, Wai-On; Wong, Yiu-Tung

    2010-01-01

    An HPLC method with a fluorescence detector (HPLC-FLD) was described for the quantitative determination of closantel and rafoxanide in bovine and ovine muscles. A structural analog closely related to rafoxanide, viz., N-[4-(4-chlorophenoxy)phenyl]-2-hydroxy-3,5-diiodobenzamide, was synthesized as an internal standard. Bovine and ovine muscles were extracted with acetonitrile-acetone (60 + 40, v/v) followed by cleanup on mixed mode anionic exchange SPE cartridges. After evaporation and reconstitution with the mobile phase, the sample was analyzed by HPLC-FLD using internal standard calibration. The method was validated by using fortified bovine and ovine muscles at 15, 30, and 60 microg/kg. The accuracy and RSD were 70-110% and < or =10%, respectively.

  13. High-throughput and sensitive screening of compounds with deoxyribonucleic acid-binding activity by a high-performance liquid chromatography-tandem mass spectrometry-fluorescence detection technique using palmatine as a fluorescence probe.

    Science.gov (United States)

    Fu, Qingrong; Wang, Hong; Lan, Yuexiang; Li, Sen; Hashi, Yuki; Chen, Shizhong

    2014-01-03

    A high-throughput biochemical detection method based on the combination of high-performance liquid chromatography (HPLC), multiple-stage mass spectrometry (MS(n)) and DNA-binding activity assay was developed and validated for the simultaneous screening and identification of DNA-binding compounds in complex samples. Palmatine was used as a sensitive, nontoxic and environmentally friendly DNA fluorescence probe. HPLC fingerprints, ultraviolet absorption spectra, MS(n) fragments of components, and DNA-binding activity profiles could be simultaneously recorded during real-time analysis. Using the proposed method, 25 compounds were identified from Lophatherum gracile Brongn extracts, of which 18 were novel compounds first identified in these extracts. Nineteen compounds showed DNA-binding activity, most of which were flavone glycosides, with distinct dose-effect and structure-activity relationships. The method was validated and was proven to have a good linearity in the range of concentrations used in the study. The limit of detection was 0.2020nmol. Our study indicated that the proposed method was sensitive, accurate, precise and reliable to be used for simultaneous screening and identification of DNA-binding compounds in complex samples.

  14. Simultaneous determination of four trace estrogens in feces, leachate, tap and groundwater using solid-liquid extraction/auto solid-phase extraction and high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Liu, Na; Shi, Yue-e; Li, Mengyan; Zhang, Ting-di; Gao, Song

    2015-10-01

    A simple and selective high-performance liquid chromatography method coupled with fluorescence detection was developed for the simultaneous measurement of trace levels of four estrogens (estrone, estradiol, estriol and 17α-ethynyl estradiol) in environmental matrices. For feces samples, solid-liquid extraction was applied with a 1:1 v/v mixture of acetonitrile and ethyl acetate as the extraction solvent. For liquid samples (e.g., leachate and groundwater), hydrophobic/lipophilic balanced automated solid-phase extraction disks were selected due to their high recoveries compared to conventional C18 disks. Chromatographic separations were performed on a reversed-phase C18 column gradient-eluted with a 45:55 v/v mixture of acetonitrile and water. The detection limits were down to 1.1 × 10(-2) (estrone), 4.11 × 10(-4) (estradiol), 5.2 × 10(-3) (estriol) and 7.18 × 10(-3) μg/L (17α-ethynyl estradiol) at excitation/emission wavelengths of 288/310 nm, with recoveries in the range of 96.9 ± 3.2-105.4 ± 3.2% (n = 3). The method was successfully applied to determine estrogens in feces and water samples collected at livestock farms and a major river in Northeast China. We observed relatively high abundance and widespread distribution of all four estrogens in our sample collections, implying the urgency for a comprehensive and intricate investigation of estrogenic fate and contamination in our researched area.

  15. Standard test method for determination of low concentrations of uranium in oils and organic liquids by X-ray fluorescence

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This test method covers the steps necessary for the preparation and analysis by X-ray fluorescence (XRF) of oils and organic solutions containing uranium. Two different preparation techniques are described. 1.2 The procedure is valid for those solutions containing 20 to 2000 μg uranium per mL as presented to the spectrometer for the solution technique and 200 to 50 000 μg uranium per g for the pellet technique. 1.3 This test method requires the use of an appropriate internal standard. Care must be taken to ascertain that samples analyzed by this test method do not contain the internal standard or that this contamination, whenever present, has been corrected for mathematically. Such corrections are not addressed in this procedure. Care must be taken that the internal standard and sample medium are compatible; that is, samples must be miscible with tri-n-butyl phosphate (TBP) and must not remove the internal standard from solution. Alternatively, a scatter line may be used as the internal standard. 1....

  16. The Determination of Six Ionophore Coccidiostats in Feed by Liquid Chromatography with Postcolumn Derivatisation and Spectrofotometric/Fluorescence Detection

    Directory of Open Access Journals (Sweden)

    Małgorzata Olejnik

    2013-01-01

    Full Text Available The control of levels of anticoccidial feed additives in targeted feeds plays an important role in the assurance of efficiency of animal treatment, prevention of drug resistance, and food safety. The robust and labour-efficient method for the simultaneous determination of six ionophore coccidiostats (lasalocid, maduramicin, monensin, narasin, salinomycin, and semduramicin in targeted feed has been developed. Properly grinded and homogenized feed sample was spiked with internal standard (monesin methyl ester and extracted with methanol. The extract was analysed with reversed phase HPLC without any further purification. The separation of the analytes with conventional C18 and core-shell columns was compared. Lasalocid was analysed with fluorescence detection, whereas other ionophores were detected with UV-Vis detector after derivatisation with vanillin in the presence of sulfuric acid. Fortified samples and targeted feeds at authorized levels were used for method validation. Recovery was in the range of 85–110%, depending on the analyte. The within-laboratory reproducibility did not exceed the target value from Horwitz equation. The results of the proficiency tests (z-scores in the range of −1.0 to 1.9 confirmed the reliability of the developed protocol.

  17. Metasploit penetration testing cookbook

    CERN Document Server

    Agarwal, Monika

    2013-01-01

    This book follows a Cookbook style with recipes explaining the steps for penetration testing with WLAN, VOIP, and even cloud computing. There is plenty of code and commands used to make your learning curve easy and quick.This book targets both professional penetration testers as well as new users of Metasploit, who wish to gain expertise over the framework and learn an additional skill of penetration testing, not limited to a particular OS. The book requires basic knowledge of scanning, exploitation, and the Ruby language.

  18. Determination of Aflatoxins and Ochratoxin A in Ginseng and Other Botanical Roots by Immunoaffinity Column Cleanup and Liquid Chromatography with Fluorescence Detection

    Science.gov (United States)

    Trucksess, Mary; Weaver, Carol; Oles, Carolyn; D’Ovidio, Kathleen; Rader, Jeanne

    2008-01-01

    Mycotoxins are toxic secondary metabolites produced by certain molds and are common contaminants of many important food crops, such as grains, nuts, and spices. Some mycotoxins are found in fruits, vegetables, and botanical roots. These contaminants have a broad range of toxic effects, including carcinogenicity, immunotoxicity, neurotoxicity, and reproductive and developmental toxicity. The public health concerns related to both acute and chronic effects of mycotoxins in animals have prompted more than 100 countries to establish regulatory limits for some of the well-known mycotoxins, such as the aflatoxins (AFL). Our research focused on method development for 2 of these toxins, AFL and ochratoxin A (OTA), in ginseng and other selected botanical roots. Methods using an immunoaffinity column (IAC) cleanup, liquid chromatographic separation, and fluorescence detection were modified and evaluated. Two types of IAC cleanup were evaluated: IAC for AFL, and IAC for both AFL and OTA. Three derivatization techniques to enhance the fluorescence of the AFL were compared: precolumn trifluoroacetic acid, postcolumn bromination, and postcolumn ultraviolet irradiation. No derivatization was needed for OTA. Results for AFL using the single analyte IAC cleanup and the 3 derivatization techniques were all comparable for ginseng and for other roots such as ginger, licorice, and kava-kava. Recoveries of added AFL for ginseng at levels from 2 to 16 ng/g were about 80%. Using IAC cleanup for both AFL and OTA recoveries of added AFL for ginseng at 4–16 ng/g were about 70%, and for ginger, licorice, and kava-kava were about 60%. Recoveries of added OTA for ginseng, ginger, and echinacea at 4 ng/g were about 55%. PMID:16792061

  19. Simultaneous determination of thiamphenicol, florfenicol and florfenicol amine in eggs by reversed-phase high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Xie, Kaizhou; Jia, Longfei; Yao, Yilin; Xu, Dong; Chen, Shuqing; Xie, Xing; Pei, Yan; Bao, Wenbin; Dai, Guojun; Wang, Jinyu; Liu, Zongping

    2011-08-01

    A specific, sensitive and widely applicable reversed-phase high-performance liquid chromatography with fluorescence detection (RP-HPLC-FLD) method was developed for the simultaneous determination of thiamphenicol (TAP), florfenicol (FF) and florfenicol amine (FFA) in eggs. Samples were extracted with ethyl acetate-acetonitrile-ammonium hydroxide (49:49:2, v/v), defatted with hexane, followed by RP-HPLC-FLD determination. Liquid chromatography was performed on a 5 μm LiChrospher C(18) column using a mobile phase composed of acetonitrile (A), 0.01 M sodium dihydrogen phosphate containing 0.005 M sodium dodecyl sulfate and 0.1% triethylamine, adjusted to pH 4.8 by 85% phosphoric acid (B) (A:B, 35:65 v/v), at a flow rate of 1.0 mL/min. The fluorescence detector of HPLC was set at 224 nm for excitation wavelength and 290 nm for emission wavelength. Limits of detection (LODs) were 1.5 μg/kg for TAP and FF, 0.5 μg/kg for FFA in eggs; limits of quantitation (LOQs) were 5 μg/kg for TAP and FF, 2 μg/kg for FFA in eggs. Linear calibration curves were obtained over concentration ranges of 0.025-5.0 μg/mL for TAP with determination coefficients of 0.9997, 0.01-10.0 μg/mL for FF with determination coefficients of 0.9997 and 0.0025-2.50 μg/mL for FFA with determination coefficients of 0.9998, respectively. The recovery values ranged from 86.4% to 93.8% for TAP, 87.4% to 92.3% for FF and from 89.0% to 95.2% for FFA. The corresponding intra-day and inter-day variation (relative standard deviation, R.S.D.) found to be less than 6.7% and 10.8%, respectively.

  20. Penetration testing with Perl

    CERN Document Server

    Berdeaux, Douglas

    2014-01-01

    If you are an expert Perl programmer interested in penetration testing or information security, this guide is designed for you. However, it will also be helpful for you even if you have little or no Linux shell experience.

  1. Development of a sensitive and reliable high performance liquid chromatography method with fluorescence detection for high-throughput analysis of multi-class mycotoxins in Coix seed.

    Science.gov (United States)

    Kong, Wei-Jun; Li, Jun-Yuan; Qiu, Feng; Wei, Jian-He; Xiao, Xiao-He; Zheng, Yuguo; Yang, Mei-Hua

    2013-10-17

    As an edible and medicinal plant, Coix seed is readily contaminated by more than one group of mycotoxins resulting in potential risk to human health. A reliable and sensitive method has been developed to determine seven mycotoxins (aflatoxins B1, B2, G1, G2, zearalenone, α-zearalenol, and β-zearalenol) simultaneously in 10 batches of Coix seed marketed in China. The method is based on a rapid ultrasound-assisted solid-liquid extraction (USLE) using methanol/water (80/20) followed by immunoaffinity column (IAC) clean-up, on-line photochemical derivatization (PCD), and high performance liquid chromatography coupled with fluorescence detection (HPLC-FLD). Careful optimization of extraction, clean-up, separation and detection conditions was accomplished to increase sample throughput and to attain rapid separation and sensitive detection. Method validation was performed by analyzing samples spiked at three different concentrations for the seven mycotoxins. Recoveries were from 73.5% to 107.3%, with relative standard deviations (RSDs) lower than 7.7%. The intra- and inter-day precisions, expressed as RSDs, were lower than 4% for all studied analytes. Limits of detection and quantification ranged from 0.01 to 50.2 μg kg(-1), and from 0.04 to 125.5 μg kg(-1), respectively, which were below the tolerance levels for mycotoxins set by the European Union. Samples that tested positive were further analyzed by HPLC tandem electrospray ionization mass spectrometry for confirmatory purposes. This is the first application of USLE-IAC-HPLC-PCD-FLD for detecting the occurrence of multi-class mycotoxins in Coix seed.

  2. Measurements of the liquid phase temperature in fuel sprays via exciplex fluorescence method. 1st Report. Development of the measuring technique and application to fuel sprays injected into atmospheric pressure and high temperature environments; Exciplex keikoho ni yoru nenryo funmu no ekiso ondo bunpu sokutei. 1. Sokutei shuho no kaihatsu to joatsu koon fun`ikichu ni okeru funmu eno tekiyo

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizaki, T.; Nishida, K.; Hiroyasu, H. [Hiroshima University, Hiroshima (Japan). Faculty of Engineering; Funahashi, T.

    1998-07-25

    A measuring method based on the exciplex fluorescence technique has been developed for planar measurements of the liquid phase temperature distribution in fuel sprays. The liquid fuel (n-hexadecane or squalane) was doped with pyrene (C16H10). The fluorescence intensity ratios of the pyrene monomer and excimer emissions has temperature dependence, and were used to determine the liquid phase temperatures in the fuel sprays. The spray was excited by laser radiation at 266 nm, and the resulting fluorescence was imaged by an intensified CCD camera. The cross-sectional distribution of the liquid phase temperature was estimated from the fluorescence image by the temperature dependence of the intensity ratio. The results demonstrate that this laser-based thermometry technique is available for 2-D measurements of the liquid phase temperature in fuel sprays. 13 refs., 15 figs., 2 tabs.

  3. Determination of sulphonamide residues in cattle meats by the Charm-II system and validation with high performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Mor, F; Sahindokuyucu Kocasari, F; Ozdemir, G; Oz, B

    2012-10-01

    The purpose of this study was determination of sulphonamide residues (sulphanilamide, sulphadiazine, sulphathiazole, sulphamerazine, sulphamethazine, sulphamethoxazole, and sulphadimethoxine) in cattle meat by the Charm II technique and the validation of sulphonamide levels by high performance liquid chromatography with fluorescence detector (HPLC-FLD). Of 157 meat samples, 9 samples (5.73%) were found positive by the Charm II method. To make quantitative confirmation of sulphonamide content of positive samples, HPLC-FLD was used and four samples were confirmed as positive. In HPLC analysis, the limit of detection (LOD) was in the range 8-15 μg/kg and the limit of quantification (LOQ) was 13-25 μg/kg. Average recoveries of sulphonamides ranged from 44.6% to 81% with relative standard deviations below 6% (n=6). In conclusion, we consider that the results obtained in field screening by only using the Charm II system, as is common practice in Turkey and worldwide, are inadequate and thus the results should be confirmed by sensitive systems like HPLC.

  4. [Effect of alcoholic strength on the determination of ethyl carbamate in Chinese spirits by high performance liquid chromatography-fluorescence detection].

    Science.gov (United States)

    Chen, Dawei; Miao, Hong; Zhao, Yunfeng; Wu, Yongning

    2013-12-01

    A high performance liquid chromatography-fluorescence detection (HPLC-FLD) method was established for rapid determination of ethyl carbamate (EC) in Chinese spirits. Through the analysis and comparison of the EC peak areas in different alcoholic strengths determined by HPLC-FLD, the effect of alcoholic strength on the determination of the content of EC was found. The alcoholic strength and the peak area of EC showed good linearity in the range of 5% to 65% (v/v) alcohol content, and the correlation coefficients (R2) were higher than 0.98. Furthermore, the conversion between the peak area of EC with different alcoholic strengths was established by the relative correction coefficient. The method showed a good linearity in the range of 10 to 500 microg/L for EC with the average recoveries of 98.9%-108.2% and RSDs of 0.6%-4.9%. The reliability of the established HPLC-FLD method was evaluated by comparison with GC-MS method. The results showed that the results of two methods were not significantly different. The developed method is simple, sensitive, accurate, and suitable for the rapid determination of EC in Chinese spirits.

  5. Study of molecularly imprinted solid-phase extraction of gonyautoxins 2,3 in the cultured dinoflagellate Alexandrium tamarense by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Lian, Zi-Ru; Wang, Jiang-Tao

    2013-11-01

    A highly selective sample cleanup procedure combined with molecularly imprinted solid-phase extraction (MISPE) was developed for the isolation of gonyautoxins 2,3 (GTX2,3) from Alexandrium tamarense sample. The molecularly imprinted polymer microspheres (MIPMs) were prepared by suspension polymerization using caffeine as the dummy template molecule, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker and polyvinyl alcohol as the dispersive reagent. The polymer microspheres were used as a selective sorbent for the solid-phase extraction of gonyautoxins 2,3. An off-line MISPE method followed by high-performance liquid chromatography (HPLC) with fluorescence detection for the analysis of gonyautoxins 2,3 was established. Finally, the extract samples from Alexandrium tamarense were analyzed. The results showed the imprinted polymer microspheres exhibited high affinity and selectivity for gonyautoxins 2,3. The interference matrix in the extract were obviously cleaned by MISPE and the extraction efficiency of gonyautoxins 2,3 in the sample ranged from 81.74% to 85.86%.

  6. Development of a high-performance liquid chromatography with fluorescence detection method for quantification of piperazine in animal products by using precolumn derivatization.

    Science.gov (United States)

    Park, Jin-A; Zhang, Dan; Kim, Dong-Soon; Kim, Seong-Kwan; Cho, Sang-Hyun; Jeong, Daun; Kim, Jin-Suk; Shim, Jae-Han; Abd El-Aty, A M; Shin, Ho-Chul

    2016-04-01

    A new high-performance liquid chromatography with ​fluorescence detection (HPLC-FLD) method was developed for determination of piperazine residues in food animal products. Samples were extracted with formic acid in water and purified using the PCX cartridge. Following purification, the samples were derivatized using dansyl chloride, and the analyte was separated using water/acetonitrile as a mobile phase. The calibration curves showed good linearity over a concentration range of 20-120 ng/g with coefficient of determination (R(2))⩾0.996. The intra-day accuracy (presented as recovery %) and precision (presented as relative standard deviation, RSD %) were 81-97.3% and 0.83-6.87%, whereas, the inter-day values were 80.5-96.8% and 1.7-6.8%, respectively. The limit of quantification (LOQ) was 20 ng/g, which was considerably lower than the maximum residue limit (MRL). The developed method was used to monitor market samples, and piperazine was not detected in any of the samples. To our knowledge, this is the first study in which the detection of piperazine in various food and animal products by using a sensitive and reliable analytical method has been described.

  7. Determination of autoinducer-2 in biological samples by high-performance liquid chromatography with fluorescence detection using pre-column derivatization.

    Science.gov (United States)

    Song, Xiang-Ning; Qiu, Hai-Bin; Xiao, Xiang; Cheng, Yuan-Yuan; Li, Wen-Wei; Sheng, Guo-Ping; Li, Xiao-Yan; Yu, Han-Qing

    2014-09-26

    Autoinducer-2 (AI-2), as a small-molecular-weight organic molecule secreted and perceived by various bacteria, enables intra- and inter-species communications. Quantitative determination of AI-2 is essential for exploring the bacterial AI-2-related physiological and biochemical processes. However, current strategies for sensitive detection of AI-2 require sophisticated instruments and complicated procedures. In this work, on the basis of the derivatization of AI-2 with 2,3-diaminonaphthalene, a simple, sensitive and cost-effective high-performance liquid chromatography with fluorescence detector (HPLC-FLD) method is developed for the quantitative detection of AI-2. Under the optimized conditions, this method had a broad linear range of 10-14,000 ng/ml (R(2)=0.9999), and a low detection limit of 1.0 ng/ml. Furthermore, the effectiveness of this approach was further validated through measuring the AI-2 concentrations in the cell-free culture supernatants of both Escherichia coli and Vibrio harveyi.

  8. Evaluation of high-performance liquid chromatography laser-induced fluorescence for serum protein profiling for early diagnosis of oral cancer

    Science.gov (United States)

    Patil, Ajeetkumar; Prabhu, Vijendra; Choudhari, K. S.; Unnikrishnan, V. K.; George, Sajan D.; Ongole, Ravikiran; Pai, Keerthilatha M.; Shetty, Jayarama K.; Bhat, Sujatha; Kartha, Vasudevan Bhaskaran; Chidangil, Santhosh

    2010-11-01

    The present work deals with the evaluation of a high-performance liquid chromatography laser-induced fluorescence (HPLC-LIF) technique developed in our laboratory for early detection of oral cancer from protein profiles of body fluids. The results show that protein profiles of serum samples from a given class of samples, say, normal, premalignant, or malignant, are statistically very close to each other, while profiles of members of any class are significantly different from other classes. The performance of the technique is evaluated by the use of sensitivity and specificity pairs, receiver operating characteristic (ROC) analysis, and Youden's Index. The technique uses protein profile differences in serum samples, registered by the HPLC-LIF technique. The study is carried out using serum samples from volunteers diagnosed as normal or premalignant clinically, and as malignant by histopathology. The specificities and sensitivities of the HPLC-LIF method at an ideal threshold (M-distance = 2) for normal, malignant, and premalignant classes are 100, 69.5, and 61.5%, and 86.5, 87.5, and 87.5% respectively.

  9. Analysis of alkylresorcinols in cereal grains and products using ultrahigh-pressure liquid chromatography with fluorescence, ultraviolet, and CoulArray electrochemical detection.

    Science.gov (United States)

    Ross, Alastair B

    2012-09-12

    Alkylresorcinols are phenolic lipids, with homologues ranging from C17 to C25, found in high concentrations in whole grain wheat and rye, lower concentrations in barley, and negligible concentrations in refined wheat flour. The analysis of alkylresorcinols is of importance due to their potential as biomarkers of whole grain intake and emerging evidence for some biological effects. Present HPLC methods have insufficient resolution for accurately quantitating the mix of alkyl- and alkenylresorcinols found in rye. An ultrahigh-pressure liquid chromatography method was developed, and three detection methods (CoulArray (CAED), ultraviolet (UV), and fluorescence detection (FD)) were compared for cereal alkylresorcinol analysis. The lower limits of quantitation and detection were 50 and 20 pg injected, 5 pg and 2 pg injected, and 500 and 1250 pg injected for FD, CAED, and UV, respectively. FD and CAED provided similar results, with some bias for higher results with FD (<10% difference). UV detection generally resulted in overestimation of alkylresorcinol concentrations. The method was applied to cereal (15) and cereal product (90) samples mainly from the United States with results in the same range as previous methods. The improved resolution with this method allows facile analysis of alkylresorcinols from cereal products, including minor unsaturated homologues such as those found in rye.

  10. Simultaneous analysis of six aristolochic acids and five aristolactams in herbal plants and their preparations by high-performance liquid chromatography-diode array detection-fluorescence detection.

    Science.gov (United States)

    Yuan, Jinbin; Liu, Qian; Zhu, Weifeng; Ding, Li; Tang, Fei; Yao, Shouzhuo

    2008-02-22

    Aristolochic acid analogues, including aristolochic acids (AAs) and aristolactams (ALs), are known to be nephrotoxic, carcinogenic and mutagenic. In this paper, a high-performance liquid chromatography-diode array detection-fluorescence detection (HPLC-DAD-FLD) method was developed for the simultaneous determination of six AAs together with five ALs. Baseline separation was obtained on an ODS C18 analytical column with 0.2% HAc/methanol gradient elution. The hyphenation of DAD and FLD allows the method to directly meet the analysis requirements of most herbal plants with high sensitivity and selectivity. For trace analysis, aristolochic acids were reduced to their corresponding aritstolactams in acidic solution containing iron powder, and then high sensitive detection and quantification were carried out. The method was successfully validated in the matrices of various Aristolochiaceae plants and their preparations. Linearities of around 3-4 orders of magnitude were obtained with correlation coefficients exceeding 0.9970. The detection limits were decreased to 0.2ng/ml. Satisfactory intra-day and inter-day precisions were achieved with RSDs less than 5.74%, and the average recovery factors were in the range of 94.5-99.2%.

  11. Exploring in vivo violacein biosynthesis by application of multivariate curve resolution on fused UV-VIS absorption, fluorescence, and liquid chromatography-mass spectrometry data.

    Science.gov (United States)

    Dantas, Clecio; Tauler, Romà; Ferreira, Márcia Miguel Castro

    2013-02-01

    In this work, the application of multivariate curve resolution-alternating least squares (MCR-ALS) is proposed for extracting information from multitechnique fused multivariate data (UV-VIS absorption, fluorescence, and liquid chromatography-mass spectrometry) gathered during the biosynthesis of violacein pigment. Experimental data sets were pretreated and arranged in a row-wise augmented data matrix before their chemometric investigation. Five different chemical components were resolved. Kinetic and spectral information about these components were obtained and their relationship with violacein biosynthesis was established. Three new chemical compounds with molar masses of 453, 465, and 479 u, until now not reported in the literature, were identified and proposed as intermediates in the biosynthesis of other indolocarbazoles. The precursor (tryptophan), one intermediate (deoxyviolacein), and the final product (violacein) of violacein biosynthesis were identified and characterized using the proposed approach. The chemometric procedure based on the MCR-ALS method has proved to be a powerful tool to investigate violacein biosynthesis and its application can be easily extended to the study of other bioprocesses.

  12. Bioanalytical Applications of Fluorescence Line-Narrowing and Non-Line-Narrowing Spectroscopy Interfaced with Capillary Electrophoresis and High-Performance Liquid Chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Kenneth Paul [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    Capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) are widely used analytical separation techniques with many applications in chemical, biochemical, and biomedical sciences. Conventional analyte identification in these techniques is based on retention/migration times of standards; requiring a high degree of reproducibility, availability of reliable standards, and absence of coelution. From this, several new information-rich detection methods (also known as hyphenated techniques) are being explored that would be capable of providing unambiguous on-line identification of separating analytes in CE and HPLC. As further discussed, a number of such on-line detection methods have shown considerable success, including Raman, nuclear magnetic resonance (NMR), mass spectrometry (MS), and fluorescence line-narrowing spectroscopy (FLNS). In this thesis, the feasibility and potential of combining the highly sensitive and selective laser-based detection method of FLNS with analytical separation techniques are discussed and presented. A summary of previously demonstrated FLNS detection interfaced with chromatography and electrophoresis is given, and recent results from on-line FLNS detection in CE (CE-FLNS), and the new combination of HPLC-FLNS, are shown.

  13. On-line high-performance liquid chromatography-fluorescence detection-electrospray ionization-mass spectrometry profiling of human milk oligosaccharides derivatized with 2-aminoacridone.

    Science.gov (United States)

    Galeotti, Fabio; Coppa, Giovanni V; Zampini, Lucia; Maccari, Francesca; Galeazzi, Tiziana; Padella, Lucia; Santoro, Lucia; Gabrielli, Orazio; Volpi, Nicola

    2012-11-01

    A high-resolution normal-phase high-performance liquid chromatography-fluorescence detection-electrospray ionization-mass spectrometry separation and structural characterization of the main oligosaccharides along with lactose from human milk samples is described. A total of 22 commercially available oligosaccharides were fluorotagged with 2-aminoacridone and separated on an amide column and identified on the basis of their retention times and mass spectra. Derivatized species having mass lower than approximately 800 to 900 exhibited mainly [M-H](-1) anions, oligomers with mass up to approximately 1000 to 1100 were represented by both [M-H](-1) and [M-2H](-2) anions, and oligomers greater than approximately 1200 to 1300 were characterized by a charge state of -3. Furthermore, the retention times were directly related to the glycans' molecular mass. Human milk samples from the four groups of donors (Se±/Le±) were analyzed for their composition and amount of free oligosaccharides after rapid and simple prepurification and derivatization steps also in the presence of lactose in high content. This analytical approach enabled us to perform the determination of species not detected by traditional techniques, such as sialic acid, as well as of species present in low content easily mistaken with other peaks. Finally, labeled human milk oligosaccharides were analyzed without any interference from excess fluorophore or interference from proteins, peptides, salts, and other impurities normally present in this complex biological fluid.

  14. Bioanalytical Applications of Fluorescence Line-Narrowing and Non-Line-Narrowing Spectroscopy Interfaced with Capillary Electrophoresis and High-Performance Liquid Chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Kenneth Paul Roberts

    2002-06-27

    Capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) are widely used analytical separation techniques with many applications in chemical, biochemical, and biomedical sciences. Conventional analyte identification in these techniques is based on retention/migration times of standards; requiring a high degree of reproducibility, availability of reliable standards, and absence of coelution. From this, several new information-rich detection methods (also known as hyphenated techniques) are being explored that would be capable of providing unambiguous on-line identification of separating analytes in CE and HPLC. As further discussed, a number of such on-line detection methods have shown considerable success, including Raman, nuclear magnetic resonance (NMR), mass spectrometry (MS), and fluorescence line-narrowing spectroscopy (FLNS). In this thesis, the feasibility and potential of combining the highly sensitive and selective laser-based detection method of FLNS with analytical separation techniques are discussed and presented. A summary of previously demonstrated FLNS detection interfaced with chromatography and electrophoresis is given, and recent results from on-line FLNS detection in CE (CE-FLNS), and the new combination of HPLC-FLNS, are shown.

  15. Low axial drift stage and temperature controlled liquid cell for z-scan fluorescence correlation spectroscopy in an inverted confocal geometry.

    Science.gov (United States)

    Allgeyer, Edward S; Sterling, Sarah M; Neivandt, David J; Mason, Michael D

    2011-05-01

    A recent iteration of fluorescence correlation spectroscopy (FCS), z-scan FCS, has drawn attention for its elegant solution to the problem of quantitative sample positioning when investigating two-dimensional systems while simultaneously providing an excellent method for extracting calibration-free diffusion coefficients. Unfortunately, the measurement of planar systems using (FCS and) z-scan FCS still requires extremely mechanically stable sample positioning, relative to a microscope objective. As axial sample position serves as the inherent length calibration, instabilities in sample position will affect measured diffusion coefficients. Here, we detail the design and function of a highly stable and mechanically simple inverted microscope stage that includes a temperature controlled liquid cell. The stage and sample cell are ideally suited to planar membrane investigations, but generally amenable to any quantitative microscopy that requires low drift and excellent axial and lateral stability. In the present work we evaluate the performance of our custom stage system and compare it with the stock microscope stage and typical sample sealing and holding methods.

  16. Parallel microscope-based fluorescence, absorbance and time-of-flight mass spectrometry detection for high performance liquid chromatography and determination of glucosamine in urine.

    Science.gov (United States)

    Xiong, Bo; Wang, Ling-Ling; Li, Qiong; Nie, Yu-Ting; Cheng, Shuang-Shuang; Zhang, Hui; Sun, Ren-Qiang; Wang, Yu-Jiao; Zhou, Hong-Bin

    2015-11-01

    A parallel microscope-based laser-induced fluorescence (LIF), ultraviolet-visible absorbance (UV) and time-of-flight mass spectrometry (TOF-MS) detection for high performance liquid chromatography (HPLC) was achieved and used to determine glucosamine in urines. First, a reliable and convenient LIF detection was developed based on an inverted microscope and corresponding modulations. Parallel HPLC-LIF/UV/TOF-MS detection was developed by the combination of preceding Microscope-based LIF detection and HPLC coupled with UV and TOF-MS. The proposed setup, due to its parallel scheme, was free of the influence from photo bleaching in LIF detection. Rhodamine B, glutamic acid and glucosamine have been determined to evaluate its performance. Moreover, the proposed strategy was used to determine the glucosamine in urines, and subsequent results suggested that glucosamine, which was widely used in the prevention of the bone arthritis, was metabolized to urines within 4h. Furthermore, its concentration in urines decreased to 5.4mM at 12h. Efficient glucosamine detection was achieved based on a sensitive quantification (LIF), a universal detection (UV) and structural characterizations (TOF-MS). This application indicated that the proposed strategy was sensitive, universal and versatile, and it was capable of improved analysis, especially for analytes with low concentrations in complex samples, compared with conventional HPLC-UV/TOF-MS.

  17. Development and validation of a pre-column reversed phase liquid chromatographic method with fluorescence detection for the determination of primary phenethylamines in dietary supplements and phytoextracts.

    Science.gov (United States)

    Gatti, Rita; Lotti, Cinzia

    2011-07-15

    A sensitive and selective reversed-phase liquid chromatographic (RP-LC) method was developed and validated to determine octopamine, tyramine and Tyrosine (Tyr) in complex matrices as formulations and phytoextracts (Citrus aurantium), after pre-column derivatization with o-phthaldialdehyde (OPA) reagent. The chromatographic separations were performed at room temperature on a Phenomenex Luna C18 column using methanol and sodium acetate buffer (pH 5.5) by varying composition gradient elution as mobile phase and detected flurometrically at λ(em)=455 nm with λ(ex)=340 nm. The results obtained by the proposed method were compared with those achieved by a validated direct RP-LC method with fluorescence detection at λ(em)=310 nm with λ(ex)=275 nm, as reference method, using a Phenomenex Gemini C18 column under isocratic elution conditions with acetonitrile and sodium 1-heptanesulphonate (pH 3), as mobile phase. The higher sensitivity of the derivatization method (detection limit about 0.06 pmol) allowed the sure determination of octopamine present in traces in the examined samples. The repeatability of method (RSD) was ≤1.90% and there was no significant difference between repeatability and intermediate precision data. Recovery studies showed good results 99.5-101.3% with RSD ranging from 0.8 to 1.2%. All analyses were performed by mild conditions in absence of preliminary difficult extraction methodologies or laborious step of sample pre-treatment.

  18. Application of magnetic solid phase extraction for separation and determination of aflatoxins B ₁ and B₂ in cereal products by high performance liquid chromatography-fluorescence detection.

    Science.gov (United States)

    Hashemi, Mahdi; Taherimaslak, Zohreh; Rashidi, Somayeh

    2014-06-01

    A simple and sensitive method based on the magnetic solid phase extraction with modified magnetic nanoparticles followed by high performance liquid chromatography with fluorescence detection has been developed for extraction and determination of aflatoxins B1 (AFB1) and B2 (AFB2) in cereal products. Magnetic nanoparticle coated with 3-(trimethoxysilyl)-1-propanthiol (TMSPT) and modified with 2-amino-5-mercapto-1,3,4-thiadiazole (AMT) was used as an antibody-free adsorbent. Under the optimal conditions, the calibration curves for AFB1 and AFB2 were linear in the ranges of 0.2-15 μg L(-1) and 0.04-3 μg L(-1), respectively. Detection limit was 0.041 μg L(-1) for AFB1 and 0.013 μg L(-1) for AFB2. The proposed method was successfully applied to the determination of AFB1 and AFB2 in spiked corn and rice samples with an average recovery of 93.5%. The results demonstrated that the developed method is simple, rapid, inexpensive, accurate and remarkably free from interference effects.

  19. Online screening of nitric oxide scavengers in natural products using high performance liquid chromatography coupled with tandem diode array and fluorescence detection.

    Science.gov (United States)

    Li, Dapeng; Wang, Ting; Guo, Yujie; Hu, Yuanjia; Yu, Boyang; Qi, Jin

    2015-12-18

    Nitric oxide (NO) is an important cellular signaling molecule with extensive physiological and pathophysiological effects. NO scavengers have the potential to treat inflammation, septic shock and other related diseases, and numerous examples have been chemically synthesized or isolated from natural products. The chemical diversity of natural products, however, means that a huge effort is necessary to efficiently screen and identify bioactive compounds, especially NO scavengers. In this article, we propose an effective analytical method to screen for NO scavengers in three natural products using an online system that couples high performance liquid chromatography with tandem diode array and fluorescence detection (HPLC-DAD-FLD). Eighteen compounds from radix of Scutellaria baicalensis Georgi and green tea displayed significant NO scavenging activity whereas components of Pueraria lobata (Willd.) Ohwi had no discernable activity. The structures of the active compounds were elucidated using Agilent Accurate-Mass Q-TOF LC/MS system. Preliminary analysis of structure-activity relationships indicated that, in flavonoids, a 2,3-double bond and a 3-H atom or a 3-OH group are essential for activity. In tannins, poly-hydroxyl groups are important for NO scavenging activity. Method validation indicated that the newly developed method is both reliable and repeatable. The online method that we present provides a simple, rapid and effective way to identify and characterize NO scavengers present in natural products.

  20. Determination of manassantin B in rat plasma using a high performance liquid chromatography with fluorescence detection and its quantitative application to pharmacokinetic study.

    Science.gov (United States)

    Lee, Jae-Young; Song, Jae-Hyoung; Yoon, In-Soo; Ko, Hyun-Jeong; Kim, Dae-Duk; Cho, Hyun-Jong

    2016-02-01

    A simple, sensitive, rapid, and reproducible analytical method of manassantin B in rat plasma by high performance liquid chromatography with fluorescence detection (HPLC-FL) was developed for its application to pharmacokinetic study in rats. Valsartan (VST) was used as an internal standard (IS) in this quantitative analytical method. Manassantin B and VST were extracted by simple and efficient protein precipitation method. Manassantin B was detected at 282/322nm (excitation/emission) wavelengths using FL detector. The chromatographic separation was obtained with reverse phase C18 column and the mobile phase composed of potassium phosphate buffer containing 0.025% trifluoroacetic acid (pH 2.5; 5mM) and acetonitrile including 0.025% trifluoroacetic acid (20:80, v/v) at 1.0mL/min flow rate. The linearity was established at 25.0-10000ng/mL and the lower limit of detection (LLOD) was 7ng/mL. The intra- and inter-day accuracy and precision values of manassantin B were within±15% of the theroretical values and manassantin B after stability tests were also within the acceptable ranges. Developed assay was also successfully applied to pharmacokinetic study after intravenous administration of manassantin B in rats.

  1. On-line anion exchange solid-phase extraction coupled to liquid chromatography with fluorescence detection to determine quinolones in water and human urine.

    Science.gov (United States)

    Lara, Francisco J; Del Olmo-Iruela, Monsalud; García-Campaña, Ana M

    2013-10-04

    An analytical method based on on-line solid-phase extraction coupled to liquid chromatography with fluorescence detection has been developed to determine quinolones in tap water and human urine. A home-made setup was used to percolate 10 mL of sample through a solid-phase extraction column. Analytes were retained onto the sorbent by an anion exchange mechanism which ensures an optimum compatibility with the subsequent chromatographic separation. A C-18 column containing core-shell particles (2.6 μm) was used to achieve peak efficiencies up to 200,000 plates/m, at a flow rate of 1.2 mL/min and without the need for special pumps. The method allowed the determination of 11 quinolones directly in tap water samples in less than 20 min and with limits of detection ranging between 7 and 110 ng/L. The sensitivity achieved made possible the direct determination of 9 quinolones in human urine without any sample treatment, just dilution with water. Relative recoveries between 94 and 109% were obtained meaning that the matrix effect in human urine is negligible after dilution. Satisfactory results were also obtained in terms of precision since relative standard deviations were always below 13%.

  2. Low axial drift stage and temperature controlled liquid cell for z-scan fluorescence correlation spectroscopy in an inverted confocal geometry

    Energy Technology Data Exchange (ETDEWEB)

    Allgeyer, Edward S. [Department of Physics and Astronomy, University of Maine, Orono, Maine 04469 (United States); Sterling, Sarah M. [Graduate School of Biomedical Sciences, University of Maine, Orono, Maine 04469 (United States); Department of Chemical and Biological Engineering, University of Maine, Orono, Maine 04469 (United States); Neivandt, David J. [Graduate School of Biomedical Sciences, University of Maine, Orono, Maine 04469 (United States); Department of Chemical and Biological Engineering, University of Maine, Orono, Maine 04469 (United States); Institute for Molecular Biophysics, Orono, Maine 04469 (United States); Mason, Michael D. [Department of Chemical and Biological Engineering, University of Maine, Orono, Maine 04469 (United States); Institute for Molecular Biophysics, Orono, Maine 04469 (United States)

    2011-05-15

    A recent iteration of fluorescence correlation spectroscopy (FCS), z-scan FCS, has drawn attention for its elegant solution to the problem of quantitative sample positioning when investigating two-dimensional systems while simultaneously providing an excellent method for extracting calibration-free diffusion coefficients. Unfortunately, the measurement of planar systems using (FCS and) z-scan FCS still requires extremely mechanically stable sample positioning, relative to a microscope objective. As axial sample position serves as the inherent length calibration, instabilities in sample position will affect measured diffusion coefficients. Here, we detail the design and function of a highly stable and mechanically simple inverted microscope stage that includes a temperature controlled liquid cell. The stage and sample cell are ideally suited to planar membrane investigations, but generally amenable to any quantitative microscopy that requires low drift and excellent axial and lateral stability. In the present work we evaluate the performance of our custom stage system and compare it with the stock microscope stage and typical sample sealing and holding methods.

  3. Speciation analysis of inorganic arsenic in coal samples by microwave-assisted extraction and high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry.

    Science.gov (United States)

    Sun, Mei; Liu, Guijian; Wu, Qianghua; Liu, Wenqi

    2013-03-15

    A new method was developed for the speciation analysis of inorganic arsenic in coal samples by high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry after microwave-assisted extraction. Effective extract of As(III) and As(V) in coal sample was achieved by 1.0 mol L(-1)H₃PO₄ and 0.1 mol L(-1)ascorbic acid. Under the optimized conditions, the limits of detection (LOD) were 0.01 μg L(-1) and 0.02 μg L(-1), the relative standard deviations (RSD) were 2.4% and 3.3% (c=10.0 μg L(-1), n=7), recoveries were 102.5% and 96.5% for As(III) and As(V). The proposed method was successfully applied for the determination of speciation of inorganic arsenic in coal samples and GBW11117 coal standard reference material with complex matrix. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Methylmercury in water samples at the pg/L level by online preconcentration liquid chromatography cold vapor-atomic fluorescence spectrometry

    Science.gov (United States)

    Brombach, Christoph-Cornelius; Chen, Bin; Corns, Warren T.; Feldmann, Jörg; Krupp, Eva M.

    2015-03-01

    Ultra-traces of methylmercury at the sub-ppt level can be magnified in the foodweb and is of concern. In environmental monitoring a routine robust analytical method is needed to determine methylmercury in water. The development of an analytical method for ultra-trace speciation analysis of methylmercury (MeHg) in water samples is described. The approach is based on HPLC-CV-AFS with on-line preconcentration of water samples up to 200 mL, resulting in a detection limit of 40 pg/L (ppq) for MeHg, expressed as Hg. The unit consists of an optimized preconcentration column filled with a sulfur-based sorption material, on which mercury species are preconcentrated and subsequently eluted, separated and detected via HPLC-CV-AFS (high performance liquid chromatography-cold vapor atomic fluorescence spectrometry). During the method development a type of adsorbate material, the pH dependence, the sample load rate and the carry-over were investigated using breakthrough experiments. The method shows broad pH stability in the range of pH 0 to 7, without the need for buffer addition and shows limited matrix effects so that MeHg is quantitatively recovered from sewage, river and seawater directly in the acidified samples without sample preparation.

  5. Enantioselective determination of metoprolol and its metabolites in human urine high-performance liquid chromatography with fluorescence detection (HPLC-FLD) and tandem mass spectrometry (MS/MS).

    Science.gov (United States)

    Baranowska, Irena; Adolf, Weronika; Magiera, Sylwia

    2015-11-01

    A sensitive, stereoselective assay using solid phase extraction and high-performance liquid chromatography (HPLC) with fluorescence detection (FLD) was developed and validated for the analysis of enantiomers of metoprolol and its metabolites (α-hydroxymetoprolol, O-desmethylmetoprolol). Chiral separation was achieved using a CHIRALCEL OD-RH column, packed with cellulose tris-(3,5-dimethylphenyl-carbamate) stationary phase, employing a mobile phase composed by a mixture of 0.2% diethylamine in water and acetonitrile in gradient elution mode. Linear calibration curves were obtained over the range of 0.025-2.0μg/mL (R(2)>0.994) in urine for both enantiomers of metoprolol and its metabolites with quantitation limit of 0.025μg/mL. Intra and inter-day precision and accuracy were below 15% for both metoprolol and metabolites enantiomers. The recovery of enantiomer of metoprolol and its metabolite was greater than 68.0%, utilizing a SPE procedure. The method was tested with urine quality control samples and human urine fractions after administration of 50mg rac-metoprolol.

  6. Organic solvent-free reversed-phase ion-pairing liquid chromatography coupled to atomic fluorescence spectrometry for organoarsenic species determination in several matrices.

    Science.gov (United States)

    Monasterio, Romina P; Londonio, Juan A; Farias, Silvia S; Smichowski, Patricia; Wuilloud, Rodolfo G

    2011-04-27

    A novel method has been developed to determine As-containing animal feed additives including roxarsone (ROX), p-arsanilic acid (p-ASA) and nitarsone (NIT), as well as other organic As species (dimethylarsonic acid (DMAA) and monomethylarsonic acid (MMAA)) by ion-pairing high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry (IP-HPLC-HG-AFS). A simple isocratic reversed-phase (RP) HPLC method with a mobile phase containing citric acid and sodium hexanesulfonate (pH 2.0) was developed using a C(18) column. The use of an organic solvent free mobile phase turns this methodology into an environmentally friendly alternative. Several ion pair forming agents, such as sodium hexanesulfonate, tetrabutylammonium bisulfate and perfluoroheptanoic acid, were studied. The limits of detection for As species were calculated in standard solution and resulted to be 0.2, 0.5, 0.6, 1.6, and 1.6 μg As L(-1) for MMAA, DMAA, p-ASA, ROX and NIT, respectively. This method exhibited convenient operation, high sensitivity and good repeatability. It was applied to As speciation in different samples including arugula, dog food, dog urine and chicken liver.

  7. Quantitative analysis of phenylalanine, tyrosine, tryptophan and kynurenine in rat model for tauopathies by ultra-high performance liquid chromatography with fluorescence and mass spectrometry detection.

    Science.gov (United States)

    Galba, Jaroslav; Michalicova, Alena; Parrak, Vojtech; Novak, Michal; Kovac, Andrej

    2016-01-01

    We developed and validated a simple and sensitive ultra-high performance liquid chromatography (UHPLC) method for the analysis of phenylalanine (Phe), tyrosine (Tyr), tryptophan (Trp) and kynurenine (Kyn) in rat plasma. Analytes were separated on Acquity UPLC HSS T3 column (2.1 mm×50 mm, 1.8 μm particle size) using a 4 min ammonium acetate (pH 5) gradient and detected by fluorescence and positive ESI mass spectrometry. Sample preparation involved dilution of plasma, deproteinization by trichloroacetic acid and centrifugation. The procedure was validated in compliance with the FDA guideline. The limits of quantification (LOQ) were 0.3 μM for Kyn and from 1.5 to 3 μM for Phe, Tyr, Trp. The method showed excellent linearity with regression coefficients higher than 0.99. The accuracy was within the range of 86-108%. The inter-day precision (n=5 days), expressed as % RSD, was in the range 1-13%. The benefit of using UHPLC is a short analysis period and thus, a very good sample throughput. Using this method, we analyzed plasma samples and detected significant changes of Kyn and Phe in transgenic rat model for tauopathies.

  8. Improved Quantitation of Gluten in Wheat Starch for Celiac Disease Patients by Gel-Permeation High-Performance Liquid Chromatography with Fluorescence Detection (GP-HPLC-FLD).

    Science.gov (United States)

    Scherf, Katharina Anne; Wieser, Herbert; Koehler, Peter

    2016-10-12

    Purified wheat starch (WSt) is commonly used in gluten-free products for celiac disease (CD) patients. It is mostly well-tolerated, but doubts about its safety for CD patients persist. One reason may be that most ELISA kits primarily recognize the alcohol-soluble gliadin fraction of gluten, but insufficiently target the alcohol-insoluble glutenin fraction. To address this problem, a new sensitive method based on the sequential extraction of gliadins, glutenins, and gluten from WSt followed by gel-permeation high-performance liquid chromatography with fluorescence detection (GP-HPLC-FLD) was developed. It revealed that considerable amounts of glutenins were present in most WSt. The gluten contents quantitated by GP-HPLC-FLD as sum of gliadins and glutenins were higher than those by R5 ELISA (gluten as gliadin content multiplied by a factor of 2) in 19 out of 26 WSt. Despite its limited selectivity, GP-HPLC-FLD may be applied as confirmatory method to ELISA to quantitate gluten in WSt.

  9. Simultaneous determination of acetylsalicylic acid and salicylic acid in human plasma by isocratic high-pressure liquid chromatography with post-column hydrolysis and fluorescence detection.

    Science.gov (United States)

    Hobl, Eva-Luise; Jilma, Bernd; Ebner, Josef; Schmid, Rainer W

    2013-06-01

    A selective, sensitive and rapid high-performance liquid chromatography method with post-column hydrolysis and fluorescence detection was developed for the simultaneous quantification of acetylsalicylic acid and its metabolite salicylic acid in human plasma. Following the addition of 2-hydroxy-3-methoxybenzoic acid as internal standard and simple protein precipitation with acetonitrile, the analytes were separated on a ProntoSIL 120 C18 ace-EPS column (150 × 2 mm, 3 µm) protected by a C8 guard column (5 µm). The mobile phase, 10 mm formic acid in water (pH 2.9) and acetonitrile (70:30, v/v), was used at a flow rate of 0.35 mL/min. After on-line post-column hydrolysis of acetylsalicylic acid (ASA) to salicylic acid (SA) by addition of alkaline solution, the analytes were measured at 290 nm (λex ) and 400 nm (λem ). The method was linear in the concentration ranges between 0.05 and 20 ng/μL for both ASA and SA with a lower limit of quantification of 25 pg/μL for SA and 50 pg/μL for ASA. The limit of detection was 15 pg/μL for SA and 32.5 pg/μL for ASA. The analysis of ASA and SA can be carried out within 8 min; therefore this method is suitable for measuring plasma concentrations of salicylates in clinical routine.

  10. Determination of acrolein in serum by high-performance liquid chromatography with fluorescence detection after pre-column fluorogenic derivatization using 1,2-diamino-4,5-dimethoxybenzene.

    Science.gov (United States)

    Imazato, Takahiro; Kanematsu, Mariko; Kishikawa, Naoya; Ohyama, Kaname; Hino, Takako; Ueki, Yukitaka; Maehata, Eisuke; Kuroda, Naotaka

    2015-09-01

    Acrolein is a major unsaturated aldehyde that is generated during the lipid peroxidation process. The measurement of acrolein in biological samples should be useful to estimate the degree of lipid peroxidation and to evaluate the effect of hazardous properties of acrolein on human health. In this study, a highly sensitive and selective high-performance liquid chromatography with fluorescence detection method was developed for the determination of acrolein in human serum. The proposed method involves the pre-column fluorogenic derivatization of acrolein with 1,2-diamino-4,5-dimethoxybenzene (DDB) as a reagent. The fluorescent derivative of acrolein could be detected clearly without any interfering reagent blank peaks because DDB does not have intrinsic fluorescence itself, and the detection limit was 10 nM (signal-to-noise ratio = 3). The proposed method could selectively detect acrolein in human serum with a simple protein precipitation treatment.

  11. Quantification of harman alkaloids in sour passion fruit pulp and seeds by a novel dual SBSE-LC/Flu (stir bar sorptive extraction-liquid chromatography with fluorescence detector) method

    OpenAIRE

    PEREIRA, Cíntia A. M.; Rodrigues,Thyago R.; YARIWAKE, Janete H.

    2014-01-01

    A method for the quantification of the alkaloids harmane and harmine in sour passion fruit (Passiflora edulis f. flavicarpa O. Degener, Passifloraceae) pulp and seeds by stir-bar sorptive extraction and high performance liquid chromatography with fluorescence detection (dual SBSE-LC/Flu) is described. The SBSE parameters were optimized using a fractional factorial design, and the dual SBSE-LC/Flu method was validated following the International Conference on Harmonisation of Technical Require...

  12. Rapid resolution liquid chromatography-mass spectrometry and high-performance liquid chromatography-fluorescence detection for metabolism and pharmacokinetic studies of ergosta-4,6,8(14),22-tetraen-3-one.

    Science.gov (United States)

    Zhao, Ying-Yong; Qin, Xiang-Yang; Cheng, Xian-Long; Liu, Xue-Ying; Lin, Rui-Chao; Zhang, Yongmin; Li, Xiao-Ye; Sun, Xiao-Li; Sun, Wen-Ji

    2010-08-24

    Ergosta-4,6,8(14),22-tetraen-3-one (ergone) from many medicinal plants has been demonstrated to possess a variety of pharmacological activities in vivo and in vitro, including cytotoxic, diuretic and immunosuppressive activity. Metabolism and pharmacokinetic studies on rat were conducted for ergone. Rapid resolution liquid chromatography with atmospheric pressure chemical ionization tandem multi-stage mass spectrometry (RRLC-APCI-MS(n)) and high-performance liquid chromatography with fluorescence detection (HPLC-FLD) methods were applied for the identification and quantification of ergone and its metabolite from rat plasma, faeces and urine. A metabolite was identified by RRLC-DAD-APCI-MS(n): 22,23-epoxy-ergosta-4,6,8(14)-triaen-3-one (epoxyergone). The concentrations of the analyte with its metabolites were determined by HPLC-FLD at excitation wavelength of 370 nm and emission wavelength of 485 nm. The samples were deproteinized with methanol after addition of camptothecin as internal standard (IS). The analysis was performed on a Diamonsil C18 column (150 mm x 4.6 mm x 5 microm) with a mobile phase gradient consisting of methanol and water at a flow rate of 1 mL min(-1). The assay was linear over the concentration range of 42-1500, 36-7500 and 42-1500 ng mL(-1) for plasma, faecal homogenate and urine respectively. The absolute recoveries were found to be 97.0+/-1.2%, 98.1+/-0.7% and 96.6+/-1.8% for plasma, faecal homogenate and urine respectively. The intra-day and inter-day relative standard deviations (RSD) were less than 10%. The previous HPLC-MS/MS method is not affordable for most laboratories because of the specialty requirement and high equipment cost. However, the HPLC-FLD method is economic and operating simply for quantitative determination of ergone and its metabolite in rat plasma, faeces and urine. In addition, liquid chromatography coupled with ion trap multi-stage mass spectrometry is becoming a useful technique for ergone metabolite identification.

  13. Physics of Armour penetration

    Directory of Open Access Journals (Sweden)

    Sampooran Singh

    1953-01-01

    Full Text Available When a “Shaped-Charge” projectile is spin-stabilized during its flight, its penetration is greatly reduced, hence such a projectile is fin-stabilized and consequently the range is less and accuracy is poor. Attempts are being made to combine the penetrating power of a bazooka, and range and accuracy of rifled weapon. Just as the introduction of fire-arms brought about the extinction of the armour knights because a bullet could easily penetrate the kind of armour that the knights could put on; similarly “Shaped-Charge” projectiles having the range and accuracy of a rifled weapon will seriously affect the tactical use of amour in the battle-field.

  14. Enhanced chlorhexidine skin penetration with eucalyptus oil

    Directory of Open Access Journals (Sweden)

    Worthington Tony

    2010-09-01

    Full Text Available Abstract Background Chlorhexidine digluconate (CHG is a widely used skin antiseptic, however it poorly penetrates the skin, limiting its efficacy against microorganisms residing beneath the surface layers of skin. The aim of the current study was to improve the delivery of chlorhexidine digluconate (CHG when used as a skin antiseptic. Method Chlorhexidine was applied to the surface of donor skin and its penetration and retention under different conditions was evaluated. Skin penetration studies were performed on full-thickness donor human skin using a Franz diffusion cell system. Skin was exposed to 2% (w/v CHG in various concentrations of eucalyptus oil (EO and 70% (v/v isopropyl alcohol (IPA. The concentration of CHG (μg/mg of skin was determined to a skin depth of 1500 μm by high performance liquid chromatography (HPLC. Results The 2% (w/v CHG penetration into the lower layers of skin was significantly enhanced in the presence of EO. Ten percent (v/v EO in combination with 2% (w/v CHG in 70% (v/v IPA significantly increased the amount of CHG which penetrated into the skin within 2 min. Conclusion The delivery of CHG into the epidermis and dermis can be enhanced by combination with EO, which in turn may improve biocide contact with additional microorganisms present in the skin, thereby enhancing antisepsis.

  15. Session: Hard Rock Penetration

    Energy Technology Data Exchange (ETDEWEB)

    Tennyson, George P. Jr.; Dunn, James C.; Drumheller, Douglas S.; Glowka, David A.; Lysne, Peter

    1992-01-01

    This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of five presentations: ''Hard Rock Penetration - Summary'' by George P. Tennyson, Jr.; ''Overview - Hard Rock Penetration'' by James C. Dunn; ''An Overview of Acoustic Telemetry'' by Douglas S. Drumheller; ''Lost Circulation Technology Development Status'' by David A. Glowka; ''Downhole Memory-Logging Tools'' by Peter Lysne.

  16. Ground penetrating radar

    CERN Document Server

    Daniels, David J

    2004-01-01

    Ground-penetrating radar has come to public attention in recent criminal investigations, but has actually been a developing and maturing remote sensing field for some time. In the light of recent expansion of the technique to a wide range of applications, the need for an up-to-date reference has become pressing. This fully revised and expanded edition of the best-selling Surface-Penetrating Radar (IEE, 1996) presents, for the non-specialist user or engineer, all the key elements of this technique, which span several disciplines including electromagnetics, geophysics and signal processing. The

  17. Cell-penetrating Peptide YARA-mediated Transduction of Enhanced Green Fluorescent Protein into Human Vascular Smooth Muscle Cells%YARA介导增强型绿色荧光蛋白穿透人血管平滑肌细胞

    Institute of Scientific and Technical Information of China (English)

    陈思思; 王家宁; 黄永章; 郭凌郧; 孔霞

    2012-01-01

    Objective To investigate the penetrating ability of fusion protein YARA-EGFP with human vascular smooth muscle cells (HVSMC). Methods The prokaryotic expression plastnids YARA-EGFP was constructed and transformed into E. coli BL21 (DE3) to express fusion protein YARA-EGFP. The fusion protein YARA-EGFP was purified with Ni2 + -resin affinity chromatography and transduced into HVSMC. Results YARA-EGFP fusion protein could transduce into HVSMC and distribute in cytoplasm and nucleus after 6 h incubation. Conclusion The successful expression and purification of YARA-EGFP fusion protein can transduce into human vascular smooth muscle cells. This study provides a basis for the research on transduction of antiproliferative proteins such as p27 and p21 mediated by the cell-penetrating peptide, YARA,in protein therapy for the diabetic vascular diseases.%目的:研究细胞穿透肽YARA介导大分子蛋白穿透人血管平滑肌细施(human vascular smooth musle cells,HVSMC)细胞膜的能力.方法:用基因工程的方法制备并纯化YARA-EGFP融合蛋白,将其和培养的人平滑肌细胞共同孵育,在荧光显微镜下直接观察YARA介导目的蛋白EGFP转导入人平滑肌细胞的能力.结果:荧光显微镜下观察到,荧光蛋白穿透细胞膜进入并分布在入血管平滑肌细胞内.结论:YARA能有效携带目的蛋白进入人血管平滑肌细胞,这为将来用细胞穿透肽YARA介导有生物活性的大分子抗血管平滑肌细胞增殖,进行糖尿病血管病变的蛋白治疗奠定了基础.

  18. Determination of hydrogen sulfide and volatile thiols in air samples by mercury probe derivatization coupled with liquid chromatography-atomic fluorescence spectrometry.

    Science.gov (United States)

    Bramanti, Emilia; D'Ulivo, Lucia; Lomonte, Cristina; Onor, Massimo; Zamboni, Roberto; Raspi, Giorgio; D'Ulivo, Alessandro

    2006-10-02

    A new procedure is proposed for the sampling and storage of hydrogen sulphide (H2S) and volatile thiols (methanethiol or methyl mercaptan, ethanethiol and propanethiol) for their determination by liquid chromatography. The sampling procedure is based on the trapping/pre-concentration of the analytes in alkaline aqueous solution containing an organic mercurial probe p-hydroxymercurybenzoate, HO-Hg-C6H4-COO- (PHMB), where they are derivatized to stable PHMB complexes based on mercury-sulfur covalent bonds. PHMB complexes are separated on a C18 reverse phase column, allowing their determination by liquid chromatography coupled with sequential non-selective UV-vis (DAD) and mercury specific (chemical vapor generation atomic fluorescence spectrometry, CVGAFS) on-line detectors. PHMB complexes, S(PHMB)2CH3S-PHMB, C2H5S-PHMB and C3H7S-PHMB, are stable alt least for 12 h at room temperature and for 3 months if stored frozen (-20 degrees C). The best analytical figures of merits in the optimized conditions were obtained by CVGAFS detection, with detection limits (LODc) of 9.7 microg L(-1) for H2S, 13.7 microg L(-1) for CH(3)SH, 17.7 microg L(-1) for C2H5SH and 21.7 microg L(-1) for C3H7SH in the trapping solution in form of RS-PHMB complexes, the relative standard deviation (R.S.D.) ranging between 1.0 and 1.5%, and a linear dynamic range (LDR) between 10 and 9700 microg L(-1). Conventional UV absorbance detectors tuned at 254 nm can be employed as well with comparable R.S.D. and LDR, but with LODc one order of magnitude higher than AFS detector and lower specificity. The sampling procedure followed by LC-DAD-CVGAFS analysis has been validated, as example, for H2S determination by a certified gas permeation tube as a source of 3.071+/-0.154 microg min(-1) of H2S, giving a recovery of 99.8+/-7% and it has been applied to the determination of sulfur compounds in real gas samples (biogas and the air of a plant for fractional distillation of crude oil).

  19. Determination of hydrogen sulfide and volatile thiols in air samples by mercury probe derivatization coupled with liquid chromatography-atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Bramanti, Emilia [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy)]. E-mail: emilia@ipcf.cnr.it; D' Ulivo, Lucia [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy); Lomonte, Cristina [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy); Ambiente s.c.r.l., Via Frassina 21, 54033, Carrrara, Massa (Italy); Onor, Massimo [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy); Zamboni, Roberto [Department of Chemistry and Industrial Chemistry, University of Pisa, Via Risorgimento 35, 56126 Pisa (Italy); Raspi, Giorgio [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy); D' Ulivo, Alessandro [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy)

    2006-10-02

    A new procedure is proposed for the sampling and storage of hydrogen sulphide (H{sub 2}S) and volatile thiols (methanethiol or methyl mercaptan, ethanethiol and propanethiol) for their determination by liquid chromatography. The sampling procedure is based on the trapping/pre-concentration of the analytes in alkaline aqueous solution containing an organic mercurial probe p-hydroxymercurybenzoate, HO-Hg-C{sub 6}H{sub 4}-COO{sup -} (PHMB), where they are derivatized to stable PHMB complexes based on mercury-sulfur covalent bonds. PHMB complexes are separated on a C{sub 18} reverse phase column, allowing their determination by liquid chromatography coupled with sequential non-selective UV-vis (DAD) and mercury specific (chemical vapor generation atomic fluorescence spectrometry, CVGAFS) on-line detectors. PHMB complexes, S(PHMB){sub 2}CH{sub 3}S-PHMB, C{sub 2}H{sub 5}S-PHMB and C{sub 3}H{sub 7}S-PHMB, are stable alt least for 12 h at room temperature and for 3 months if stored frozen (-20 deg. C). The best analytical figures of merits in the optimized conditions were obtained by CVGAFS detection, with detection limits (LODc) of 9.7 {mu}g L{sup -1} for H{sub 2}S, 13.7 {mu}g L{sup -1} for CH{sub 3}SH, 17.7 {mu}g L{sup -1} for C{sub 2}H{sub 5}SH and 21.7 {mu}g L{sup -1} for C{sub 3}H{sub 7}SH in the trapping solution in form of RS-PHMB complexes, the relative standard deviation (R.S.D.) ranging between 1.0 and 1.5%, and a linear dynamic range (LDR) between 10 and 9700 {mu}g L{sup -1}. Conventional UV absorbance detectors tuned at 254 nm can be employed as well with comparable R.S.D. and LDR, but with LODc one order of magnitude higher than AFS detector and lower specificity. The sampling procedure followed by LC-DAD-CVGAFS analysis has been validated, as example, for H{sub 2}S determination by a certified gas permeation tube as a source of 3.071 {+-} 0.154 {mu}g min{sup -1} of H{sub 2}S, giving a recovery of 99.8 {+-} 7% and it has been applied to the determination of

  20. Methylmercury in water samples at the pg/L level by online preconcentration liquid chromatography cold vapor-atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Brombach, Christoph-Cornelius [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Chen, Bin; Corns, Warren T. [PS Analytical, Arthur House, Crayfields Industrial Estate, Main Road, Orpington, Kent BR5 3HP (United Kingdom); Feldmann, Jörg [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Krupp, Eva M., E-mail: e.krupp@abdn.ac.uk [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom)

    2015-03-01

    Ultra-traces of methylmercury at the sub-ppt level can be magnified in the foodweb and is of concern. In environmental monitoring a routine robust analytical method is needed to determine methylmercury in water. The development of an analytical method for ultra-trace speciation analysis of methylmercury (MeHg) in water samples is described. The approach is based on HPLC-CV-AFS with on-line preconcentration of water samples up to 200 mL, resulting in a detection limit of 40 pg/L (ppq) for MeHg, expressed as Hg. The unit consists of an optimized preconcentration column filled with a sulfur-based sorption material, on which mercury species are preconcentrated and subsequently eluted, separated and detected via HPLC-CV-AFS (high performance liquid chromatography–cold vapor atomic fluorescence spectrometry). During the method development a type of adsorbate material, the pH dependence, the sample load rate and the carry-over were investigated using breakthrough experiments. The method shows broad pH stability in the range of pH 0 to 7, without the need for buffer addition and shows limited matrix effects so that MeHg is quantitatively recovered from sewage, river and seawater directly in the acidified samples without sample preparation. - Highlights: • We demonstrate that a novel mixture of thiourea-thiolsilica shows an excellent trapping of MeHg between a broad pH range 1–6. • We develop the method so that it can potentially be automated for inorganic and methyl-mercury. • The method is matrix independent with highly accurate results for MeHg in hair CRM extracts and spiked water samples • The limit of detection is around 40 pg/L when just 200 mL sample is used, without any intensive preparation.

  1. Speciation analysis of mercury in sediments, zoobenthos and river water samples by high-performance liquid chromatography hyphenated to atomic fluorescence spectrometry following preconcentration by solid phase extraction

    Energy Technology Data Exchange (ETDEWEB)

    Margetinova, Jana; Houserova-Pelcova, Pavlina [Department of Chemistry and Biochemistry, Mendel University of Agriculture and Forestry, Zemedelska 1, Brno CZ 613 00 (Czech Republic); Kuban, Vlastimil [Department of Chemistry and Biochemistry, Mendel University of Agriculture and Forestry, Zemedelska 1, Brno CZ 613 00 (Czech Republic)], E-mail: kuban@mendelu.cz

    2008-05-19

    A high-pressure microwave digestion was applied for microwave-assisted extraction (MAE) of mercury species from sediments and zoobenthos samples. A mixture containing 3 mol L{sup -1} HCl, 50% aqueous methanol and 0.2 mol L{sup -1} citric acid (for masking co-extracted Fe{sup 3+}) was selected as the most suitable extraction agent. The efficiency of proposed extraction method was better than 95% with R.S.D. below 6%. A preconcentration method utilizing a 'homemade' C18 solid phase extraction (SPE) microcolumns was developed to enhance sensitivity of the mercury species determination using on-column complex formation of mercury-2-mercaptophenol complexes. Methanol was chosen for counter-current elution of the retained mercury complexes achieving a preconcentration factor as much as 1000. The preconcentration method was applied for the speciation analysis of mercury in river water samples. The high-performance liquid chromatography-cold vapour atomic fluorescence spectrometric (HPLC/CV-AFS) method was used for the speciation analysis of mercury. The complete separation of four mercury species was achieved by an isocratic elution of aqueous methanol (65%/35%) on a Zorbax SB-C18 column (4.6 mm x 150 mm, 5 {mu}m) using the same complexation reagent (2-mercaptophenol). The limits of detection were 4.3 {mu}g L{sup -1} for methylmercury (MeHg{sup +}), 1.4 {mu}g L{sup -1} for ethylmercury (EtHg{sup +}), 0.8 {mu}g L{sup -1} for inorganic mercury (Hg{sup 2+}), 0.8 {mu}g L{sup -1} for phenylmercury (PhHg{sup +})

  2. Arsenic speciation in edible alga samples by microwave-assisted extraction and high performance liquid chromatography coupled to atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Salgado, S. [Departamento de Ingenieria Civil: Tecnologia Hidraulica y Energetica, Escuela Universitaria de Ingenieria Tecnica de Obras Publicas, Universidad Politecnica de Madrid, Alfonso XII 3 y 5, 28014 Madrid (Spain); Quijano, M.A., E-mail: marian.quijano@upm.es [Departamento de Ingenieria Civil: Tecnologia Hidraulica y Energetica, Escuela Universitaria de Ingenieria Tecnica de Obras Publicas, Universidad Politecnica de Madrid, Alfonso XII 3 y 5, 28014 Madrid (Spain); Bonilla, M.M. [Departamento de Ingenieria Civil: Tecnologia Hidraulica y Energetica, Escuela Universitaria de Ingenieria Tecnica de Obras Publicas, Universidad Politecnica de Madrid, Alfonso XII 3 y 5, 28014 Madrid (Spain)

    2012-02-10

    Highlights: Black-Right-Pointing-Pointer Total As and As species were analyzed in edible marine algae. Black-Right-Pointing-Pointer A microwave-assisted extraction method with deionized water was applied. Black-Right-Pointing-Pointer As compounds identified comprised DMA, As(V) and four arsenosugars Black-Right-Pointing-Pointer Considerably high As(V) concentrations were found in the most of the algae studied. - Abstract: Twelve commercially available edible marine algae from France, Japan and Spain and the certified reference material (CRM) NIES No. 9 Sargassum fulvellum were analyzed for total arsenic and arsenic species. Total arsenic concentrations were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) after microwave digestion and ranged from 23 to 126 {mu}g g{sup -1}. Arsenic species in alga samples were extracted with deionized water by microwave-assisted extraction and showed extraction efficiencies from 49 to 98%, in terms of total arsenic. The presence of eleven arsenic species was studied by high performance liquid chromatography-ultraviolet photo-oxidation-hydride generation atomic-fluorescence spectrometry (HPLC-(UV)-HG-AFS) developed methods, using both anion and cation exchange chromatography. Glycerol and phosphate sugars were found in all alga samples analyzed, at concentrations between 0.11 and 22 {mu}g g{sup -1}, whereas sulfonate and sulfate sugars were only detected in three of them (0.6-7.2 {mu}g g{sup -1}). Regarding arsenic toxic species, low concentration levels of dimethylarsinic acid (DMA) (<0.9 {mu}g g{sup -1}) and generally high arsenate (As(V)) concentrations (up to 77 {mu}g g{sup -1}) were found in most of the algae studied. The results obtained are of interest to highlight the need to perform speciation analysis and to introduce appropriate legislation to limit toxic arsenic species content in these food products.

  3. Magnetic microsphere-confined graphene for the extraction of polycyclic aromatic hydrocarbons from environmental water samples coupled with high performance liquid chromatography-fluorescence analysis.

    Science.gov (United States)

    Wang, Weina; Ma, Ruiyang; Wu, Qiuhua; Wang, Chun; Wang, Zhi

    2013-06-07

    In this paper, a magnetic microsphere-confined graphene adsorbent (Fe3O4@SiO2-G) was fabricated and used for the extraction of five polycyclic aromatic hydrocarbons (fluorene, anthracene, phenanthrene, fluoranthene and pyrene) from environmental water samples prior to high performance liquid chromatography with fluorescence detection. The Fe3O4@SiO2-G was characterized by various instrumental methods. Various experimental parameters that could affect the extraction efficiencies, such as the amount of Fe3O4@SiO2-G, the pH and ionic strength of sample solution, the extraction time and the desorption conditions, were investigated. Due to the high surface area and excellent adsorption capacity of the Fe3O4@SiO2-G, satisfactory extraction can be achieved with only 15mg of the adsorbent per 250mL solution and 5min extraction. Under the optimum conditions, a linear response was observed in the concentration range of 5-1500ngL(-1) for fluorene, 2.5-1500ngL(-1) for anthracene and 15-1500ngL(-1) for phenanthrene, fluoranthene and pyrene, with the correlation coefficients (r) ranging from 0.9897 to 0.9961. The limits of detection (S/N=3) of the method were between 0.5 and 5.0ngL(-1). The relative standard deviations (RSDs) were less than 5.6%. The recoveries of the method were in the range between 83.2% and 108.2%. The results indicated that this graphene-based magnetic nanocomposite had a great adsorptive ability toward the five polycyclic aromatic hydrocarbons from environmental water samples.

  4. Graphene-derivatized silica as an efficient solid-phase extraction sorbent for pre-concentration of fluoroquinolones from water followed by liquid-chromatography fluorescence detection.

    Science.gov (United States)

    Speltini, Andrea; Sturini, Michela; Maraschi, Federica; Consoli, Luana; Zeffiro, Alberto; Profumo, Antonella

    2015-01-30

    This work presents a novel analytical method based on graphene for the determination of five widely used fluoroquinolones (FQs) in aqueous matrices. The procedure entails solid-phase extraction (SPE) on graphene-derivatized silica (200mg), followed by liquid chromatography with fluorescence detection. Monolayer graphene oxide (GO) flakes were covalently bonded onto aminopropyl silica microparticles, and then treated with aqueous hydrazine to obtain the reduced GO (RGO). The final material (RGO-silica) was characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and BET analysis, and for the first time evaluated as mixed-mode sorbent for the SPE of FQs from natural waters. Accuracy was studied on tap/raw river water in the concentration range 5-10,000ngL(-1), obtaining mean absolute recoveries from 72 to 118%. The inter-day precision was good, showing relative standard deviations (RSDs) in the range 5-15%. Sample volumes up to 1L provided enrichment factors up to 1000, achieving accurate quantification of concentrations as low as 5ngL(-1). The analytes were simultaneously and quantitatively eluted from the RGO-silica cartridge in a single fraction by using acetonitrile combined with aqueous tetrabutyl ammonium hydroxide. The batch-to-batch reproducibility was verified on three independently prepared RGO-silica samples. RGO-silica was advantageous in terms of adsorption capacity and reusability with respect to commercial sorbents; the cartridge proved to be reusable for at least 10 consecutive extractions, with no significant loss of efficiency (recovery >70%). The analytical procedure was applied to the determination of FQs in actual environmental waters.

  5. Development and validation of a liquid chromatography-fluorescence-mass spectrometry method to measure glyphosate and aminomethylphosphonic acid in rat plasma.

    Science.gov (United States)

    Bernal, J; Bernal, J L; Martin, M T; Nozal, M J; Anadón, A; Martínez-Larrañaga, M R; Martínez, M A

    2010-12-01

    A simple and fast method has been developed and validated to measure glyphosate (GLYP) and aminomethylphosphonic acid (AMPA) in rat plasma based on reversed-phase high performance liquid chromatography (RP-HPLC) coupled to fluorescence (FLD) and electrospray ionization mass spectrometry (ESI-MS) detection. After protein precipitation with acetonitrile, GLYP and AMPA were derivatized with 9-fluorenylmethylchloroformate (FMOC-Cl) and then separated on a C(12) column (250mm×4.60mm i.d.) using a gradient of an ammonium formate (20mM, pH 8.5) and acetonitrile mobile phase. Selected ion monitoring (SIM) mode of the MS was used to obtain maximum sensitivity when quantifying GLYP and AMPA. The validation shows the method to be consistent and reliable, with an intra- and inter-day precision for GLYP and AMPA>9% for both detectors. For both compounds the accuracy ranged from 2.1% to 7.8% for the intra-day readings, and from 4.1% to 8.6% for the inter-day values. The efficacy of GLYP extraction ranged from 87% to 93% and it was between 76% and 88% for AMPA. Moreover, the limits of quantification (LOQ) for GLYP and AMPA were 5 and 10ng/mL, respectively with FLD, and 0.4 and 2ng/mL with ESI-MS. The method was successfully applied to simultaneously measure both compounds in rat plasma samples several days after oral administration of glyphosate.

  6. A simple method for the determination of glyphosate and aminomethylphosphonic acid in seawater matrix with high performance liquid chromatography and fluorescence detection.

    Science.gov (United States)

    Wang, Shu; Liu, Baomin; Yuan, Dongxing; Ma, Jian

    2016-12-01

    Glyphosate (GLYP) is an important herbicide which is also used as the phosphorus source for marine organisms. The wide applications of GLYP can lead to its accumulation in oceans and coastal waters, thus creating environmental issues. However, there is limited methods for detection of GLYP and its degradation product, aminomethylphosphonic acid (AMPA) in saline samples. Therefore, a simple and fast method for the quantification of GLYP and AMPA in seawater matrix has been developed based on the derivatization with 9-fluorenylmethylchloroformate (FMOC-Cl), separation with high performance liquid chromatography (HPLC) and detection with fluorescence detector (FLD). In order to maximize sensitivity, the derivatization procedure was carefully optimized regarding concentration of FMOC-Cl, volume of borate buffer, pH of borate buffer, mixing and derivatization time. The derivatization reaction could be completed within 30min in seawater samples without any additional clean-up or desalting steps. Under the optimized conditions, the developed HPLC method showed a wide linear response (up to several mg/L, R(2)>0.99). The limits of detection were 0.60μg/L and 0.30μg/L for GLYP and AMPA in seawater matrix, respectively. The relative standard deviation was 14.0% for GLYP (1.00mg/L) and 3.1% for AMPA (100μg/L) in saline samples with three different operators (n=24). This method was applied to determine the concentration of GLYP and AMPA in seawater culture media and the recovery data indicated minimal matrix interference. Due to its simplicity, high reproducibility and successful application in seawater culture media analysis, this method is a potentially useful analytical technique for both marine research and environmental science.

  7. Development and validation of a high-performance liquid chromatography-fluorescence detection method for the accurate quantification of colistin in human plasma.

    Science.gov (United States)

    Chepyala, Divyabharathi; Tsai, I-Lin; Sun, Hsin-Yun; Lin, Shu-Wen; Kuo, Ching-Hua

    2015-02-01

    Recently, colistin has become one of the most important drugs for treating infections caused by multidrug-resistant Gram-negative bacteria. Therapeutic drug monitoring is recommended to ensure the safety and efficacy of colistin and to improve clinical outcomes. This study developed an accurate and sensitive high-performance liquid chromatography-fluorescence detection (HPLC-FLD) method for the quantification of colistin in human plasma. The sample preparation included protein precipitation using trichloroacetic acid (TCA) and methanol, followed by in-solid phase extraction (In-SPE) derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). A Poroshell 120 EC-C18 2.1×100mm (2.7μm) column was used in the HPLC method with a mobile phase composed of acetonitrile (ACN), tetrahydrofuran (THF), and deionized (DI) water (82%, 2%, 16% (v/v), respectively). Polymyxin B1 was used as the internal standard. The total analysis time was 22min under optimal separation conditions. The HPLC-FLD method was validated over a therapeutic range of 0.3-6.0μgmL(-1). The intra-day and inter-day precisions for colistin A and colistin B were below 9.9% and 4.5% relative standard deviations, respectively. The accuracy test results were between 100.2 and 118.4%. The extraction recoveries were between 81.6 and 94.1%. The method was linear over the test range, with a 0.9991 coefficient of determination. The limit of detection was 0.1μgmL(-1). The validated HPLC-FLD method was successfully applied to quantify the colistin concentrations in 2 patient samples for therapeutic drug monitoring.

  8. Tumor penetrating peptides

    Directory of Open Access Journals (Sweden)

    Tambet eTeesalu

    2013-08-01

    Full Text Available Tumor-homing peptides can be used to deliver drugs into tumors. Phage library screening in live mice has recently identified homing peptides that specifically recognize the endothelium of tumor vessels, extravasate, and penetrate deep into the extravascular tumor tissue. The prototypic peptide of this class, iRGD (CRGDKGPDC, contains the integrin-binding RGD motif. RGD mediates tumor homing through binding to αv integrins, which are selectively expressed on various cells in tumors, including tumor endothelial cells. The tumor-penetrating properties of iRGD are mediated by a second sequence motif, R/KXXR/K. This C-end Rule (or CendR motif is active only when the second basic residue is exposed at the C-terminus of the peptide. Proteolytic processing of iRGD in tumors activates the cryptic CendR motif, which then binds to neuropilin-1 activating an endocytic bulk transport pathway through tumor tissue. Phage screening has also yielded tumor-penetrating peptides that function like iRGD in activating the CendR pathway, but bind to a different primary receptor. Moreover, novel tumor-homing peptides can be constructed from tumor-homing motifs, CendR elements and protease cleavage sites. Pathologies other than tumors can be targeted with tissue-penetrating peptides, and the primary receptor can also be a vascular zip code of a normal tissue. The CendR technology provides a solution to a major problem in tumor therapy, poor penetration of drugs into tumors. The tumor-penetrating peptides are capable of taking a payload deep into tumor tissue in mice, and they also penetrate into human tumors ex vivo. Targeting with these peptides specifically increases the accumulation in tumors of a variety of drugs and contrast agents, such as doxorubicin, antibodies and nanoparticle-based compounds. Remarkably the drug to be targeted does not have to be coupled to the peptide; the bulk transport system activated by the peptide sweeps along any compound that is

  9. High-performance liquid chromatography with fluorescence detection and ultra-performance liquid chromatography with electrospray tandem mass spectrometry method for the determination of indoleamine neurotransmitters and their metabolites in sea lamprey plasma.

    Science.gov (United States)

    Wang, Huiyong; Walaszczyk, Erin J; Li, Ke; Chung-Davidson, Yu-Wen; Li, Weiming

    2012-04-06

    We present a comparison of two sensitive methods, HPLC with fluorescence detector (HPLC/FLD) and UPLC with electrospray tandem mass spectrometry (UPLC/MS/MS), for the determination of indoleamine neurotransmitters (NTs) and their metabolites in sea lamprey plasma samples. Liquid-liquid extraction (LLE) and solid-phase extraction (SPE) were also tested for recovery and matrix effect. The recoveries of SPE determined by HPLC/FLD and UPLC/MS/MS ranged from 75 to 123% and 78 to 105%, respectively, while the recoveries of LLE ranged from 45 to 73% and 48 to 75%, respectively. SPE combined with HPLC/FLD and UPLC/MS/MS to determine the target analytes in plasma samples were validated of the sensitivity, reproducibility, accuracy and precision. Both methods exhibited excellent linearity in the range of 0.2-50 ng mL(-1) for all analytes. The limits of detection (LOD) varied from 0.04 ng mL(-1) to 0.13 ng mL(-1) for HPLC/FLD method and 0.003 ng mL(-1) to 0.02 ng mL(-1) for UPLC/MS/MS method. The inter-day accuracy ranged from 82.5 to 127.0% for HPLC/FLD and 93.0 to 113.0% for UPLC/MS/MS. The inter-day precision ranged from 9.9 to 32.3% for HPLC/FLD and 5.4 to 13.2% for UPLC/MS/MS. These results demonstrated that the values obtained by both methods were within the satisfactory range and the UPLC/MS/MS method provided more accurate and precise measurements than HPLC/FLD method. The comparison is of great importance to determine the available detectors, considering the complexity and expensiveness versus quality parameters. These two methods were applied to the analysis of four important indoleamine neurotransmitter analytes (5-hydroxytryptamine, 5-hydroxyindole-3-acetic acid, tryptamine and melatonin) in sea lamprey plasma samples.

  10. Python penetration testing essentials

    CERN Document Server

    Mohit

    2015-01-01

    If you are a Python programmer or a security researcher who has basic knowledge of Python programming and want to learn about penetration testing with the help of Python, this book is ideal for you. Even if you are new to the field of ethical hacking, this book can help you find the vulnerabilities in your system so that you are ready to tackle any kind of attack or intrusion.

  11. Market penetration of biodiesel

    Directory of Open Access Journals (Sweden)

    Kenneth R. Szulczyk, Bruce A. McCarl

    2010-01-01

    Full Text Available This research examines in detail the technology and economics of substituting biodiesel for diesel #2. This endeavor examines three areas. First, the benefits of biodiesel are examined, and the technical problems of large-scale implementation. Second, the biodiesel production possibilities are examined for soybean oil, corn oil, tallow, and yellow grease, which are the largest sources of feedstocks for the United States. Examining in detail the production possibilities allows to identity the extent of technological change, production costs, byproducts, and greenhouse gas (GHG emissions. Finally, a U.S. agricultural model, FASOMGHG was used to predict market penetration of biodiesel, given technological progress, variety of technologies and feedstocks, market interactions, energy prices, and carbon dioxide equivalent prices. FASOMGHG has several interesting results. First, diesel fuel prices have an expansionary impact on the biodiesel industry. The higher the diesel fuel prices, the more biodiesel is produced. However, given the most favorable circumstances, the maximum biodiesel market penetration is 9% in 2030 with a wholesale diesel price of $4 per gallon. Second, the two dominant sources of biodiesel are from corn and soybeans. Sources like tallow and yellow grease are more limited, because they are byproducts of other industries. Third, GHG prices have an expansionary impact on the biodiesel prices, because biodiesel is quite GHG efficient. Finally, U.S. government subsidies on biofuels have an expansionary impact on biodiesel production, and increase market penetration at least an additional 3%.

  12. Market penetration of biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Szulczyk, Kenneth R. [Department of Economics, Orbita 3, Suleyman Demirel University, Almaty, 050043 (Kazakhstan); McCarl, Bruce A. [Department of Agricultural Economics, 2124 TAMU, Texas A& amp; M University, College Station, Texas, 77843 (United States)

    2010-07-01

    This research examines in detail the technology and economics of substituting biodiesel for diesel number 2. This endeavor examines three areas. First, the benefits of biodiesel are examined, and the technical problems of large-scale implementation. Second, the biodiesel production possibilities are examined for soybean oil, corn oil, tallow, and yellow grease, which are the largest sources of feedstocks for the United States. Examining in detail the production possibilities allows to identity the extent of technological change, production costs, byproducts, and greenhouse gas (GHG) emissions. Finally, a U.S. agricultural model, FASOMGHG was used to predict market penetration of biodiesel, given technological progress, variety of technologies and feedstocks, market interactions, energy prices, and carbon dioxide equivalent prices. FASOMGHG has several interesting results. First, diesel fuel prices have an expansionary impact on the biodiesel industry. The higher the diesel fuel prices, the more biodiesel is produced. However, given the most favorable circumstances, the maximum biodiesel market penetration is 9% in 2030 with a wholesale diesel price of $4 per gallon. Second, the two dominant sources of biodiesel are from corn and soybeans. Sources like tallow and yellow grease are more limited, because they are byproducts of other industries. Third, GHG prices have an expansionary impact on the biodiesel prices, because biodiesel is quite GHG efficient. Finally, U.S. government subsidies on biofuels have an expansionary impact on biodiesel production, and increase market penetration at least an additional 3%.

  13. Prediction of alumina penetration

    Energy Technology Data Exchange (ETDEWEB)

    Mandell, D A

    1993-02-01

    The MESA hydrocode was used to predict two-dimensional tests of L/D 10 and L/D 15 tungsten rods impacting AD 90 alumina with a steel backing. The residual penetration into the steel is the measured quantity in these experiments conducted at the Southwest Research Institute (SWR). The interface velocity as a function of time between an alumina target and a lithium fluoride window, impacted by an alumina disk at velocities between 544 m/s and 2329 m/s, was also predicted. These one-dimensional flyer plate experiments were conducted at Sandia National Laboratories using Coors AD 995 alumina. The material strength and fracture models are important in the prediction of ceramic experiments. The models used in these predictions are discussed. The penetrations in the two-dimensional tests were predicted to 11.4 percent or better. In five of the six experiments, the predicted penetration depth was deeper than the measured value. This trend is expected since the calculation is based on ideal conditions. The results show that good agreement between the 1-D flyer plate data and the MESA predictions exists at the lower impact velocities, but the maximum velocity is overpredicted as the flyer plate velocity increases. At a flyer plate velocity of 2329 m/s the code overpredicted the data by 12.3 percent.

  14. Mathematical model and simulation of partial penetrated weld pool

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The qualitative analysis on the behavior of partial penetrated weld pool transferring from pulsed peak current to base current in pulsed TIG welding is carried out in this paper. Based on the analysis results, the mathematical models for 3D liquid surface shape of partial penetrated weld pool in pulsed TIG welding are created including surface potential energy model, gravitational energy model and volumetric potential energy. The numerical simulation with these models and the experiments on low carbon steel are carried out using the software Surface Evolver. The simulation results and model are then amended with experimental results. Two important characteristic quantities, the liquid metal coverage ratio and the stripping width of liquid metal, are put forward in this paper, which paves a way for further weld pool full penetration control.

  15. An Overview of Penetration Testing

    OpenAIRE

    2011-01-01

    Penetration testing is a series of activities undertaken to identify and exploit security vulnerabilities. It helps confirm the effectiveness or ineffectiveness of the security measures that have been implemented. This paper provides an overview of penetration testing. It discusses the benefits, the strategies and the methodology of conducting penetration testing. The methodology of penetration testing includes three phases: test preparation, test and test analysis. The test phase involves ...

  16. Determination of mercury species by the diffusive gradient in thin film technique and liquid chromatography – atomic fluorescence spectrometry after microwave extraction

    Energy Technology Data Exchange (ETDEWEB)

    Pelcová, Pavlína, E-mail: pavlina.pelcova@mendelu.cz; Dočekalová, Hana, E-mail: hana.docekalova@mendelu.cz; Kleckerová, Andrea, E-mail: andrea.kleckerova@mendelu.cz

    2015-03-25

    Highlights: • DGT–MAE–LC–CV-AFS method was developed for determination of four mercury species. • The microwave extraction was used for isolation of mercury species from resin gels. • Optimized DGT–MAE–LC–CV-AFS method provides low detection limits (13–38 ng L{sup −1}). • The diffusion coefficients of four mercury species were simultaneously determined. - Abstract: A diffusive gradient in thin films technique (DGT) was combined with liquid chromatography (LC) and cold vapor atomic fluorescence spectrometry (CV-AFS) for the simultaneous quantification of four mercury species (Hg{sup 2+}, CH{sub 3}Hg{sup +}, C{sub 2}H{sub 5}Hg{sup +}, and C{sub 6}H{sub 5}Hg{sup +}). After diffusion through an agarose diffusive layer, the mercury species were accumulated in resin gels containing thiol-functionalized ion-exchange resins (Duolite GT73, and Ambersep GT74). A microwave-assisted extraction (MAE) in the presence of 6 M HCl and 5 M HCl (55 °C, 15 min) was used for isolation of mercury species from Ambersep and Duolite resin gels, respectively. The extraction efficiency was higher than 95.0% (RSD 3.5%). The mercury species were separated with a mobile phase containing 6.2% methanol + 0.05% 2-mercaptoethanol + 0.02 M ammonium acetate with a stepwise increase of methanol content up to 80% in the 16th min on a Zorbax C18 reverse phase column. The LODs of DGT–MAE–LC–CV-AFS method were 38 ng L{sup −1} for CH{sub 3}Hg{sup +}, 13 ng L{sup −1} for Hg{sup 2+}, 34 ng L{sup −1} for C{sub 2}H{sub 5}Hg{sup +} and 30 ng L{sup −1} for C{sub 6}H{sub 5}Hg{sup +} for 24 h DGT accumulation at 25 °C.

  17. Simultaneous Determination of Bergapten, Imperatorin, Notopterol, and Isoimperatorin in Rat Plasma by High Performance Liquid Chromatography with Fluorescence Detection and Its Application to Pharmacokinetic and Excretion Study after Oral Administration of Notopterygium incisum Extract

    Directory of Open Access Journals (Sweden)

    John Teye Azietaku

    2016-01-01

    Full Text Available A specific, sensitive, and reliable high performance liquid chromatography with fluorescence detection (HPLC-FLD was first optimized and then used in the simultaneous quantification of bergapten, imperatorin, notopterol, and isoimperatorin in rat plasma using osthole as the internal standard. Liquid-liquid extraction with ethyl acetate was employed in treating the rat plasma samples obtained. Separation was carried out with a Hedera™ ODS column (4.6 × 250 mm, 5 μm by gradient elution at a temperature of 40°C. Excitation and emission of the fluorescence detector were set to 300 and 490 nm, respectively. The lower limits of quantification for bergapten, imperatorin, notopterol, and isoimperatorin in rat plasma were 4, 40, 4, and 2 ng mL−1, respectively. The intraday and interday precision and accuracy for the four coumarins were within acceptable criteria. The recovery of the method was satisfactory with a range of 80.3–114%. The validated method was successfully used for the simultaneous determination of the four coumarins in Notopterygium incisum extracts and also for the pharmacokinetic and excretion study of bergapten, imperatorin, notopterol, and isoimperatorin in rats.

  18. Simultaneous Determination of Bergapten, Imperatorin, Notopterol, and Isoimperatorin in Rat Plasma by High Performance Liquid Chromatography with Fluorescence Detection and Its Application to Pharmacokinetic and Excretion Study after Oral Administration of Notopterygium incisum Extract

    Science.gov (United States)

    Teye Azietaku, John; Yu, Xie-an; Li, Jin; Hao, Jia; An, Mingrui; Tan, Zhijing

    2016-01-01

    A specific, sensitive, and reliable high performance liquid chromatography with fluorescence detection (HPLC-FLD) was first optimized and then used in the simultaneous quantification of bergapten, imperatorin, notopterol, and isoimperatorin in rat plasma using osthole as the internal standard. Liquid-liquid extraction with ethyl acetate was employed in treating the rat plasma samples obtained. Separation was carried out with a Hedera™ ODS column (4.6 × 250 mm, 5 μm) by gradient elution at a temperature of 40°C. Excitation and emission of the fluorescence detector were set to 300 and 490 nm, respectively. The lower limits of quantification for bergapten, imperatorin, notopterol, and isoimperatorin in rat plasma were 4, 40, 4, and 2 ng mL−1, respectively. The intraday and interday precision and accuracy for the four coumarins were within acceptable criteria. The recovery of the method was satisfactory with a range of 80.3–114%. The validated method was successfully used for the simultaneous determination of the four coumarins in Notopterygium incisum extracts and also for the pharmacokinetic and excretion study of bergapten, imperatorin, notopterol, and isoimperatorin in rats. PMID:28115935

  19. The isolated perfused human skin flap model: A missing link in skin penetration studies?

    OpenAIRE

    Ternullo, Selenia; de Weerd, Louis; Flaten, Gøril Eide; Holsæter, Ann Mari; Skalko-Basnet, Natasa

    2016-01-01

    Development of effective (trans)dermal drug delivery systems requires reliable skinmodels to evaluate skin drug penetration. The isolated perfused human skin flap remainsmetabolically active tissue for up to 6 h during in vitro perfusion. We introduce the isolated perfused human skin flap as a close-to-in vivo skin penetration model. To validate the model's ability to evaluate skin drug penetration the solutions of a hydrophilic (calcein) and a lipophilic (rhodamine) fluorescence ...

  20. An Overview of Penetration Testing

    Directory of Open Access Journals (Sweden)

    Aileen G. Bacudio

    2011-12-01

    Full Text Available Penetration testing is a series of activities undertaken to identify and exploit security vulnerabilities. It helps confirm the effectiveness or ineffectiveness of the security measures that have been implemented. This paper provides an overview of penetration testing. It discusses the benefits, the strategies and the methodology of conducting penetration testing. The methodology of penetration testing includes three phases: test preparation, test and test analysis. The test phase involves the following steps: information gathering, vulnerability analysis, and vulnerability exploit. This paper further illustrates how to apply this methodology to conduct penetration testing on two example web applications.

  1. Liposome surface charge influence on skin penetration behaviour.

    Science.gov (United States)

    Gillet, A; Compère, P; Lecomte, F; Hubert, P; Ducat, E; Evrard, B; Piel, G

    2011-06-15

    Vesicular systems have shown their ability to increase dermal and transdermal drug delivery. Their mechanism of drug transport into and through the skin has been investigated but remains a much debated question. Several researchers have outlined that drug penetration can be influenced by modifying the surface charge of liposomes. In the present work we study the influence of particle surface charge on skin penetration. The final purpose is the development of a carrier system which is able to enhance the skin delivery of two model drugs, betamethasone and betamethasone dipropionate. Liposomes were characterised by their size, morphology, zeta potential, encapsulation efficiency and stability. Ex vivo diffusion studies using Franz diffusion cells were performed. Confocal microscopy was performed to visualise the penetration of fluorescently labelled liposomes into the skin. This study showed the potential of negatively charged liposomes to enhance the skin penetration of betamethasone and betamethasone dipropionate.

  2. Impact and Penetration of Nanoparticle Suspension Drops into Porous Membranes

    Science.gov (United States)

    Sahu, Rakesh; Yarin, Alexander; Pourdeyhimi, Behnam

    2014-03-01

    The impacts and dynamic penetration of drops with suspended nanoparticles into porous membranes are studied experimentally and theoretically. This type of penetration is radically different from the wettability-driven imbibition. Two types of membranes are used in the experiments: (i) glass fiber filter membrane (wettable) and (ii) PTFE depth filter (non-wettable). The nanoparticle entrainment and deposition inside the membrane bulk is used to mostly visualize the ultimate penetration fronts of the carrier fluid by observing the cut cross-sections of the filter membranes, albeit also provides an insight into potentially new applications like circuit printing on nonwovens. The experimental results demonstrate that during the dynamic focusing responsible for water penetration into micro- and nanopores, water can penetrate into a non-wettable porous medium (PTFE). Water also penetrates by the same focusing mechanism into the wettable glass fiber membrane, where it additionally spreads on a much longer time scale due to the wettability-driven flow. A theory explaining dynamic penetration of liquid into porous medium after drop impact is proposed. It is used to explain and predict water penetration into the non-wettable media after drop impact, and the results are compared with the experimental data. The work was supported by the Nonwovens Cooperative Research Center (NCRC).

  3. Development and application of a high-speed planar laser-induced fluorescence imaging system to evaluate liquid and vapor phases of sprays from a multi-hole diesel fuel injector

    Science.gov (United States)

    Parrish, S. E.; Zink, R. J.

    2013-02-01

    A high-speed imaging system capable of acquiring elastic scattering images and planar laser-induced fluorescence (PLIF) images in a near-simultaneous fashion has been developed. Acquiring both elastic scattering and PLIF images enables the liquid phase to be discriminated from the vapor phase. High-speed imaging allows the temporal evolution of flow structures to be evaluated. Images of sprays from a multi-hole diesel fuel injector operating under engine-like conditions were acquired. The vapor phase images reveal intricate fluid dynamic structures that exhibit a high degree of variability, indicative of a turbulent gas jet.

  4. High performance liquid chromatography coupled to atomic fluorescence spectrometry for the speciation of the hydride and chemical vapour-forming elements As, Se, Sb and Hg: A critical review

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yuwei [Department of Chemistry and Biochemistry, Laurentian University, Ramsey Lake Road, Sudbury P3E 2C6 (Canada); Belzile, Nelson, E-mail: nbelzile@laurentian.ca [Department of Chemistry and Biochemistry, Laurentian University, Ramsey Lake Road, Sudbury P3E 2C6 (Canada); Cooperative Freshwater Ecology Unit, Laurentian University, Ramsey Lake Road, Sudbury P3E 2C6 (Canada)

    2010-06-25

    We present the most recent applications of high performance liquid chromatography (HPLC) hyphenated to hydride generation or chemical vapour generation and atomic fluorescence spectrometry (HG/CVG-AFS), for the determination and speciation of the selected hydride-forming elements arsenic (As), selenium (Se) and antimony (Sb) and the chemical vapour-forming metal Hg. The review focuses on sample preparation, post-column treatments and on the applications of this technique to various liquid and solid samples. This review also intends to discuss some limitations associated to HPLC-HG/CVG-AFS due to the necessity on post-column treatments, including the oxidation of organo-element compounds and the pre-reduction to a suitable valence. Nevertheless, the hyphenated technique HPLC-HG/CVG-AFS remains an efficient, sensitive and affordable approach to perform speciation of the four studied elements as shown by the variety of applications presented and discussed in this review.

  5. Penetration Testing: A Review

    Directory of Open Access Journals (Sweden)

    Kumar Shravan

    2014-04-01

    Full Text Available : Network Security is becoming more and more crucial as the volume of data being exchanged on the Internet increases. When people use Internet, they have certain expectations. They expect confidentiality, data integrity and authentication (CIA Standards. In 1980’s most organizations had only a physical boundary that needed protection of the assets. Today, due to the changes in the way resources are made available Organizations are forced to verify that their assets are protected from both the external and internal threats that our working environment has enabled. Due to the increasing dependency of our society on networked information system the overall security of these systems should be measured and improved. The most accurate method to evaluate organization’s information security stance is to observe how it stands up against an attack. Network administrators have often tried their best by improving their network security, however with rapid surface of new exploits; the best way of ensuring that the system is secure is to attempt penetration testing. This would be the most effective way to find exploits and to proof whether a system is vulnerable. Penetration test ing often allows the security analyst to find new vulnerabilities.

  6. 9-fluorenylmethyl chloroformate as a fluorescence-labeling reagent for derivatization of carboxylic acid moiety of sodium valproate using liquid chromatography/tandem mass spectrometry for binding characterization: a human pharmacokinetic study.

    Science.gov (United States)

    Mohammadi, Bahareh; Majnooni, Mohammad Bagher; Khatabi, Pyman Malek; Jalili, Ronak; Bahrami, Gholamreza

    2012-01-01

    In High Performance Liquid Chromatographic (HPLC) determination of chemicals with acidic functions, different labeling agents are used to improve sensitivity of the assay. 9-Fluorenylmethyl chloroformate (FMOC-Cl), on the other hand, is a suitable labeling agent, which reacts with both primary and secondary amines and less readily with hydroxyl groups in alkaline conditions. However, the reagent has not been applied in labeling of chemicals with acidic function yet. In this study which is the first report on application of FMOC-Cl in derivatization and analysis of a drug with acidic function, valproic acid (VPA), one of a series of fatty carboxylic acids with anticonvulsant activity, was derivatized using the reagent and quantified in serum samples by HPLC with fluorescence detection. In addition, to document the reaction between the labeling agent and carboxylic acid moiety of the drug, we developed a liquid chromatography-tandem MS/MS (LC-MS/MS) method. Following liquid-liquid extraction, derivatization of the drug and an internal standard was achieved in alkaline medium. The elute was monitored by a fluorescence detector with respective excitation and emission wavelengths of 265 and 315 nm. The present method is more sensitive comparing with other published HPLC procedures for analysis of VPA. The assay is sensitive enough to measure drug levels obtained in human single dose studies with a limit of quantification of 0.01 μg/mL. Also the method is linear over the concentrations range of 0.01-32 μg/mL of VPA in human serum using 100 μL serum sample and 5 μL injection. The coefficient variation values of both inter and intra day analysis were less than 12% and the percentage error was less than 4%. The method performance was studied and the validated procedure applied in a randomized cross-over bioequivalence study of two different VPA preparations in 24 healthy volunteers.

  7. Theory of activated penetrant diffusion in viscous fluids and colloidal suspensions.

    Science.gov (United States)

    Zhang, Rui; Schweizer, Kenneth S

    2015-10-14

    We heuristically formulate a microscopic, force level, self-consistent nonlinear Langevin equation theory for activated barrier hopping and non-hydrodynamic diffusion of a hard sphere penetrant in very dense hard sphere fluid matrices. Penetrant dynamics is controlled by a rich competition between force relaxation due to penetrant self-motion and collective matrix structural (alpha) relaxation. In the absence of penetrant-matrix attraction, three activated dynamical regimes are predicted as a function of penetrant-matrix size ratio which are physically distinguished by penetrant jump distance and the nature of matrix motion required to facilitate its hopping. The penetrant diffusion constant decreases the fastest with size ratio for relatively small penetrants where the matrix effectively acts as a vibrating amorphous solid. Increasing penetrant-matrix attraction strength reduces penetrant diffusivity due to physical bonding. For size ratios approaching unity, a distinct dynamical regime emerges associated with strong slaving of penetrant hopping to matrix structural relaxation. A crossover regime at intermediate penetrant-matrix size ratio connects the two limiting behaviors for hard penetrants, but essentially disappears if there are strong attractions with the matrix. Activated penetrant diffusivity decreases strongly with matrix volume fraction in a manner that intensifies as the size ratio increases. We propose and implement a quasi-universal approach for activated diffusion of a rigid atomic/molecular penetrant in a supercooled liquid based on a mapping between the hard sphere system and thermal liquids. Calculations for specific systems agree reasonably well with experiments over a wide range of temperature, covering more than 10 orders of magnitude of variation of the penetrant diffusion constant.

  8. Theory of activated penetrant diffusion in viscous fluids and colloidal suspensions

    Science.gov (United States)

    Zhang, Rui; Schweizer, Kenneth S.

    2015-10-01

    We heuristically formulate a microscopic, force level, self-consistent nonlinear Langevin equation theory for activated barrier hopping and non-hydrodynamic diffusion of a hard sphere penetrant in very dense hard sphere fluid matrices. Penetrant dynamics is controlled by a rich competition between force relaxation due to penetrant self-motion and collective matrix structural (alpha) relaxation. In the absence of penetrant-matrix attraction, three activated dynamical regimes are predicted as a function of penetrant-matrix size ratio which are physically distinguished by penetrant jump distance and the nature of matrix motion required to facilitate its hopping. The penetrant diffusion constant decreases the fastest with size ratio for relatively small penetrants where the matrix effectively acts as a vibrating amorphous solid. Increasing penetrant-matrix attraction strength reduces penetrant diffusivity due to physical bonding. For size ratios approaching unity, a distinct dynamical regime emerges associated with strong slaving of penetrant hopping to matrix structural relaxation. A crossover regime at intermediate penetrant-matrix size ratio connects the two limiting behaviors for hard penetrants, but essentially disappears if there are strong attractions with the matrix. Activated penetrant diffusivity decreases strongly with matrix volume fraction in a manner that intensifies as the size ratio increases. We propose and implement a quasi-universal approach for activated diffusion of a rigid atomic/molecular penetrant in a supercooled liquid based on a mapping between the hard sphere system and thermal liquids. Calculations for specific systems agree reasonably well with experiments over a wide range of temperature, covering more than 10 orders of magnitude of variation of the penetrant diffusion constant.

  9. Theory of activated penetrant diffusion in viscous fluids and colloidal suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Rui; Schweizer, Kenneth S., E-mail: kschweiz@illinois.edu [Department of Materials Science and Frederick Seitz Materials Research Laboratory, University of Illinois, 1304 West Green Street, Urbana, Illinois 61801 (United States)

    2015-10-14

    We heuristically formulate a microscopic, force level, self-consistent nonlinear Langevin equation theory for activated barrier hopping and non-hydrodynamic diffusion of a hard sphere penetrant in very dense hard sphere fluid matrices. Penetrant dynamics is controlled by a rich competition between force relaxation due to penetrant self-motion and collective matrix structural (alpha) relaxation. In the absence of penetrant-matrix attraction, three activated dynamical regimes are predicted as a function of penetrant-matrix size ratio which are physically distinguished by penetrant jump distance and the nature of matrix motion required to facilitate its hopping. The penetrant diffusion constant decreases the fastest with size ratio for relatively small penetrants where the matrix effectively acts as a vibrating amorphous solid. Increasing penetrant-matrix attraction strength reduces penetrant diffusivity due to physical bonding. For size ratios approaching unity, a distinct dynamical regime emerges associated with strong slaving of penetrant hopping to matrix structural relaxation. A crossover regime at intermediate penetrant-matrix size ratio connects the two limiting behaviors for hard penetrants, but essentially disappears if there are strong attractions with the matrix. Activated penetrant diffusivity decreases strongly with matrix volume fraction in a manner that intensifies as the size ratio increases. We propose and implement a quasi-universal approach for activated diffusion of a rigid atomic/molecular penetrant in a supercooled liquid based on a mapping between the hard sphere system and thermal liquids. Calculations for specific systems agree reasonably well with experiments over a wide range of temperature, covering more than 10 orders of magnitude of variation of the penetrant diffusion constant.

  10. Penetration Dynamics of Earth Penetration Warhead into Composite Target Media

    Directory of Open Access Journals (Sweden)

    P. K. Roy

    1987-07-01

    Full Text Available Attempts have been made to develop a suitable computer code that can find solutions to the axi-symmetric penetration of an Earth Penetrating Warhead yielding complete space-time histories of the resistive force offered by the target medium. The consequent warhead deceleration and velocity reduction, the resulting axial compressive stress developed in warhead casing as the penetration process progresses into the composite target media consisting of hard concrete of specified thickness followed by earth soil have been discussed.

  11. Purification and characterization of a novel cell-penetrating carrier similar to cholera toxin chimeric protein.

    Science.gov (United States)

    Lin, Weiping; Zheng, Xi; Wang, Huaqian; Yu, Lin; Zhou, Xiaofen; Sun, Yunxiao; Zhao, Suqing; Du, Zhiyun; Zhang, Kun

    2017-01-01

    Developing a recombinant vector for noninvasively delivering biological macromolecules into the brain is important. This study constructed and purified a protein complex based on the cholera toxin (CT) molecular structure. Enhanced green fluorescent protein (EGFP)-modified A2 subunits of CT (CTA2) were used as tracer molecules for introduction of transactivator of transcription (TAT) through the A subunit into cells. The protein complex EGFP-CTA2-TAT/(CTB)5 (CTB: B subunit of CT) was obtained using an in vitro recombination method and verified by monosialoganglioside-enzyme-linked immunosorbent assay and high performance liquid chromatography assay. The protein complexes bound more strongly to monosialoganglioside (GM1) than (CTB)5 at low concentrations (0.625-1.25 μg/mL). In vitro assays revealed that the transmembrane function of TAT was also maintained. The GM1-binding activity and cell membrane-penetrating ability suggested that a CT structure-based protein complexes could be used to design a delivery carrier for intranasal administration through GM1 binding. The expression vector introduced in this study provides a feasible expression frame for constructing several new macromolecular protein drugs for effective cell penetration.

  12. Localizing Ground-Penetrating Radar

    Science.gov (United States)

    2014-11-01

    ing Ground-Penetrating Radar (LGPR) uses very high frequency (VHF) radar reflections of underground features to generate base- line maps and then...Innovative ground- penetrating radar that maps underground geological features provides autonomous vehicles with real-time localization. Localizing...NOV 2014 2. REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Localizing Ground-Penetrating Radar 5a. CONTRACT NUMBER

  13. Determination of trace biogenic amines with 1,3,5,7-tetramethyl-8-(N-hydroxysuccinimidyl butyric ester)-difluoroboradiaza-s-indacene derivatization using high-performance liquid chromatography and fluorescence detection.

    Science.gov (United States)

    Gao, Pan-Feng; Guo, Xiao-Feng; Wang, Hong; Zhang, Hua-Shan

    2011-06-01

    A reversed-phase high-performance liquid chromatographic method based on chemical derivatization with fluorescence detection has been developed for analyzing biogenic amines in food and environmental samples. A BODIPY-based fluorescent reagent, 1,3,5,7-tetramethyl-8-(N-hydroxysuccinimidyl butyric ester)-difluoroboradiaza-s-indacene (TMBB-Su), was employed for the derivatization of these biogenic amines at 20 °C for 20 min in pH 7.20 borate buffer after careful investigation of the derivatization conditions including reagent concentration, buffer solution, reaction temperature and reaction time. Separation of biogenic amines with gradient elution was conducted on a C8 column with methanol-tetrahydrofuran-water as mobile phase. The detection limits were obtained in the range from 0.1 to 0.2 nM (signal-to-noise=3). This procedure has been validated using practical samples. The study results demonstrated a potential of employing high-performance liquid chromatography (HPLC) with 1,3,5,7-tetramethyl-8-(N-hydroxysuccinimidyl butyric ester)-difluoroboradiaza-s-indacene labeling as a tool for quantitative analysis of biogenic amines involved in various matrices.

  14. Mercury speciation by high-performance liquid chromatography atomic fluorescence spectrometry using an integrated microwave/UV interface. Optimization of a single step procedure for the simultaneous photo-oxidation of mercury species and photo-generation of Hg0

    Science.gov (United States)

    de Quadros, Daiane P. C.; Campanella, Beatrice; Onor, Massimo; Bramanti, Emilia; Borges, Daniel L. G.; D'Ulivo, Alessandro

    2014-11-01

    We described the hyphenation of photo-induced chemical vapor generation with high performance liquid chromatography-atomic fluorescence spectrometry (HPLC-AFS) for the quantification of inorganic mercury, methylmercury (MeHg) and ethylmercury (EtHg). In the developed procedure, formic acid in mobile phase was used for the photodecomposition of organomercury compounds and reduction of Hg2 + to mercury vapor under microwave/ultraviolet (MW/UV) irradiation. We optimized the proposed method studying the influence of several operating parameters, including the type of organic acid and its concentration, MW power, composition of HPLC mobile phase and catalytic action of TiO2 nanoparticles. Under the optimized conditions, the limits of detection were 0.15, 0.15 and 0.35 μg L- 1 for inorganic mercury, MeHg and EtHg, respectively. The developed method was validated by determination of the main analytical figures of merit and applied to the analysis of three certified reference materials. The online interfacing of liquid chromatography with photochemical-vapor generation-atomic fluorescence for mercury determination is simple, environmentally friendly, and represents an attractive alternative to the conventional tetrahydroborate (THB) system.

  15. Fluorescence spectroscopy

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2016-01-01

    Fluorescence spectroscopy is a powerful experimental tool used by scientists from many disciplines. During the last decades there have been important developments on distinct fluorescence methods, particularly those related to the study of biological phenomena. This chapter discusses...

  16. Penetration Tester's Open Source Toolkit

    CERN Document Server

    Faircloth, Jeremy

    2011-01-01

    Great commercial penetration testing tools can be very expensive and sometimes hard to use or of questionable accuracy. This book helps solve both of these problems. The open source, no-cost penetration testing tools presented do a great job and can be modified by the user for each situation. Many tools, even ones that cost thousands of dollars, do not come with any type of instruction on how and in which situations the penetration tester can best use them. Penetration Tester's Open Source Toolkit, Third Edition, expands upon existing instructions so that a professional can get the most accura

  17. Physical Penetration Testing: A Whole New Story in Penetration Testing

    NARCIS (Netherlands)

    Dimkov, Trajce; Pieters, Wolter

    2011-01-01

    Physical penetration testing plays an important role in assuring a company that the security policies are properly enforced and that the security awareness of the employees is on the appropriate level. In physical penetration tests the tester physically enters restricted locations and directly inter

  18. Transconjunctival penetration of mitomycin C

    Directory of Open Access Journals (Sweden)

    Velpandian T

    2008-01-01

    Full Text Available Aims: The study was performed to estimate transconjunctival penetration of mitomycin C (MMC to Tenon′s tissue following application over the intact conjunctiva before routine trabeculectomy. Settings and Design: Institution-based case series. Materials and Methods: In 41 eyes of 41 patients, MMC (0.4 mg/ml for 3 min was applied over the intact conjunctiva before beginning trabeculectomy. Tenon′s capsule directly beneath the site of application was excised during trabeculectomy and was homogenized, centrifuged and MMC concentrations were analyzed using high-performance liquid chromatography (HPLC. Statistical Analysis Used: Statistical analysis was performed using stata0 8.0 version software (STATA Corporation, Houston, TX, USA. In this study, P -values less than 0.05 were considered as statistically significant. Results: The average weight of the sample of Tenon′s tissue excised was 5.51 ± 4.42 mg (range: 0.9-17.1 and the average estimated MMC concentration found to be present in Tenon′s tissue using HPLC was 18.67 ± 32.36 x 10−6 moles/kg of the tissue (range: 0.38-197.05 x 10−6 . In 36 of the 41 patients (87.80%, the MMC concentration reached above 2 x 10−6 moles/kg of the tissue concentration required to inhibit human conjunctival fibroblasts. Conclusions: Mitomycin C does permeate into the subconjunctival tissue after supraconjunctival application for 3 min. Application of MMC over the conjunctiva may be a useful alternative to subconjunctival or subscleral application during routine trabeculectomy and as an adjunct for failing blebs.

  19. Determination of fluorescence-labeled asparaginyl-oligosaccharide in glycoprotein by reversed-phase ultraperformance liquid chromatography with electrospray ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Kurihara, Takamasa; Min, Jun Zhe; Toyo'oka, Toshimasa; Fukushima, Takeshi; Inagaki, Shinsuke

    2007-11-15

    Eight fluorescence reagents, i.e., DBD-F, NBD-F, DNS-Cl, NDA, PSC, FITC, Fmoc-Cl, and DMEQ-COCl, which are reactive to an amino functional group, were tested for the labeling of asparaginyl-oligosaccharides in a glycoprotein. Although the optimal reaction conditions and the fluorescence maximal wavelengths were different for each reagent, the highly sensitive fluorescence detection at the femtomole level of Disialo-Asn (a representative asparaginyl-oligosaccharide) was obtained from the labeling utilizing these reagents. Among them, PSC was the most reliable reagent in terms of detection sensitivity (approximately 3 fmol, signal-to-noise ratio of 5 (S/N = 5) on the chromatogram). However, the structural information could not be obtained from the fluorescence detection. Thus, the on-line determination of a real sample was carried out by UPLC-ESI-TOF-MS. The detection limit of the PSC-labeled Disialo-Asn by selected-ion chromatography was 58 fmol (S/N = 5). When the proposed procedure was applied to the determination of oligosaccharides in ovalbumin, 15 species of PSC-labeled oligosaccharides possessing Man, GlcNAc, and Gal units were identified from the UPLC-ESI-TOF-MS. The number of identified oligosaccharides was relatively greater than the method using Fmoc-Cl. Based on the ovalbumin results, the proposed labeling with PSC followed by UPLC-ESI-TOF-MS detection seems to be useful for the on-line asparaginyl-oligosaccharide analysis.

  20. LeciPlex, invasomes, and liposomes: A skin penetration study.

    Science.gov (United States)

    Shah, Sanket M; Ashtikar, Mukul; Jain, Ankitkumar S; Makhija, Dinesh T; Nikam, Yuvraj; Gude, Rajiv P; Steiniger, Frank; Jagtap, Aarti A; Nagarsenker, Mangal S; Fahr, Alfred

    2015-07-25

    The present study compares three vesicular systems, cationic LeciPlex, invasomes, and conventional liposomes for their ability to deliver drugs deep into the skin. Skin penetration ability of the three vesicular systems was studied for two drugs namely idebenone (antioxidant/anticancer) and azelaic acid (antiacne). All systems showed sizes in nanometer range with small polydispersity indices. Vesicular systems were characterized by CryoTEM studies to understand the differences in morphology of the vesicular systems. Ex vivo human skin penetration studies suggested a pattern in penetration of drugs in different layers of the skin: LeciPlex showed higher penetration for idebenone whereas invasomes showed higher penetration of azelaic acid. Ex vivo study using a fluorescent dye (DiI) was performed to understand the differences in the penetration behavior of the three vesicular systems on excised human skin. In vitro cytotoxicity studies on B16F10 melanoma cell lines revealed, when loaded with idebenone, LeciPlex formulations had the superior activity followed by invasomes and liposomes. In vitro antimicrobial study of azelaic acid loaded systems on Propionibacterium acne revealed high antimicrobial activity for DDAB leciplex followed by almost equal activity for invasomes and CTAB LeciPlex followed by liposomes. Whereas antiacne efficacy study in rats for azelaic acid loaded systems, invasomes exhibited the best antiacne efficacy followed by liposomes and LeciPlex.

  1. Failure Engineered Heavy Metal Penetrators

    Science.gov (United States)

    1992-12-01

    ARMY RESEARCH LABORATORY Failure Engineered Heavy Metal Penetrators, Phase I, SBIR ARL-CR-5· R. Cavalieri, W. Tiarn, and D. Nicholson prepared...REPORT DATE S. REPORT TYPE AND DATES COVERED December 1992 Final Report-1/1/92 - 7/31/92 4. TITLE AND SUBTITLE FAILURE ENGINEERED HEAVY METAL PENETRATORS

  2. Electromagnetic Field Penetration Studies

    Science.gov (United States)

    Deshpande, M.D.

    2000-01-01

    A numerical method is presented to determine electromagnetic shielding effectiveness of rectangular enclosure with apertures on its wall used for input and output connections, control panels, visual-access windows, ventilation panels, etc. Expressing EM fields in terms of cavity Green's function inside the enclosure and the free space Green's function outside the enclosure, integral equations with aperture tangential electric fields as unknown variables are obtained by enforcing the continuity of tangential electric and magnetic fields across the apertures. Using the Method of Moments, the integral equations are solved for unknown aperture fields. From these aperture fields, the EM field inside a rectangular enclosure due to external electromagnetic sources are determined. Numerical results on electric field shielding of a rectangular cavity with a thin rectangular slot obtained using the present method are compared with the results obtained using simple transmission line technique for code validation. The present technique is applied to determine field penetration inside a Boeing-757 by approximating its passenger cabin as a rectangular cavity filled with a homogeneous medium and its passenger windows by rectangular apertures. Preliminary results for, two windows, one on each side of fuselage were considered. Numerical results for Boeing-757 at frequencies 26 MHz, 171-175 MHz, and 428-432 MHz are presented.

  3. Top Sounder Ice Penetration

    Science.gov (United States)

    Porter, D. L.; Goemmer, S. A.; Sweeney, J. H.

    2014-12-01

    Ice draft measurements are made as part of normal operations for all US Navy submarines operating in the Arctic Ocean. The submarine ice draft data are unique in providing high resolution measurements over long transects of the ice covered ocean. The data has been used to document a multidecadal drop in ice thickness, and for validating and improving numerical sea-ice models. A submarine upward-looking sonar draft measurement is made by a sonar transducer mounted in the sail or deck of the submarine. An acoustic beam is transmitted upward through the water column, reflecting off the bottom of the sea ice and returning to the transducer. Ice thickness is estimated as the difference between the ship's depth (measured by pressure) and the acoustic range to the bottom of the ice estimated from the travel time of the sonar pulse. Digital recording systems can provide the return off the water-ice interface as well as returns that have penetrated the ice. Typically, only the first return from the ice hull is analyzed. Information regarding ice flow interstitial layers provides ice age information and may possibly be derived with the entire return signal. The approach being investigated is similar to that used in measuring bottom sediment layers and will involve measuring the echo level from the first interface, solving the reflection loss from that transmission, and employing reflection loss versus impedance mismatch to ascertain ice structure information.

  4. An Earth Penetrating Modeling Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Stokes, E; Yarrington, P; Glenn, L

    2005-06-21

    Documentation of a study to assess the capability of computer codes to predict lateral loads on earth penetrating projectiles under conditions of non-normal impact. Calculations simulated a set of small scale penetration tests into concrete targets with oblique faces at angles of 15 and 30 degrees to the line-of-flight. Predictive codes used by the various calculational teams cover a wide range of modeling approaches from approximate techniques, such as cavity expansion, to numerical methods, such as finite element codes. The modeling assessment was performed under the auspices of the Phenomenology Integrated Product Team (PIPT) for the Robust Nuclear Earth Penetrator Program (RNEP). Funding for the penetration experiments and modeling was provided by multiple earth penetrator programs.

  5. Study of cell-differentiation and assembly of photosynthetic proteins during greening of etiolated Zea mays leaves using confocal fluorescence microspectroscopy at liquid-nitrogen temperature.

    Science.gov (United States)

    Shibata, Yutaka; Katoh, Wataru; Tahara, Yukari

    2013-04-01

    Fluorescence microspectroscopy observations were used to study the processes of cell differentiation and assemblies of photosynthesis proteins in Zea mays leaves under the greening process. The observations were done at 78K by setting the sample in a cryostat to avoid any undesired progress of the greening process during the measurements. The lateral and axial spatial resolutions of the system were 0.64μm and 4.4μm, respectively. The study revealed the spatial distributions of protochlorophyllide (PChld) in both the 632-nm-emitting and 655-nm-emitting forms within etiolated Zea mays leaves. The sizes of the fluorescence spots attributed to the former were larger than those of the latter, validating the assignment of the former and latter to the prothylakoid and prolamellar bodies, respectively. In vivo microspectroscopy observations of mature Zea mays leaves confirmed the different photosystem II (PS I)/photosystem I (PS II) ratio between the bundle sheath (BS) and mesophyll (MS) cells, which is specific for C4-plants. The BS cells in Zea mays leaves 1h after the initiation of the greening process tended to show fluorescence spectra at shorter wavelength side (at around 679nm) than the MS cells (at around 682nm). The 679-nm-emitting chlorophyll-a form observed mainly in the BS cells was attributed to putative precursor complexes to PS I. The BS cells under 3-h greening showed higher relative intensities of the PS I fluorescence band at around 735nm, suggesting the reduced PS II amount in the BS cells in this greening stage. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Construção e avaliação de célula de fluxo para estudo da tensão interfacial dinâmica da interface fluxo líquido - sólido por despolarização da fluorescência Development of a flow cell to study dynamic interfacial tension of solid-liquid flow by fluorescence depolarization

    Directory of Open Access Journals (Sweden)

    Martha T. P. O. Castro

    2005-03-01

    Full Text Available A simple low-cost flow cell was developed, built and optimized in order to observe dynamic interfacial tension of continuous flow systems. Distinct materials can be used in one of the cell walls in order to observe the intermolecular forces between the flowing liquid and the chemical constitution of the walls. The fluorescence depolarization was evaluated using Rhodamine B as fluorescent probe seeded in ethylene glycol. The effects of the positioning angles on the data acquired across the cell are reported. The reproducibility of the data was evaluated with a spectrometer assembled in-house and the relative standard deviation was below 3%.

  7. Speciation of AsIII and AsV in fruit juices by dispersive liquid–liquid microextraction and hydride generation-atomic fluorescence spectrometry

    Science.gov (United States)

    A new procedure was developed to speciate and quantify As(III) and As(V) in fruit juices. At pH 3.0, As(III) and ammonium pyrrolidine dithiocarbamate (APDC) formed a complex, which was extracted into carbon tetrachloride by dispersive liquid–liquid microextraction (DLLME) and subsequently quantified...

  8. Physical Penetration Testing: A Whole New Story in Penetration Testing

    OpenAIRE

    2011-01-01

    Physical penetration testing plays an important role in assuring a company that the security policies are properly enforced and that the security awareness of the employees is on the appropriate level. In physical penetration tests the tester physically enters restricted locations and directly interacts with the employees to convince them to break a policy or provide credentials. The physical access and the direct interaction with the employees complicate the execution of the tests and have e...

  9. Effect of realgar on extracellular amino acid neurotransmitters in hippocampal CA1 region determined by online microdialysis–dansyl chloride derivatization–high-performance liquid chromatography and fluorescence detection.

    Science.gov (United States)

    Huo, Taoguang; Zhang, Yinghua; Li, Weikai; Yang, Huilei; Jiang, Hong; Sun, Guifan

    2014-09-01

    An online microdialysis (MD)–dansyl chloride (Dns) derivatization–high-performance liquid chromatography (HPLC) and fluorescence detection (FD) system was developed for simultaneous determination of eight extracellular amino acid neurotransmitters in hippocampus. The MD probe was implanted in hippocampal CA1 region. Dialysate and Dns were online mixed and derivatized. The derivatives were separated on an ODS column and detected by FD. The developed online system showed good linearity, precision, accuracy and recovery. This online MD-HPLC system was applied to monitor amino acid neurotransmitters levels in rats exposed to realgar (0.3, 0.9 and 2.7 g/kg body weight). The result shows that glutamate concentrations were significantly increased (pHPLC–FD system provides a new experimental method for studying the effect of toxic Chinese medicines on amino acid neurotransmitters.

  10. Penetration through the Skin Barrier

    DEFF Research Database (Denmark)

    Nielsen, Jesper Bo; Benfeldt, Eva; Holmgaard, Rikke

    2016-01-01

    . During recent decades, the latter has received increased attention as a route for intentionally delivering drugs to patients. This has stimulated research in methods for sampling, measuring and predicting percutaneous penetration. Previous chapters have described how different endogenous, genetic...... and exogenous factors may affect barrier characteristics. The present chapter introduces the theory for barrier penetration (Fick's law), and describes and discusses different methods for measuring the kinetics of percutaneous penetration of chemicals, including in vitro methods (static and flow......-through diffusion cells) as well as in vivo methods (microdialysis and microperfusion). Then follows a discussion with examples of how different characteristics of the skin (age, site and integrity) and of the penetrants (size, solubility, ionization, logPow and vehicles) affect the kinetics of percutaneous...

  11. Differential coulometric oxidation following post column-switching high pressure liquid chromatography for fluorescence measurement of unmetabolized folic acid in human plasma.

    Science.gov (United States)

    Bailey, Steven W; Ayling, June E

    2013-11-08

    Although many countries have fortified their grain supplies with folic acid (FA) to decrease the incidence of neural tube defects, others have not due to concerns that this synthetic folate might have some adverse effects. Persistent unmetabolized FA has been found even in plasma from fasted subjects. To facilitate measurement of low levels of folic acid in human plasma, post-column coulometric oxidative cleavage was used to convert poorly fluorescent FA into a highly fluorescent compound determined to be 6-formyl-pterin. To minimize sample work-up and maximize recovery, column-switching HPLC transferred a window of eluate containing the FA from the first column (C8) onto a second column (phenyl-hexyl). The pH of two mobile phases were adjusted to be above and then below a pK of the FA α-carboxyl group, thus promoting separation from compounds coeluting from the C8-column. This permitted sample preparation using only a simple high recovery protein precipitation. Definitive identification of FA in human plasma was accomplished by duplicate injections of sample with the electrochemical voltage set above and below its half-potential. The LOD (S/N=3) was 0.10 nM. The intra- and inter-assay CV's were 2.3% and 5%, respectively. Comparison of these results with those obtained by HPLC/MS/MS with stable isotope internal standard showed a slope of 1.00 ± 0.019. This simple, sensitive, and repeatable assay facilitates a more thorough investigation of the response of various human populations to folic acid intake. Post-column differential coulometric electrochemistry can expand the variety of compounds amenable to fluorescence detection.

  12. Determination of Biotin in Infant, Pediatric, and Adult Nutritionals by High-Performance Liquid Chromatography and Fluorescence Detection: Single-Laboratory Validation, First Action 2016.11.

    Science.gov (United States)

    Lin, Qi; Ding, Yi; Poh, Fiona; Zhang, Chunyan; Pan, Shang-Jing; Schimpf, Karen J

    2017-01-01

    A reversed-phase HPLC method with postcolumn protein conjugation and fluorescence detection for the quantitative determination of biotin in infant, pediatric, and adult nutritionals was developed and evaluated in a single-laboratory validation (SLV). Sample of appropriate size is mixed with 2% metaphosphoric acid to precipitate out the protein. The filtrate is injected onto a C18 HPLC column in which biotin and riboflavin are separated with an appropriate mobile phase. The biotin, after eluting from the column, binds with the streptavidin fluorescein to become a fluorescent conjugate. The conjugate is then detected by fluorescence at λex = 495 nm and λem = 518 nm. A column switch is used in the method as an option to shorten the run time from 30 to 15 min, by eluting out riboflavin at a higher flow rate. In this SLV, a total of 19 AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals matrixes representing a range of infant, pediatric, and adult formulas were evaluated for their biotin content. The analytical range was 1.66-142 μg/100 g reconstituted final product. The repeatability and intermediate precision ranged from 0.5 to 3.0% RSDr and from 1.3 to 4.5% RSDiR, respectively. Recovery from spiked matrixes varied from 95 to 111%, and accuracy of quantification using Standard Reference Material 1849a ranged from 99 to 105%. The LOQ in reconstituted product was estimated to be 0.8 μg/100 g. The method was approved by the Expert Review Panel as First Action at the 2016 AOAC INTERNATIONAL Mid-Year Meeting.

  13. 高效液相色谱-荧光检测法测定人血浆中的匹伐他汀%Determination of Pitavastatin from Human Plasma Using High Performance Liquid Chromatography with Fluorescence Detection

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Pitavastatin belongs to the class of coenzyme A reductase inhibitors. Very few methods of assaying pitavastatin from human plasma are available in literature. An analytical method is presented for the determination of the drug from human plasma making use of the fluorescent property of the drug. The drug is extracted from plasma using ethyl acetate under neutral condition and then analyzed by reversed-phase high performance liquid chromatography (HPLC) with fluorescence detection (λEx 245 nm;λEm 420 nm). Analysis of pitavastatin was carried out on a C18 HPLC column using a gradient flow of mobile phase (0.01 mol/L monobasic potassium phosphate (pH 3.20)-acetonitrile, 63∶37, v/v). Fluorescein isothiocyanate was used as internal standard. The dynamic range of assay was 3 to 50 ng/mL. The intraday precision was less than 10% and accuracy ranged from 95.2% to 112.6% . The same for interday check was less than 12% and 92.8% to 105.1% , respectively. The drug was found to be stable under the assay conditions. The developed method is simple, precise, accurate, and stable. This indicates that it can be applied to routine analysis of this drug in human subjects where there are large numbers of samples without the need of specialized instruments like column switching.

  14. Characterization of newfound natural luminescent properties of melamine, and development and validation of a method of high performance liquid chromatography with fluorescence detection for its determination in kitchen plastic ware.

    Science.gov (United States)

    Finete, Virginia de Lourdes Mendes; Gouvêa, Marcos Martins; Marques, Flávia Ferreira de Carvalho; Netto, Annibal Duarte Pereira

    2014-06-01

    Experimental studies of the natural photoluminescence of melamine in aqueous solutions showed that its fluorescence intensity (at 250/365 nm) was appropriated for analytical purposes. The exploitation of such melamine property provided the basis of development of a new, simple, precise and accurate method based on high performance liquid chromatography with fluorescence detection (HPLC-Fluo) to determine melamine in kitchen plastic ware following aqueous extraction using a microwave oven. Optimization of analytical parameters such as solvent composition, pH and extraction conditions led to limits of detection and quantification of melamine of 0.0081 and 0.027 μg mL(-1), respectively, with a linear range up to 10 μg mL(-1). Sample extracts fortified with melamine at three concentration levels produced an average recovery of 98±6%, which was in agreement with the results achieved with a reference HPLC-UV method. Different samples of kitchen plastic ware analyzed by the developed and optimized method showed melamine concentrations in the aqueous extract up to 17 µg mL(-1), which corresponded to 86.0 mg kg(-1) in these utensils. The results obtained indicate that the use of kitchen plastic ware made of melamine can contaminate food with this compound after heating in a microwave oven.

  15. Cement penetration after patella venting.

    Science.gov (United States)

    Jones, Christopher W; Lam, Li-On; Butler, Adam; Wood, David J; Walsh, William R

    2009-01-01

    There is a high rate of patellofemoral complications following total knee arthroplasty. Optimization of the cement-bone interface by venting and suction of the tibial plateau has been shown to improve cement penetration. Our study was designed to investigate if venting the patella prior to cementing improved cement penetration. Ten paired cadaver patellae were allocated prior to resurfacing to be vented or non-vented. Bone mineral density (BMD) was measured by DEXA scanning. In vented specimens, a 1.6 mm Kirschner wire was used to breach the anterior cortex at the center. Specimens were resurfaced with standard Profix instrumentation and Versabond bone cement (Smith and Nephew PLC, UK). Cement penetration was assessed from Faxitron and sectioned images by a digital image software package (ImageJ V1.38, NIH, USA). Wilcoxon rank sum test was used to assess the difference in cement penetration between groups. The relationship between BMD and cement penetration was analyzed by Pearson correlation coefficient. There was a strong negative correlation between peak BMD and cement penetration when analyzed independent of experimental grouping (r(2)=-0.812, p=0.004). Wilcoxon rank sum testing demonstrated no significant difference (rank sum statistic W=27, p=0.579) in cement penetration between vented (10.53%+/-4.66; mean+/-std dev) and non-vented patellae (11.51%+/-6.23; mean+/-std dev). Venting the patella using a Kirschner wire does not have a significant effect on the amount of cement penetration achieved in vitro using Profix instrumentation and Versabond cement.

  16. Is Color Experience Cognitively Penetrable?

    Science.gov (United States)

    Brogaard, Berit; Gatzia, Dimitria E

    2017-01-01

    Is color experience cognitively penetrable? Some philosophers have recently argued that it is. In this paper, we take issue with the claim that color experience is cognitively penetrable. We argue that the notion of cognitive penetration that has recently dominated the literature is flawed since it fails to distinguish between the modulation of perceptual content by non-perceptual principles and genuine cognitive penetration. We use this distinction to show that studies suggesting that color experience can be modulated by factors of the cognitive system do not establish that color experience is cognitively penetrable. Additionally, we argue that even if color experience turns out to be modulated by color-related beliefs and knowledge beyond non-perceptual principles, it does not follow that color experience is cognitively penetrable since the experiences of determinate hues involve post-perceptual processes. We conclude with a brief discussion of the implications that these ideas may have on debates in philosophy. Copyright © 2016 Cognitive Science Society, Inc.

  17. Oligosaccharide mapping of heparinase I-treated heparins by hydrophilic interaction liquid chromatography separation and online fluorescence detection and electrospray ionization-mass spectrometry characterization.

    Science.gov (United States)

    Galeotti, Fabio; Volpi, Nicola

    2016-05-06

    Oligosaccharide mapping based on enzyme cleavage provides a useful molecular fingerprint of the heparin structure revealing detailed structural information regarding its sequence and the content of part of the ATIII-binding region. This approach is performed by strong-anion exchange (SAX)-HPLC separation which is incompatible with MS requiring purification of oligosaccharides for their conclusive identification. We report a novel oligosaccharide mapping strategy based on the HILIC separation of the main heparin disaccharides/oligosaccharides released by heparinase I, fluorotagged with 2-aminoacridone and on-line detected by a fluorescence detector and characterized by ESI-MS. The application of a polar solvent having a high pH with acetonitrile avoided desulfation enabling a simple and accurate structural oligosaccharide assignment. Oligosaccharide mapping, or merely complete disaccharide composition, may be performed on nanogram-scale by the fluorescence detector vs micrograms useful for classical SAX-HPLC. Additionally, only widely commercially available heparin lyase I is necessary, without the use of expensive heparinases II and III. Contrary to SAX-HPLC, this novel HILIC approach is able to separate and identify the saturated trisulfated disaccharide belonging to the non-reducing end of heparin chains. Finally, the content of 3-O-sulfo groups of the ATIII-binding region is determined.

  18. Sorptive extraction using polydimethylsiloxane/metal-organic framework coated stir bars coupled with high performance liquid chromatography-fluorescence detection for the determination of polycyclic aromatic hydrocarbons in environmental water samples.

    Science.gov (United States)

    Hu, Cong; He, Man; Chen, Beibei; Zhong, Cheng; Hu, Bin

    2014-08-22

    In this work, metal-organic frameworks (MOFs, Al-MIL-53-NH₂) were synthesized via the hydrothermal method, and novel polydimethylsiloxane/metal-organic framework (PDMS/MOFs, PDMS/Al-MIL-53-NH₂)-coated stir bars were prepared by the sol-gel technique. The preparation reproducibility of the PDMS/MOFs-coated stir bar was good, with relative standard deviations (RSDs) ranging from 4.8% to 14.9% (n=7) within one batch and from 6.2% to 16.9% (n=6) among different batches. Based on this fact, a new method of PDMS/MOFs-coated stir bar sorptive extraction (SBSE) and ultrasonic-assisted liquid desorption (UALD) coupled with high performance liquid chromatography-fluorescence detection (HPLC-FLD) was developed for the determination of polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. To obtain the best extraction performance for PAHs, several parameters affecting SBSE, such as extraction time, stirring rate, and extraction temperature, were investigated. Under optimal experimental conditions, wide linear ranges and good RSDs (n=7) were obtained. With enrichment factors (EFs) of 16.1- to 88.9-fold (theoretical EF, 142-fold), the limits of detection (LODs, S/N=3) of the developed method for the target PAHs were found to be in the range of 0.05-2.94 ng/L. The developed method was successfully applied to the analysis of PAHs in Yangtze River and East Lake water samples.

  19. Determinação de 3,4-metilenodioximetanfetamina (MDMA em comprimidos de Ecstasy por cromatografia líquida de alta eficiência com detecção por fluorescência (CLAE-DF Determination of 3,4-methylenedioxymethamphetamine (MDMA in Ecstasy tablets by high performance liquid chromatography with fluorescence detection (HPLC-FD

    Directory of Open Access Journals (Sweden)

    José Luiz da Costa

    2009-01-01

    Full Text Available This paper describes the development and validation of simple and selective analytical method for determination of 3.4-methylenedioxymethamphetamine (MDMA in Ecstasy tablets, using high performance liquid chromatography with fluorescence detection. Analysis was performed in a reversed phase column (LiChrospher 100 C18, 150 x 4.6 mm, 5 µm, isocratic elution with phosphate buffer 25 mmol/L pH 3.0 and acetonitrile (95:5, v/v. The method presents adequate linearity, selectivity, precision and accuracy. MDMA concentration in analyzed tablets showed a remarkable variability (from 8.5 to 59.5 mg/tablet although the tablet weights were uniform, indicating poor manufacturing control thus imposing additional health risks to the users.

  20. Penetration of urea-formaldehyde adhesives in wood tissue, part I: Radial penetration of UF adhesives into beech

    Directory of Open Access Journals (Sweden)

    Gavrilović-Grmuša Ivana

    2008-01-01

    Full Text Available Adhesive penetration plays an important role in wood adhesion, since wood is a porous material. The degree of penetration mostly depends on the wood factors, resin type and formulation and processing parameters. Tangentially cut 5 mm thick beech wood (Fagus moesiaca plies, 100 mm long (parallel to grain and 30 mm wide, were prepared for this study. The urea-formaldehyde (UF adhesive was applied to the surface of one ply. Two plies were assembled into sample so that the grains of two plies were parallel. Samples were pressed in a hydraulic press at 120°C and 0,7 MPa for 15 min. Microtome test-specimens were cut of each sample. 20 μm thick microtomes were cut by sliding microtome apparatus, exposing a bondline with a cross-sectional surface. The lack of more exhausting research on the penetration of urea-formaldehyde adhesives in wood is evident. Since ureaformaldehyde (UF glue resins were the most important type of adhesives in the wood industry in the last 60 years (Dunky, 2000, the objective of this research was microscopic detection of UF adhesive penetration in wood tissue. Four types of UF resins with different levels of polycondensation were used in this research. Safranin was added in resins, since epi-fluorescence microscope was used in this research for measuring the adhesive penetration.

  1. Determination of l-arginine and NG, NG - and NG, NG' -dimethyl-L-arginine in plasma by liquid chromatography as AccQ-Fluor fluorescent derivatives.

    Science.gov (United States)

    Heresztyn, Tamila; Worthley, Matthew I; Horowitz, John D

    2004-06-15

    A new HPLC assay for the detection of L-arginine, NG, NG-dimethyl-L-arginine (ADMA) and NG, NG' -dimethyl-L-arginine (SDMA) in plasma using the derivatisation reagent AccQ-Fluor (6-aminoquinolyl-N-hydroxysuccinimidyl carbamate) is described. The fluorescent derivatives produced are extremely stable enabling routine processing of large numbers of samples. Arginine and its metabolites are extracted from plasma on strong cation exchange (SCX) cartridges with NG-monomethyl-L-arginine (NMMA) as internal standard, derivatised and separated on a C18 column with acetonitrile in 0.1M sodium acetate buffer pH 6. Separation of the stereoisomers ADMA and SDMA was excellent and improvements to the solid phase extraction (SPE) procedure enabled good recovery (>80%) of arginine, ADMA and SDMA. The utility of the method is exemplified by comparison of plasma concentrations of ADMA, SDMA and arginine in healthy volunteers and diabetic/ischaemic patients.

  2. An investigation of penetrant techniques for detection of machining-induced surface-breaking cracks on monolithic ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Forster, G.A.; Ellingson, W.A.

    1996-02-01

    The purpose of this effort was to evaluate penetrant methods for their ability to detect surface-breaking cracks in monolithic ceramic materials with an emphasis on detection of cracks generated by machining. There are two basic penetrant types, visible and fluorescent. The visible penetrant method is usually augmented by powder developers and cracks detected can be seen in visible light. Cracks detected by fluorescent penetrant are visible only under ultraviolet light used with or without a developer. The developer is basically a powder that wicks up penetrant from a crack to make it more observable. Although fluorescent penetrants were recommended in the literature survey conducted early in this effort, visible penetrants and two non-standard techniques, a capillary gaseous diffusion method under development at the institute of Chemical Physics in Moscow, and the {open_quotes}statiflux{close_quotes} method which involves use of electrically charged particles, were also investigated. SiAlON ring specimens (1 in. diameter, 3/4 in. wide) which had been subjected to different thermal-shock cycles were used for these tests. The capillary gaseous diffusion method is based on ammonia; the detector is a specially impregnated paper much like litmus paper. As expected, visible dye penetrants offered no detection sensitivity for tight, surface-breaking cracks in ceramics. Although the non-standard statiflux method showed promise on high-crack-density specimens, it was ineffective on limited-crack-density specimens. The fluorescent penetrant method was superior for surface-breaking crack detection, but successful application of this procedure depends greatly on the skill of the user. Two presently available high-sensitivity fluorescent penetrants were then evaluated for detection of microcracks on Si{sub 3}N{sub 4} and SiC from different suppliers. Although 50X optical magnification may be sufficient for many applications, 200X magnification provides excellent delectability.

  3. Quantification of Temozolomide in Nonhuman Primate Fluids by Isocratic Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry to Study Brain Tissue Penetration Following Intranasal or Intravenous Delivery

    Directory of Open Access Journals (Sweden)

    Cody J. Peer

    2016-02-01

    Full Text Available A sensitive and selective ultra-high performance liquid chromatography-tandem mass spectrometric method was developed for the quantification of temozolomide (TMZ in nonhuman primate (NHP plasma, cerebrospinal fluid (CSF, and brain extracellular fluid (ECF following microdialysis. Ethyl acetate was used to extract the plasma and CSF samples, using theophylline as the internal standard (IS. ECF samples were diluted with acetonitrile prior to analysis. TMZ was separated on a Waters UPLC® BEH C18 column with an isocratic mobile phase of ammonium acetate (10 mM-0.1% formic acid/acetonitrile (30:70, v/v in a positive-ion multiple reaction monitoring mode (m/z 195.5→137.6 for TMZ; m/z 181.5→124.2 for IS. The retention time of TMZ and theophylline was 0.45 min with a total run time of 2.5 min. The method was validated over the range from 5–2000 ng/mL in NHP plasma, CSF, and ECF with respect to linearity, accuracy, precision, selectivity, and stability. This method was successfully applied toward the measurement of pharmacokinetic samples following various routes of drug administration.

  4. Evaluation of nicotinamide microemulsion on the skin penetration enhancement.

    Science.gov (United States)

    Boonme, Prapaporn; Boonthongchuay, Chalida; Wongpoowarak, Wibul; Amnuaikit, Thanaporn

    2016-01-01

    This study purposed to evaluate a microemulsion containing nicotinamide for its characteristics, stability, and skin penetration and retention comparing with a solution of nicotinamide in 2:1 mixture of water and isopropyl alcohol (IPA). The microemulsion system was composed of 1:1 mixture of Span80 and Tween80 as a surfactant mixture, isopropyl palmitate (IPP) as an oil phase, and 2:1 mixture of water and IPA as an aqueous phase. Nicotinamide microemulsion was prepared by dissolving the active in the aqueous phase before simply mixing with the other components. It was determined for its characteristics and stability under various conditions. The skin penetration and retention studies of nicotinamide microemulsion and solution were performed by modified Franz diffusion cells, using newborn pig skin as the membrane. The results showed that nicotinamide microemulsion could be obtained as clear yellowish liquid, was water-in-oil (w/o) type, possessed Newtonian flow, and exhibited physicochemical stability when kept at 4 °C and room temperature (≈30 ± 2 °C) during 3 months. From the skin penetration data, the microemulsion could enhance the skin penetration of nicotinamide comparing with the solution. Additionally, nicotinamide microemulsion could provide much higher amount of skin retention than that of skin penetration, resulting in suitability for a cosmeceutical product.

  5. Quantitative profiling of 4'-geranyloxyferulic acid and its conjugate with l-nitroarginine methyl ester in mononuclear cells by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Taddeo, Vito Alessandro; Genovese, Salvatore; Carlucci, Giuseppe; Ferrone, Vincenzo; Patruno, Antonia; Ferrone, Alessio; de Medina, Philippe; Fiorito, Serena; Epifano, Francesco

    2017-01-30

    Oxyprenylated natural products were shown to exert in vitro and in vivo remarkable anti-cancer and anti-inflammatory effects. This paper describes a rapid, selective, and sensitive HPLC method with fluorescence detection for determination of 4'-geranyloxyferulic acid (GOFA) and its conjugate with l-nitroarginine methyl ester (GOFA-L-NAME) in mononuclear cells. Analytes were extracted from cells using methanol and eluted on a GraceSmart RP18 analytical column (250×4.6mm i.d., 5μm particle size) kept at 25°C. A mixture of formic acid 1% in water (A) and methanol (B) were used as mobile phase, at a flow-rate of 1.2mL/min in gradient elution. A fluorescence detector (excitation/emission wavelength of 319/398nm for GOFA and GOFA-L-NAME), was used for the two analytes. Calibration curves of GOFA and GOFA-L-NAME were linear over the concentration range of 1.0-50μg/mL, with correlation coefficients (r(2))≥0.9995. Intra- and inter-assay precision do not exceed 6.8%. The accuracy was from 94% to 105% for quality control samples (2.0, 25.0 and 40μg/mL). The mean (RSD%) extraction recoveries (n=5) for GOFA and GOFA-L-NAME from spiked cells at 2.0, 25.0 and 40.0μg/mL were 92.4±1.5%, 94.7±0.9% and 93.8±1.1%, for GOFA and 95.3±1.2%, 94.8±1.0% and 93.9±1.3%, for GOFA-L-NAME. The limits of detection and quantification were 0.3μg/mL and 1.0μg/mL for GOFA and GOFA-L-NAME. This method was successfully applied to measure GOFA and GOFA-L-NAME concentrations in a mononuclear cells.

  6. Case Report: Penetrating Cardiac Injury

    Directory of Open Access Journals (Sweden)

    Adem Grbolar

    2013-10-01

    Full Text Available Summary: Penetrating cardiac injurys caused by gunshots and penetrating tools have high mortality rates. The way of injury, how the cardiac area is effected and the presence of cardiac tamponadecauses mortality in different rates. However the better treatment quality of hospitals, increasingoperative techniques, and internel care unit quality has not been change during the years. Searching the literature, we want to present a 42 years old male patient whowas injured by knife and had a 1 cm skin wound on chest with cardiac tamponade. After sternotomy a 7 cm laseration was observed in heart. Cardioraphy was performed.

  7. Probing solute-solvent interaction in 1-ethyl-3-methylimidazolium-based room temperature ionic liquids: A time-resolved fluorescence anisotropy study.

    Science.gov (United States)

    Das, Sudhir Kumar; Sarkar, Moloy

    2014-03-01

    Rotational diffusion of two organic solutes, coumarin153 (C153) and 4-aminophthalimide (AP) has been investigated in four ionic liquids (ILs), viz. 1-ethyl-3-methylimidazolium trifluoroacetate (EMIMTFA), 1-ethyl-3-methylimidazolium ethylsulfate (EMIMESU), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMTFB) and 1-ethyl-3-methylimidazolium tetracyanoborate (EMIMTCB), as a function of temperature. Between the two probes, AP can act as hydrogen-bond-donor to the solvents having hydrogen bond acceptor ability. The results indicate that the rotational dynamics of C153 is mainly governed by the viscosity of the medium. On the other hand, the rotational motion of AP is found to be significantly hindered in the ILs depending on the nature of anions of the ILs. Rotational coupling constant values for AP in the ILs follow the order TFA > ESU > TCB > TFB. The slower rotational motion of AP in these ILs has been attributed to the specific hydrogen bonding interaction between AP and anions of ILs.

  8. Development and validation of a method to determine thiabendazole and o-phenylphenol in wastewater using micellar liquid chromatography-fluorescence detection.

    Science.gov (United States)

    Peris-Vicente, Juan; Roca-Genovés, Pasqual; Tayeb-Cherif, Khaled; Esteve-Romero, Josep

    2016-10-01

    A micellar liquid chromatographic method to determine thiabendazole (TBZ) and o-phenylphenol in wastewater is described here. The sample was directly injected without any additional treatment other filtration. The pesticides were resolved in phenylphenol, respectively. The method was validated following the directives of the Validation and Peer Review of U.S. Environmental Protection Agency Chemical Methods of Analysis guidelines in terms of selectivity, quantitation range (0.01-0.02 to 2 mg/L), detection limit (0.005-0.008 mg/L), trueness (92.1-104.2%), precision (phenylphenol in wastewater samples from citrus packing plants, agricultural gutters, urban sewage, as well as in influent and effluent wastewater treatment plants.

  9. The influence of grain boundary structure on the penetration of gallium into aluminum grain boundaries

    Science.gov (United States)

    Hugo, Richard Charles

    1998-12-01

    Liquid Metal Embrittlement is a form of environmental embrittlement that dramatically reduces the fracture toughness of many metals and alloys. It occurs when surfaces of certain solid metals are wet by certain liquid metals. The Al-Ga system provides a remarkable example of intergranular attack. The Al-Ga equilibrium phase diagram reveals no intermetallic compounds and very limited mutual solubilities, which implies that interactions between Al and Ga should be minimal. Yet when liquid Ga wets the surface of an unstressed Al specimen, the Ga will penetrate the Al grain boundaries, replacing each boundary with a liquid layer. The driving force is generally considered to be the reduction in energy when a grain boundary is replaced by two Ga-Al interfaces. Once an Al sample has been penetrated by Ga, it fails at almost no load. In this dissertation, in-situ Transmission Electron Microscope (TEM) studies are presented that elucidate the physical nature of the Ga penetration front. Although many of the TEM specimens were bicrystals, all but one of the grain boundaries studied were "general" boundaries; that is, they were low symmetry boundaries with high-index rotation axes, and no low-index planes common to both grains. Since the atomic structure of these grain boundaries cannot be resolved experimentally, atomistic computer models were constructed to assist in interpreting TEM results. TEM observations indicated that the penetration front is a line defect, possessing a stress field that interacts with lattice dislocations. The penetration front was also observed to interact with structural variations within the grain boundary. Interactions with lattice dislocations were used to estimate the penetration front thickness. Penetration speeds were not found to be determined by grain boundary energy or grain boundary excess volume. Penetration speeds were, however, found to depend qualitatively on the presence of penetration barriers in the grain boundary.

  10. Bioanalysis of bevacizumab and infliximab by high-temperature reversed-phase liquid chromatography with fluorescence detection after immunoaffinity magnetic purification.

    Science.gov (United States)

    Todoroki, Kenichiro; Nakano, Tatsuki; Eda, Yasuhiro; Ohyama, Kaname; Hayashi, Hideki; Tsuji, Daiki; Min, Jun Zhe; Inoue, Koichi; Iwamoto, Naoki; Kawakami, Atsushi; Ueki, Yukitaka; Itoh, Kunihiko; Toyo'oka, Toshimasa

    2016-04-15

    This study presents two simple and rapid methods for the quantification of therapeutic mAbs based on LC. Two mAbs (bevacizumab and infliximab) in plasma samples were purified using magnetic beads immobilized with a commercially-available idiotype antibody for each mAb. Purified mAbs were separated with HT-RPLC and detected with their native fluorescence. Using immunoaffinity beads, each mAb was selectively purified and detected as a single peak in the chromatogram. The HT-RPLC achieved good separation for the mAbs with sharp peaks within 20 min. The calibration curves of the two mAbs ranged from 1 to 20 μg mL(-1) (bevacizumab) and 1-10 μg mL(-1) (infliximab), and they had strong correlation coefficients (r(2) > 0.998). The LOD of bevacizumab and infliximab was 0.07 and 0.15 μg mL(-1), and the LLOQ of bevacizumab and infliximab was 0.12 and 0.25 μg mL(-1), respectively. Thus, the sensitivities were sufficient for clinical analysis. Immunoaffinity purification with HT-RPLC produced a selective and accurate bioanalysis without an LC-MS/MS instrument. Both methods could become general-purpose analytical methods and complement the results obtained with conventional LBA.

  11. Determination of metoprolol and its two metabolites in human plasma and urine by high performance liquid chromatography with fluorescence detection and its application in pharmacokinetics.

    Science.gov (United States)

    Xu, Tao; Bao, Shihui; Geng, Peiwu; Luo, Jun; Yu, Lei; Pan, Peipei; Chen, Yi; Hu, Guoxin

    2013-10-15

    A simple, specific and sensitive HPLC method has been developed for the determination of metoprolol and its two metabolites in human plasma and urine. Separation of metoprolol, α-hydroxymetoprolol, O-desmethylmetoprolol and esmolol (internal standard) was achieved on an Agilent XDB-C18 column (150mm×4.6mm, 5μm) using fluorescence detection with Ex 216nm and Em 312nm. The mobile phase consisted of ACN-H2O-0.1%TFA. The analysis was performed in less than 16min with a flow rate of 0.8mL/min. The assay was linear over the concentration range of 5-600ng/mL and 2.5-300ng/mL for metoprolol and its metabolites, respectively. The LOQ were 5.0 and 2.5ng/mL for plasma and urine, respectively. Good precision and accuracy for metoprolol and its two metabolites were obtained. The extraction recoveries were found to be more than 86.91% both in plasma and urine. At the same time, the method was successfully applied to nine healthy volunteers who had been given an oral tablet of 100mg metoprolol.

  12. Comparative biotransformation and disposition studies of nabumetone in humans and minipigs using high-performance liquid chromatography with ultraviolet, fluorescence and mass spectrometric detection.

    Science.gov (United States)

    Nobilis, M; Kopecký, J; Kvetina, J; Svoboda, Z; Pour, M; Kunes, J; Holcapek, M; Kolárová, L

    2003-08-08

    The disposition of the non-steroidal anti-inflammatory drug (NSAID) nabumetone after a single oral dose administration of nabumetone tablets to humans and minipigs was investigated. Nabumetone is a prodrug, which is metabolized in the organism to the principal pharmacodynamically active metabolite -- 6-methoxy-2-naphthylacetic acid (6-MNA), and some other minor metabolites (carbonyl group reduction products, O-desmethylation products and their conjugates with glucuronic and sulphuric acids). Standards of the above-mentioned metabolites were prepared using simple synthetic procedures and their structures were confirmed by NMR and mass spectrometry. A simple HPLC method for the simultaneous determination of nabumetone, 6-MNA and the other metabolites was developed, validated and used for xenobiochemical and pharmacokinetic studies in humans and minipigs and for distribution studies in minipigs. Naproxen was chosen as the internal standard (I.S.), both UV (for higher concentrations) and fluorescence detection (for very low concentrations) were used. The identity of the nabumetone metabolites in biological samples was confirmed using HPLC-MS experiments. Pharmacokinetics of nabumetone, 6-MNA and 6-HNA (6-hydroxy-2-naphthylacetic acid) in human and minipig plasma was evaluated and compared. The concentration levels of nabumetone metabolites in urine, bile and synovial fluid were also evaluated.

  13. 基于离子液体的分散液液微萃取-柱前荧光衍生高效液相色谱法测定水样中8种磺胺类药物%Combination of dispersive liquid-liquid microextraction based on ionic liquid and pre-column fluorescence derivatization-high performance liquid chromatography for determination of eight sulfonamides in water samples

    Institute of Scientific and Technical Information of China (English)

    吴翠琴; 雷金妹; 李韵灵; 王韵靓; 陈迪云; 龚剑

    2014-01-01

    建立了一种基于离子液体的分散液液微萃取技术结合柱前荧光衍生高效液相色谱( IL-DLLME-HPLC-FL)对8种磺胺类药物进行检测的方法,并成功应用于实际环境水样的分析。实验考察了萃取参数对磺胺萃取效率的影响及衍生产物的稳定性。最佳实验条件:以40μL[C6MIM][PF6]为萃取剂,0.1 mL 丙酮为分散剂,对 pH=4且不含 NaCl的水溶液进行不超声的分散液液微萃取,并衍生化反应6 h。结果表明:在最佳实验条件下,该法在0.2~10μg/L和10~500μg/L两个浓度范围内线性良好,线性相关系数 r ≥0.9989;检出限为0.08~0.5μg/L( S/N=3)。对实验室自来水、湖水、珠江水、池塘水分别加标5、50、200μg/L的回收率为87.2%~101.4%,相对标准偏差为3.7%~6.2%。该法环保、简便,可用于测定实际水样中磺胺类药物。%Dispersive liquid-liquid microextraction based on ionic liquid coupled with high per-formance liquid chromatography ( HPLC ) and pre-column fluorescent derivatization method ( IL-DLLME-HPLC-FL)was developed for the determination of eight sulfonamides( SAs). The influence of IL-DLLME parameters on extraction efficiency and the stability of derivatives of the eight SAs were investigated. The optimized experimental conditions were as follows:40 μL [C6MIM][PF6]as extraction solvent,0. 1 mL acetone as dispersion solvents;water sample with 0% NaCl( pH 4)was extracted by dispersive liquid-liquid microextraction without ultra-sonic-assistance and then derivatized for 6 h. Under the optimized experimental conditions,the results indicated that the eight sulfanilamides showed good linearities when their mass concen-trations were in 0. 2-10 μg/L and 10-500 μg/L,and the linear correlation coefficients were no less than 0. 998 9. The detection limits ranged from 0. 08 μg/L to 0. 5 μg/L( S/N=3). The pro-posed method was applied to the analysis of four water samples from

  14. Novel cell-penetrating peptide targeting mitochondria.

    Science.gov (United States)

    Cerrato, Carmine Pasquale; Pirisinu, Marco; Vlachos, Efstathios Nikolaos; Langel, Ülo

    2015-11-01

    Cell-penetrating peptides (CPPs) are short, nontoxic peptides with cationic and/or amphipathic properties able to cross the cellular membrane. CPPs are used for the delivery of a wide variety of cargoes, such as proteins, oligonucleotides, and therapeutic molecules. The aim of the present study was to synthesize unusually small novel CPPs targeting mitochondria based on the Szeto-Schiller peptide (SS-31) to influence intramitochondrial processes and to improve the biologic effects. All the peptides used were synthesized manually using 9-fluorenylmethyloxycarbonyl chemistry. In the first part of the study, HeLa 705, U87, and bEnd.3 cells were used as in vitro delivery model. Cells were incubated for 24 h at 37°C and 5% CO2 with different concentrations of our peptides. Cell proliferation assay was performed to evaluate cell viability. Biologic effects such as mitochondrial membrane potential and antioxidant activity were evaluated. H2O2 was used as positive control. Uptake studies were performed using peptides conjugated with 5(6)-carboxyfluorescein (FAM). Fluorescent microscopy was used to determine presence and localization of peptides into the cells. Isolated mitochondria from pretreated cells and mitochondria treated after isolation were used to confirm the targeting ability of the peptide. Uptake of FAM alone was used as negative control. Microscopy studies confirmed the ability of peptides to penetrate cell. Localization analysis showed increase in uptake by 35% compared with SS-31. Mitochondrial CPP 1 (mtCPP-1) had no effect on mitochondrial membrane potential and prevented reactive oxygen species formation in bEnd.3 cells by 2-fold compared with SS-31. No cytotoxicity was observed even at high concentration (100 µM). These data suggest that mtCPP-1 is a mitochondrial CPP and protect mitochondria from oxidative damage due to its own antioxidant activities. © FASEB.

  15. The Penetration of Shaped Charges

    Institute of Scientific and Technical Information of China (English)

    Wu Mingde

    1996-01-01

    @@ In order to get the best perforating effect, many facts have to be considered. Perforating job is often design by computer. A perforating engineer has to decide the perforating technology and procedure, the gun and charge system, the shot density and phasing, the penetration and hole size, etc.

  16. Simulation of laser penetration efficiency

    Science.gov (United States)

    Semak, V. V.; Miller, T. F.

    2013-09-01

    The results of numerical simulation of laser beam interaction with a hypothetical metallic material with properties similar to a steel alloy are reported. The numerical simulation was performed using a physical model that includes detailed consideration of surface evaporation, evaporative cooling of the surface and evaporation recoil induced melt ejection. The laser beam ‘penetration’ is considered in terms of melting through the sample or drilling through the sample due to both evaporation and recoil ejection of material. As a demonstration of the predictive capabilities of the model, the average velocity of penetration through a material with steel-like properties is numerically predicted for various laser interaction parameters such as, laser beam radius, laser pulse duration (including CW regime), laser pulse energy and pulse repetition. In particular, the average penetration velocities through a sample due to melting are compared for pulsed and CW lasers of the same power. For the sake of another demonstration of penetration simulation, the temporal dynamics of the position of melt front relative to the sample surface irradiated by a laser beam was computed for different laser pulse repetition rates and constant average laser power. An illustration of the penetration efficiency (W parameter) defined as the amount of energy per unit volume delivered into a target in order to achieve either melting of drilling through a target wall is shown in a wide range of laser pulse parameters covering regimes corresponding to domination of melting through and drilling through.

  17. Stylet penetration activities by aphids

    NARCIS (Netherlands)

    Tjallingii, W.F.

    1985-01-01

    The composition of stylet penetration behaviour in aphids and its possible role in food-plant selection is the subject of these studies. Evidence is presented that the labium is devoid of external chemoreceptors (Chapter 1). In addition to other morphological data (Wensler & Filshie, 1969; Wensler,

  18. Penetration Physics of Armor Glass

    Science.gov (United States)

    2009-11-30

    Penetration Response of Borosilicate Glass during Short Rod Impact”, Proc. 23rd Int. Symp. Ballistics, 2, 1251-1258, Graficas Couche, Madrid, Spain (2007...glass”, Proc. 23rd Int. Symp. Ballistics, 2, 1049-1056, Graficas Couche, Madrid, Spain (2007). 8D. R. Curran, “Comparison of Mesomechanical and

  19. Enhanced fluorescence sensitivity by coupling yttrium-analyte complexes and three-way fast high-performance liquid chromatography data modeling

    Energy Technology Data Exchange (ETDEWEB)

    Alcaraz, Mirta R.; Culzoni, María J., E-mail: mculzoni@fbcb.unl.edu.ar; Goicoechea, Héctor C., E-mail: hgoico@fbcb.unl.edu.ar

    2016-01-01

    The present study reports a sensitive chromatographic method for the analysis of seven fluoroquinolones (FQs) in environmental water samples, by coupling yttrium-analyte complex and three-way chromatographic data modeling. This method based on the use of HPLC-FSFD does not require complex or tedious sample treatments or enrichment processes before the analysis, due to the significant fluorescence increments of the analytes reached by the presence of Y{sup 3+}. Enhancement achieved for the FQs signals obtained after Y{sup 3+} addition reaches 103- to 1743-fold. Prediction results corresponding to the application of MCR-ALS to the validation set showed relative error of prediction (REP%) values below 10% in all cases. A recovery study that includes the simultaneous determination of the seven FQs in three different environmental aqueous matrices was conducted. The recovery studies assert the efficiency and the accuracy of the proposed method. The LOD values calculated are in the order of part per trillion (below 0.5 ng mL{sup −1} for all the FQs, except for enoxacin). It is noteworthy to mention that the method herein proposed, which does not include pre-concentration steps, allows reaching LOD values in the same order of magnitude than those achieved by more sophisticated methods based on SPE and UHPLC-MS/MS. - Highlights: • Highly sensitive method for the analysis of seven fluoroquinolones. • Coupling of yttrium-analyte complex and three-way modeling. • Complex or tedious sample treatments or enrichment processes are nor required. • Accuracy on the quantitation of fluoroquinolones in real water river samples.

  20. Determination of methylglyoxal in human blood plasma using fluorescence high performance liquid chromatography after derivatization with 1,2-diamino-4,5-methylenedioxybenzene.

    Science.gov (United States)

    Ogasawara, Yuki; Tanaka, Ryo; Koike, Shin; Horiuchi, Yasue; Miyashita, Mitsuhiro; Arai, Makoto

    2016-09-01

    Methylglyoxal (MG) is a highly reactive dicarbonyl compound that promotes the non-enzymatic glycation of proteins to yield irreversible advanced glycated end products, leading to the cross-linking or degradation of proteins. The physiological relevance of MG currently remains unclear because its metabolic behavior has not yet been elucidated in detail. Although several labeling methods that require a HPLC system have been developed and used to measure MG, a standard method to analyze the content of MG in biological samples has not been established. We herein present a practical method based on HPLC with fluorescence detection to measure low MG levels. MG concentrations were also measured in human blood plasma using the present method in order to demonstrate its utility. A calibration curve was produced using freshly purified MG at concentrations ranging between 0.05 and 1.0μM. The intra-day and inter-day relative standard diviations of the method were 2.55% and 4.03%, respectively. The limit of detection and limit of quantification were 60fmol and 200fmol, respectively for MG with a 10-μl injection volume of the derivatized sample solution. When the optimized method was applied to human plasma, the resulting concentrations of MG in the plasma of healthy subjects (n=23) ranged between 0.024 and 0.258μM (mean±SD=0.098±0.066). Thus, the method developed herein is simple, sensitive, and easy to operate for the measurement of MG in biological samples.

  1. Enantioseparation of N-derivatized amino acids by micro-liquid chromatography/laser induced fluorescence detection using quinidine-based monolithic columns.

    Science.gov (United States)

    Wu, Huihui; Wang, Qiqin; Ruan, Meng; Peng, Kun; Zhu, Peijie; Crommen, Jacques; Han, Hai; Jiang, Zhengjin

    2016-03-20

    A novel carbamoylated quinidine based monolith, namely poly(O-9-[2-(methacryloyloxy)-ethylcarbamoyl]-10,11-dihydroquinidine-co-ethylene dimethacrylate (poly(MQD-co-EDMA)), was prepared for the micro-LC enantioseparation of N-derivatized amino acids. The influence of the mobile phase composition, including the organic modifier proportion, the apparent pH and the buffer concentration, on the enantioresolution of N-derivatized amino acids was systematically investigated. Satisfactory column performance in terms of permeability, efficiency and reproducibility was obtained in most cases. The majority of the enantiomers of the tested N-protected amino acids, including 3,5-DNB, 3,5-DClB, FMOC, 3,5-DMB, p-NB, m-ClB, p-ClB and B derivatives, could be baseline separated on the poly(MQD-co-EDMA) monolithic column within 25min. A self-assembled laser induced fluorescence (LIF) detector was employed to improve sensitivity when analyzing 7-nitro-2,1,3-benzoxadiazole (NBD) derivatives of amino acids. Ten NBD-derivatized amino acids, including arginine and histidine whose enantioseparation on quinidine carbamate based CSPs has not been reported so far, were enantioresolved on the poly(MQD-co-EDMA) monolith column. It is worth noting that the d-enantiomers of NBD-derivatized amino acids eluted first, except in the case of glutamic acid. The LOD values obtained with the LIF detector were comparable to those reported using conventional LC-FL methods. The prepared poly(MQD-co-EDMA) monolithic column coupled with the LIF detector opens up interesting perspectives to the determination of trace D-amino acids in biological samples.

  2. Interlaboratory comparison of two AOAC liquid chromatographic fluorescence detection methods for paralytic shellfish toxin analysis through characterization of an oyster reference material.

    Science.gov (United States)

    Turner, Andrew D; Lewis, Adam M; Rourke, Wade A; Higman, Wendy A

    2014-01-01

    An interlaboratory ring trial was designed and conducted by the Centre for Environment, Fisheries, and Aquaculture Science to investigate a range of issues affecting the analysis of a candidate Pacific oyster paralytic shellfish toxin reference material. A total of 21 laboratories participated in the study and supplied results using one or more of three instrumental methods, specifically precolumn oxidation (Pre-COX) LC with fluorescence detection (FLD; AOAC Official Method 2005.06), postcolumn oxidation (PCOX) LC-FLD (AOAC Official Method 2011.02), and hydrophilic interaction LC/MS/MS. Each participant analyzed nine replicate samples of the oyster tissue in three separate batches of three samples over a period of time longer than 1 week. Results were reported in a standardized format, reporting both individual toxin concentrations and total sample toxicity. Data were assessed to determine the equivalency of the two AOAC LC methods and the LC/MS/MS method as well as an assessment of intrabatch and interbatch repeatability and interlaboratory reproducibility of each method. Differences among the results reported using the three methods were shown to be statistically significant, although visual comparisons showed an overlap between results generated by the majority of tests, the exception being the Pre-COX quantitation of N-hydroxylated toxins in post ion-exchange fractions. Intralaboratory repeatability and interlaboratory reproducibility were acceptable for most of the results, with the exception of results generated from fractions. The results provided good evidence for the acceptable performance of the PCOX method for the quantitation of C toxins. Overall the study showed the usefulness of interlaboratory analysis for the characterization of paralytic shellfish poisoning matrix reference materials, highlighting some issues that may need to be addressed with further method assessment at individual participant laboratories.

  3. Angiopep-2 and activatable cell penetrating peptide dual modified nanoparticles for enhanced tumor targeting and penetrating.

    Science.gov (United States)

    Mei, Ling; Zhang, Qianyu; Yang, Yuting; He, Qin; Gao, Huile

    2014-10-20

    Delivering chemotherapeutics by nanoparticles into tumor was influenced by at least two factors: specific targeting and highly efficient penetrating of the nanoparticles. In this study, two targeting ligands, angiopep-2 and activatable cell penetrating peptide (ACP), were functionalized onto nanoparticles for tumor targeting delivery. In this system, angiopep-2 is a ligand of low-density lipoprotein receptor-related protein-1 (LRP1) which was highly expressed on tumor cells, and the ACP was constructed by the conjugation of RRRRRRRR (R8) with EEEEEEEE through a matrix metalloproteinase-2 (MMP-2) sensitive linker, enabling the ACP with tumor microenvironment-responsive cell penetrating property. 4h incubation of ACP with MMP-2 leads to over 80% cleavage of ACP, demonstrating ACP indeed possessed MMP-2 responsive property. The constructed dual targeting nanoparticles (AnACNPs) were approximately 110 nm with a polydispersity index of 0.231. In vitro, ACP modification and angiopep-2 modification could both enhance the U-87 MG cell uptake because of the high expression of MMP-2 and LRP-1 on C6 cells. AnACNPs showed higher uptake level than the single ligand modified nanoparticles. The uptake of all particles was time- and concentration-dependent and endosomes were involved. In vivo, AnACNPs showed best tumor targeting efficiency. The distribution of AnACNPs in tumor was higher than all the other particles. After microvessel staining with anti-CD31 antibody, the fluorescent distribution demonstrated AnACNPs could distribute in the whole tumor with the highest intensity. In conclusion, a novel drug delivery system was developed for enhanced tumor dual targeting and elevated cell internalization.

  4. Rapid and sensitive determination of benzo[a]pyrene in black ginseng using fluorescence detector and high performance liquid chromatography-tandem mass spectrometry

    Science.gov (United States)

    Cho, Hyun-jeong; Kim, Hye-jin; Son, Byeong-cheol; Jo, Dong-keun; Cho, Byung-lim

    2013-05-01

    Black ginseng is produced by steaming a ginseng root followed by drying repeatedly 9 times during the process and it is changed to be black color, so it is known that a black ginseng has more contents of saponins than red ginseng. However a fake black ginseng which is produced to be black color at high temperature in a short period of time generate carcinogenic benzo[a]pyrene(BaP) through the process. In this year, maximum residue level(MRL) for BaP was established to 2 ug/kg in black ginseng and more sensitive method was developed to quantitatively analyze the BaP by high performance liquid chromatography (HPLC) coupling with florescence detector and tandem mass spectrometry (atmospheric pressure chemical ionization-MS/MS). Chromatographic separation was performed on a Supelcosil™ LC-PAH column (3 μm, 3 mm x 50 mm). Mobile phase A was water and mobile phase B was acetonitrile. BaP was exactly separated from other 15 polycyclic aromatic hydrocarbons (PAHs) which have been selected as priority pollutants by the US Environmental Protection Agency (EPA). Linearity of detection was in the range of 0.2~20 μg/kg and limit of detection (LOD) for BaP was lower than 0.1 μg/kg, limit of quantification (LOQ) was 0.2 μg/kg. The recovery of Bap was 92.54%+/-6.3% in black ginseng.

  5. Determination of ciprofloxacin in Jiaozhou Bay using molecularly imprinted solid-phase extraction followed by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Lian, Ziru; Wang, Jiangtao

    2016-10-15

    A high selective pre-treatment method for the cleanup and preconcentration of ciprofloxacin in natural seawater samples was developed based on molecularly imprinted solid-phase extraction (MISPE). The ciprofloxacin imprinted polymers were synthesized and the characteristics of obtained polymers were evaluated by scanning electron microscopy, Fourier transform infrared spectroscopy and binding experiments. The imprinted materials showed high adsorption ability for ciprofloxacin and were applied as special solid-phase extraction sorbents for selective separation of ciprofloxacin. An off-line MISPE procedure was optimized and the developed MISPE method allowed direct purification and enrichment of the ciprofloxacin from the aqueous samples prior to high-performance liquid chromatography analysis. The recoveries of spiked seawater on the MISPE cartridges ranged from 75.2 to 112.4% and the relative standard deviations were less than 4.46%. Five seawater samples from Jiaozhou Bay were analyzed and ciprofloxacin was detected in two samples with the concentrations of 0.24 and 0.38μgL(-1), respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. [Determination of netilmicin in rat plasma by reversed-phase high performance liquid chromatography with fluorescence detection and pre-column derivatization].

    Science.gov (United States)

    Chang, Xiaojuan; Peng, Jingdong; Liu, Shaopu; Liu, Limin; Dai, Yongkuang

    2009-11-01

    A new, simple and sensitive method based on pre-column derivatization by reversed-phase high performance liquid chromatography (HPLC) is described for the separation and quantification of netilmicin in plasma, using 9-fluorenylmethyl chloroformate (FMOC-Cl) as the derivatization reagent. Its pharmacokinetics is also presented. The derivatization modes and chromatographic conditions were optimized. The separation was performed on an Agilent ZORBAX Eclipse XDB-C8 column (150 mm x 4.6 mm, 5 microm) with a mixture of water-acetonitrile (15:85, v/v) as mobile phase and the flow rate was 1.0 mL/min. The excitation wavelength was 265 nm and the emission wavelength was 315 nm. The linear range was 0.045-8.88 mg/L and the correlation coefficient (r) was 0.9993. The limit of detection (LOD) (S/N = 3) was about 0.01 mg/L, and the limit of quantification was 0.03 mg/L (3LOD) for netilmicin. The relative standard deviation was less than 3% for intra-day assay (n = 5) and 3.5% for inter-day assay (n = 5) and the relative recovery was in the range of 96.62%-100.84% (n = 3). The plasma volume of 30 microL was sufficient for the determination of netilmicin. The method provides a reliable bioanalytical methodology to carry out netilmicin pharmacokinetics in rat plasma.

  7. Single-laboratory validation of a high-performance liquid chromatographic-diode array detector-fluorescence detector/mass spectrometric method for simultaneous determination of water-soluble vitamins in multivitamin dietary tablets.

    Science.gov (United States)

    Chen, Pei; Atkinson, Renata; Wolf, Wayne R

    2009-01-01

    The purpose of this study was to develop a single-laboratory validated (SLV) method using high-performance liquid chromatography with different detectors [diode array detector (DAD); fluorescence detector (FLD); and mass spectrometry (MS)] for determination of 7 B-complex vitamins (B1-thiamin, B2-riboflavin, B3-nicotinamide, B6-pyridoxine, B9-folic acid, pantothenic acid, and biotin) and vitamin C in multivitamin/multimineral dietary supplements. The method involves the use of a reversed-phase octadecylsilyl column (4 microm, 250 x 2.0 mm id) and a gradient mobile phase profile. Gradient elution was performed at a flow rate of 0.25 mL/min. After a 5 min isocratic elution at 100% A (0.1% formic acid in water), a linear gradient to 50% A and 50% B (0.1% formic acid in acetonitrile) at 15 min was employed. Detection was performed with a DAD as well as either an FLD or a triple-quadrupole MS detector in the multiple reaction monitoring mode. SLV was performed using Standard Reference Material (SRM) 3280 Multivitamin/Multimineral Tablets, being developed by the National Institute of Standards and Technology, with support by the Office of Dietary Supplements of the National Institutes of Health. Phosphate buffer (10 mM, pH 2.0) extracts of the NIST SRM 3280 were analyzed by the liquid chromatographic (LC)-DAD-FLDIMS method. Following extraction, the method does not require any sample cleanup/preconcentration steps except centrifugation and filtration.

  8. Probing the Interaction between a DNA Nucleotide (Adenosine-5'-Monophosphate Disodium) and Surface Active Ionic Liquids by Rotational Relaxation Measurement and Fluorescence Correlation Spectroscopy.

    Science.gov (United States)

    Roy, Arpita; Banerjee, Pavel; Dutta, Rupam; Kundu, Sangita; Sarkar, Nilmoni

    2016-10-02

    This article demonstrates the interaction of a deoxyribonucleic acid (DNA) nucleotide, adenosine-5'-monophosphate disodium (AMP) with a cationic surface active ionic liquid (SAIL) 1-dodecyl-3-methylimidazoium chloride (C12mimCl) and an anionic SAIL, 1-butyl-3-methylimidazolium n-octylsulfate ([C4mim][C8SO4]). Dynamic light scattering (DLS) measurements and 1H NMR (nuclear magnetic resonance) studies indicate that substantial interaction is taking place among the DNA nucleotide, AMP and the SAILs. Moreover, cryogenic transmission electron microscopy (cryo-TEM) suggests that SAILs containing micellar assemblies are transformed into larger micellar assemblies in presence of DNA nucleotide. Additionally, the rotational motion of two oppositely charged molecules, Rhodamine 6G perchlorate (R6G) and Fluorescein sodium salt (Fl-Na) have been monitored in these aggregates. The rotational motion of R6G and Fl-Na differs significantly between SAILs micelles, and SAILs-AMP containing larger micellar aggregates. The effect of negatively charged DNA nucleotide (AMP) addition into the cationic and anionic SAILs is more prominent for the cationic charged molecule R6G than that of anionic probe Fl-Na due to the favourable electrostatic interaction between the AMP and cationic R6G. Moreover, the influence of the anionic DNA nucleotide on the cationic and anionic SAIL micelles is monitored through the variation of the lateral diffusion motion of oppositely charged probe molecules (R6G and Fl-Na) inside these aggregates. This variation in diffusion coefficient values also suggests that interaction pattern of these oppositely charged probes are different within the SAILs-nucleotide containing aggregates. Therefore, both rotational and translational diffusion measurements confirm that the DNA nucleotide (AMP) renders more rigid microenvironment within the micellar solution of SAILs.

  9. Control of penetration zone GMAW

    Directory of Open Access Journals (Sweden)

    Віталій Петрович Iванов

    2016-11-01

    Full Text Available Thermal properties of the base metal, shielding medium and the nature of the electrode metal transfer to a great extent determine the penetration area formation in gas-arc welding. It is not always possible to take into account the influence of these factors on penetration front forming within the existing models. The aim of the work was to research the penetration area forming in gas-arc welding. The research of the penetration area forming in gas-arc welding of CrNi austenitic steels was made. The parameters of the regime as well as the kind of the gaseous medium influence on the formation of the penetration zone were studied. The article shows a linear proportional relationship between the electrode feed rate and the size of the base metal plate. The penetration area formation mode for welding in argon and carbon dioxide have been worked out. Diameter, feed rate and the speed of the electrode movement have been chosen as the main input parameters. Multiple regression analysis method was used to make up the modes. The relations of the third order that make it possible to take into account the electrode metal transfer and thermal properties change of the materials to be welded were used. These relationships show quite good agreement with the experimental measurements in the calculation of the fusion zone shape with consumable electrode in argon and carbon dioxide. It was determined that the shape of the melting front curve can be shown as a generalized function in which the front motion parameters depend on feed rate and the diameter of the electrode. Penetration zone growth time is determined by the welding speed and is calculated as a discrete function of the distance from the electrode with the spacing along the movement coordinate. The influence of the mode parameters on the formation of the fusion zone has been investigated and the ways to manage and stabilize the weld pool formation have been identified. The modes can be used to develop

  10. Optimization of ultrasonic extraction and clean-up protocol for the determination of polycyclic aromatic hydrocarbons in marine sediments by high-performance liquid chromatography coupled with fluorescence detection

    Science.gov (United States)

    Peng, Xuewei; Yan, Guofang; Li, Xianguo; Guo, Xinyun; Zhou, Xiao; Wang, Yan

    2012-09-01

    The procedures of ultrasonic extraction and clean-up were optimized for the determination of polycyclic aromatic hydrocarbons (PAHs) in marine sediments. Samples were ultrasonically extracted, and the extracts were purified with a miniaturized silica gel chromatographic column and analyzed with high performance liquid chromatography (HPLC) with a fluorescence detector. Ultrasonication with methanol-dichloromethane (2:1, v/v) mixture gave higher extraction efficiency than that with dichloromethane. Among the three elution solvents used in clean-up step, dichloromethane-hexane (2:3, v/v) mixture was the most satisfactory. Under the optimized conditions, the recoveries in the range of 54.82% to 94.70% with RSDs of 3.02% to 23.22% for a spiked blank, and in the range of 61.20% to 127.08% with RSDs of 7.61% to 26.93% for a spiked matrix, were obtained for the 15 PAHs studied, while the recoveries for a NIST standard reference SRM 1941b were in the range of 50.79% to 83.78% with RSDs of 5.24% to 21.38%. The detection limits were between 0.75 ng L-1 and 10.99 ng L-1for different PAHs. A sample from the Jiaozhou Bay area was examined to test the established methods.

  11. Magnetic solid-phase extraction for determination of the total malachite green, gentian violet and leucomalachite green, leucogentian violet in aquaculture water by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Zhao, Jiao; Wei, Daqiao; Yang, Yaling

    2016-06-01

    In this study, magnetic multi-walled carbon nanotube nanoparticles were synthesized and used as the adsorbent for the sums of malachite green, gentian violet and leucomalachite green, leucogentian violet in aquaculture water samples followed by high performance liquid chromatography with fluorescence detection. This method was based on in situ reduction of chromic malachite green, gentian violet to colorless leucomalachite green, leucogentian violet with potassium borohydride, respectively. The obtained adsorbent combines the advantages of carbon nanotubes and Fe3 O4 nanoparticles in one material for separation and preconcentration of the reductive dyes in aqueous media. The structure and properties of the prepared nanoparticles were characterized by transmission and scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. The main parameters affecting the adsorption recoveries were investigated and optimized, including reducing agent concentration, type and amount of sorbent, sample pH, and eluting conditions. Under the optimum conditions, the limits of detection in this method were 0.22 and 0.09 ng/mL for malachite green and gentian violet, respectively. Product recoveries ranged from 87.0 to 92.8% with relative standard deviations from 4.6 to 5.9%. The results indicate that the sorbent is a suitable material for the removal and concentration of triphenylmethane dyes from polluted environmental samples.

  12. The combined application of urinary liquid-based cytology with fluorescence in situ hybridization and p16/Ki-67 dual immunostaining is valuable for improving the early diagnosis of upper tract urothelial carcinomas.

    Science.gov (United States)

    Sun, Xueqi; Liu, Xubin; Xia, Meng; Yang, Shicong; Fei, Lingyan; Zhang, Mengqi; Ma, Hanyu; Wang, Liantang; Chen, Shangwu; Yu, Li

    2017-08-11

    To evaluate the diagnostic values of urine liquid-based cytology (LBC), fluorescence in situ hybridization (FISH), and p16/Ki-67 dual immunostaining in the detection of upper tract urothelial carcinomas (UTUCs). Sixty-one patients with UTUCs were retrospectively analyzed. All patients were diagnosed both by urine cytology and by FISH, and histologically confirmed as UTUCs. Thirty-two patients had been stained with p16/Ki-67 dual labeling. The sensitivities for low-grade UTUCs (LGUTUCs) and high-grade UTUCs (HGUTUCs) were 33.3% and 67.4% by LBC, 60% and 69.6% by FISH, and 12.5% and 66.7% by p16/Ki-67 dual labeling, respectively. Our results indicated that LBC was more suitable to identify HGUTUCs, FISH was highly valuable for predicting LGUTUCs, and p16/Ki-67 dual labeling was useful for distinguishing HGUTUCs from LGUTUCs. The combined application of these methods may improve the sensitivity or accuracy in the detection or diagnosis of UTUCs. © 2017 Wiley Periodicals, Inc.

  13. Analysis of polynuclear aromatic hydrocarbons in olive oil after solid-phase extraction using a dual-layer sorbent cartridge followed by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Stenerson, Katherine K; Shimelis, Olga; Halpenny, Michael R; Espenschied, Ken; Ye, Maochun M

    2015-05-27

    A simple and easy direct solid-phase extraction (SPE) method was developed for the analysis of polynuclear aromatic hydrocarbons (PAHs) in olive oil using a dual-layer cartridge containing activated Florisil and a mixture of octadecyl (C18)-bonded and zirconia-coated silicas. Undiluted olive oil was applied directly to the SPE cartridge, and the sample was eluted with acetonitrile solvent. Background in the extract was found to be low enough for either gas chromatography-mass spectrometry (GC-MS) or high-performance liquid chromatography with fluorescence detection (HPLC-FLD) analysis. Average recoveries for 16 different PAHs from spiked olive oil replicates were >75%, with intraday precisions of <20% relative standard deviation (% RSD). Detection limits ranged from 0.2 to 1.0 μg/kg and, specifically for the PAHs listed in EC Regulation 835/2011, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, and benzo(a)pyrene, were from 0.3 to 0.7 μg/kg. The method was then applied to determine the PAH content present in commercial samples of refined versus extra-virgin olive oils.

  14. Simple determination of o-phenylphenol in skin lotion by high-performance liquid chromatography coupled with fluorescence detection after pre-column derivatization with 4-(N-chloroformylmethyl-N-methylamino)-7-nitro-2,1,3-benzoxadiazole.

    Science.gov (United States)

    Higashi, Yasuhiko; Konno, Kazunori

    2015-01-01

    o-Phenylphenol (OPP) in skin lotion was quantitated by high-performance liquid chromatography coupled with fluorescence detection after pre-column derivatization with 4-(N-chloroformylmethyl-N-methylamino)-7-nitro-2,1,3-benzoxadiazole (NBD-COCl) in borate buffer (pH 8.5) at room temperature for 2 min. The column [150 mm x 3.0 mm internal diameter (i.d.)], which contained 5 μm particles of C18 packing material, was eluted at room temperature (flow rate: 0.5 ml/min) with mobile phase prepared by addition of acetonitrile (550 ml) to 450 ml of Milli-Q water containing trifluoroacetic acid (0.1 v/v%). 2-Hydroxyfluorene was used as an internal standard. The retention times of NBD-CO-OPP and NBD-CO-IS derivatives were 16.2 and 22.2 min, respectively. The calibration plot was linear in the range of 0.01-0.2 μg/ml with an r2 value of 0.9960, and the lower limit of detection was 0.003 μg/ml (at a signal-to-noise ratio of 3:1; absolute amount of 12 pg/20 μl injection). The coefficient of variation was less than 8.8%. Contents of OPP in three skin lotions were determined with the present system, and the recovery from spiked samples was satisfactory.

  15. Optimization of Ultrasonic Extraction and Clean-up Protocol for the Determination of Polycyclic Aromatic Hydrocarbons in Marine Sediments by High-performance Liquid Chromatography Coupled with Fluorescence Detection

    Institute of Scientific and Technical Information of China (English)

    PENG Xuewei; YAN Guofang; LI Xianguo; GUO Xinyun; ZHOU Xiao; WANG Yan

    2012-01-01

    The procedures of ultrasonic extraction and clean-up were optimized for the determination of polycyclic aromatic hydrocarbons(PAHs)in marine sediments.Samples were ultrasonically extracted,and the extracts were purified with a miniaturized silica gel chromatographic column and analyzed with high performance liquid chromatography(HPLC)with a fluorescence detector.Ultrasonication with methanol-dichloromethane(2:1,v/v)mixture gave higher extraction efficiency than that with dichloromethane.Among the three elution solvents used in clean-up step,dichloromethane-hexane(2:3,v/v)mixture was the most satisfactory.Under the optimized conditions,the recoveries in the range of 54.82% to 94.70% with RSDs of 3.02% to 23.22% for a spiked blank,and in the range of 61.20% to 127.08% with RSDs of 7.61% to 26.93% for a spiked matrix,were obtained for the 15 PAHs studied,while the recoveries for a NIST standard reference SRM 1941b were in the range of 50.79% to 83.78% with RSDs of 5.24% to 21.38%.The detection limits were between 0.75ngL-1 and 10.99ngL-1for different PAHs.A sample from the Jiaozhou Bay area was examined to test the established methods.

  16. Quantitative determination of the macrolide antibiotics erythromycin, roxithromycin, azithromycin and clarithromycin in human serum by high-performance liquid chromatography using pre-column derivatization with 9-fluorenylmethyloxycarbonyl chloride and fluorescence detection.

    Science.gov (United States)

    Sastre Toraño, J; Guchelaar, H J

    1998-12-11

    A validated, highly sensitive and precise high-performance liquid chromatographic (HPLC) method for the determination of the macrolides erythromycin, azithromycin, clarithromycin and roxithromycin in human serum is described. A diethyl ether extract, obtained from serum using a saturated sodium carbonate solution, was treated with 9-fluorenylmethyl-oxycarbonyl chloride (FMOC-Cl) for 40 min at 40 degrees C and chromatographed on a base-deactivated octadecyl column, maintained at 50 degrees C during elution, using an eluent composed of acetonitrile-hydrogenphosphate buffer, pH 7.5, with 0.125% triethylamine (3:2, v/v). Fluorescence detection was used at an excitation wavelength of 255 nm and an emission wavelength of 315 nm. Erythromycin, clarithromycin, roxithromycin and azithromycin were found to have retention times of 8.8, 15.7, 17.1 and 20.7 min, respectively. Recoveries ranging from 93 to 104% were found with reproducibility coefficients of variation of 1.1-5%. Mean correlation coefficients of 0.9997, 0.9998, 0.9996 and 0.9994 were found for the linear calibration curves (n = 2) of erythromycin (0.320-16.1 mg/l), roxithromycin (3.24-19.4 mg/l), clarithromycin (0.190-19.4 mg/l) and azithromycin (0.0988-4.94 mg/l), respectively.

  17. Fluorescent microspheres

    Science.gov (United States)

    Rembaum, A.

    1978-01-01

    Latex particles with attached antibodies have potential biochemical and environmental applications. Human red blood cells and lymphocytes have been labeled with fluorescent microspheres by either direct or indirect immunological technique. Immunolatex spheres can also be used for detecting and localizing specific cell surface receptors. Hormones and toxins may also be bondable.

  18. Identification of a novel skin penetration enhancement peptide by phage display peptide library screening.

    Science.gov (United States)

    Kumar, Sunny; Sahdev, Preety; Perumal, Omathanu; Tummala, Hemachand

    2012-05-07

    Skin is an important site for local or systemic application of drugs. However, a majority of drugs have poor permeability through the skin's topmost layer, stratum corneum (SC). The aim of this study was to identify safe and smaller peptides that could enhance the skin penetration of drug molecules. By screening phage display peptide library, we have identified a T2 peptide (LVGVFH), which enhanced the penetration of bacteriophages (~800 nm long bacterial viruses) across porcine and mouse skin. Pretreating the skin with synthetic T2 peptide at pH 4.5 resulted in significant penetration enhancement of hydrophilic drug 5-fluorouracil (5-FU) across skin. FTIR spectroscopy showed that the T2 peptide interacted with skin lipids to enhance the skin penetration. Pretreating the skin with T2 peptide enhanced the partitioning of small molecules with different lipophilicities (5-FU, fluorescein isothiocyanate, and rhodamine 123 hydrochloride) into skin. Fluorescence studies showed that T2 peptide enhanced the diffusion of these molecules into intercellular lipids of SC and thus enhanced the penetration into the skin. Histidine at the c-terminus of T2 peptide was identified to be critical for the skin penetration enhancement. T2 peptide interacted with skin lipids to cause skin penetration enhancement. The study identified a novel, safe, and noninvasive peptide to improve the skin penetration of drugs without chemical conjugation.

  19. Assessing high wind energy penetration

    DEFF Research Database (Denmark)

    Tande, J.O.

    1995-01-01

    In order to convincingly promote installing wind power capacity as a substantial part of the energy supply system, a set of careful analyses must be undertaken. This paper applies a case study concentrated on assessing the cost/benefit of high wind energy penetration. The case study considers...... expanding the grid connected wind power capacity in Praia, the capital of Cape Verde. The currently installed 1 MW of wind power is estimated to supply close to 10% of the electric energy consumption in 1996. Increasing the wind energy penetration to a higher level is considered viable as the project...... with the existing wind power, supply over 30% of the electric consumption in 1996. Applying the recommended practices for estimating the cost of wind energy, the life-cycle cost of this 2.4 MW investment is estimated at a 7% discount rate and a 20 year lifetime to 0.26 DKK/kW h....

  20. Weld penetration and defect control

    Energy Technology Data Exchange (ETDEWEB)

    Chin, B.A.

    1992-05-15

    Highly engineered designs increasingly require the use of improved materials and sophisticated manufacturing techniques. To obtain optimal performance from these engineered products, improved weld properties and joint reliability are a necessarily. This requirement for improved weld performance and reliability has led to the development of high-performance welding systems in which pre-programmed parameters are specified before any welding takes place. These automated systems however lack the ability to compensate for perturbations which arise during the welding process. Hence the need for systems which monitor and control the in-process status of the welding process. This report discusses work carried out on weld penetration indicators and the feasibility of using these indicators for on-line penetration control.

  1. IPMN penetration of the stomach.

    Science.gov (United States)

    Nakano, Masakazu; Tominaga, Keiichi; Watanabe, Hidetaka; Kanke, Kazunari; Tamano, Masaya; Hiraishi, Hideyuki

    2010-01-01

    An 83-year old Japanese man was transferred to our hospital due to a 1-week history of melena and signs of disordered awareness. Esophagogastroduodenoscopy showed a villous tumor associated with massive white mucous discharge in the posterior wall of the gastric corpus, where pathologically identified mucin-producing epithelium with nuclear atypia had developed into a papillary form. An abdominal enhanced computed tomography scan demonstrated communication between the dilated main pancreatic duct and the gastric lumen. Based on these findings, we reached a diagnosis of gastric penetration by an intraductal papillary mucinous neoplasm (IPMN) of the main pancreatic duct. IPMN is partly characterized by expansive mucinous growth that may result in penetration into adjacent organs.

  2. Penetration Testing in Wireless Networks

    OpenAIRE

    Lamichhane, Shree

    2017-01-01

    This thesis illustrates the security measures and mechanisms behind the encryption and decryption of data while transmitting data in a wireless network. Furthermore, this thesis describes and demonstrates several security threats in a wireless network that are widely experienced. It also explains shortly the evolution of the widely implemented IEEE 802.11 standard and its amendments. Kali Linux tools were used to perform a penetration test in a WPA secured test network. In-formation on th...

  3. Transconjunctival penetration of mitomycin C

    OpenAIRE

    Velpandian T; Sihota Ramanjit; Sinha Ankur; Gupta Viney

    2008-01-01

    Aims: The study was performed to estimate transconjunctival penetration of mitomycin C (MMC) to Tenon′s tissue following application over the intact conjunctiva before routine trabeculectomy. Settings and Design: Institution-based case series. Materials and Methods: In 41 eyes of 41 patients, MMC (0.4 mg/ml for 3 min) was applied over the intact conjunctiva before beginning trabeculectomy. Tenon′s capsule directly beneath the site of application was excised during trabecule...

  4. Cardiac Penetrating Injuries and Pseudoaneurysm

    Institute of Scientific and Technical Information of China (English)

    CHEN Shifeng

    2002-01-01

    Objective To discuss the early diagnosis and treatment of cardiac penetrating injuries and pseudoaneurysm. Methods 18 cases of cardiac penetrating injuries, in which 2 cases were complicated with pseudoaneurysm, were diagnosed by emergency operation and color Doppler echocardiography between May 1973 and Dec. 2001 in our hospital. The basis for emergency operation is the injured path locating in cardiac dangerous zone, severe shock or pericardial tamponade. ResultsAmong 18 cases of this study, 17 cases underwent emergency operation. During the operation, 11 cases were found injured in right ventricle, 2 cases were found injured in right atrium, 1 case was found injured in pulmonary artery,4 cases were found injured in left ventricle, 2 cases were found complicated with pseudoaneurysm. 17cases underwent cardiac repair including 1 case of rupture of aneurysm. 1 case underwent elective aneurysm resection. In whole group, 15 cases survived(83.33% ), 3 cases died( 16.67%). The cause of death is mainly hemorrhagic shock. Conclusion Highly suspicious cardiac penetrating injuries or hemopericaridium should undergo direct operative exploration. Pseudoaneurysm should be resected early,which can prevent severe complications.

  5. Locating a buried earth penetrator

    Energy Technology Data Exchange (ETDEWEB)

    Caffey, T.W.H.

    1977-11-01

    The purpose of this work was to assist the recovery of a buried earth penetrator by locating the vertical projection of the penetator upon the surface within a horizontal radius error of one meter. The penetrator will carry a small coil which is driven by an alternating current to form a magnetic dipole. Five measurements of the magnetic field vector upon the surface of the earth are shown to be sufficient for determining not only the xyz-coordinates of the dipole, but also the orientation of the dipole axis. The theory, computation process, and field tests are comprehensively described. Results of 26 field tests with the dipole at 9 different combinations of location and orientation are given. Average radial and vertical location errors are 0.27 m and -0.05 m, respectively, while the mean errors in the tilt and orientation angles of the dipole axis are 3 degrees and 8 degrees, respectively. The results are applied to the design of a locating system for a Pershing II penetrator which contains a recessed, rear-mounted coil.

  6. Correlation Between Cone Penetration Rate And Measured Cone Penetration Parameters In Silty Soils

    DEFF Research Database (Denmark)

    Poulsen, Rikke; Nielsen, Benjaminn Nordahl; Ibsen, Lars Bo

    2013-01-01

    penetration tests with varying penetration rates conducted at a test site where the subsoil primary consists of sandy silt. It is shown how a reduced penetration rate influences the cone penetration measurements e.g. the cone resistance, pore pressure, and sleeve friction.......This paper shows, how a change in cone penetration rate affects the cone penetration measurements, hence the cone resistance, pore pressure, and sleeve friction in silty soil. The standard rate of penetration is 20 mm/s, and it is generally accepted that undrained penetration occurs in clay while...... drained penetration occurs in sand. When lowering the penetration rate, the soil pore water starts to dissipate and a change in the drainage condition is seen. In intermediate soils such as silty soils, the standard cone penetration rate may result in a drainage condition that could be undrained...

  7. Storage Conditions of Skin Affect Tissue Structure and Subsequent in vitro Percutaneous Penetration

    DEFF Research Database (Denmark)

    Nielsen, J B; Plasencia, I; Sørensen, J A

    2011-01-01

    fluorescence microscopy) and in vitro percutaneous penetration of caffeine under four different storage conditions using skin samples from the same donors: fresh skin, skin kept at -20°C for 3 weeks (with or without the use of polyethylene glycol) and at -80°C. Our results show a correlation between increasing...

  8. AN IN-VITRO EVALUATION OF FLUORESCEIN PENETRATION INTO NATURAL ROOT SURFACE CARIOUS LESIONS

    NARCIS (Netherlands)

    VANDERVEEN, MH; TENBOSCH, JJ

    1993-01-01

    In order to develop a method for detection and quantification of initial root surface carious lesions, the use of fluorescein sodium as a fluorescent dye is evaluated. The penetration depth of fluorescein sodium into human roots containing natural carious lesions was measured on approximately

  9. Ethical Dilemmas and Dimensions in Penetration Testing

    OpenAIRE

    Faily, Sharmal; McAlaney, John; Iacob, C

    2015-01-01

    Penetration testers are required to attack systems to evaluate their security, but without engaging in unethical behaviour while doing so. Despite work on hacker values and studies into security practice, there is little literature devoted to the ethical pressures associated with penetration testing. This paper presents several ethical dilemmas and dimensions associated with penetration testing;\\ud these shed light on the ethical positions taken by Penetration testers, and help identify poten...

  10. The production process for water penetrated brick

    Institute of Scientific and Technical Information of China (English)

    SunGuofeng

    2005-01-01

    Waste penetrated brick, which is a green building material with good water penetration, high strength, lower firing temperature, lower production cost, good appearance and good structure, can holding ground water lever. This article analysis the production process and related factor for water penetrated brick:proper particle size distribution, proper shaping method, proper press and proper firing can ensure to produce good quality water penetrated brick.

  11. Penetration Testing: A Roadmap to Network Security

    OpenAIRE

    2009-01-01

    Network penetration testing identifies the exploits and vulnerabilities those exist within computer network infrastructure and help to confirm the security measures. The objective of this paper is to explain methodology and methods behind penetration testing and illustrate remedies over it, which will provide substantial value for network security Penetration testing should model real world attacks as closely as possible. An authorized and scheduled penetration testing will probably detected ...

  12. Network Penetration Testing and Research

    Science.gov (United States)

    Murphy, Brandon F.

    2013-01-01

    This paper will focus the on research and testing done on penetrating a network for security purposes. This research will provide the IT security office new methods of attacks across and against a company's network as well as introduce them to new platforms and software that can be used to better assist with protecting against such attacks. Throughout this paper testing and research has been done on two different Linux based operating systems, for attacking and compromising a Windows based host computer. Backtrack 5 and BlackBuntu (Linux based penetration testing operating systems) are two different "attacker'' computers that will attempt to plant viruses and or NASA USRP - Internship Final Report exploits on a host Windows 7 operating system, as well as try to retrieve information from the host. On each Linux OS (Backtrack 5 and BlackBuntu) there is penetration testing software which provides the necessary tools to create exploits that can compromise a windows system as well as other operating systems. This paper will focus on two main methods of deploying exploits 1 onto a host computer in order to retrieve information from a compromised system. One method of deployment for an exploit that was tested is known as a "social engineering" exploit. This type of method requires interaction from unsuspecting user. With this user interaction, a deployed exploit may allow a malicious user to gain access to the unsuspecting user's computer as well as the network that such computer is connected to. Due to more advance security setting and antivirus protection and detection, this method is easily identified and defended against. The second method of exploit deployment is the method mainly focused upon within this paper. This method required extensive research on the best way to compromise a security enabled protected network. Once a network has been compromised, then any and all devices connected to such network has the potential to be compromised as well. With a compromised

  13. In vivo targeting of hydrogen peroxide by activatable cell-penetrating peptides.

    Science.gov (United States)

    Weinstain, Roy; Savariar, Elamprakash N; Felsen, Csilla N; Tsien, Roger Y

    2014-01-22

    A hydrogen peroxide (H2O2)-activated cell-penetrating peptide was developed through incorporation of a boronic acid-containing cleavable linker between polycationic cell-penetrating peptide and polyanionic fragments. Fluorescence labeling of the two ends of the molecule enabled monitoring its reaction with H2O2 through release of the highly adhesive cell-penetrating peptide and disruption of fluorescence resonance energy transfer. The H2O2 sensor selectively reacts with endogenous H2O2 in cell culture to monitor the oxidative burst of promyelocytes and in vivo to image lung inflammation. Targeting H2O2 has potential applications in imaging and therapy of diseases related to oxidative stress.

  14. Assessment of Quantum Dot Penetration into Skin in Different Species Under Different Mechanical Actions

    Science.gov (United States)

    Monteiro-Riviere, N. A.; Zhang, L. W.

    Skin penetration is one of the major routes of exposure for nanoparticles to gain access to a biological system. QD nanoparticles have received a great deal of attention due to their fluorescent characteristics and potential use in medical applications. However, little is known about their permeability in skin. This study focuses on three types of quantum dots (QD) with different surface coatings and concentrations on their ability to penetrate skin. QD621 (polyethylene glycol coated, PEG) was studied for 24 h in porcine skin flow-through diffusion cells. QD565 and QD655 coated with carboxylic acid were studied for 8 and 24 h in flow-through diffusion cells with flexed, tape stripped and abraded rat skin to determine if these mechanical actions could perturb the barrier and affect penetration. Confocal microscopy depicted QD621 penetration through the uppermost layers of the stratum corneum (SC) and fluorescence was found in the SC and near hair follicles. QD621 were found in the intercellular lipid layers of the SC by transmission electron microscopy (TEM). QD565 and 655 with flexed and tape-stripped skin did not show penetration; only abraded skin showed penetration in the viable dermal layers. In all QD studies, inductively coupled plasma-optical emission spectroscopy (ICP-OES) analysis for cadmium (Cd) and fluorescence for QD did not detect Cd or fluorescence signal in the perfusate at any time point, concentration or type of QD. These results indicate that porcine skin penetration of QD621 is minimal and limited primarily to the outer SC layers, while QD565 and 655 penetrated into the dermis of abraded skin. The anatomical complexity of skin and species differences should be taken into consideration when selecting an animal model to study nanoparticle absorption/penetration. These findings are of importance to risk assessment for nanoscale materials because it indicates that if skin barrier is altered such as in wounds, scrapes, or dermatitis conditions could

  15. 7 CFR 2902.14 - Penetrating lubricants.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Penetrating lubricants. 2902.14 Section 2902.14... Items § 2902.14 Penetrating lubricants. (a) Definition. Products formulated to provide light lubrication..., will give a procurement preference for qualifying biobased penetrating lubricants. By that...

  16. Kali Linux wireless penetration testing essentials

    CERN Document Server

    Alamanni, Marco

    2015-01-01

    This book is targeted at information security professionals, penetration testers and network/system administrators who want to get started with wireless penetration testing. No prior experience with Kali Linux and wireless penetration testing is required, but familiarity with Linux and basic networking concepts is recommended.

  17. Liquids and liquid mixtures

    CERN Document Server

    Rowlinson, J S; Baldwin, J E; Buckingham, A D; Danishefsky, S

    2013-01-01

    Liquids and Liquid Mixtures, Third Edition explores the equilibrium properties of liquids and liquid mixtures and relates them to the properties of the constituent molecules using the methods of statistical thermodynamics. Topics covered include the critical state, fluid mixtures at high pressures, and the statistical thermodynamics of fluids and mixtures. This book consists of eight chapters and begins with an overview of the liquid state and the thermodynamic properties of liquids and liquid mixtures, including vapor pressure and heat capacities. The discussion then turns to the thermodynami

  18. An easy-to-use excimer fluorescence derivatization reagent, 2-chloro-4-methoxy-6-(4-(pyren-4-yl)butoxy)-1,3,5-triazine, for use in the highly sensitive and selective liquid chromatography analysis of histamine in Japanese soy sauces.

    Science.gov (United States)

    Nakano, Tatsuki; Todoroki, Kenichiro; Ishii, Yasuhiro; Miyauchi, Chiemi; Palee, Arpaporn; Min, Jun Zhe; Inoue, Koichi; Suzuki, Kuniaki; Toyo'oka, Toshimasa

    2015-06-23

    In this study, a novel pre-column excimer fluorescence derivatization reagent, 2-chloro-4-methoxy-6-(4-(pyren-4-yl)butoxy)-1,3,5-triazine (CMPT), was developed for polyamines, specifically histamine. By CMPT derivatization, the polyamines, histamine and tyramine were converted to polypyrene derivatives, and emitted intra-molecular excimer fluorescence at 475nm. This could clearly be distinguished from the normal fluorescence emitted from reagent blanks at 375 nm. Unlike conventional excimer fluorescence derivatization reagents, CMPT is chemically stable and its reactivity sustained over at least 36 days even in solution state. We successfully applied this reagent to the sensitive and selective analysis of histamine in different kinds of Japanese commercial soy sauces. The detection and quantification limits of histamine were 15 and 50 μg L(-1), respectively, equating to 1.35 pmol and 4.5 pmol for a 6 μL injection. This sensitivity helped the direct analysis of soy sauce samples only treated by one-step liquid-liquid extraction without concentration. The histamine levels of commercial soy sauce samples (koikuchi, usukuchi and saishikomi) investigated were 1.24-768.5 mg L(-1).

  19. Web penetration testing with Kali Linux

    CERN Document Server

    Muniz, Joseph

    2013-01-01

    Web Penetration Testing with Kali Linux contains various penetration testing methods using BackTrack that will be used by the reader. It contains clear step-by-step instructions with lot of screenshots. It is written in an easy to understand language which will further simplify the understanding for the user.""Web Penetration Testing with Kali Linux"" is ideal for anyone who is interested in learning how to become a penetration tester. It will also help the users who are new to Kali Linux and want to learn the features and differences in Kali versus Backtrack, and seasoned penetration testers

  20. Exploring the potentialities of an improved ultrasound-assisted quick, easy, cheap, effective, rugged, and safe-based extraction technique combined with ultrahigh pressure liquid chromatography-fluorescence detection for determination of Zearalenone in cereals.

    Science.gov (United States)

    Porto-Figueira, Priscilla; Camacho, Irene; Câmara, José S

    2015-08-21

    Zearalenone (ZEA), a secondary metabolite from Fusarium graminearum fungi that invade crops and grow during blooming in moist cool field conditions, is a nonsteroidal oestrogen, biologically very potent, although hardly toxic. Different analytical methods, among which a quick, easy, cheap, effective, rugged, and safe (QuEChERS) strategy, combined with or liquid chromatography, have been proposed for ZEA determination in foods. However, this extraction procedure has the disadvantage of using large amount of organic solvents, partitioning salts and sample volume, which limits the technique application on the fields where the sample amount is critical. Therefore in this work an improved sample preparation step based on the original QuEChERS (O-QuEChERS) approach, the μ-QuEChERS, combined with ultrasound-assisted extraction (USAE) and ultrahigh pressure liquid chromatography (UHPLC) analysis with fluorescence detection (FLR) is proposed for the sensitive and high-throughput quantification of ZEA in cereals. The proposed analytical strategy, μ-QuEChERSUSAE, uses up to 32 times lower amounts of partitioning salts, lower sample amount and lower extraction solvents, in comparison with O-QuEChERS technique. The performance of the analytical approach was assessed by studying the selectivity, specificity, limits of detection and quantification, linear dynamic range, matrix effect and precision. Good linearity (r(2)>0.99) was achieved for ZEA, and limits of detection (LOD=3.4μgkg(-1)) and limits of quantification (LOQ=4.7μgkg(-1)) were found below the tolerance levels set by European Commission. Good recoveries were obtained with different spiked concentrations, ranged from 80.2% to 109.7%, with relative standard deviations (RSD) lower than 5.0%. The comparison of the analytical performance of the proposed μ-QuEChERSUSAE with O-QuEChERS showed the powerful ability of the proposed strategy since it gives comparable results but using lower amounts of sample, partitioning

  1. Statistical Mechanical Theory of Penetrant Diffusion in Polymer Melts and Glasses

    Science.gov (United States)

    Zhang, Rui; Schweizer, Kenneth

    We generalize our force-level, self-consistent nonlinear Langevin equation theory of activated diffusion of a dilute spherical penetrant in hard sphere fluids to predict the long-time diffusivity of molecular penetrants in supercooled polymer liquids and non-aging glasses. Chemical complexity is treated using an a priori mapping to a temperature-dependent hard sphere mixture model where polymers are disconnected into effective spheres based on the Kuhn length as the relevant coarse graining scale. A key parameter for mobility is the penetrant to polymer segment diameter ratio, R. Our calculations agree well with experimental measurements for a wide range of temperatures, penetrant sizes (from gas molecules with R ~0.3 to aromatic molecules with R ~1) and diverse amorphous polymers, over 10 decades variation of penetrant diffusivity. Structural parameter transferability is good. We have also formulated a theory at finite penetrant loading for the coupled penetrant-polymer dynamics in chemically (nearly) matched mixtures (e.g., toluene-polystyrene) which captures well the increase of penetrant diffusivity and decrease of polymer matrix vitrification temperature with increasing loading.

  2. Binding and interstitial penetration of liposomes within avascular tumor spheroids.

    Science.gov (United States)

    Kostarelos, Kostas; Emfietzoglou, Dimitris; Papakostas, Alexandros; Yang, Wei-Hong; Ballangrud, Ase; Sgouros, George

    2004-11-20

    The liposomal delivery of cancer therapeutics, including gene therapy vectors, is an area of intense study. Poor penetration of liposomes into interstitial tumor spaces remains a problem, however. In this work, the penetration of different liposomal formulations into prostate carcinoma spheroids was examined. Spheroid penetration was assessed by confocal microscopy of fluorescently labeled liposomes. The impact of liposomal surface charge, mean diameter, lipid bilayer fluidity and fusogenicity on spheroid penetration was examined. A variety of different liposome systems relevant to clinical or preclinical protocols have been studied, including classical zwitterionic (DMPC:chol) and sterically stabilized liposomes (DMPC:chol:DOPE-PEG2000), both used clinically, and cationic liposomes (DMPC:DOPE:DC-chol and DOTAP), forming the basis of the vast majority of nonviral gene transfer vectors tested in various cancer trials. Surface interactions between strongly cationic vesicles and the tumor cells led to an electrostatically derived binding-site barrier effect, inhibiting further association of the delivery systems with the tumor spheroids (DMPC:DC-chol). However, inclusion of the fusogenic lipid DOPE and use of a cationic lipid of lower surface charge density (DOTAP instead of DC-chol) led to improvements in the observed intratumoral distribution characteristics. Sterically stabilized liposomes did not interact with the tumor spheroids, whereas small unilamellar classical liposomes exhibit extensive distribution deeper into the tumor volume. Engineering liposomal delivery systems with a relatively low charge molar ratio and enhanced fusogenicity, or electrostatically neutral liposomes with fluid bilayers, offered enhanced intratumoral penetration. This study shows that a delicate balance exists between the strong affinity of delivery systems for the tumor cells and the efficient penetration and distribution within the tumor mass, similar to previous work studying

  3. Penetration testing with Raspberry Pi

    CERN Document Server

    Muniz, Joseph

    2015-01-01

    If you are looking for a low budget, small form-factor remotely accessible hacking tool, then the concepts in this book are ideal for you. If you are a penetration tester who wants to save on travel costs by placing a low-cost node on a target network, you will save thousands by using the methods covered in this book. You do not have to be a skilled hacker or programmer to use this book. It will be beneficial to have some networking experience; however, it is not required to follow the concepts covered in this book.

  4. Penetration Testing: A Roadmap to Network Security

    CERN Document Server

    Naik, Nitin A; Khamitkar, Santosh D; Kalyankar, Namdeo V

    2009-01-01

    Network penetration testing identifies the exploits and vulnerabilities those exist within computer network infrastructure and help to confirm the security measures. The objective of this paper is to explain methodology and methods behind penetration testing and illustrate remedies over it, which will provide substantial value for network security Penetration testing should model real world attacks as closely as possible. An authorized and scheduled penetration testing will probably detected by IDS (Intrusion Detection System). Network penetration testing is done by either or manual automated tools. Penetration test can gather evidence of vulnerability in the network. Successful testing provides indisputable evidence of the problem as well as starting point for prioritizing remediation. Penetration testing focuses on high severity vulnerabilities and there are no false positive.

  5. Spatially Resolved Two-Color Diffusion Measurements in Human Skin Applied to Transdermal Liposome Penetration

    DEFF Research Database (Denmark)

    Brewer, Jonathan; Bloksgaard, Maria; Kubiak, Jakub

    2013-01-01

    A multiphoton excitation-based fluorescence fluctuation spectroscopy method, Raster image correlation spectroscopy (RICS), was used to measure the local diffusion coefficients of distinct model fluorescent substances in excised human skin. In combination with structural information obtained...... of the liposome composition (phospholipids or transfersomes), our results show a clear lack of cross-correlation below the skin surface, indicating that the penetration of intact liposomes is highly compromised by the skin barrier.Journal of Investigative Dermatology advance online publication, 6 December 2012...... is very heterogeneous on a microscopic scale. This diffusion-based strategy was further exploited to investigate the integrity of liposomes during transdermal penetration. Specifically, the diffusion of dual-color fluorescently labeled liposomes-containing an amphiphilic fluorophore in the lipid bilayer...

  6. Rapid, sensitive and simultaneous determination of fluorescence-labeled designated substances controlled by the Pharmaceutical Affairs Law in Japan by ultra-performance liquid chromatography coupled with electrospray-ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Min, Jun Zhe; Hatanaka, Suguru; Toyo'oka, Toshimasa; Inagaki, Shinsuke; Kikura-Hanajiri, Ruri; Goda, Yukihiro

    2009-11-01

    A simultaneous determination method based on ultra-performance liquid chromatography (UPLC) with fluorescence (FL) detection and electrospray-ionization time-of-flight mass spectrometry (ESI-TOF-MS) was developed for 16 "designated substances" (Shitei-Yakubutsu) controlled by the Pharmaceutical Affairs Law in Japan. These substances were first labeled with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole at 60 degrees C for 2 h in 0.1 M borax (pH 9.3). The resulting fluorophores were well separated by reversed-phase chromatography using an Acquity UPLC BEH C(18) column (1.7 microm, 100 mm x 2.1 mm i.d.) by isocratic elution with a mixture of water and acetonitrile-methanol (20:80) containing 0.1% formic acid. The separated derivatives were sensitively detected by both FL and TOF-MS. However, the determination of several designated substances by FL detection showed interference from endogenous substances in biological samples. Therefore, the determination in real samples was carried out by a combination of UPLC separation and ESI-TOF-MS detection. The structures of the designated substances were identified from the protonated-molecular ions [M+H](+) obtained from the TOF-MS measurement. The calibration curves obtained from the peak area ratios of the internal standard (I.S.), i.e., 3-phenyl-1-propylamine, and the designated substances versus the injection amounts showed good linearity. The limits of detection (S/N = 3) and the limits of quantification (S/N = 10) in 0.1 mL of human plasma and urine for the present method were 0.30-150 pmol and 1.0-500 pmol, respectively. Good accuracy and precision (according to intraday and interday assays) were also obtained with the present procedure. This method was applied to analyses of human plasma, urine and real products.

  7. Simultaneous determination of 11 antibiotics and their main metabolites from four different groups by reversed-phase high-performance liquid chromatography-diode array-fluorescence (HPLC-DAD-FLD) in human urine samples.

    Science.gov (United States)

    Fernandez-Torres, R; Consentino, M Olías; Lopez, M A Bello; Mochon, M Callejon

    2010-05-15

    A new, accurate and sensitive reversed-phase high-performance liquid chromatography (RP-HPLC) as analytical method for the quantitative determination of 11 antibiotics (drugs) and the main metabolites of five of them present in human urine has been worked out, optimized and validated. The analytes belong to four different groups of antibiotics (sulfonamides, tetracyclines, penicillins and anphenicols). The analyzed compounds were sulfadiazine (SDI) and its N(4)-acetylsulfadiazine (NDI) metabolite, sulfamethazine (SMZ) and its N(4)-acetylsulfamethazine (NMZ), sulfamerazine (SMR) and its N(4)-acetylsulfamerazine (NMR), sulfamethoxazole (SMX), trimetroprim (TMP), amoxicillin (AMX) and its main metabolite amoxicilloic acid (AMA), ampicillin (AMP) and its main metabolite ampicilloic acid (APA), chloramphenicol (CLF), thiamphenicol (TIF), oxytetracycline (OXT) and chlortetracycline (CLT). For HPLC analysis, diode array (DAD) and fluorescence (FLD) detectors were used. The separation of the analyzed compounds was conducted by means of a Phenomenex Gemini C(18) (150mm x 4.6mm I.D., particle size 5microm) analytical column with LiChroCART LiChrospher C(18) (4mm x 4mm, particle size 5microm) guard column. Analyzed drugs were determined within 34min using formic acid 0.1% in water and acetonitrile in gradient elution mode as mobile phase. A linear response was observed for all compounds in the range of concentration studied. Two procedures were optimized for sample preparation: a direct treatment with methanol and acetonitrile and a solid phase extraction procedure using Bond Elut Plexa columns. The method was applied to the determination of the analytes in human urine from volunteers under treatment with different pharmaceutical formulations. This method can be successfully applied to routine determination of all these drugs in human urine samples.

  8. Simultaneous determination of 4-hydroxyphenyl lactic acid, 4-hydroxyphenyl acetic acid, and 3-4-hydroxyphenyl propionic acid in human urine by Ultra high performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Yang, Yongli; Liu, Fan; Wan, Yiqun

    2017-03-27

    A simple and reliable method was established for simultaneous determination of 4-hydroxyphenyl acetic acid, 4-hydroxyphenyl lactic acid, and 3-4-hydroxyphenyl propionic acid in human urine by high-performance liquid chromatography with fluorescence detection. Solid-phase extraction was used to eliminate the interferences in urine. The separation of three analytes was achieved using a C18 column and a mobile phase formed by a 95:5 v/v mixture of 50 mmol/L ammonium acetate buffer at pH 6.8 that contained 5 mmol/L tetrabutyl ammonium bromide and acetonitrile. Under the optimized conditions, the detection limits of 4-hydroxyphenyl acetic acid, 4-hydroxyphenyl lactic acid, and 3-4-hydroxyphenyl propionic acid were 4.8 × 10(-3) , 8.80 × 10(-3) , and 9.00 × 10(-3) mg/L, respectively, and the recoveries were in the range of 85.0-120.0% with relative standard deviations of 1.5-3.1%. This method was used to analyze urine samples from breast cancer patients, healthy people and postsurgery breast cancer patients. Significant differences of urinary levels of 4-hydroxyphenyl acetic acid and 4-hydroxyphenyl lactic acid could be found between the breast cancer patients group and other two groups. No effect of age and sex was observed on the urinary levels of 4-hydroxyphenyl acetic acid and 4-hydroxyphenyl lactic acid. This method might be helpful for cancer biomarkers discovery in urine. This article is protected by copyright. All rights reserved.

  9. Speciation of the immediately mobilisable As(III), As(V), MMA and DMA in river sediments by high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry following ultrasonic extraction

    Energy Technology Data Exchange (ETDEWEB)

    Huerga, A. [Departamento de Quimica Analitica y Alimentaria, Area de Quimica Analitica, Facultad de Ciencias (Quimica), Universidad de Vigo, As Lagoas-Marcosende s/n, 36200 Vigo (Spain); Lavilla, I. [Departamento de Quimica Analitica y Alimentaria, Area de Quimica Analitica, Facultad de Ciencias (Quimica), Universidad de Vigo, As Lagoas-Marcosende s/n, 36200 Vigo (Spain); Bendicho, C. [Departamento de Quimica Analitica y Alimentaria, Area de Quimica Analitica, Facultad de Ciencias (Quimica), Universidad de Vigo, As Lagoas-Marcosende s/n, 36200 Vigo (Spain)]. E-mail: bendicho@uvigo.es

    2005-04-04

    In this work, a fast method is developed for the speciation of As(III), As(V), MMA and DMA in the immediately mobilisable fraction of river sediments (i.e. water-soluble and phosphate-exchangeable) by high performance liquid chromatography-hydride generation-atomic fluorescence detection (HPLC-HG-AFD) after extraction using focused ultrasound. The influence of relevant parameters influencing an ion-pairing chromatographic separation following isocratic elution (i.e. amount of MeOH in the mobile phase, ion pair reagent concentration, pH, flow rate) was studied. Focused ultrasound transmitted from an ultrasonic probe provided the same extractable contents as conventional extraction with no changes in the species distribution. The effect of the drying step over extraction of As species was investigated. The following drying procedures were compared: freeze-, oven-, microwave- and air-drying. No influence of the drying operation on the water-extractable fraction was observed. However, freeze- and air-drying yielded significantly higher phosphate-extractable amounts of As(III) and As(V) as compared to oven and microwaves. Detection limits for the As species were in the range 1.3-4.1 ng/g for the water-soluble fraction and 1.6-4.8 ng/g for the phosphate buffer exchangeable fraction. The method was applied to the speciation of immediately mobilisable As(III), As(V), DMA and MMA in 11 sediment samples collected along the beds of the Louro River (southern Galicia, Spain)

  10. A magnetic-based dispersive micro-solid-phase extraction method using the metal-organic framework HKUST-1 and ultra-high-performance liquid chromatography with fluorescence detection for determining polycyclic aromatic hydrocarbons in waters and fruit tea infusions.

    Science.gov (United States)

    Rocío-Bautista, Priscilla; Pino, Verónica; Ayala, Juan H; Pasán, Jorge; Ruiz-Pérez, Catalina; Afonso, Ana M

    2016-03-04

    A hybrid material composed by the metal-organic framework (MOF) HKUST-1 and Fe3O4 magnetic nanoparticles (MNPs) has been synthetized in a quite simple manner, characterized, and used in a magnetic-assisted dispersive micro-solid-phase extraction (M-d-μSPE) method in combination with ultra-high-performance liquid chromatography (UHPLC) and fluorescence detection (FD). The application was devoted to the determination of 8 heavy polycyclic aromatic hydrocarbons (PAHs) in different aqueous samples, specifically tap water, wastewaters, and fruit tea infusion samples. The overall M-d-μSPE-UHPLC-FD method was optimized and validated. The method is characterized by: its simplicity in both the preparation of the hybrid material (simple mixing) and the magnetic-assisted approach (∼10min extraction time), the use of low sorbent amounts (20mg of HKUST-1 and 5mg of Fe3O4 MNPs), and the low organic solvent consumption in the overall M-d-μSPE-UHPLC-FD method (1.5mL of acetonitrile in the M-d-μSPE method and 2.8mL of acetonitrile in the UHPLC-FD run). The resulting method has high sensitivity, with LODs down to 0.8ngL(-1); adequate intermediate precision, with relative standard deviation values (RSD) always lower than 6.3% (being the range 5.9-9.0% in tap water for a spiked level of 45ngL(-1), 6.1-14% in wastewaters for a spiked level of 45ngL(-1), and 7.2-17% in fruit tea infusion samples for a spiked level of 45ngL(-1)); and adequate relative recoveries, with average values of 82% in tap water, and 94% and 75% in wastewater and fruit tea infusion samples, respectively, if using the proper matrix-matched calibration.

  11. Synthesis of mimic molecularly imprinted ordered mesoporous silica adsorbent by thermally reversible semicovalent approach for pipette-tip solid-phase extraction-liquid chromatography fluorescence determination of estradiol in milk.

    Science.gov (United States)

    Wang, Lu; Yan, Hongyuan; Yang, Chunliu; Li, Zan; Qiao, Fengxia

    2016-07-22

    A mimic molecularly imprinted ordered mesoporous silica (MIOMS) adsorbent was prepared utilizing a thermally reversible semicovalent approach. The thermally reversible covalent template-monomer complex was firstly synthesized by employing 4,4'-sulfonyldiphenol (BPS) and (3-isocyanatopropyl) triethoxysilane (ICPTES) as template and monomer, respectively. The template-monomer complex was incorporated into ordered mesoporous silica via a simple self-assembly process. The adsorption experiment illustrated that the imprint-removed silica (MIOMS-ir) had higher special recognition ability (250μgg(-1)) for estradiol (E2) than the non-imprinted silica (NIOMS-ir) (25μgg(-1)). MIOMS-ir was applied as an adsorbent in pipette-tip solid-phase extraction (PT-SPE) coupled with liquid chromatography-fluorescence detector (LC-FLD) for determination of E2 in milk samples. Under the optimized conditions, only 3mg of the adsorbent, 0.3mL of water as washing solvent, and 0.5mL of acetonitrile-acetic acid (96:4, v/v) as elution solvent were used in the pretreatment procedure of milk samples. Good calibration linearity was obtained in a range of 25ngL(-1) to 1000ngL(-1), and the recoveries at three spiked levels were ranged from 95.4% to 107.0% with relative standard deviations (RSDs) ≤3.1% (n=3). The proposed MIOMS-ir-PT-SPE-LC-FLD method combined the advantages of PT-SPE and ordered mesoporous material such as ease assembly, low cost, high extraction efficiency and large specific surface area, so it is a potential pretreatment strategy for the extraction and determination of E2 in complex milk samples.

  12. Penetration of tamoxifen citrate loaded ethosomes and liposomes across human skin: a comparative study with confocal laser scanning microscopy.

    Science.gov (United States)

    Sarwa, Khomendra K; Suresh, Preeti K; Rudrapal, Mithun; Verma, Vinod K

    2014-01-01

    In the present study, ethosomal and liposomal formulations containing tamoxifen citrate were prepared and evaluated for their penetration properties in human cadaver skin using Franz diffusion cell and confocal laser scanning microscope (CLSM). The results clearly revealed that ethosomal vesicles showed a better drug permeation profile than that of liposomal vesicles. In addition, low fluorescence intensity in CLSM was recorded with liposomes as compared to ethosomes, indicating lower cumulative amount of drug permeation from liposomal vesicles. Furthermore, CLSM showed uniform fluorescence intensity across the entire depth of skin in ethosomal treatment, indicating high penetrability of ethosomal vesicles through human cadaver skin. In contrast, low penetrability of conventional liposomal vesicles was recorded as penetration was limited to the 7(th) section (i.e. upper epidermis layer) of skin as evident from visualization of intact liposomal vesicles in CLSM.

  13. Heat Loads Due to Small Penetrations in Multilayer Insulation Blankets

    Science.gov (United States)

    Johnson, W. L.; Heckle, K. W.; Fesmire, J. E.

    2017-01-01

    The main penetrations (supports and piping) through multilayer insulation systems for cryogenic tanks have been previously addressed by heat flow measurements. Smaller penetrations due to fasteners and attachments are now experimentally investigated. The use of small pins or plastic garment tag fasteners to each the handling and construction of multilayer insulation (MLI) blankets goes back many years. While it has long been understood that penetrations and other discontinuities degrade the performance of the MLI blanket, quantification of this degradation has generally been lumped into gross performance multipliers (often called degradation factors or scale factors). Small penetrations contribute both solid conduction and radiation heat transfer paths through the blanket. The conduction is down the stem of the structural element itself while the radiation is through the hole formed during installation of the pin or fastener. Analytical models were developed in conjunction with MLI perforation theory and Fouriers Law. Results of the analytical models are compared to experimental testing performed on a 10 layer MLI blanket with approximately 50 small plastic pins penetrating the test specimen. The pins were installed at 76-mm spacing inches in both directions to minimize the compounding of thermal effects due to localized compression or lateral heat transfer. The testing was performed using a liquid nitrogen boil-off calorimeter (Cryostat-100) with the standard boundary temperatures of 293 K and 78 K. Results show that the added radiation through the holes is much more significant than the conduction down the fastener. The results are shown to be in agreement with radiation theory for perforated films.

  14. Sulfonamidas em leite por cromatografia líquida de alta eficiência com derivação pré-coluna e detecção por fluorescência Sulfonamides in milk by high performance liquid chromatography with pre-column derivatization and fluorescence detection

    Directory of Open Access Journals (Sweden)

    Janete Alaburda

    2007-11-01

    Full Text Available O objetivo deste trabalho foi avaliar e validar um método para deteminação de resíduos de sulfatiazol (STZ, sulfametazina (SMZ e sulfadimetoxina (SDM em leite UHT integral. A extração foi realizada com diclorometano e coluna de extração em fase sólida de sílica. Os resíduos, após derivação com fluorescamina, foram quantificados por cromatografia líquida de alta eficiência com detector de fluorescência. O limite de detecção das três sulfas em amostra de leite integral foi 0,3 µg L-1 e o limite de quantificação foi 1 µg L-1 para STZ e SMZ e 2,5 µg L-1 para SDM, com coeficientes de variação entre 4,4 e 6,6%. Os valores de recuperação para STZ, SMZ e SDM foram 63,2, 91,2 e 63,2%, respectivamente. Considerando o limite máximo de resíduo estabelecido pela legislação brasileira de 100 µg kg-1 para a soma das concentrações totais de STZ, SMZ e SDM, o método descrito permite a determinação simultânea dos três analitos em amostras de leite UTH integral.The objective of this work was to evaluate and validate a method for analysis of sulfathiazole (STZ, sulfamethazine (SMZ and sulfadimethoxine (SDM residues in milk. Extraction was carried out with diclhoromethane followed by silica solid phase extraction. The extracts were derivatizated with fluorescamine and quantified by reversed-phase high performance liquid chromatography with fluorescence detection. The detection limit for the three sulfonamides was 0.3 µg L-1 and the quantification limit was 1 µg L-1 for STZ and SMZ and 2.5 µg L-1 for SDM, with coefficient of variation ranging from 4.4 to 6.6%. The recoveries for STZ, SMZ and SDM were 63.2, 91.2 and 63.2%, respectively. Considering that Brazilian regulation sets maximum residue limit in milk of 100 µg kg-1 for total sulfonamide concentrations (STZ, SMZ and SDM, the present method is adequate to quantify the residues of three sulfonamides simultaneously in UHT milk.

  15. Pegylated Polyaspartamide-Polylactide-Based Nanoparticles Penetrating Cystic Fibrosis Artificial Mucus.

    Science.gov (United States)

    Craparo, Emanuela Fabiola; Porsio, Barbara; Sardo, Carla; Giammona, Gaetano; Cavallaro, Gennara

    2016-03-14

    Here, the preparation of mucus-penetrating nanoparticles for pulmonary administration of ibuprofen in patients with cystic fibrosis is described. A fluorescent derivative of α,β-poly(N-2-hydroxyethyl)-D,L-aspartamide is synthesized by derivatization with rhodamine, polylactide, and poly(ethylene glycol), to obtain polyaspartamide-polylactide derivatives with different degrees of pegylation. Starting from these copolymers, fluorescent nanoparticles with different poly(ethylene glycol) content, empty and loaded with ibuprofen, showed spherical shape, colloidal size, slightly negative ζ potential, and biocompatibility toward human bronchial epithelial cells. The high surface poly(ethylene glycol) density of fluorescent nanoparticles and poly(ethylene glycol) brush-like conformation assumed on their surface, conferred to pegylated nanoparticles the mucus-penetrating properties, properly demonstrated by assessing their ability to avoid interactions with mucus components and to penetrate cystic fibrosis artificial mucus. Finally, ibuprofen release profile and uptake capacity within human bronchial epithelial cells in the presence of cystic fibrosis artificial mucus showed how these mucus-penetrating nanoparticles could rapidly diffuse through the mucus barrier reaching the mucosal surface, where they could offer a sustained delivery of ibuprofen at the site of disease.

  16. Human skin penetration and local effects of topical nano zinc oxide after occlusion and barrier impairment.

    Science.gov (United States)

    Leite-Silva, V R; Sanchez, W Y; Studier, H; Liu, D C; Mohammed, Y H; Holmes, A M; Ryan, E M; Haridass, I N; Chandrasekaran, N C; Becker, W; Grice, J E; Benson, H A E; Roberts, M S

    2016-07-01

    Public health concerns continue to exist over the safety of zinc oxide nanoparticles that are commonly used in sunscreen formulations. In this work, we assessed the effects of two conditions which may be encountered in everyday sunscreen use, occlusion and a compromised skin barrier, on the penetration and local toxicity of two topically applied zinc oxide nanoparticle products. Caprylic/capric triglyceride (CCT) suspensions of commercially used zinc oxide nanoparticles, either uncoated or with a silane coating, were applied to intact and barrier impaired skin of volunteers, without and with occlusion for a period of six hours. The exposure time was chosen to simulate normal in-use conditions. Multiphoton tomography with fluorescence lifetime imaging was used to noninvasively assess zinc oxide penetration and cellular metabolic changes that could be indicative of toxicity. We found that zinc oxide nanoparticles did not penetrate into the viable epidermis of intact or barrier impaired skin of volunteers, without or with occlusion. We also observed no apparent toxicity in the viable epidermis below the application sites. These findings were validated by ex vivo human skin studies in which zinc penetration was assessed by multiphoton tomography with fluorescence lifetime imaging as well as Zinpyr-1 staining and toxicity was assessed by MTS assays in zinc oxide treated skin cryosections. In conclusion, applications of zinc oxide nanoparticles under occlusive in-use conditions to volunteers are not associated with any measurable zinc oxide penetration into, or local toxicity in the viable epidermis below the application site.

  17. Ethical hacking and penetration testing guide

    CERN Document Server

    Baloch, Rafay

    2014-01-01

    Requiring no prior hacking experience, Ethical Hacking and Penetration Testing Guide supplies a complete introduction to the steps required to complete a penetration test, or ethical hack, from beginning to end. You will learn how to properly utilize and interpret the results of modern-day hacking tools, which are required to complete a penetration test. The book covers a wide range of tools, including Backtrack Linux, Google reconnaissance, MetaGooFil, dig, Nmap, Nessus, Metasploit, Fast Track Autopwn, Netcat, and Hacker Defender rootkit. Supplying a simple and clean explanation of how to effectively utilize these tools, it details a four-step methodology for conducting an effective penetration test or hack.Providing an accessible introduction to penetration testing and hacking, the book supplies you with a fundamental understanding of offensive security. After completing the book you will be prepared to take on in-depth and advanced topics in hacking and penetration testing. The book walks you through each ...

  18. Cable Braid Electromagnetic Penetration Model.

    Energy Technology Data Exchange (ETDEWEB)

    Warne, Larry K. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Langston, William L. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Basilio, Lorena I. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Johnson, W. A. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-06-01

    The model for penetration of a wire braid is rigorously formulated. Integral formulas are developed from energy principles and reciprocity for both self and transfer immittances in terms of potentials for the fields. The detailed boundary value problem for the wire braid is also setup in a very efficient manner; the braid wires act as sources for the potentials in the form of a sequence of line multipoles with unknown coefficients that are determined by means of conditions arising from the wire surface boundary conditions. Approximations are introduced to relate the local properties of the braid wires to a simplified infinite periodic planar geometry. This is used in a simplified application of reciprocity to be able to treat nonuniform coaxial geometries including eccentric interior coaxial arrangements and an exterior ground plane.

  19. Bodily action penetrates affective perception

    Directory of Open Access Journals (Sweden)

    Carlo Fantoni

    2016-02-01

    Full Text Available Fantoni & Gerbino (2014 showed that subtle postural shifts associated with reaching can have a strong hedonic impact and affect how actors experience facial expressions of emotion. Using a novel Motor Action Mood Induction Procedure (MAMIP, they found consistent congruency effects in participants who performed a facial emotion identification task after a sequence of visually-guided reaches: a face perceived as neutral in a baseline condition appeared slightly happy after comfortable actions and slightly angry after uncomfortable actions. However, skeptics about the penetrability of perception (Zeimbekis & Raftopoulos, 2015 would consider such evidence insufficient to demonstrate that observer’s internal states induced by action comfort/discomfort affect perception in a top-down fashion. The action-modulated mood might have produced a back-end memory effect capable of affecting post-perceptual and decision processing, but not front-end perception. Here, we present evidence that performing a facial emotion detection (not identification task after MAMIP exhibits systematic mood-congruent sensitivity changes, rather than response bias changes attributable to cognitive set shifts; i.e., we show that observer’s internal states induced by bodily action can modulate affective perception. The detection threshold for happiness was lower after fifty comfortable than uncomfortable reaches; while the detection threshold for anger was lower after fifty uncomfortable than comfortable reaches. Action valence induced an overall sensitivity improvement in detecting subtle variations of congruent facial expressions (happiness after positive comfortable actions, anger after negative uncomfortable actions, in the absence of significant response bias shifts. Notably, both comfortable and uncomfortable reaches impact sensitivity in an approximately symmetric way relative to a baseline inaction condition. All of these constitute compelling evidence of a genuine top

  20. Spatially resolved two-color diffusion measurements in human skin applied to transdermal liposome penetration.

    Science.gov (United States)

    Brewer, Jonathan; Bloksgaard, Maria; Kubiak, Jakub; Sørensen, Jens Ahm; Bagatolli, Luis A

    2013-05-01

    A multiphoton excitation-based fluorescence fluctuation spectroscopy method, Raster image correlation spectroscopy (RICS), was used to measure the local diffusion coefficients of distinct model fluorescent substances in excised human skin. In combination with structural information obtained by multiphoton excitation fluorescence microscopy imaging, the acquired diffusion information was processed to construct spatially resolved diffusion maps at different depths of the stratum corneum (SC). Experiments using amphiphilic and hydrophilic fluorescently labeled molecules show that their diffusion in SC is very heterogeneous on a microscopic scale. This diffusion-based strategy was further exploited to investigate the integrity of liposomes during transdermal penetration. Specifically, the diffusion of dual-color fluorescently labeled liposomes--containing an amphiphilic fluorophore in the lipid bilayer and a hydrophilic fluorophore encapsulated in the liposome lumen--was measured using cross-correlation RICS. This type of experiment allows discrimination between separate (uncorrelated) and joint (correlated) diffusion of the two different fluorescent probes, giving information about liposome integrity. Independent of the liposome composition (phospholipids or transfersomes), our results show a clear lack of cross-correlation below the skin surface, indicating that the penetration of intact liposomes is highly compromised by the skin barrier.

  1. A Multiple Scattering Theory for Proton Penetration

    Institute of Scientific and Technical Information of China (English)

    YANG Dai-Lun; WU Zhang-Wen; JIANG Steve-Bin; LUO Zheng-Ming

    2004-01-01

    @@ We extend the electron small-angle multiple scattering theory to proton penetration. After introducing the concept of narrow energy spectra, the proton energy loss process is included in the proton deep penetration theory. It precisely describes the whole process of proton penetration. Compared to the Monte Carlo method,this method maintains the comparable precision and possesses much higher computational efficiency. Thus, it shows the real feasibility of applying this algorithm to proton clinical radiation therapy.

  2. Feasibility of Penetrant Testing on Surface Axial-Radial Cracks of GH4169 Super Alloy Turbine Disk

    Directory of Open Access Journals (Sweden)

    QIAO Haiyan

    2016-12-01

    Full Text Available The post emulsifiable and water-washable fluorescent penetrant testing were carried out with ZL-27A and ZL67 respectively. Ultrasonic cleaning by detergent were used for 30 minutes before penetrant. The parts were immersed and drained for 60 minutes. The macroscopic and microscopic characteristics of cracks were researched using the split mirror and scanning electron microscope. The results show that the outgrowth of high temperature oxidation plugs up the forging cracks. Thus the penetrant testing is not effective in detecting this type of cracks.

  3. Standard practice for visible penetrant testing using the Water-Washable process

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice describes procedures for visible liquid penetrant examination utilizing the water-washable process. It is a nondestructive practice for detecting discontinuities that are open to the surface such as cracks, seams, laps, cold shuts, laminations, isolated porosity, through leaks or lack of fusion and is applicable to in-process, final, and maintenance examination. This practice can be effectively used in the examination of nonporous, metallic materials, both ferrous and nonferrous, and of nonmetallic materials such as glazed or fully densified ceramics, and certain nonporous plastics, and glass. 1.2 This practice also provides the following references: 1.2.1 A reference by which visible penetrant examination procedures using the water-washable process can be reviewed to ascertain their applicability and completeness. 1.2.2 For use in the preparation of process specifications dealing with the visible, water-washable liquid penetrant examination of materials and parts. Agreement between the user...

  4. In-place HEPA filter penetration test

    Energy Technology Data Exchange (ETDEWEB)

    Bergman, W.; Wilson, K.; Elliott, J. [Lawrence Livermore National Lab., CA (United States)] [and others

    1997-08-01

    We have demonstrated the feasibility of conducting penetration tests on high efficiency particulate air (HEPA) filters as installed in nuclear ventilation systems. The in-place penetration test, which is designed to yield equivalent penetration measurements as the standard DOP efficiency test, is based on measuring the aerosol penetration of the filter installation as a function of particle size using a portable laser particle counter. This in-place penetration test is compared to the current in-place leak test using light scattering photometers for single HEPA filter installations and for HEPA filter plenums using the shroud method. Test results show the in-place penetration test is more sensitive than the in-place leak test, has a similar operating procedure, but takes longer to conduct. Additional tests are required to confirm that the in-place penetration test yields identical results as the standard dioctyl phthalate (DOP) penetration test for HEPA filters with controlled leaks in the filter and gasket and duct by-pass leaks. Further development of the procedure is also required to reduce the test time before the in-place penetration test is practical. 14 refs., 14 figs., 3 tabs.

  5. Determination of fluorescent whitening agents in plastic food contact materials by high performance liquid chromatography with fluorescence detector%高效液相色谱-荧光检测法测定食品接触材料塑料制品中荧光增白剂

    Institute of Scientific and Technical Information of China (English)

    焦艳娜; 丁利; 朱绍华; 傅善良; 龚强; 李晖; 王利兵

    2013-01-01

    建立了同时测定食品接触材料塑料制品(食品包装袋)中荧光增白剂的高效液相色谱-荧光检测法.样品用20 mL 三氯甲烷作提取剂,超声提取30 min,提取温度为40℃,用高效液相色谱进行定性定量分析.采用EclipseXDB-C18(250 mm×4.6 mm,5μm)为分析柱,以5 mmol/L乙酸铵溶液和乙腈为流动相,梯度洗脱,荧光激发波长为350 nm,发射波长为430 nm.结果显示,4种荧光增白剂4,4'-双[2-(邻氰苯基)乙烯基]苯(1,4-bis(4-cyanostyryl) benzene,C.I.199)、1,4-双(2-苯并恶唑)萘(1,4-bis (2-benzoxazolyl) naphthalene,C.I.367)、4,4'-双(2-甲氧苯乙烯基)联苯(4,4'-bis(2-methoxystyryl)biphenyl,C.I.378)和2,5-双(5-叔丁基-2-苯并恶唑基)噻吩(2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole),C.I.184)可以较好地分离;检出限(S/N=3)分别为0.3、0.1、0.05、0.14 mg/L,定量限(S/N=10)分别为1.0、0.4、0.2、0.5 mg/L,回收率范围为78.9% ~ 101.1%,相对标准偏差小于10%,线性关系良好.该法简便、结果准确、灵敏度高,能够满足进出口食品包装材料塑料制品中荧光增白剂的日常检测.%A method for the determination of fluorescent whitening agents in plastic food contact materials by high performance liquid chromatography (HPLC) with fluorescence detector was developed. The samples were extracted with trichloromethane by sonication for 30 min at 40 ℃. The HPLC method was performed on a column of Eclipse XDB-C18 (250 mm ×4. 6 mm, 5 μm) by gradient elution using 5 mmol/L ammonium acetate and acetonitrile as the mobile phases, and detected by the fluorescence detector at an excitation wavelength of 350 nm and an emission wavelength of 430 nm. The experimental results indicated that the four fluorescent whitening agents were separated well. The limits of detection (LOD) (S/N = 3) were 0. 3 , 0. 1, 0. 05 , 0. 14 mg/L, and the limits of quantification (LOQ) (S/N = 10) were 1.0, 0. 4, 0. 2, 0. 5 mg/L for 1, 4-bis (4-cyanostyryl

  6. Comparative analysis of the effects of CO2 fractional laser and sonophoresis on human skin penetration with 5-aminolevulinic acid.

    Science.gov (United States)

    Choi, J H; Shin, E J; Jeong, K H; Shin, M K

    2017-08-19

    Successful delivery of a photosensitizer into the skin is an important factor for effective photodynamic therapy (PDT). The effective method to increase drug penetration within short incubation time overcoming skin barrier have been investigated. This study was performed to analyze and compare the effectiveness of ablative fractional laser (FXL) pretreatment and/or sonophoresis for enhancing the penetration of 5-aminolevulinic acid (ALA) into human skin in vivo. Twenty-four identical 1 × 1 cm(2) treatment areas were mapped on the backs of ten healthy male subjects. Each area received FXL pretreatment and/or sonophoresis with different energy settings and ALA incubation times. After treatments, porphyrin fluorescence reflecting the ALA penetration were measured. Application of ablative CO2 FXL pretreatment resulted to higher fluorescence intensities than the non-treatment group. Incubation times were positively correlated with the increments of ALA penetration. However, increasing pulse energy or combining with sonophoresis did not show additional positive effects on ALA penetration. Ablative CO2 FXL pretreatment effectively facilitated ALA penetration in human skin in vivo. Ablative CO2 FXL alone without sonophoresis setting pulse energy of 10 and 20 mJ with more than 60 min of ALA incubation time could be an ideal setting for ALA penetration.

  7. 高效液相色谱荧光检测法测定豆芽中尿素含量%Determination of Urea Residue in Soybean Sprouts Using High-performance Liquid Chromatography with Fluorescence Detection

    Institute of Scientific and Technical Information of China (English)

    宋薇; 宋桂雪; 李荣斌; 陈晓旭; 赵永彪

    2014-01-01

    A method of urea contents in soybean sprouts tested using high performance liquid chromatography fluorescence detection was developed. Samples were extracted using ethanol, derivatized with acidic xanthydrol solution and separated with RP C18 column, the mobile phases were acetonitrile and 0.02 mol/L sodium acetate solution, performed with gradient elution and determined with fluorescence detection atλex 213 nm andλem 308 nm. The results showed there was a good linear correlation for peak areas and urea contents in the range of 1.0 mg/L-50 mg/L;the r2 was greater than 0.999. The limit of detection (S/N=3) was 0.5 mg/kg.When spiked with 5, 25 and 50 mg/kg, the spiked recoveries were 98.5%-106%, respectively, RSD%was less than 4%. Urea contents of lab germinated soybean sprouts, green food labeled and bulk soybean sprouts purchased in market were in the range of 3.5-14.1 (n=6), 5.7-10.4 (n=4) and 7.6-148 (n=35) mg/kg, respectively. It is a simple accurate, sensitive and highly specific method with good reproducibility.%建立了高效液相色谱荧光检测法测定豆芽中尿素的方法。样品用乙醇提取,提取液在酸性条件下用呫吨氢醇衍生,衍生产物经Agilent Eclipse XDB-C18柱(150 mm ×4.6 mm,5μm)分离,乙腈和0.02 mol/L乙酸钠溶液为流动相,梯度洗脱,荧光检测器检测波长λex 213 nm和λem 308 nm。结果表明:尿素的质量浓度在1.0 mg/L~50 mg/L范围内,峰面积与质量浓度呈良好的线性关系,r2大于0.999,方法检出限为(S/N=3)0.5 mg/kg;尿素添加浓度为5、25、50 mg/kg时,加标回收率98.5%~106%,RSD%小于4%。采用该方法检测实验室自发豆芽、绿色食品标签豆芽和市售散装豆芽(绿豆芽和黄豆芽)尿素含量不等,浓度范围分别在3.5 mg/kg~14.1 mg/kg(n=6),5.7 mg/kg~10.4 mg/kg(n=4)和7.6 mg/kg~148 mg/kg (n=35)。该方法简便、准确、灵敏、专一性强、重现性好。

  8. Influence of jet thrust on penetrator penetration when studying the structure of space object blanket

    Directory of Open Access Journals (Sweden)

    N. A. Fedorova

    2014-01-01

    Full Text Available The article presents the calculation-and-theory-based research results to examine the possibility for using the jet thrust impulse to increase a penetration depth of high-velocity penetrator modules. Such devices can be used for studies of Earth surface layer composition, and in the nearest future for other Solar system bodies too. Research equipment (sensors and different instruments is housed inside a metal body of the penetrator with a sharpened nose that decreases drag force in soil. It was assumed, that this penetrator is additionally equipped with the pulse jet engine, which is fired at a certain stage of penetrator motion into target.The penetrator is considered as a rigid body of variable mass, which is subjected to drag force and reactive force applied at the moment the engine fires. A drag force was represented with a binomial empirical law, and penetrator nose part was considered to be conical. The jet thrust force was supposed to be constant during its application time. It was in accordance with assumption that mass flow and flow rate of solid propellant combustion products were constant. The amount of propellant in the penetrator was characterized by Tsiolkovsky number Z, which specifies the ratio between the fuel mass and the penetrator structure mass with no fuel.The system of equations to describe the penetrator dynamics was given in dimensionless form using the values aligned with penetration of an equivalent inert penetrator as the time and penetration depth scales. Penetration dynamics of penetrator represented in this form allowed to eliminate the influence of penetrator initial mass and its cross-section diameter on the solution results. The lack of such dependency is convenient for comparing the calculation results since they hold for penetrators of various initial masses and cross-sections.To calculate the penetration a lunar regolith was taken as a soil material. Calculations were carried out for initial velocities of

  9. Simultaneous analysis of aspartame and its hydrolysis products of Coca-Cola Zero by on-line postcolumn derivation fluorescence detection and ultraviolet detection coupled two-dimensional high-performance liquid chromatography.

    Science.gov (United States)

    Cheng, Cheanyeh; Wu, Shing-Chen

    2011-05-20

    An innovative two-dimensional high-performance liquid chromatography system was developed for the simultaneous analysis of aspartame and its hydrolysis products of Coca-Cola Zero. A C8 reversed-phase chromatographic column with ultraviolet detection was used as the first dimension for the determination of aspartame, and a ligand-exchange chromatographic column with on-line postcolumn derivation fluorescence detection was employed as the second dimension for the analysis of amino acid enantiomers. The fluorimetric derivative reagent of amino acid enantiomers was o-phthaldialdehyde. The hydrolysis of aspartame in Coca-Cola Zero was induced by electric-heating or microwave heating. Aspartame was quantified by the matrix matched external standard calibration curve with a linear concentration range of 0-50 μg mL(-1) (r(2)=0.9984). The limit of detection (LOD) and the limit of quantification (LOQ) were 1.3 μg mL(-1) and 4.3 μg mL(-1), respectively. The amino acid enantiomers was analyzed by the matrix matched internal standard calibration method (D-leucine as the internal standard) with a linear concentration range of 0-10 μg mL(-1) (r(2)=0.9988-0.9997). The LODs and LOQs for L- and D-aspartic acid and L- and D-phenylalanine were 0.16-0.17 μg mL(-1) and 0.52-0.55 μg mL(-1), respectively, that was 12-13 times more sensitive than ultraviolet detection. The overall analysis accuracy for aspartame and amino acid enantiomers was 90.2-99.2% and 90.4-96.2%, respectively. The overall analysis precision for aspartame and amino acid enantiomers was 0.1-1.7% and 0.5-6.7%, respectively. Generally, the extent of aspartame hydrolysis increases with the increase of electro-thermal temperature, microwave power, and the duration of hydrolysis time. D-aspartic acid and D-phenylalanine can be observed with the electro-thermal racemization at the hydrolysis temperature 120°C for 1 day and only D-aspartic acid can be observed at the hydrolysis temperature 90°C for 2 and 3 days. For

  10. Drop spreading and penetration into pre-wetted powders

    KAUST Repository

    Marston, Jeremy

    2013-05-01

    We present results from an experimental study of the impact of liquid drops onto powder beds which are pre-wetted with the impacting liquid. Using high-speed video imaging, we study both the dynamics of the initial spreading regime and drainage times once the drop has reached its maximum spread on the surface. During the initial spreading stage, we compare our experimental data to a previously developed model which incorporates imbibition into the spreading dynamics and observe reasonable agreement. We find that the maximum spread is a strong function of the moisture content in the powder bed and that the total time from impact to complete drainage is always shorter than that for dry powder. Our results indicate that there is an optimum moisture content (or saturation) which leads to the fastest penetration. We use simple scaling arguments which also identify an optimum moisture content for fastest penetration, which agrees very well with the experimental result. © 2013 Elsevier B.V.

  11. Penetration profile of microspheres in follicular targeting of terminal hair follicles.

    Science.gov (United States)

    Toll, R; Jacobi, U; Richter, H; Lademann, J; Schaefer, H; Blume-Peytavi, U

    2004-07-01

    The transfollicular administration of pharmacologically active molecules is of current therapeutic interest, mainly with regard to delivery to specific sites of the hair follicle (HF) and the reduction of hepatic metabolism and systemic toxicity. HF are privileged pathways for specific molecules depending on formulations, which enter faster into these shunts than through the stratum corneum. The aim was to optimize the delivery of fluorescent microspheres into the HF, thereby, developing a standardized protocol for follicular targeting with microspheres. The number of HF showing penetration, as well as the depth of penetration, was determined. Freshly excised skin samples with terminal HF were divided into groups, with or without prior treatment with cyanoacrylate skin surface stripping-technique (CSSS). Thereafter microspheres at a size of 0.75-6.0 microm were applied according to the developed standardized protocol. Skin biopsies were obtained, shock-frozen, and sectioned in 5 microm slices. We demonstrated a selective penetration route of the microspheres into the HF. Optimal microsphere size proved to be approximately 1.5 microm, with a 55% rate of all HF, and with a maximum penetration depth of >2300 microm. Without previous CSSS treatment of the skin, the transfollicular microsphere penetration was below 27% with a maximum penetration depth of 1000 microm. Thus, the basis for follicular targeting of essential structures containing stem cells for keratinocytes, melanocytes, and mast cells has been laid.

  12. Penetration and performance of isocyanate wood binders on selected wood species

    Directory of Open Access Journals (Sweden)

    Gruver, T. M., and

    2006-11-01

    Full Text Available The penetration and performance of polymeric diphenylmethane diisocyanate (pMDI wood binder was investigated according to three factors: substrate species (aspen, yellow-poplar, or southern yellow pine; anatomical bonding plane (radial or tangential; and moisture content (0%, 5%, or 12%. Compression shear block tests and fluorescence microscopy were used to examine bond performance and resin penetration. Statistically, each of the aforementioned factors impacted results. As moisture content increased, observed bond strengths and wood failure increased. Bond formation did not occur when the substrates were equilibrated to 0% moisture content, except for the radial bonding surfaces of pine, which did adhere. At 5 and 12% moisture contents, tangential bonding surfaces out-performed radial bonding surfaces. In terms of resin penetration, moisture content was clearly the most important variable. Little penetration was observed at 0% moisture content, while extensive resin penetration was observed at elevated moisture contents. Pine was the only wood species to exhibit resin flow through radial cells, possibly explaining the enhanced resin penetration depths observed in pine samples.

  13. The isolated perfused human skin flap model: A missing link in skin penetration studies?

    Science.gov (United States)

    Ternullo, Selenia; de Weerd, Louis; Flaten, Gøril Eide; Holsæter, Ann Mari; Škalko-Basnet, Nataša

    2017-01-01

    Development of effective (trans)dermal drug delivery systems requires reliable skin models to evaluate skin drug penetration. The isolated perfused human skin flap remains metabolically active tissue for up to 6h during in vitro perfusion. We introduce the isolated perfused human skin flap as a close-to-in vivo skin penetration model. To validate the model's ability to evaluate skin drug penetration the solutions of a hydrophilic (calcein) and a lipophilic (rhodamine) fluorescence marker were applied. The skin flaps were perfused with modified Krebs-Henseleit buffer (pH7.4). Infrared technology was used to monitor perfusion and to select a well-perfused skin area for administration of the markers. Flap perfusion and physiological parameters were maintained constant during the 6h experiments and the amount of markers in the perfusate was determined. Calcein was detected in the perfusate, whereas rhodamine was not detectable. Confocal images of skin cross-sections shoved that calcein was uniformly distributed through the skin, whereas rhodamine accumulated in the stratum corneum. For comparison, the penetration of both markers was evaluated on ex vivo human skin, pig skin and cellophane membrane. The proposed perfused flap model enabled us to distinguish between the penetrations of the two markers and could be a promising close-to-in vivo tool in skin penetration studies and optimization of formulations destined for skin administration.

  14. Penetration of resin-based materials into initial erosion lesion: A confocal microscopic study.

    Science.gov (United States)

    Ionta, Franciny Querobim; Boteon, Ana Paula; Moretto, Marcelo Juliano; Júnior, Odair Bim; Honório, Heitor Marques; Silva, Thiago Cruvinel; Wang, Linda; Rios, Daniela

    2016-02-01

    The application of resin-based materials is an alternative of treatment for eroded lesions. Nevertheless, there are no studies about the penetration of these materials into eroded lesion, which might affect its adhesion. Therefore, this study evaluated the penetration of four resin-based materials, with and without enamel etching. By using an in vitro protocol, types of treatment were studied at five levels (AdheSE(®) , Tetric N-Bond(®) , Single Bond 2(®) , Helioseal Clear(®) , Icon(®) ) and types of enamel etching in two levels (with and without). Materials were stained with 0.02 mg/mL ethanolic solution of tetramethylrhodamine isothiocyanate. Bovine enamel samples (4 × 4 mm) were immersed in 0.01 M HCl, pH 2.3, for 30 seconds to produce initial eroded lesions. Afterward, the materials were applied on half of sample enamel surface following the manufacturer's instructions. On the other half of sample, the materials were applied without etching the enamel. Materials penetration into the enamel was assessed by Confocal Laser Scanning Microscopy on reflection and fluorescence modes. The penetration depth (PD) was measured using ImageJ software. Data were analyzed by two-way ANOVA and Tukey test (P material, etched enamel resulted in higher PD than non-etched (P  0.05). It can be concluded that prior enamel etching increased the materials penetration into eroded enamel and the Icon(®) -infiltrant presented highest penetration.

  15. Penetrating Moral Education in English Teaching

    Institute of Scientific and Technical Information of China (English)

    汪中跃

    2015-01-01

    Middle school students’ moral education is not ful y implemented or even ignored in the present English teaching,so in this paper,the importance of penetrating the cultivation of middle school students’ moral education in English teaching is analyzed,the strategies of penetrating moral education are discussed and the significance is also pointed out.

  16. Quantitative penetration testing with item response theory

    NARCIS (Netherlands)

    Arnold, Florian; Pieters, Wolter; Stoelinga, Mariëlle

    2014-01-01

    Existing penetration testing approaches assess the vulnerability of a system by determining whether certain attack paths are possible in practice. Thus, penetration testing has so far been used as a qualitative research method. To enable quantitative approaches to security risk management, including

  17. Quantitative penetration testing with item response theory

    NARCIS (Netherlands)

    Pieters, W.; Arnold, F.; Stoelinga, M.I.A.

    2013-01-01

    Existing penetration testing approaches assess the vulnerability of a system by determining whether certain attack paths are possible in practice. Therefore, penetration testing has thus far been used as a qualitative research method. To enable quantitative approaches to security risk management, in

  18. Quantitative penetration testing with item response theory

    NARCIS (Netherlands)

    Arnold, Florian; Pieters, Wolter; Stoelinga, Mariëlle

    2013-01-01

    Existing penetration testing approaches assess the vulnerability of a system by determining whether certain attack paths are possible in practice. Thus, penetration testing has so far been used as a qualitative research method. To enable quantitative approaches to security risk management, including

  19. Endoscopic biopsy: Duodenal ulcer penetrating into liver

    Institute of Scientific and Technical Information of China (English)

    Baybora Kircali; Tülay Saricam; Aysegul Ozakyol; Eser Vardareli

    2005-01-01

    @@ TO THE EDITOR We have read with interest the recent report by E Kayacetin and S Kayacetin of Gastric ulcer penetrating to liver diagnosed by endoscopic biopsy[1] since we diagnosed the duodenal ulcer which penetrated into liver similarly. This is a rather unusual case because of the fifth case in the literature and responding to medical therapy.

  20. Efficient Calculation of Earth Penetrating Projectile Trajectories

    Science.gov (United States)

    2006-09-01

    CALCULATION OF EARTH PENETRATING PROJECTILE TRAJECTORIES by Daniel F . Youch September 2006 Thesis Advisor: Joshua Gordis... Daniel F . Youch 5. FUNDING NUMBERS 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval Postgraduate School Monterey, CA 93943-5000 8. PERFORMING...EFFICIENT CALCULATION OF EARTH PENETRATING PROJECTILE TRAJECTORIES Daniel F . Youch Lieutenant Commander, United States Navy B.S., Temple

  1. 分散液液微萃取-衍生化高效液相色谱-荧光检测法测定环境水样中4种酚类内分泌干扰物%Determination of four phenolic endocrine disruptors in environmental water samples by high performance liquid chromatography-fluorescence detection using dispersive liquid-liquid microextraction coupled with derivatization

    Institute of Scientific and Technical Information of China (English)

    王晓燕; 亓伟梅; 赵先恩; 吕涛; 王西亚; 郑龙芳; 闫业浩; 尤进茂

    2014-01-01

    为实现小体积环境水样中酚类化合物的准确、快速、高灵敏测定,通过分散液液微萃取( DLLME)和荧光衍生化的结合,建立了高效液相色谱-荧光检测(HPLC-FLD)双酚 A、壬基酚、辛基酚和对特辛基酚的分析方法。考察并优化了 DLLME 和衍生化条件,结果表明,最优的 DLLME 条件为萃取剂氯仿用量70μL,分散剂乙腈用量400μL,漩涡振荡3 min,高速离心2 min。以2-[2-(7H-二苯并[a,g]咔唑-乙氧基)]-乙基氯甲酸酯(DBCEC-Cl)为柱前衍生试剂,在 pH 10.5的 Na2 CO3-NaHCO 3缓冲液/乙腈溶液、50℃下衍生反应3 min 得到稳定的衍生产物,于10 min 内实现了4种酚衍生物的分离。方法的检出限为0.9~1.6 ng / L,定量限为3.8~7.1 ng / L,具有良好的线性、精密度和回收率,与以往报道的方法相比具有一定的优势和实用性,可用于造纸厂废水、湖水、生活废水、自来水中4种酚类内分泌干扰物的测定。%To achieve accurate,fast and sensitive detection of phenolic endocrine disruptors in small volume of environmental water samples,a method of dispersive liquid-liquid microextrac-tion(DLLME)coupled with fluorescent derivatization was developed for the determination of bisphenol A,nonylphenol,octylphenol and 4-tert-octylphenol in environmental water samples by high performance liquid chromatography-fluorescence detection( HPLC-FLD). The DLLME and derivatization conditions were investigated,and the optimized DLLME conditions for small volume of environmental water samples(pH 4. 0)at room temperature were as follows:70 μL chloroform as extraction solvent,400 μL acetonitrile as dispersing solvent,vortex mixing for 3 min,and then high-speed centrifugation for 2 min. Using 2-[2-(7H-dibenzo[ a,g]carbazol-7-yl)-ethoxy]ethyl chloroformate( DBCEC-Cl)as precolumn derivatization reagent,the stable derivatives of the four phenolic endocrine disruptors were obtained in pH 10. 5 Na

  2. Measurement of the Depth of Penetration of UV Photons into Mars Relevant Rock Samples to Constrain Habitability and Limits of Detection for the SHERLOC Mars 2020 Instrument

    Science.gov (United States)

    Carrier, B. L.; Beegle, L. W.; Bhartia, R.; Abbey, W. J.

    2015-12-01

    We report on the depth of penetration of UV photons into a suite of Mars relevant materials in order to better characterize what constitutes a habitable environment on Mars, as well as to characterize the sensitivities of the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument on the Mars 2020 payload. To date, UV transparency of these rock types have not been fully characterized, and we have performed a systematic study to better constrain the UV attenuation over a wide range of materials relevant to Mars. At one point during the history of Mars, the surface may have been habitable, with flowing liquid water and access to food and energy sources. As surface conditions changed, it is not unreasonable to assume that life would have migrated into the protected interior of porous rocks, veins, fissures, and the subsurface as a means to protect itself from harsh surface conditions, such as the UV flux that we observe today. Given geological time, the depth that UV light penetrates into the subsurface will play a role in altering and/or effecting the preservation of organic molecule containing biosignatures. However, the extent to which various rock types can shield organic material currently is not well understood. In addition to constraining the UV-driven habitable "zone", the data also helps constrain the SHERLOC instrument limits of detection. SHERLOC is a deep UV fluorescence and Raman imaging instrument. This is achieved by spatially scanning a deep UV laser at 248.6 nm to stimulate fluorescence emissions and Raman scattering from the sample. Specifically, fluorescence is generated from electronic transition from aromatic organics and Raman scatter is generated from vibrational bonds from both organics and minerals. Given the excitation wavelength, and the emission/scattering wavelengths (250-350), the mineral transparency will affect the interrogation volume of analysis and thus constrain the limits of

  3. Modelling of microcracks image treated with fluorescent dye

    Science.gov (United States)

    Glebov, Victor; Lashmanov, Oleg U.

    2015-06-01

    The main reasons of catastrophes and accidents are high level of wear of equipment and violation of the production technology. The methods of nondestructive testing are designed to find out defects timely and to prevent break down of aggregates. These methods allow determining compliance of object parameters with technical requirements without destroying it. This work will discuss dye penetrant inspection or liquid penetrant inspection (DPI or LPI) methods and computer model of microcracks image treated with fluorescent dye. Usually cracks on image look like broken extended lines with small width (about 1 to 10 pixels) and ragged edges. The used method of inspection allows to detect microcracks with depth about 10 or more micrometers. During the work the mathematical model of image of randomly located microcracks treated with fluorescent dye was created in MATLAB environment. Background noises and distortions introduced by the optical systems are considered in the model. The factors that have influence on the image are listed below: 1. Background noise. Background noise is caused by the bright light from external sources and it reduces contrast on the objects edges. 2. Noises on the image sensor. Digital noise manifests itself in the form of randomly located points that are differing in their brightness and color. 3. Distortions caused by aberrations of optical system. After passing through the real optical system the homocentricity of the bundle of rays is violated or homocentricity remains but rays intersect at the point that doesn't coincide with the point of the ideal image. The stronger the influence of the above-listed factors, the worse the image quality and therefore the analysis of the image for control of the item finds difficulty. The mathematical model is created using the following algorithm: at the beginning the number of cracks that will be modeled is entered from keyboard. Then the point with random position is choosing on the matrix whose size is

  4. In vitro investigation of the follicular penetration of porcine ear skin using a nanoparticle-emulsion containing the antiseptic polihexanide In vitro investigation of the follicular penetration of porcine ear skin

    Science.gov (United States)

    Ulmer, M.; Patzelt, A.; Vergou, T.; Lademann, J.; Richter, H.; Kramer, A.; Müller, G.; Sterry, W.; Lange-Asschenfeldt, B.

    2012-05-01

    Earlier investigations regarding the distribution of the bacterial flora on the human skin demonstrate that the hair follicle acts as a bacterial reservoir, providing a quick source for secondary recontamination. These findings highlight the importance of the hair follicle as a target for modern antiseptics. In the present study, we have assessed the follicular penetration of a curcumin-labeled particle-associated antiseptic into porcine skin by laser scanning microscopy. Therefore, the follicular penetration depth of the curcumin-labeled particle-associated antiseptic was compared to the follicular penetration depth of curcumin-labeled particles without antiseptic. The investigation was performed in vitro using porcine skin biopsies. By superposition of the images acquired in the transmission and the fluorescent modus, it was possible to visualize the distribution of the fluorescent dye inside the hair follicles. Quantitative and qualitative results showed that both dispersions penetrated efficiently into the hair follicles. The average penetration depth of the particles with attached antiseptic polihexanide was significantly higher than that of particles without the attached antiseptic. Also, whilst very little sample preparation was needed, laser scanning microscopy was found to be an efficient tool to visualize the skin relief and in particular the hair follicle shaft and localize fluorescent markers within the skin tissue and hair follicles.

  5. THE PENETRATION OF VESICANT VAPORS INTO HUMAN SKIN.

    Science.gov (United States)

    Nagy, S M; Golumbic, C; Stein, W H; Fruton, J S; Bergmann, M

    1946-07-20

    Analytical methods which are accurate to about 1 per cent have been developed for the determination of small amounts (ca. 500 gamma) of bis(beta-chloroethyl)-sulfide (H), ethyl-bis(beta-chloroethyl)amine (EBA), tris(beta-chloroethyl)amine (TBA), beta-chloroethyl-benzylsulfide (benzyl-H), and beta-chloroethyl-ethylsulfide (ethyl-H). The determinations are made by micro titration of the HCl liberated upon complete hydrolysis of the vesicants. A description is given of an apparatus suitable for applying vapors of vesicants to unit areas of skin. A very precise and reproducible micropipetting technique is described for the introduction of the vesicants into the penetration apparatus. By means of this penetration apparatus studies have been made of several factors which may influence the rate at which vesicant vapors penetrate into skin. Model experiments have been performed in which H was allowed to vaporize and the vapor was absorbed on a surface such as that of diethylene glycol or vaseline. It has been found that if the surface of liquid H is increased by spreading the agent on filter paper, the rate of evaporation is markedly increased. Furthermore, if the vapor is agitated by means of a magnetically driven fan, the rate of absorption by diethylene glycol is greatly accelerated. With vaseline as the absorbing surface it has been found that the area of the absorbing surface has an effect on the rate of absorption of H vapor. More H is absorbed by vaseline spread on filter paper to give a rough surface than is absorbed by a smooth film of vaseline. Measurements of the rate of penetration into human skin of H, EBA, TBA, benzyl-H, and ethyl-H vapors have been performed at 21-23 degrees C. and 30-31 degrees C. by means of the penetration apparatus described in this paper. The measurements were carred out on human volunteers under conditions of controlled temperature and humidity. When human skin is exposed to air saturated with H vapor, the H penetrates the skin of the

  6. Quantitative wood-adhesive penetration with X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Paris, Jesse L.; Kamke, Frederick A. [Oregon State U.

    2017-03-21

    Micro X-ray computed tomography (XCT) was used to analyze the 3D adhesive penetration behavior of different wood–adhesive bondlines. Three adhesives, a phenol formaldehyde (PF), a polymeric diphenylmethane diisocyanate (pMDI), and a hybrid polyvinyl acetate (PVA), all tagged with iodine for enhanced X-ray attenuation, were used to prepare single-bondline laminates in two softwoods, Douglas-fir and loblolly pine, and one hardwood, a hybrid polar. Adhesive penetration depth was measured with two separate calculations, and results were compared with 2D fluorescent micrographs. A total of 54 XCT scans were collected, representing six replicates of each treatment type; each replicate, however, consisted of approximately 1500 individual, cross-section slices stacked along the specimen length. As these adhesives were highly modified, the presented results do not indicate typical behavior for their broader adhesive classes. Still, clear penetration differences were observed between each adhesive type, and between wood species bonded with both the PF and pMDI adhesives. Furthermore, penetration results depended on the calculation method used. Two adhesive types with noticeably different resin distributions in the cured bondline, showed relatively similar penetration depths when calculated with a traditional effective penetration equation. However, when the same data was calculated with a weighted penetration calculation, which accounts for both adhesive area and depth, the results appeared to better represent the different distributions depicted in the photomicrographs and tomograms. Additionally, individual replicate comparisons showed variation due to specimen anatomy, not easily observed or interpreted from 2D images. Finally, 3D views of segmented 3D adhesive phases offered unique, in-situ views of the cured adhesive structures. In particular, voids formed by CO2 bubbles generated during pMDI cure were clearly visible in penetrated columns of the solidified

  7. 液相色谱-串联质谱法分析爆米花桶水浸泡液中的荧光增白剂%Analysis of Fluorescent Substance Migration of Popcorn Cup by Liquid Chromatography-tandem Mass Spectrometry Method

    Institute of Scientific and Technical Information of China (English)

    刘峻; 李军; 李建中; 秦紫明

    2013-01-01

    使用液相色谱-串联质谱(LC-MS)的方法测试了市面的爆米花桶中荧光增白剂的种类和含量,实验选用VBL、APC、SPP、APH 4种荧光增白剂作为目标化合物,在信噪比为10(S/N=10)的条件下,4种荧光增白剂的检出限均小于10 ng/mL,相对标准偏差(RSD) <10%.实验初步表明,本次上海地区含荧光增白剂的爆米花桶中添加的荧光增白剂均为APC,可迁移量从0.653 mg/kg到23.166 mg/kg不等.该方法可以有效分离荧光增白剂,并对其进行定性定量判定.%This experiment use liquid chromatography-tandem mass spectrometry (LC-MS) to test the type and content of the fluorescent substance in the popcorn cups in the market. VBL, APC, SPP, APH four fluorescent brighteners were identified as the target compound. 10 times of the signal-to-noise ratio was used to confirm the detection limit, and all fluorescent brighteners' limits were less than 10 ng /mL, the method precision (RSD) was < 10%. It proved that the fluorescent substances added in the examined popcorn cups were APC. The migration amounts ranged from 0.653 mg/kg to 23.166 mg/kg. The method can effectively separate the fluorescent substance and further be defined qualitatively and quantitatively.

  8. Modeling pollutant penetration across building envelopes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, De-Ling; Nazaroff, William W.

    2001-04-01

    As air infiltrates through unintentional openings in building envelopes, pollutants may interact with adjacent surfaces. Such interactions can alter human exposure to air pollutants of outdoor origin. We present modeling explorations of the proportion of particles and reactive gases (e.g., ozone) that penetrate building envelopes as air enters through cracks and wall cavities. Calculations were performed for idealized rectangular cracks, assuming regular geometry, smooth inner crack surface and steady airflow. Particles of 0.1-1.0 {micro}m diameter are predicted to have the highest penetration efficiency, nearly unity for crack heights of 0.25 mm or larger, assuming a pressure difference of 4 Pa or greater and a flow path length of 3 cm or less. Supermicron and ultrafine particles are significantly removed by means of gravitational settling and Brownian diffusion, respectively. In addition to crack geometry, ozone penetration depends on its reactivity with crack surfaces, as parameterized by the reaction probability. For reaction probabilities less than {approx}10{sup -5}, penetration is complete for cracks heights greater than 1 mm. However, penetration through mm scale cracks is small if the reaction probability is {approx}10{sup -4} or greater. For wall cavities, fiberglass insulation is an efficient particle filter, but particles would penetrate efficiently through uninsulated wall cavities or through insulated cavities with significant airflow bypass. The ozone reaction probability on fiberglass fibers was measured to be 10{sup -7} for fibers previously exposed to high ozone levels and 6 x 10{sup -6} for unexposed fibers. Over this range, ozone penetration through fiberglass insulation would vary from >90% to {approx}10-40%. Thus, under many conditions penetration is high; however, there are realistic circumstances in which building envelopes can provide substantial pollutant removal. Not enough is yet known about the detailed nature of pollutant penetration

  9. Sphere impact and penetration into wet sand

    Science.gov (United States)

    Marston, J. O.; Vakarelski, I. U.; Thoroddsen, S. T.

    2012-08-01

    We present experimental results for the penetration of a solid sphere when released onto wet sand. We show, by measuring the final penetration depth, that the cohesion induced by the water can result in either a deeper or shallower penetration for a given release height compared to dry granular material. Thus the presence of water can either lubricate or stiffen the granular material. By assuming the shear rate is proportional to the impact velocity and using the depth-averaged stopping force in calculating the shear stress, we derive effective viscosities for the wet granular materials.

  10. Earthquakes induced by deep penetrating bombing?

    Institute of Scientific and Technical Information of China (English)

    Serguei Yu. Balassanian

    2005-01-01

    The data of M≥5 earthquakes occurred in one year before and after 4 deep penetrating bombs in the region within 500 km and 1 000 km from the shooting site are presented. The 4 bombs are those happened in 1999 Kosovo of Yugoslavia, the 1991 Baghdad of Iraq, the 2001 Tora Bora of Afghanistan, and the 2003 Kirkuk of Iraq, respectively. The data indicate that the deep penetrating bombs may have remotely triggered some earthquakes. The deep penetrating bombs in seismically active regions should be forbidden.

  11. Percutaneous penetration studies for risk assessment

    DEFF Research Database (Denmark)

    Sartorelli, Vittorio; Andersen, Helle Raun; Angerer, Jürgen

    2000-01-01

    . In order to predict the systemic risk of dermally absorbed chemicals and to enable agencies to set safety standards, data is needed on the rates of percutaneous penetration of important chemicals. Standardization of in vitro tests and comparison of their results with the in vivo data could produce...... of percutaneous penetration. This paper is an outcome of the meetings of the Percutaneous Penetration Subgroup and reports the presentations on the key issues identified throughout the 3-year duration of the Dermal Exposure Network (1997-1999)....

  12. Sphere impact and penetration into wet sand

    KAUST Repository

    Marston, J. O.

    2012-08-07

    We present experimental results for the penetration of a solid sphere when released onto wet sand. We show, by measuring the final penetration depth, that the cohesion induced by the water can result in either a deeper or shallower penetration for a given release height compared to dry granular material. Thus the presence of water can either lubricate or stiffen the granular material. By assuming the shear rate is proportional to the impact velocity and using the depth-averaged stopping force in calculating the shear stress, we derive effective viscosities for the wet granular materials.

  13. Simulated meteoroid penetration of reusable surface insulation

    Science.gov (United States)

    Lehman, J. K.; Christensen, H. E.

    1973-01-01

    Meteoroid impact simulation test results on insulation tiles were used to determine penetration resistance of reusable surface insulation attached to simulated shuttle structures. The probability of no meteoroid damage to a typical shuttle orbiter was determined. Specimens were plasma jet tested to determine effects of various size meteoroid cavities on their thermal performance. None of the tiles failed catastrophically, but large, egg-shaped craters did result from meteoroid penetration. The metallic side of a specimen that was completely penetrated showed a petalled hole typical for thin gage shielded structures.

  14. Relationship between DIAGNOdent values and sealant penetration depth on occlusal fissures.

    Science.gov (United States)

    Rodrigues, Jonas A; Diniz, Michele B; Hug, Isabel; Cordeiro, Rita C L; Lussi, Adrian

    2010-12-01

    The aim of this in vitro study was to evaluate the relationship between laser fluorescence values and sealant penetration depth on occlusal fissures. One hundred and sixty-six permanent molars were selected and divided into four groups, which were each treated using a different sealant (two clear and two opaque). The teeth were independently measured twice by two experienced dentists using two laser fluorescence devices-DIAGNOdent (LF and LFpen)-before and after sealing, and then thermoclycled. After measuring, the teeth were histologically prepared and assessed for caries extension. Digital photographs of the cut sealed sites were assessed, and the sealant penetration depth was measured. All 166 sites were measured by one of the examiners taking as limits the outer and inner surface of the sealant into the fissure. For each device (LF and LFpen) and each group, the difference between the values at baseline and after sealing was plotted against the sealant penetration depth and scatter plots were provided. It could be observed that most of the points were concentrated around the zero line, for both LF and LFpen in the four groups. In conclusion, there is no relation between changes in DIAGNOdent values and increasing of depth sealant penetration within the occlusal fissures.

  15. Discovery and characterization of a new cell-penetrating protein.

    Science.gov (United States)

    Simeon, Rudo L; Chamoun, Ana Maria; McMillin, Thomas; Chen, Zhilei

    2013-12-20

    We describe a new cell-penetrating protein, B1, capable of delivering conjugated proteins and nucleic acids into mammalian cells. B1 is a 244-amino-acid product of a single-base frameshift in the gene encoding enhanced green fluorescent protein (eGFP). The molecule has a net positive charge of 43 and a very high charge-to-mass ratio of 1.5. eGFP-fused B1 potently penetrates both adherent and suspension cells with >80% of cells taking up the protein when exposed to concentrations as low as 1 μM. The protein was found to cluster in the paranuclear region of TZM-bl cells. Most importantly, we show that B1 not only facilitates cellular uptake but allows biomolecular cargo to reach sites of biological relevance. For example, baby hamster kidney cells underwent DNA recombination when exposed to B1-tagged Cre recombinase at protein concentrations as low as 2.5 μM, indicating potent nuclear delivery of functional protein cargos. Additionally, B1 delivers noncovalently conjugated RNA and DNA across the cell membrane to cytosolic and nuclear sites accessible to the cellular translation and transcription machinery, as gauged by detection of encoded reporter functions, with efficiency comparable to commercially available cationic lipid reagents. B1 appears to utilize cell-surface glycans and multiple competing endocytic pathways to enter and traffic through cells. These studies provide both a new tool for intracellular delivery of biomolecules and insights that could aid in the design of more effective cell penetrating proteins.

  16. The release and transdermal penetration of baclofen formulated in a poloxamer lecithin organogel.

    Science.gov (United States)

    Arnold, John J; Asbill, Scott

    2009-01-01

    The purpose of this study was to evaluate the in vitro release and ex vivo penetration of baclofen following incorporation into a 2% poloxamer lecithin organogel. Franz cells were utilized for both the release and penetration studies. Semi-permeable dialysis membranes were used as the model skin for the penetration study. Baclofen release and penetration at predetermined time points were assessed using high-performamce liquid chromatographic analysis. Results demonstrated that baclofen release from the poloxamer lecithin organogel was significantly higher than its penetration through porcine skin. The amount of baclofen released by the poloxamer lecithin organogel was linear up to 12 hours. Approximately 20% of applied drug was released over the duration of the study period. In comparison with drug released, the ex vivo penetration of baclofen through porcine skin was very low with only minute detectable quantities (significantly less than 1%) after the 12-hour study period. These results suggest that the request to include baclofen into a compounded poloxamer lecithin organogel should be approached cautiously by compounding pharmacists.

  17. A Mass Loss Penetration Model to Investigate the Dynamic Response of a Projectile Penetrating Concrete considering Mass Abrasion

    OpenAIRE

    NianSong Zhang; Dong; Wang; Bei Peng; Yong He

    2015-01-01

    A study on the dynamic response of a projectile penetrating concrete is conducted. The evolutional process of projectile mass loss and the effect of mass loss on penetration resistance are investigated using theoretical methods. A projectile penetration model considering projectile mass loss is established in three stages, namely, cratering phase, mass loss penetration phase, and remainder rigid projectile penetration phase.

  18. Depth of penetration of bubbles entrained by a plunging water jet

    Science.gov (United States)

    Clanet, Christophe; Lasheras, Juan C.

    1997-07-01

    A model is proposed to predict the depth of penetration of the air bubbles entrained by a round water jet impacting into a flat, liquid pool. This depth is shown to be determined only by the initial jet momentum and by the non-monotonic nature of the bubble terminal velocities as a function of their size. The model is shown to be in excellent agreement with measurements of the depth and width of penetration of the bubbles performed over a wide range of jet diameters, velocities, and plunging angles.

  19. Molecules for Fluorescence Detection of Specific Chemicals

    Science.gov (United States)

    Fedor, Steve

    2008-01-01

    A family of fluorescent dye molecules has been developed for use in on-off fluorescence detection of specific chemicals. By themselves, these molecules do not fluoresce. However, when exposed to certain chemical analytes in liquid or vapor forms, they do fluoresce (see figure). These compounds are amenable to fixation on or in a variety of substrates for use in fluorescence-based detection devices: they can be chemically modified to anchor them to porous or non-porous solid supports or can be incorporated into polymer films. Potential applications for these compounds include detection of chemical warfare agents, sensing of acidity or alkalinity, and fluorescent tagging of proteins in pharmaceutical research and development. These molecules could also be exploited for use as two-photon materials for photodynamic therapy in the treatment of certain cancers and other diseases. A molecule in this family consists of a fluorescent core (such as an anthracene or pyrene) attached to two end groups that, when the dye is excited by absorption of light, transfer an electron to the core, thereby quenching the fluorescence. The end groups can be engineered so that they react chemically with certain analytes. Upon reaction, electrons on the end groups are no longer available for transfer to the core and, consequently, the fluorescence from the core is no longer quenched. The chemoselectivity of these molecules can be changed by changing the end groups. For example, aniline end groups afford a capability for sensing acids or acid halides (including those contained in chemical warfare agents). Pyridine or bipyridyl end groups would enable sensing of metal ions. Other chemicals that can be selectively detected through suitable choice of end groups include glucose and proteins. Moreover, the fluorescent cores can be changed to alter light-absorption and -emission characteristics: anthracene cores fluoresce at wavelengths around 500 nm, whereas perylene cores absorb and emit at

  20. Conformational analysis of Infectious bursal disease virus (IBDV derived cell penetrating peptide (CPP analogs

    Directory of Open Access Journals (Sweden)

    Vinay G. Joshi

    2013-12-01

    Full Text Available Aim: This study was designed to develop peptide analogs of Infectious Bursal Disease (IBD virus VP5 protein segment having cell penetrating ability to improve their interaction with cargo molecule (Nucleic acid without affecting the backbone conformation. Materials and Methods: IBDV VP5 protein segment designated as RATH peptide were synthesized using solid phase peptide synthesis and their solution conformation was elucidated using CD spectroscopy in polar (water and apolar (TFE solvents. Cell penetrating ability of RATH-CONH2 was observed using FITC labeled peptide internalization in to HeLa cells under fluorescent microscopy. The efficacy of RATH analog interactions with nucleic acids was evaluated using FITC labeled oligonucleotides by fluorescence spectroscopy and plasmid constructs in gel retardation assay. Results: CD spectra of RATH analogs in water and apolar trifluroethanol (TFE helped to compare their secondary structures which were almost similar with dominant beta conformations suggesting successful induction of positive charge in the analogs without affecting back bone conformation of CPP designed. Cell penetrating ability of RATH CONH2 in HeLa cell was more than 90%. The fluorescence spectroscopy and plasmid constructs in gel retardation assay demonstrated successful interaction of amide analogs with nucleic acid. Conclusion: Intentional changes made in IBDV derived peptide RATH COOH to RATH CONH2 did not showed major changes in backbone conformation and such modifications may help to improve the cationic charge in most CPPs to interact with nucleic acid. [Vet World 2013; 6(6.000: 307-312

  1. FISH BILIARY POLYCYCLIC AROMATIC HYDROCARBON METABOLITES ESTIMATED BY FIXED-WAVELENGTH FLUORESCENCE: COMPARISON WITH HPLC-FLUORESCENT DETECTION

    Science.gov (United States)

    Fixed wavelength fluorescence (FF) was compared to high-performance liquid chromatography with fluorescence detection (HPLC-F) as an estimation of polycyclic aromatic hydrocarbon (PAH) exposure to fish. Two excitation/emission wavelength pairs were used to measure naphthalene- an...

  2. Modulation of quantum dot photoluminescence in porous silicon photonic crystals as a function of the depth of their penetration

    Science.gov (United States)

    Dovzhenko, Dmitriy S.; Martynov, Igor L.; Samokhvalov, Pavel S.; Mochalov, Konstantin E.; Chistyakov, Alexander A.; Nabiev, Igor

    2016-04-01

    Photonic crystals doped with fluorescent nanoparticles offer a plenty of interesting applications in photonics, laser physics, and biosensing. Understanding of the mechanisms and effects of modulation of the photoluminescent properties of photonic crystals by varying the depth of nanoparticle penetration should promote targeted development of nanocrystal-doped photonic crystals with desired optical and morphological properties. Here, we have investigated the penetration of semiconductor quantum dots (QDs) into porous silicon photonic crystals and performed experimental analysis and theoretical modeling of the effects of the depth of nanoparticle penetration on the photoluminescent properties of this photonic system. For this purpose, we fabricated porous silicon microcavities with an eigenmode width not exceeding 10 nm at a wavelength of 620 nm. CdSe/CdS/ZnS QDs fluorescing at 617 nm with a quantum yield of about 70% and a width at half-height of about 40 nm were used in the study. Confocal microscopy and scanning electron microscopy were used to estimate the depth of penetration of QDs into the porous silicon structure; the photoluminescence spectra, kinetics, and angular fluorescence distribution were also analyzed. Enhancement of QD photoluminescence at the microcavity eigenmode wavelength was observed. Theoretical modeling of porous silicon photonic crystals doped with QDs was performed using the finite-difference time-domain (FDTD) approach. Theoretical modeling has predicted, and the experiments have confirmed, that even a very limited depth of nanoparticle penetration into photonic crystals, not exceeding the first Bragg mirror of the microcavity, leads to significant changes in the QD luminescence spectrum determined by the modulation of the local density of photonic states in the microcavity. At the same time, complete and uniform filling of a photonic crystal with nanoparticles does not enhance this effect, which is as strong as in the case of a very

  3. 3D Ground Penetrating Imaging Radar

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    GPiR (ground-penetrating imaging radar) is a new technology for mapping the shallow subsurface, including society’s underground infrastructure. Applications for this technology include efficient and precise mapping of buried utilities on a large scale.

  4. Penetration testing protecting networks and systems

    CERN Document Server

    Henry, Kevin M

    2012-01-01

    This book is a preparation guide for the CPTE examination, yet is also a general reference for experienced penetration testers, ethical hackers, auditors, security personnel and anyone else involved in the security of an organization's computer systems.

  5. Identifying structural damage with ground penetrating radar

    CSIR Research Space (South Africa)

    Van Schoor, Abraham M

    2008-07-01

    Full Text Available Ground penetrating radar (GPR) and electrical resistance tomography (ERT) surveys were conducted in an urban environment in an attempt to identify the cause of severe structural damage to a historically significant residential property...

  6. Kali Linux wireless penetration testing beginner's guide

    CERN Document Server

    Ramachandran, Vivek

    2015-01-01

    If you are a security professional, pentester, or anyone interested in getting to grips with wireless penetration testing, this is the book for you. Some familiarity with Kali Linux and wireless concepts is beneficial.

  7. Airborne ground penetrating radar: practical field experiments

    CSIR Research Space (South Africa)

    Van Schoor, Michael

    2013-10-01

    Full Text Available The performance of ground penetrating radar (GPR) under conditions where the ground coupling of the antenna is potentially compromised is investigated. Of particular interest is the effect of increasing the distance between the antennae...

  8. An Observational Investigation of Penetrative Convection

    DEFF Research Database (Denmark)

    Jensen, Niels Otto; Lenschow, D. H.

    1978-01-01

    Data taken during the Air Mass Transformation Experiment (AMTEX) by the NCAR Electra aircraft have proven useful for investigating the structure of thermals penetrating into the turbulent inversion layer which caps the convective mixed layer. Variances, covariances, spectra and cospectra...

  9. Prediction of weld penetration extent in GTAW

    Institute of Scientific and Technical Information of China (English)

    Zhao Ming; Zhai Lei

    2008-01-01

    The governing equations of surface-deformation in fully-penetrated GTA W weld pool are derived. The solution scheme of the Lagrange multiplier, which makes the top sutface-deformation equation be coupled with that for the bottomsurface of a single weld pool, is given out. Through numerical analysis of weld pool surface-deformation in GTA W,it is found that there is clear correlation between the penetration extent and the Lagrange multiplier, in addition to the relationship between the penetration extent and the maximum depression and hump as well as the depressed volume of the top surface of weld pool. It lays good foundation for top-side sensing based weld penetration control.

  10. Fundamentals of fluorescence and fluorescence microscopy.

    Science.gov (United States)

    Wolf, David E

    2013-01-01

    This chapter discusses the fundamental physics of fluorescence. The application of fluorescence to microscopy represents an important transition in the development of microscopy, particularly as it applies to biology. It enables quantitating the amounts of specific molecules within a cell, determining whether molecules are complexing on a molecular level, measuring changes in ionic concentrations within cells and organelles, and measuring molecular dynamics. This chapter also discusses the issues important to quantitative measurement of fluorescence and focuses on four of quantitative measurements of fluorescence--boxcar-gated detection, streak cameras, photon correlation, and phase modulation. Although quantitative measurement presents many pitfalls to the beginner, it also presents significant opportunities to one skilled in the art. This chapter also examines how fluorescence is measured in the steady state and time domain and how fluorescence is applied in the modern epifluorescence microscope.

  11. Penetrating facial injury by a wooden log

    OpenAIRE

    Mohan, Sadanandan; Varghese, George; Kumar, Sanjay; Subramanian, Dinesh Pambungal

    2014-01-01

    Penetrating facial injuries are potentially dangerous and require emergency management because of the presence of vital structures in the face and it may be life threatening especially when the injury involves airway, major blood vessels, spinal cord and cervical spines. Penetrating injuries of facial region can occur due to missile injuries, blast injuries, accidental fall on sharp objects such as sticks or glass and motor vehicle accidents etc., Indications for immediate surgical management...

  12. Magnetic field penetration of erosion switch plasmas

    Science.gov (United States)

    Mason, Rodney J.; Jones, Michael E.; Grossmann, John M.; Ottinger, Paul F.

    1988-10-01

    Computer simulations demonstrate that the entrainment (or advection) of magnetic field with the flow of cathode-emitted electrons can constitute a dominant mechanism for the magnetic field penetration of erosion switch plasmas. Cross-field drift in the accelerating electric field near the cathode starts the penetration process. Plasma erosion propagates the point for emission and magnetic field injection along the cathode toward the load-for the possibility of rapid switch opening.

  13. Effect of penetrants on the aramid Nomex

    Indian Academy of Sciences (India)

    Anjana Jain; Kalyani Vijayan

    2000-06-01

    The response of Nomex sheets to some penetrants has been analyzed. The process of moisture uptake depends on the relative humidity (RH) of the ambient atmosphere and the initial characteristics of the polymer. In the case of common laboratory solvents, the uptake by the polymer shows an inverse dependence on the molar volume of the former. Although the calendered and the uncalendered Nomex sheets exhibit an overall similarity in their response to various penetrants, quantitative comparison reveals distinct differences.

  14. The Effect and Mechanism of Transdermal Penetration Enhancement of Fu's Cupping Therapy: New Physical Penetration Technology for Transdermal Administration with Traditional Chinese Medicine (TCM) Characteristics.

    Science.gov (United States)

    Xie, Wei-Jie; Zhang, Yong-Ping; Xu, Jian; Sun, Xiao-Bo; Yang, Fang-Fang

    2017-03-27

    In this paper, a new type of physical penetration technology for transdermal administration with traditional Chinese medicine (TCM) characteristics is presented. Fu's cupping therapy (FCT), was established and studied using in vitro and in vivo experiments and the penetration effect and mechanism of FCT physical penetration technology was preliminarily discussed. With 1-(4-chlorobenzoyl)-5-methoxy-2-methylindole-3-ylacetic acid (indomethacin, IM) as a model drug, the establishment of high, medium, and low references was completed for the chemical permeation system via in vitro transdermal tests. Furthermore, using chemical penetration enhancers (CPEs) and iontophoresis as references, the percutaneous penetration effect of FCT for IM patches was evaluated using seven species of in vitro diffusion kinetics models and in vitro drug distribution; the IM quantitative analysis method in vivo was established using ultra-performance liquid chromatography-tandem mass spectrometry technology (UPLC-MS/MS), and pharmacokinetic parameters: area under the zero and first moment curves from 0 to last time t (AUC0-t, AUMC0-t), area under the zero and first moment curves from 0 to infinity (AUC0-∞, AUMC0-∞), maximum plasma concentration (Cmax) and mean residence time (MRT), were used as indicators to evaluate the percutaneous penetration effect of FCT in vivo. Additionally, we used the 3(K) factorial design to study the joint synergistic penetration effect on FCT and chemical penetration enhancers. Through scanning electron microscopy (SEM) and transmission electron microscope (TEM) imaging, micro- and ultrastructural changes on the surface of the stratum corneum (SC) were observed to explore the FCT penetration mechanism. In vitro and in vivo skin permeation experiments revealed that both the total cumulative percutaneous amount and in vivo percutaneous absorption amount of IM using FCT were greater than the amount using CPEs and iontophoresis. Firstly, compared with the

  15. Penetration of Bdellovibrio bacteriovorus into host cells.

    Science.gov (United States)

    Abram, D; Castro e Melo, J; Chou, D

    1974-05-01

    Electron microscopy reveals that, in Bdellovibrio infection, after the formation of a passage pore in the host cell wall, the differentiated parasite penetration pole is associated with the host protoplast. This firm contact persists throughout the parasite penetration and after this process is completed. In penetrated hosts this contact is also apparent by phase microscopy. The association between the walls of the parasite and the host at the passage pore, on the other hand, is transient. Bdellovibrio do not penetrate hosts whose protoplast and cell walls are separated by plasmolysis, or in which the membrane-wall relationship is affected by low turgor pressure. It is concluded, therefore, that for penetration to occur it is essential that the host protoplast be within reach of the parasite, so that a firm contact can be established between them. A penetration mechanism is proposed that is effected by forces generated by fluxes of water and solutes due to structural changes in the infected host envelope. These forces cause a differential expansion of the host protoplast and cell wall and their separation from each other around the entry site, while the parasite remains firmly anchored to the host protoplast. Consequently, the parasite ends up enclosed in the expanded host periplasm. The actual entry, therefore, is a passive act of the parasite.

  16. Estimating Consequences of MMOD Penetrations on ISS

    Science.gov (United States)

    Evans, H.; Hyde, James; Christiansen, E.; Lear, D.

    2017-01-01

    The threat from micrometeoroid and orbital debris (MMOD) impacts on space vehicles is often quantified in terms of the probability of no penetration (PNP). However, for large spacecraft, especially those with multiple compartments, a penetration may have a number of possible outcomes. The extent of the damage (diameter of hole, crack length or penetration depth), the location of the damage relative to critical equipment or crew, crew response, and even the time of day of the penetration are among the many factors that can affect the outcome. For the International Space Station (ISS), a Monte-Carlo style software code called Manned Spacecraft Crew Survivability (MSCSurv) is used to predict the probability of several outcomes of an MMOD penetration-broadly classified as loss of crew (LOC), crew evacuation (Evac), loss of escape vehicle (LEV), and nominal end of mission (NEOM). By generating large numbers of MMOD impacts (typically in the billions) and tracking the consequences, MSCSurv allows for the inclusion of a large number of parameters and models as well as enabling the consideration of uncertainties in the models and parameters. MSCSurv builds upon the results from NASA's Bumper software (which provides the probability of penetration and critical input data to MSCSurv) to allow analysts to estimate the probability of LOC, Evac, LEV, and NEOM. This paper briefly describes the overall methodology used by NASA to quantify LOC, Evac, LEV, and NEOM with particular emphasis on describing in broad terms how MSCSurv works and its capabilities and most significant models.

  17. Giant gastric ulcer penetrating into the pancreas.

    Science.gov (United States)

    Fujihara, Shintaro; Mori, Hirohito; Nishiyama, Noriko; Kobara, Hideki; Masaki, Tsutomu

    2012-09-01

    A 57-year-old man developed haematemesis and was referred to our institution. His discomfort had begun 3 weeks earlier and localised to the upper abdomen. Abdominal CT showed a defect of gastric mucosa and gastric wall thickening. Oesophagogastroduodenoscopy showed that he had an active gastric ulcer, 40 mm in diameter, on the lesser curvature in the upper third of the corpus and the presence of a pancreatic body at the ulcer base, penetration to the pancreas. Open gastrectomy was performed with a preoperative diagnosis of localised peritonitis caused by penetration of the stomach into the pancreas. Histopathology of resected specimens showed a benign peptic ulcer, 40×40 mm in size, was found on the lesser curvature in the antrum, and this had penetrated through the pancreas. The most serious complications of PUD include haemorrhage, perforation, penetration, and gastric outlet obstruction. Approximately 7% of patients experience perforation, which occurs when an ulcer erodes through the wall and leaks air and digestive contents into the peritoneal cavity. Antral and duodenal ulcers can penetrate into the pancreas. We report a case of gastric ulcer penetrating into the pancreas.

  18. Simulation of Mine Electrical Penetration Technology

    Institute of Scientific and Technical Information of China (English)

    LIU Zhi-xin; YUE Jian-hua; LIU Shu-cai

    2007-01-01

    Based on the principle of electrical penetration, the reflection characteristics of collapse columns at different locations of a working face is numerically simulated by using a 3D finite element method. The data collected by the electrical penetration is processed and interpreted using "tunnel penetration" which is similar to radio wave penetration. Reflection characteristics of collapse columns at different locations below floors of coal seams are analyzed, providing a new paradigm and a theoretical foundation for processing and interpreting electrical penetration data. The tomography analysis is made based on data simulation and calculation results and alltransmitting-receiving points are analyzed for their corresponding maximum attenuation values and maximum absorption coefficients. On the basis of this, a new method for precisely interpreting the spatial positions of geological anomalous bodies is suggested. The simulation shows that 1) the detection result of both roof and floors of the working face by electrical penetration is a volumetric effect and 2) there exists a corresponding relation between the detection depth and the working face width, with the optimal detection depth within 40% of the working face width.

  19. In vitro penetration of bleaching agents into the pulp chamber

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Valera, M C; Mancini, M N G

    2004-01-01

    To investigate pulp chamber penetration of bleaching agents in teeth following restorative procedures.......To investigate pulp chamber penetration of bleaching agents in teeth following restorative procedures....

  20. Epiphany sealer penetration into dentinal tubules: Confocal laser scanning microscopic study

    Directory of Open Access Journals (Sweden)

    S V Ravi

    2014-01-01

    Full Text Available Aims: The aim of the following study was to evaluate the percentage and average depth of epiphany sealer penetration into dentinal tubules among the coronal, middle and apical thirds of the root using the confocal laser scanning microscopy (CLSM. Materials and Methods: A total of 10 maxillary central incisors were prepared and obturated with Resilon-Epiphany system. Sealer was mixed with fluorescent rhodamine B isothiyocyanate dye for visibility under confocal microscope. Teeth were cross-sectioned into coronal, middle and apical sections-2 mm thick. Sections were observed under CLSM. Images were analyzed for percentage and average depth of sealer penetration into dentinal tubules using the lasso tool in Adobe Photoshop CS3 (Adobe systems incorporated, San jose, CA and laser scanning microscopy (LSM 5 image analyzer. Statistical Analysis Used: One-way analysis of variance with Student Neuman Keuls post hoc tests, Kruskal-Wallis test and Wilcoxon signed-rank post hoc tests. Results: The results showed that a higher percentage of sealer penetration in coronal section-89.23%, followed by middle section-84.19% and the apical section-64.9%. Average depth of sealer penetration for coronal section was 526.02 μm, middle-385.26 μm and apical-193.49 μm. Conclusions: Study concluded that there was higher epiphany sealer penetration seen in coronal followed by middle and least at apical third of the roots.

  1. Rapid penetration into granular media visualizing the fundamental physics of rapid earth penetration

    CERN Document Server

    Iskander, Magued

    2015-01-01

    Rapid Penetration into Granular Media: Visualizing the Fundamental Physics of Rapid Earth Penetration introduces readers to the variety of methods and techniques used to visualize, observe, and model the rapid penetration of natural and man-made projectiles into earth materials. It provides seasoned practitioners with a standard reference that showcases the topic's most recent developments in research and application. The text compiles the findings of new research developments on the subject, outlines the fundamental physics of rapid penetration into granular media, and assembles a com

  2. Intraocular penetration of sequentially instilled topical moxifloxacin, gatifloxacin, and levofloxacin

    Directory of Open Access Journals (Sweden)

    Koji Sugioka

    2009-10-01

    Full Text Available Koji Sugioka1, Masahiko Fukuda1, Shohei Komoto1, Motoki Itahashi1, Masakazu Yamada2, Yoshikazu Shimomura11Department of Ophthalmology, Kinki University School of Medicine, Osaka-Sayama City, Osaka, Japan; 2Division for Vision Research, National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, JapanPurpose: The objective of the study was to compare the intraocular penetration levels of the newer fluoroquinolones, moxifloxacin, gatifloxacin, and levofloxacin in the rabbit’s cornea, aqueous humor, and conjunctiva after topical instillation.Methods: 0.5% moxifloxacin, 0.3% gatifloxacin, and 0.5% levofloxacin were instilled in random sequence in both eyes of nine New Zealand White rabbits at two-minute intervals. Instillation was repeated every 15 minutes for a total of three drops of each fluoroquinolone per eye. Three additional animals had only moxifloxacin instilled bilaterally using the same schedule. Sixty minutes after the final instillation, the rabbits were sacrificed for determination of corneal, aqueous humor, and conjunctival fluoroquinolone concentrations using highperformance liquid chromatography.Results: Moxifloxacin achieved significantly higher concentrations than levofloxacin and gatifloxacin in the cornea (P = 0.0102 and P = 0.0006, respectively, aqueous humor (P = 0.0015 and P < 0.0001, respectively, and conjunctiva (P = 0.0191 and P = 0.0236, respectively. Conclusions: 0.5% moxifloxacin eyedrops provided superior intraocular penetration in rabbits’ eyes compared with the two other fluoroquinolones, 0.5% levofloxacin and 0.3% gatifloxacin.Keywords: fluoroquinolone, gatifloxacin, levofloxacin, moxifloxacin, penetration, rabbit

  3. Applications of Liquid Chromatography with Fluorescence Detector Diodes and the Analysis of Environmental Pollutants; Aplicaciones de la Cromatografia Liquida con Detector de Diodos y Fluorescencia al Analisis de Contaminantes Medioambientales

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, S.; Perez, R. M.

    2012-04-11

    It presents a review on the determination of major types of organic pollutants in environmental samples by HPLC with diode array or fluorescence molecular detectors. Main objective has been to make a compilation of the analytical potential of the technique based on literature and our laboratory studies on the main aspects of analytical methodology used in the determination of these compounds. (Author) 53 refs.

  4. Reviews in fluorescence 2010

    CERN Document Server

    Geddes, Chris D

    2011-01-01

    ""Reviews in Fluorescence 2010"", the seventh volume of the book serial from Springer, serves as a comprehensive collection of current trends and emerging hot topics in the field of fluorescence and closely related disciplines. It summarizes the year's progress in fluorescence and its applications, with authoritative analytical reviews specialized enough to be attractive to professional researchers, yet also appealing to the wider audience of scientists in related disciplines of fluorescence. ""Reviews in Fluorescence"" offers an essential reference material for any lab working in the fluoresc

  5. Principles of fluorescence techniques

    CERN Document Server

    2016-01-01

    Fluorescence techniques are being used and applied increasingly in academics and industry. The Principles of Fluorescence Techniques course will outline the basic concepts of fluorescence techniques and the successful utilization of the currently available commercial instrumentation. The course is designed for students who utilize fluorescence techniques and instrumentation and for researchers and industrial scientists who wish to deepen their knowledge of fluorescence applications. Key scientists in the field will deliver theoretical lectures. The lectures will be complemented by the direct utilization of steady-state and lifetime fluorescence instrumentation and confocal microscopy for FLIM and FRET applications provided by leading companies.

  6. Laser Deep Penetration Welding of an Aluminum Alloy with Simultaneously Applied Vibrations

    Science.gov (United States)

    Woizeschke, Peer; Radel, Tim; Nicolay, Paul; Vollertsen, Frank

    2016-12-01

    In aluminum welding, the grain structure of produced seams is an essential factor with respect to the seam properties. In the casting technology the effect of mechanical vibrations on the grain growth during the solidification of liquid metals is known as a refinement method. In this paper, the transferability of this approach from comparatively long-time processes in the field of casting to the short-time process of laser deep penetration welding is investigated. Therefore, specimens were sinusoidal vibrated with frequencies up to 4 kHz during bead-on-plate full-penetration welding experiments. The resulting grain size was determined by applying the circular intercept procedure on the center of a cross-section micrograph of each weld. The results show that grain refinement is in general achievable by mechanical vibrations in the audible frequency range during laser full penetration keyhole welding of the aluminum alloy EN AW-5083.

  7. Standard practice for visible penetrant testing using Solvent-Removable process

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice covers procedures for visible penetrant examination utilizing the solvent-removable process. It is a nondestructive testing method for detecting discontinuities that are open to the surface such as cracks, seams, laps, cold shuts, laminations, isolated porosity, through leaks, or lack of fusion and is applicable to in-process, final, and maintenance examination. It can be effectively used in the examination of nonporous, metallic materials, both ferrous and nonferrous, and of nonmetallic materials such as glazed or fully densified ceramics and certain nonporous plastics and glass. 1.2 This practice also provides a reference: 1.2.1 By which a visible penetrant examination method using the solvent-removable process recommended or required by individual organizations can be reviewed to ascertain its applicability and completeness. 1.2.2 For use in the preparation of process specifications dealing with the visible, solvent-removable liquid penetrant examination of materials and parts. Agreement ...

  8. Fluorescence correlation spectroscopy

    NARCIS (Netherlands)

    Hink, M.A.; Verveer, P.J.

    2015-01-01

    Fluorescence fluctuation spectroscopy techniques allow the quantification of fluorescent molecules present at the nanomolar concentration level. After a brief introduction to the technique, this chapter presents a protocol including background information in order to measure and quantify the molecul

  9. A RETROSPECTIVE STUDY ON PENETRATING INJURIES ABDOMEN

    Directory of Open Access Journals (Sweden)

    Alli Muthiah

    2017-02-01

    Full Text Available BACKGROUND Penetrating abdominal injuries forms an important component of surgical emergencies. It remains one of the commonest reasons for preventable deaths in any trauma systems. 1 Abdominal injuries may be parietal or visceral or perforating through and through injury. Unnecessary exploration leads to increased morbidity. The goal in managing penetrating abdominal injuries is to identify and treat all the damages caused by the weapon and to reduce negative laparotomy and avoid missed injuries. MATERIALS AND METHODS A retrospective study that was carried out in 53 patients in Government Kilpauk Medical College and Government Royapettah Hospital from May 2007 to July 2009 on penetrating injuries abdomen. RESULTS Among 53 patients, maximum number of cases were in the age group of 30-40 years. Assault injuries account for 87% of cases of penetrating abdominal injuries. Small bowel was the commonly injured organ in this study. Laparotomy was therapeutic in 94% of the cases (64% of the cases underwent laparotomy. CONCLUSION Careful and serial clinical examination and appropriate diagnostic investigations leads to successful treatment in these patients. Computed tomography is highly sensitive in predicting both peritoneal penetration and intra-abdominal visceral injuries.

  10. Penetration enhancing effects of selected natural oils utilized in topical dosage forms.

    Science.gov (United States)

    Viljoen, Joe M; Cowley, Amé; du Preez, Jan; Gerber, Minja; du Plessis, Jeanetta

    2015-01-01

    Various natural products, including oils, have been utilized as penetration enhancers due to their "safety profiles". These oils contain fatty acids promoting skin permeability through lipid fluidization within the stratum corneum; and might therefore be able to effectively enhance transdermal drug delivery. We investigated possible penetration enhancing properties of selected oils, utilizing flurbiprofen as marker compound in emulgel formulations. The formulations were compared to a liquid paraffin emulgel and a hydrogel to establish any significant penetration enhancing effects. Gas chromatographic analysis of the natural oils was performed at ambient temperature to determine the fatty acid composition in each selected natural oils. Franz cell diffusion studies and tape stripping methods were employed to study delivery of the marker into, and through the skin. The following rank order for the emulgel flux-values was obtained: Hydrogel > olive oil > liquid paraffin > coconut oil > grape seed oil > Avocado oil ≥ Crocodile oil > Emu oil. Results suggested that oils containing predominantly mono-unsaturated oleic acid, on average increased the flux of the marker to a larger extent than oils containing an almost even mixture of both mono- and poly-unsaturated fatty acids. Oils comprising saturated fatty acids (SFAs) with alkyl chains between C12 and C14, increased the marker flux to a higher extent than oils containing C16-C18 SFAs. Effects observed for branched fatty acids, however, did not vary significantly from effects for unbranched fatty acids with the same carbon chain length. Natural oils possess penetration enhancing effects.

  11. Influence of anatomical site and topical formulation on skin penetration of sunscreens.

    Science.gov (United States)

    Benson, Heather Ae; Sarveiya, Vikram; Risk, Stacey; Roberts, Michael S

    2005-09-01

    Sunscreen products are widely used to protect the skin from sun-related damage. Previous studies have shown that some sunscreen chemicals are absorbed across the skin to the systemic circulation. The current study shows that absorption into the skin of sunscreen chemicals applied to the face is up to four times greater than that of the same product applied to the back. This has implications for the way sunscreen products are formulated and may allow the use of less potent products on the face compared with the rest of the body. The effect of formulation vehicles on the release and skin penetration of the common sunscreen agent benzophenone-3 (common name oxybenzone) was also assessed. Penetration of benzophenone-3 across excised human epidermis and high-density polyethylene (HDPE) membrane was measured using in vitro Franz-type diffusion cells. Penetration and epidermal retention was measured following application of infinite and finite (epidermis only) doses of benzophenone-3 in five vehicles: liquid paraffin, coconut oil, 50:50 ethanol:coconut oil, aqueous cream BP, and oily cream BP. Highest benzophenone-3 skin retention was observed for the ethanol:coconut oil combination. Maximal and minimal benzophenone-3 fluxes were observed from liquid paraffin and coconut oil, respectively. The alcohol-based vehicle exhibited low benzophenone-3 release from the vehicle but high skin penetration and retention.

  12. Safe biodegradable fluorescent particles

    Science.gov (United States)

    Martin, Sue I.; Fergenson, David P.; Srivastava, Abneesh; Bogan, Michael J.; Riot, Vincent J.; Frank, Matthias

    2010-08-24

    A human-safe fluorescence particle that can be used for fluorescence detection instruments or act as a safe simulant for mimicking the fluorescence properties of microorganisms. The particle comprises a non-biological carrier and natural fluorophores encapsulated in the non-biological carrier. By doping biodegradable-polymer drug delivery microspheres with natural or synthetic fluorophores, the desired fluorescence can be attained or biological organisms can be simulated without the associated risks and logistical difficulties of live microorganisms.

  13. Two methodologies for physical penetration testing using social engineering

    NARCIS (Netherlands)

    Dimkov, Trajce; Pieters, Wolter; Hartel, Pieter

    2010-01-01

    Penetration tests on IT systems are sometimes coupled with physical penetration tests and social engineering. In physical penetration tests where social engineering is allowed, the penetration tester directly interacts with the employees. These interactions are usually based on deception and if not

  14. High-performance liquid chromatographic determination of delta9-tetrahydrocannabinol and the corresponding acid in hemp containing foods with special regard to the fluorescence properties of delta9-tetrahydrocannabinol.

    Science.gov (United States)

    Zoller, O; Rhyn, P; Zimmerli, B

    2000-03-03

    A solvent programmed reversed-phase HPLC method with UV detection for the determination of delta9-tetrahydrocannabinol (THC) and delta9-tetrahydrocannabinolic acid A (THCA-A) in foods containing parts of hemp such as edible oil, herb-teas (infusion), herbal hemp or hempseed is presented. The THC peak is also detected by fluorescence. The detection limits with UV detection are 0.01 ng for THC and 0.05 ng for THCA-A and with fluorescence detection 0.1 ng for THC. The relative standard deviation under repeatability conditions of the chromatographic procedure is about 0.5% and that of the over-all analytical procedure for THC in vegetable oils 2% (concentration range of 10-100 mg/kg).

  15. Penetrating power of resonant electromagnetic induction imaging

    Science.gov (United States)

    Guilizzoni, Roberta; Watson, Joseph C.; Bartlett, Paul; Renzoni, Ferruccio

    2016-09-01

    The possibility of revealing the presence and identifying the nature of conductive targets is of central interest in many fields, including security, medicine, industry, archaeology and geophysics. In many applications, these targets are shielded by external materials and thus cannot be directly accessed. Hence, interrogation techniques are required that allow penetration through the shielding materials, in order for the target to be identified. Electromagnetic interrogation techniques represent a powerful solution to this challenge, as they enable penetration through conductive shields. In this work, we demonstrate the power of resonant electromagnetic induction imaging to penetrate through metallic shields (1.5-mm-thick) and image targets (having conductivities σ ranging from 0.54 to 59.77 MSm-1) concealed behind them.

  16. Penetrating power of resonant electromagnetic induction imaging

    Directory of Open Access Journals (Sweden)

    Roberta Guilizzoni

    2016-09-01

    Full Text Available The possibility of revealing the presence and identifying the nature of conductive targets is of central interest in many fields, including security, medicine, industry, archaeology and geophysics. In many applications, these targets are shielded by external materials and thus cannot be directly accessed. Hence, interrogation techniques are required that allow penetration through the shielding materials, in order for the target to be identified. Electromagnetic interrogation techniques represent a powerful solution to this challenge, as they enable penetration through conductive shields. In this work, we demonstrate the power of resonant electromagnetic induction imaging to penetrate through metallic shields (1.5-mm-thick and image targets (having conductivities σ ranging from 0.54 to 59.77 MSm−1 concealed behind them.

  17. Proniosomes for Penetration Enhancement in Transdermal System

    Directory of Open Access Journals (Sweden)

    Samita Singla

    2012-06-01

    Full Text Available Over the last few years an inclusive research has been done over provesicular approach for transdermal drug delivery. Skin has a very tough diffusion barrier inhibiting penetration of drug moiety which is rate limiting barrier for penetration of drugs. There are several approaches that deal with penetration enhancement across the skin. Vesicular and provesicular systems are promising amongst them. Vesicular systems including (niosomes, ethosomes, transfersomes and liposomes are promising systems to cross this permeation barrier. But their major drawback is their unstability, which can be overcome by using provesicular approaches like proniosomes, protransfersomes and proliposomes. Provesicular approaches have been proposed to enhance the stability of vesicles. These approaches may overcome skin barrier properties and enhance percutaneous absorption. In these systems both type of drugs, hydrophilic and lipophillic drugs can be incorporated. The focus of this review is to bring together different aspects related to mechanism of skin permeation of provesicular system, proniosomes preparation and its applications as a carrier system

  18. Opportunities for high wind energy penetration

    DEFF Research Database (Denmark)

    Tande, J.O.; Hansen, J.C.

    1997-01-01

    Wind power is today a mature technology, which at windy locations, is economically competitive to conventional power generation technologies. This and growing global environmental concerns have led governments to encourage and plan for wind energy development, a typical aim being 10% of electricity...... consumption. The successful operation of the three major power systems of Cape Verde, with a total wind energy penetration of about 15% since December 1994, demonstrates that power systems can be operated with high penetration of wind energy by adding simple control and monitoring systems only. Thorough...... analyses conclude that expanding to even above 15% wind energy penetration in the Cape Verde power systems is economical. Worldwide, numerous locations with favorable wind conditions and power systems similar to the Capeverdean provide good opportunities for installing wind farms and achieving high wind...

  19. Diagnosis and treatment of penetrating anorectal wounds

    Institute of Scientific and Technical Information of China (English)

    LIU Xin-sheng; HUI Xi-zeng; ZHANG Yang-de; LI Kun

    2006-01-01

    Objective:To research the diagnosis and effective treatment of penetrating anorectal wounds.Methods: Retrospective analysis was done in 16 cases of penetrating anorectal wounds from 1985 to 2004.Debridement and suture of anorectal and vesical wounds,effective diversion of fecal and urinary stream and sufficient presacral drainage were performed in all cases.Results: All the 16 cases were cured. Among them, 2cases with infection in presacral space were cured by sufficient drainage after operation, one case was cured by secondary repair after anal sphincter was repaired unsuccessfully and one case with rectovesical fistula was cured with conservative treatment. None of them suffered from complications such as anal stenosis, dysuria or importence etc.Conclusions: For penetrating anorectal wound, to master early recognition of concomitant injures, to select appropriate surgical intervention and to strengthen perioperative treatment are the keys to improve the curative effects.

  20. Wireless Network Penetration Testing and Security Auditing

    Directory of Open Access Journals (Sweden)

    Wang Shao-Long

    2016-01-01

    Full Text Available IEEE802.11 wireless wireless networks have security issues that are vulnerable to a variety of attacks. Due to using radio to transport data, attackers can bypass firewalls, sniff sensitive information, intercept packets and send malicious packets. Security auditing and penetration testing is expected to ensure wireless networks security. The contributions of this work are analyzed the vulnerability and types of attacks pertaining to IEEE 802.11 WLAN, performed well known attacks in a laboratory environment to conduct penetration tests to confirm whether our wireless network is hackable or not. WAIDPS is configured as auditing tool to view wireless attacks, such as WEP/WPA/WPA2 cracking, rouge access points, denial of service attack. WAIDPS is designed to detect wireless intrusion with additional features. Penetration testing and auditing will mitigate the risk and threatening to protect WALN.