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Sample records for layer chromatographic analysis

  1. Thin layer chromatographic analysis of some common over the counter (OTC cough–cold preparations

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    Manpreet Kaur Chahal

    2016-12-01

    Full Text Available In the present study, potential utility of thin layer chromatography to differentiate some common OTC cough–cold preparations was evaluated. Twenty solvent systems were examined from which a solvent systems A comprising methanol:ammonia in the ratio of 100:1.5 (v/v and B comprising chloroform:methanol in the ratio of 90:10 (v/v were found to be most suitable as it showed a high degree of separation of different components of these preparations. It was also found that iodine fuming technique is the best visualizing method for examining the TLC chromatograms of these drug samples prior to subsequent instrumental analysis.

  2. Thin layer chromatographic analysis of food colorants from three morphotypes of annatto (Bixa orellana L.

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    Hari Pada Seal

    2012-06-01

    Full Text Available This article describes a simple solvent extraction method for the extraction of colorants from the three morphotypes such as, (Morphotype-1 (M1, Morphotype-2 (M2, and Morphotype-3 (M3 of Annatto (Bixa orellana L. seeds, and their separation, vivid, and qualitative demonstration by thin-layer chromatography. Several solvent systems (hexane, chloroform, acetone, ethanol, and a mixed-solvent having composition of CHCl3/C2H5OH/CH3COOH (80:2:1 were applied for extraction of colored components. It was observed that a large portion of colorants was extracted by chloroform. Its effluent was deep brick red in color and transparent. Furthermore, various carrier solvent systems (Benzene-Ethyl acetate were used to separate the components from the extracts. Carrier solvent system with the ratio of 7:3 was found as superior solvent for chloroform extracts. Three colored-spots were observed for all morphotypes. Among them, the first one was yellow colored having very low polarity and the second and third spots were both redbrick colored having medium and higher polarity respectively. In addition, for M1 no colorless-spot was observed in low and medium polar systems, revealing that the amount of wax and gum were minimum in the extract and superior morphotype among the three.

  3. Comparison of two detection methods in thin layer chromatographic analysis of herbicides in a coastal savannah soil

    International Nuclear Information System (INIS)

    Afful, S.; Yeboah, P.O.; Dogbe, S.A.; Akpabli, C.K.

    2004-01-01

    o-tolidine + potassium iodide and photosynthesis inhibition detection methods, were investigated for the analysis of three triazine herbicides (atrazine, ametryne, simazine), and two urea herbicides (diuron, metobromuron) in a coastal savannah soil using thin layer chromatographic methodology to compare the suitability of the two methods for the study of the herbicides. This was done by spiking 5 g of the soil sample with specific amount of the herbicides standard to generate herbicide-soil concentration of 40.23, 40.28, 41.46, 39.90 and 40.64 μ g/g for atrazine, ametryne, simazine, diuron and metobromuron respectively. Extraction was performed with acetone/hexane mixture (4:1) and the detection limit of each herbicide was then determined. In all, the photosynthesis inhibition method performed better for both the triazine and the urea herbicides, while the o-tolidine + potassium iodide method was suitable for only the triazine herbicides. With the photosynthesis inhibition method, detectability in the range of 0.004 - 0.008±0.02 μ g/g was attained for the herbicides using the unclean extracts. In the case of o-tolidine ± potassium iodide method, detectability of 0.008 - 0.40 0.02 ± g/g was obtained. With the clean up extracts, detectability in the range of 0.025 - 0.162±0.004 μ g/g was obtained using the photosynthesis inhibition method, however, metobromuron was not detected with the clean up extracts with the o-tolidine + KI method. (au)

  4. Analysis and chromatographic purification of eicosanoids multiply labeled by tritium

    International Nuclear Information System (INIS)

    Shevchenko, V.P.; Nagaev, I.Yu.; Myasoedov, N.F.

    1989-01-01

    We show the possibility of analysis and chromatographic purification of eicosanoids triply labeled by tritium. The described methods allow us to isolate chromatographically pure products obtained by selective hydrogenatin, chemical, and enzyme methods, with radiochemical purity at least 95-97%. The following methods are used to analyze the reaction mixtures and to isolate the tritium-labeled eicosanoids: gas-liquid chromatography, high-efficiency liquid chromatography, and thin-layer chromatography on supports impregnated with silver nitrate

  5. Comparison of two detection methods in thin layer chromatographic analysis of some herbicides in a coastal savannah soil in Ghana

    International Nuclear Information System (INIS)

    Afful, S.; Yeboah, P.O.; Dogbe, S.A.; Akpabli, C.K.

    2008-01-01

    o-tolidine plus potassium iodide and photosynthesis inhibition detection methods were investigated for the analysis of three triazine herbicides (atrazine, ametryne, simazine) and two urea herbicides (diuron, metbromuron) in a coastal savannah soil using thin layer chromatography to compare the suitability of the two methods for the study of the herbicides. This was done by spiking 5 g of the soil sample with specific amount of the herbicide standards to generate herbicide-soil concentration of 40.24, 41.46, 40.28, 39.90 and 40.64 μg/g for atrazine, ametryne, simazine, diuron and metbromuron, respectively. Extraction was performed with acetone/hexane mixture (4:1) and the detection limit of each herbicide was then determined. In all, the photosynthesis inhibition method performed better for both the triazine and the urea herbicides, while the o-tolidine plus potassium iodide method was suitable for only the triazine herbicides. With the photosynthesis inhibition method, detectability in the range of 0.004-0.008 ± 0.002 μg/g was attained for the herbicides using the unclean extracts. In the case of o-tolidine plus potassium iodide method, detectability of 0.008-0.406 ± 0.02 μg/g was obtained. With the clean up extracts detectability in the range of 0.025-0.162 ± 0.004 μg/g was obtained using the photosynthesis inhibition method. However, metbromuron was not detected in the cleaned up extracts when o-tolidine plus potassium iodide detection method was used. For the methods described, clean up with SPE cartridge, equipped with C-18, is not critical to obtain the desired results. (au)

  6. Chromatographic and electrophoretic approaches in ink analysis.

    Science.gov (United States)

    Zlotnick, J A; Smith, F P

    1999-10-15

    Inks are manufactured from a wide variety of substances that exhibit very different chemical behaviors. Inks designed for use in different writing instruments or printing methods have quite dissimilar components. Since the 1950s chromatographic and electrophoretic methods have played important roles in the analysis of inks, where compositional information may have bearing on the investigation of counterfeiting, fraud, forgery, and other crimes. Techniques such as paper chromatography and electrophoresis, thin-layer chromatography, high-performance liquid chromatography, gas chromatography, gel electrophoresis, and the relatively new technique of capillary electrophoresis have all been explored as possible avenues for the separation of components of inks. This paper reviews the components of different types of inks and applications of the above separation methods are reviewed.

  7. Chromatographic analysis of wheatgrass extracts

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    Masood Shah Khan

    2015-01-01

    Full Text Available Aim: Wheatgrass (WG is the shoot of Triticum aestivum Linn. belongs to the family Gramineae, and possess high chlorophyll content and essential vitamins, minerals, vital enzymes, amino acids, dietary fibers etc., It has been shown to possess anti-cancer, anti-ulcer, antioxidant, and anti-arthritic activity due to the presence of biologically active compounds, and minerals. Therefore, in the present study, high-performance thin layer chromatography (HPTLC, and high-performance liquid chromatography (HPLC methods for qualitative and quantitative analysis have been proposed, which will help in quality evaluation of wheat grass extract. Materials and Methods: Samples for analysis were prepared in methanol and water simply by sonication. These were applied on pre-coated silica plate and chromatograms were developed using toluene: Ethyl acetate: Formic acid. HPLC analysis was done on Waters HPLC system using water, methanol, and acetonitrile as mobile phase. Merck C18 column has been used. Results: HPTLC finger printing of alcoholic extracts of WG was carried out and found 10–11 spots at different wavelengths 254, 366, and 435 nm. HPLC fingerprinting produced 22 peaks at 256 nm. Quantitative HPTLC analysis was done to determine the gallic acid content, and was found to be 0.077% w/w in aqueous extract. By HPLC, the content of gallic acid and rutin was found to be 0.07%, and 0.04% w/w in aqueous extract of WG. Conclusion: The developed HPLC and HPTLC fingerprinting method can be used for the quality control, and standardization of WG and its extracts used as nutritional supplement.

  8. Chromatographic Techniques for Rare Earth Elements Analysis

    Science.gov (United States)

    Chen, Beibei; He, Man; Zhang, Huashan; Jiang, Zucheng; Hu, Bin

    2017-04-01

    The present capability of rare earth element (REE) analysis has been achieved by the development of two instrumental techniques. The efficiency of spectroscopic methods was extraordinarily improved for the detection and determination of REE traces in various materials. On the other hand, the determination of REEs very often depends on the preconcentration and separation of REEs, and chromatographic techniques are very powerful tools for the separation of REEs. By coupling with sensitive detectors, many ambitious analytical tasks can be fulfilled. Liquid chromatography is the most widely used technique. Different combinations of stationary phases and mobile phases could be used in ion exchange chromatography, ion chromatography, ion-pair reverse-phase chromatography and some other techniques. The application of gas chromatography is limited because only volatile compounds of REEs can be separated. Thin-layer and paper chromatography are techniques that cannot be directly coupled with suitable detectors, which limit their applications. For special demands, separations can be performed by capillary electrophoresis, which has very high separation efficiency.

  9. Development and validation of a simple thin-layer chromatographic method for the analysis of p-chlorophenol in treated wastewater

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    Tešić Živoslav

    2012-01-01

    Full Text Available A thin-layer chromatographic method with densitometric detection was established for quantification of p-chlorophenol in waste water. Degradation efficiency of p-chlorophenol was monitored after each treatment of the wastewater samples. Degradation of p-chlorophenol was performed with advanced oxidation processes (AOPs, using UV, H2O2/UV, O3/H2O2/UV, O3 and O3/UV. Developed TLC procedure has been found to be simple, rapid and precise. The method was characterized by high sensitivity (limit of detection was 11 ng per band and limit of quantification 35 ng per band, linear range (from 75 to 500 ng per band, r = 0.9965, and high precision, accuracy (mean percentage recovery 98.6%, and specificity. Additionally, the efficiency of degradation was monitored using HPLC giving comparable results with RP TLC measurements. [Acknowledgement. This work was performed within the framework of the research project No. 172017 supported by the Ministry of Education and Science of Serbia.

  10. Comparative Chromatographic Analysis and Pharmacodynamic ...

    African Journals Online (AJOL)

    The laboratory analysis of the Garcinia Kolanuts extracts showed receptors inhibition of Beta adrenergic sites, adenosine, melatonin, opiate, purine, calcium channel L-type and 5HT5A. Conclusion: Garcinia kolanut extract exhibits a combined effects of all the known antiglaucoma drugs used in comparison. NQJHM Vol.

  11. Impurity analysis in EC-99mTC radiotracer using chromatographic techniques

    International Nuclear Information System (INIS)

    Almeida, E.V.; Fukumori, N.T.O.; Mengatti, J.; Silva, C.P.G.; Matsuda, M.M.N.

    2008-01-01

    The objective of this study was to develop two chromatographic methods of impurity analysis in radiotracer 99m Tc-EC: the Thin Layer Chromatography (TLC) and the High Performance Liquid Chromatography Reversed Phase (HPLC-RP)

  12. GAS CHROMATOGRAPHIC AND SPECTROSCOPIC ANALYSIS OF ...

    African Journals Online (AJOL)

    Peroxyformic acid prepared in-situ was employed for epoxidation of canola oil in the presence of toluene. Gas chromatographic analysis of the product revealed the following species: C16:0; C18:0; C18:1; C18:2; C18:3; monoepoxy C18:0; monoepoxy C18:1; monoepoxy C18:2; diepoxy C18:0; diepoxy C18:1 and triepoxy ...

  13. Principles of qualitative analysis in the chromatographic context.

    Science.gov (United States)

    Valcárcel, M; Cárdenas, S; Simonet, B M; Carrillo-Carrión, C

    2007-07-27

    This article presents the state of the art of qualitative analysis in the framework of the chromatographic analysis. After establishing the differences between two main classes of qualitative analysis (analyte identification and sample classification/qualification) the particularities of instrumental qualitative analysis are commented on. Qualitative chromatographic analysis for sample classification/qualification through the so-called chromatographic fingerprint (for complex samples) or the volatiles profile (through the direct coupling headspace-mass spectrometry using the chromatograph as interface) is discussed. Next, more technical exposition of the qualitative chromatographic information is presented supported by a variety of representative examples.

  14. Simple gas chromatographic method for furfural analysis.

    Science.gov (United States)

    Gaspar, Elvira M S M; Lopes, João F

    2009-04-03

    A new, simple, gas chromatographic method was developed for the direct analysis of 5-hydroxymethylfurfural (5-HMF), 2-furfural (2-F) and 5-methylfurfural (5-MF) in liquid and water soluble foods, using direct immersion SPME coupled to GC-FID and/or GC-TOF-MS. The fiber (DVB/CAR/PDMS) conditions were optimized: pH effect, temperature, adsorption and desorption times. The method is simple and accurate (RSDfurfurals will contribute to characterise and quantify their presence in the human diet.

  15. Chromatographical analysis of phenolic acids in some species of Polygonum L. genus. Part 1 Qualitative analysis by two-dimensional thin layer chromatography (TLC

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    Helena D. Smolarz

    2014-01-01

    Full Text Available The Two-Dimensional Thin Layer Chromatography method has been used for the separation and identification of phenolic acids from six taxons of Pohygonum L. genus. The following acids were found: caffeic, p-coumaric, ferulic, p-hydroxybenzoic, m-hydroxybenzoic, vanillic, syringic, p-hydroxyphenylacetic, o-hydroxyphenylacetic, synapic, melillotic, salicylic, gentisic, elagic, gallic, chlorogenic, protocatechuic and homoprotocatechuic. Gallic, ferulic, vanillic, p-coumaric and p-hydroxybenzoic acids were isolated from herb Polygonum convolvulus L. using column chromatography.

  16. Chromatographic analysis and purification of multiply tritium-labelled eicosanoids

    International Nuclear Information System (INIS)

    Shevchenko, V.P.; Nagaev, I.Yu.; Myasoedov, N.F.

    1988-01-01

    A comparative study of different chromatographic techniques (gas-liquid (GLC), thin-layer (TLC), liquid (LC), high-pressure liquid (HPLC) chromatography) is presented. They were applied to the analysis and preparative purification of tritium-labelled eicosanoids with a molar radioactivity of 1.8-8.8 TBq/mmol, obtained by selective hydrogenation and by chemical or enzymic methods. The possibility of analyzing reaction mixtures and isolating individual multiply labelled eicosanoids with a chemical and radiochemical purity of 95-98% was demonstrated. Special features of HPLC for high molar radioactivity eicosanoids are considered. (author) 9 refs.; 6 tabs

  17. Comparison of two detection methods in thin layer chromatographic ...

    African Journals Online (AJOL)

    o-tolidine plus potassium iodide and photosynthesis inhibition detection methods were investigated for the analysis of three triazine herbicides (atrazine, ametryne, simazine) and two urea herbicides (diuron, metobromuron) in a coastal savanna soil using thin layer chromatography to compare the suitability of the two ...

  18. Physicochemical, thin layer and gas-liquid chromatographic ...

    African Journals Online (AJOL)

    DELL

    2012-05-22

    May 22, 2012 ... PEG (3 m × 3 mm I. D.) was used for gas chromatography. Physicochemical analysis ... subjected to thin layer chromatography on plates (20 × 20 cm) having 0.25 mm thick silica gel ..... Headspace solid- phase microextraction ...

  19. Liquid chromatographic analysis of phenobarbitone, ethosuximide ...

    African Journals Online (AJOL)

    A liquid chromatographic method for the simultaneous assay of four anticonvulsant drugs, phenobarbitone, ethosuximide, phenytoin and carbamazepine on a polystyrene-divinyl benzene column is described. The method was developed by the systematic study of different types of co-polymer materials, type and ...

  20. Evaluation of a thin-layer chromatographic technique for ...

    African Journals Online (AJOL)

    Methanol extracts of both fistula and bush samples were prepared and analysed by thin-layer chromatography. Chromatoplates, when visualised under ultraviolet light, revealed a number of fluorescent compounds, some of which were common in both the fistula and bush sample extracts. By comparing the presence of ...

  1. HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHIC DETERMINATION OF CAFFEIC ACID AND ROSMARINIC ACID FROM THE LEAVES OF Orthosiphon stamineus

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    M. Amzad Hossain

    2010-06-01

    Full Text Available This paper presents the studies performed on extraction of Orthosiphon stamineus, Benth by using different solvent for the identification and quantification of the caffeic acid derivatives such as caffeic acid  and rosmarinic acid which confers to the leaves of this plant with remarkable pharmaceutical properties. High performance thin-layer chromatographic (HPTLC allows the identification and the quantification of more than 20 samples in the same chromatographic run. The analysis of the samples requires 15-30 min compared with more than 2 h using a typical HPLC method. Using the techniques of the HPTLC and the UV-VIS spectra we have found that the extraction of this herb plant contain, the caffeic acid and rosmarinic acid ranging between 0.029% up to 0.506% and up to 0.24% to 2.24% respectively.     Keywords: Caffice acid derivatives, quantification, Malaysian Orthosiphon stamineus, HPTLC

  2. On-line gas chromatographic analysis of airborne particles

    Science.gov (United States)

    Hering, Susanne V [Berkeley, CA; Goldstein, Allen H [Orinda, CA

    2012-01-03

    A method and apparatus for the in-situ, chemical analysis of an aerosol. The method may include the steps of: collecting an aerosol; thermally desorbing the aerosol into a carrier gas to provide desorbed aerosol material; transporting the desorbed aerosol material onto the head of a gas chromatography column; analyzing the aerosol material using a gas chromatograph, and quantizing the aerosol material as it evolves from the gas chromatography column. The apparatus includes a collection and thermal desorption cell, a gas chromatograph including a gas chromatography column, heated transport lines coupling the cell and the column; and a quantization detector for aerosol material evolving from the gas chromatography column.

  3. Thin layer chromatographic analyses of pesticides in a soil ecosystem

    International Nuclear Information System (INIS)

    Afful, S.; Dogbe, S.A.; Ahmad, K.; Ewusie, A.T.

    2008-01-01

    Silica gel 60, silica gel 60 F 254 , and aluminium oxide as adsorbents were used to investigate their suitability for the analysis and detection of the pesticides: nitrofen, atrazine, diuron, dioxacarb, propoxur, propanil, carbaryl and cypermethrin in soil ecosystem using ethyl acetate, chloroform, dichloromethane and ethyl acetate/chloroform (1:1) as developing solvents. O-tolidine and potassium iodide reagent were used for the detection of pesticides. R f values obtained for the pesticides using the silica gel 60-ethyl acetate. silica gel 60F 254 -ethyl acetate, silica gel 60 chloroform, silica gel 60 F 254 - chloroform, silica gel 60 - (1:1) ethyl acetate/chloroform and silica gel 60 F 254 - (1:1) ethyl acetate/chloroform systems generally were within the stipulated range of 0.4-0.8. R f values obtained for the pesticides using silica gel 60-dichloromethane systems were very low except for cypermethrin and nitrofen. Analysis with aluminium oxide coated plates gave a heavy yellow background with the detection reagent making visualization of spots difficult. Aluminium oxide coated plate is, therefore, not recommended when o-tolidine plus potassium iodide is used as detection reagent. (au)

  4. Gas chromatographic column for the Viking 1975 molecular analysis experiment

    Science.gov (United States)

    Novotny, M.; Hayes, J. M.; Bruner, F.; Simmonds, P. G.

    1975-01-01

    A gas chromatographic column has been developed for use in the remote analysis of the Martian surface. The column, which utilizes a liquid-modified organic adsorbent (Tenax) as the stationary phase, provides efficient transmission and resolution of nanogram quantities of organic materials in the presence of millionfold excesses of water and carbon dioxide.

  5. Chromatographic analysis of toxic phosphylated oximes (POX): a brief overview.

    Science.gov (United States)

    Becker, Christian; Worek, Franz; John, Harald

    2010-10-01

    Poisoning with organophosphorus compounds (OP), e.g. pesticides and nerve agents, causes inhibition of acetylcholinesterase (AChE) by phosphylation of the active site serine residue. Consequently, accumulation of stimulating acetylcholine in the synaptic cleft induces cholinergic crisis which ultimately may lead to death. For standard causal therapy, enzyme reactivators are administered representing oxime derivatives of quarternary pyridinium compounds, e.g. pralidoxime (2-PAM), obidoxime and HI 6. The mechanism of action includes removal of the phosphyl moiety by a nucleophilic attack of the oximate molecule substituting the enzyme and forming a phosphylated oxime (POX). POX is produced in stoichiometric amounts of reactivated enzyme and exhibits a significantly enhanced toxicity (inhibition rate constant) when compared to the parent OP. However, stability of POX under physiological conditions appears to be highly limited. Nevertheless, the presence of POX reveals a potential critical issue for both therapeutic efficacy in vivo and pharmacokinetic and pharmacodynamic (PK-PD) modelling based on cholinesterase activity data. Detailed characterization represents an important need for elaboration of the entire oxime pharmacology.Nevertheless, reports on POX toxicity and analysis are quite rare and may therefore be indicative of the challenge of POX analysis. This review provides a concise overview of chromatographic approaches applied to POX separation. Chromatography represents the key technology for POX purification and quantification in kinetic in vitro studies using buffers and biological fluids. Applications based on reversed-phase chromatography (RPC), ion pair chromatography (IPC) and an affinity approach as well as thin layer chromatography (TLC) are discussed and novel applications and data are presented. Copyright © 2010 John Wiley & Sons, Ltd.

  6. Chromatographic fingerprint similarity analysis for pollutant source identification

    International Nuclear Information System (INIS)

    Xie, Juan-Ping; Ni, Hong-Gang

    2015-01-01

    In the present study, a similarity analysis method was proposed to evaluate the source-sink relationships among environmental media for polybrominated diphenyl ethers (PBDEs), which were taken as the representative contaminants. Chromatographic fingerprint analysis has been widely used in the fields of natural products chemistry and forensic chemistry, but its application to environmental science has been limited. We established a library of various sources of media containing contaminants (e.g., plastics), recognizing that the establishment of a more comprehensive library allows for a better understanding of the sources of contamination. We then compared an environmental complex mixture (e.g., sediment, soil) with the profiles in the library. These comparisons could be used as the first step in source tracking. The cosine similarities between plastic and soil or sediment ranged from 0.53 to 0.68, suggesting that plastic in electronic waste is an important source of PBDEs in the environment, but it is not the only source. A similarity analysis between soil and sediment indicated that they have a source-sink relationship. Generally, the similarity analysis method can encompass more relevant information of complex mixtures in the environment than a profile-based approach that only focuses on target pollutants. There is an inherent advantage to creating a data matrix containing all peaks and their relative levels after matching the peaks based on retention times and peak areas. This data matrix can be used for source identification via a similarity analysis without quantitative or qualitative analysis of all chemicals in a sample. - Highlights: • Chromatographic fingerprint analysis can be used as the first step in source tracking. • Similarity analysis method can encompass more relevant information of pollution. • The fingerprints strongly depend on the chromatographic conditions. • A more effective and robust method for identifying similarities is required

  7. Development of off-line layer chromatographic and total reflection X-ray fluorescence spectrometric methods for arsenic speciation

    Energy Technology Data Exchange (ETDEWEB)

    Mihucz, Victor G. [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary); Moricz, Agnes M. [L. Eoetvoes University, Department of Chemical Technology and Environmental Chemistry, P.O. Box 32, H-1518 Budapest (Hungary); Kroepfl, Krisztina [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Szikora, Szilvia [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Tatar, Eniko [Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary); L. Eoetvoes University, Department of Inorganic and Analytical Chemistry, P.O. Box 32, H-1518 Budapest (Hungary); Parra, Lue Meru Marco [Universidad Centro-occidental Lisandro Alvarado, Decanato de Agronomia, Departamento de Quimica y Suelos Unidad de Analisis Instrumental, Apartado Postal 4076, Cabudare 3023 (Venezuela); Zaray, Gyula [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary) and Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary) and L. Eoetvoes University, Department of Inorganic and Analytical Chemistry, P.O. Box 32, H-1518 Budapest (Hungary)]. E-mail: zaray@ludens.elte.hu

    2006-11-15

    Rapid and low cost off-line thin layer chromatography-total reflection X-ray fluorescence spectrometry and overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods have been developed for separation of 25 ng of each As(III), As(V), monomethyl arsonic acid and dimethylarsinic acid applying a PEI cellulose stationary phase on plastic sheets and a mixture of acetone/acetic acid/water = 2:1:1 (v/v/v) as eluent system. The type of eluent systems, the amounts (25-1000 ng) of As species applied to PEI cellulose plates, injection volume, development distance, and flow rate (in case of overpressured thin layer chromatography) were taken into consideration for the development of the chromatographic separation. Moreover, a microdigestion method employing nitric acid for the As spots containing PEI cellulose scratched from the developed plates divided into segments was developed for the subsequent total reflection X-ray fluorescence spectrometry analysis. The method was applied for analysis of root extracts of cucumber plants grown in As(III) containing modified Hoagland nutrient solution. Both As(III) and As(V) were detected by applying the proposed thin layer chromatography/overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods.

  8. Development of off-line layer chromatographic and total reflection X-ray fluorescence spectrometric methods for arsenic speciation

    International Nuclear Information System (INIS)

    Mihucz, Victor G.; Moricz, Agnes M.; Kroepfl, Krisztina; Szikora, Szilvia; Tatar, Eniko; Parra, Lue Meru Marco; Zaray, Gyula

    2006-01-01

    Rapid and low cost off-line thin layer chromatography-total reflection X-ray fluorescence spectrometry and overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods have been developed for separation of 25 ng of each As(III), As(V), monomethyl arsonic acid and dimethylarsinic acid applying a PEI cellulose stationary phase on plastic sheets and a mixture of acetone/acetic acid/water = 2:1:1 (v/v/v) as eluent system. The type of eluent systems, the amounts (25-1000 ng) of As species applied to PEI cellulose plates, injection volume, development distance, and flow rate (in case of overpressured thin layer chromatography) were taken into consideration for the development of the chromatographic separation. Moreover, a microdigestion method employing nitric acid for the As spots containing PEI cellulose scratched from the developed plates divided into segments was developed for the subsequent total reflection X-ray fluorescence spectrometry analysis. The method was applied for analysis of root extracts of cucumber plants grown in As(III) containing modified Hoagland nutrient solution. Both As(III) and As(V) were detected by applying the proposed thin layer chromatography/overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods

  9. Gas chromatographic isolation technique for compound-specific radiocarbon analysis

    International Nuclear Information System (INIS)

    Uchida, M.; Kumamoto, Y.; Shibata, Y.; Yoneda, M.; Morita, M.; Kawamura, K.

    2002-01-01

    Full text: We present here a gas chromatographic isolation technique for the compound-specific radiocarbon analysis of biomarkers from the marine sediments. The biomarkers of fatty acids, hydrocarbon and sterols were isolated with enough amount for radiocarbon analysis using a preparative capillary gas chromatograph (PCGC) system. The PCGC systems used here is composed of an HP 6890 GC with FID, a cooled injection system (CIS, Gerstel, Germany), a zero-dead-volume effluent splitter, and a cryogenic preparative collection device (PFC, Gerstel). For AMS analysis, we need to separate and recover sufficient quantity of target individual compounds (>50 μgC). Yields of target compounds from C 14 n-alkanes to C 40 to C 30 n-alkanes and approximately that of 80% for higher molecular weights compounds more than C 30 n-alkanes. Compound specific radiocarbon analysis of organic compounds, as well as compound-specific stable isotope analysis, provide valuable information on the origins and carbon cycling in marine system. Above PCGC conditions, we applied compound-specific radiocarbon analysis to the marine sediments from western north Pacific, which showed the possibility of a useful chronology tool for estimating the age of sediment using organic matter in paleoceanographic study, in the area where enough amounts of planktonic foraminifera for radiocarbon analysis by accelerator mass spectrometry (AMS) are difficult to obtain due to dissolution of calcium carbonate. (author)

  10. Preparation of porous hollow silica spheres via a layer-by-layer process and the chromatographic performance

    Science.gov (United States)

    Wei, Xiaobing; Gong, Cairong; Chen, Xujuan; Fan, Guoliang; Xu, Xinhua

    2017-03-01

    Hollow silica spheres possessing excellent mechanical properties were successfully prepared through a layer-by-layer process using uniform polystyrene (PS) latex fabricated by dispersion polymerization as template. The formation of hollow SiO2 micro-spheres, structures and properties were observed in detail by zeta potential, SEM, TEM, FTIR, TGA and nitrogen sorption porosimetry. The results indicated that the hollow spheres were uniform with particle diameter of 1.6 μm and shell thickness of 150 nm. The surface area was 511 m2/g and the pore diameter was 8.36 nm. A new stationary phase for HPLC was obtained by using C18-derivatized hollow SiO2 micro-spheres as packing materials and the chromatographic properties were evaluated for the separation of some regular small molecules. The packed column showed low column pressure, high values of efficiency (up to about 43 000 plates/m) and appropriate asymmetry factors.

  11. Chromatographic Methods for the Analysis of Polyphenols in Wines

    Directory of Open Access Journals (Sweden)

    Medić-Šarić, M.

    2009-03-01

    Full Text Available Wine is an excellent source of various classes of polyphenols, including phenolic acids, flavonoids, and trihydroxystilbene resveratrol (Fig.1. Polyphenols play a major role in wine quality since they contribute to the sensory characteristics of wine, particularly color and astringency. A recent interest in these substances has been stimulated by abundant evidence of their beneficial effects on human health, such as anticarcinogenic, antiinflamatory and antimicrobial activities. Therefore, numerous studies have been performed in the attempt to analyze polyphenols in wine. This paper reviews the current advances in the determination of polyphenols in wine by the major chromatographic techniques such as thin-layer chromatography (TLC and high-performance liquid chromatography (HPLC.The great complexity of the polyphenolic content of wine and the difficulty in obtaining some of the standards usually require sample preparation before analysis. Two methods for sample preparation, liquid-liquid extraction and solid-phase extraction, are most commonly applied. Hydrolysis is applied frequently, but not exclusively, to remove the sugar moieties from glycosides.TLC on silica gel plates is useful for the rapid and low-cost separation and identification of the polyphenols present in wine (Fig. 2. Densitometric quantitative analysis of polyphenols in wine extracts is usually performed by scanning the TLC plates with UV light at wavelengths of 350–365 nm or 250–260 nm (Fig. 3. For the evaluation of the most efficient mobile phase and an optimal choice of the combination of two or more mobile phases, two methods may be applied: information theory and numerical taxonomy. HPLC currently represents the most popular technique for the analysis of polyphenols in wine. For this purpose, a reversed-phase HPLC method that uses gradient elution with binary elution system is usually employed. Routine detection is based on measurement of UV-Vis absorption with a diode

  12. Technical artifacts in chromatographic analysis of Tc-99m radiopharmaceuticals

    International Nuclear Information System (INIS)

    Kowalsky, R.J.; Creekmore, J.R.

    1982-01-01

    Technical artifacts produced during chromatographic analysis of technetium radiopharmaceuticals were investigated. Such artifacts are, we found, caused by improper spotting and drying techniques; these in turn produce spuriously high impurities in Tc-99m complexes of DTPA, MDP, PPi, and GH. The ITLC-SG/acetone system produces considerable streaking of Tc-complex if the applied spot is large and not dried before development. This results in activity in the solvent front portion of the chromatographic strip indicating falsely high levels of pertechnetate impurity. Proper drying of the applied spot eliminates the artifact. The ITLC-SG/saline system yields falsely high, hydrolyzed-reduced technetium impurities if the spot is allowed to enter the solvent during development. Correct spot placement and size eliminate this problem. Strips that are allowed to dry in room air for several minutes may indicate considerable pertechnetate impurity on the chromatogram; yet this may not actually be present in the radiopharmaceutical vial. Drying spots rapidly with hot air or in a nitrogen atmosphere before development eliminates this problem

  13. Rapid thin-layer chromatographic photodensitometric method for the determination of metoclopramide and clebopride in the presence of some of their metabolic products.

    Science.gov (United States)

    Huizing, G; Beckett, A H; Segura, J

    1979-04-21

    Metoclopramide and its newly developed analogue clebopride, together with some of their metabolic products are quantitated, following extraction from biological tissues and fluids, and subsequent separation on silica gel thin-layer chromatographic plates. Diazotisation, followed by coupling with N-(1-naphthyl)ethylenediammonium dichloride, carried out on the thin-layer plate, is utilised for visualisation. The intensity of the spots is measured by photodensitometric analysis. The effect of variation of various experimental conditions is studied. The method has proven to be satisfactory for the measurement of 20 ng/ml of these compounds in biological material; the results are well within the accepted limits of deviation.

  14. High-Performance Thin-Layer Chromatographic Quantification of Rosmarinic Acid and Rutin in Abnormal Savda Munziq

    Directory of Open Access Journals (Sweden)

    S. G. Tian

    2013-01-01

    Full Text Available A high-performance thin-layer chromatographic (HPTLC method has been established for simultaneous analysis of rosmarinic acid and rutin in Abnormal Savda Munziq (ASMq. A methanol extract of ASMq was used for quantification. The compounds were separated on silica gel H thin layer plate with ethyl acetate-formic acid-acetic acid-water 15 : 1 : 1 : 1.5 (v/v as a developer, trichloroethanol as the color reagent. The plates were scanned at 365 nm. The linear calibration data of rosmarinic acid and rutin were in the range of 0.0508 to 0.2540 μg (r=0.9964, 0.2707 to 1.35354 μg (r=0.9981, respectively. The recovery rate of rosmarinic acid was 99.17% (RSD = 2.92% and rutin was 95.24% (RSD = 2.38%. The method enables rapid screening, precise, selective, and sensitive quantification for pharmaceutical analysis.

  15. Separation and determination of high-carbon alcohols using method of column chromatographic and gas-chromatographic analysis

    International Nuclear Information System (INIS)

    Kang Zhongrong; Li Biping; Zeng Yongchang

    1988-01-01

    This paper describes the separation and determination of high-carbon alcohols from amine extractant by using the method of column chromatography of aluminium oxide and gas-chromatographic analysis. The total conent of high-carbon alcohols is determined by the method of column chromatography, while the components of the high-carbon alcohols and their relative contents are determined by the method of gas-chromatography. A simple reliable and practical method is provided for the analysis of high-carbon alcohol from the amine extractant in this paper

  16. Comprehensive two-dimensional liquid chromatographic analysis of poloxamers.

    Science.gov (United States)

    Malik, Muhammad Imran; Lee, Sanghoon; Chang, Taihyun

    2016-04-15

    Poloxamers are low molar mass triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), having number of applications as non-ionic surfactants. Comprehensive one and two-dimensional liquid chromatographic (LC) analysis of these materials is proposed in this study. The separation of oligomers of both types (PEO and PPO) is demonstrated for several commercial poloxamers. This is accomplished at the critical conditions for one of the block while interaction for the other block. Reversed phase LC at CAP of PEO allowed for oligomeric separation of triblock copolymers with regard to PPO block whereas normal phase LC at CAP of PPO renders oligomeric separation with respect to PEO block. The oligomeric separation with regard to PEO and PPO are coupled online (comprehensive 2D-LC) to reveal two-dimensional contour plots by unconventional 2D IC×IC (interaction chromatography) coupling. The study provides chemical composition mapping of both PEO and PPO, equivalent to combined molar mass and chemical composition mapping for several commercial poloxamers. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Recent Advances in Water Analysis with Gas Chromatograph Mass Spectrometers

    Science.gov (United States)

    MacAskill, John A.; Tsikata, Edem

    2014-01-01

    We report on progress made in developing a water sampling system for detection and analysis of volatile organic compounds in water with a gas chromatograph mass spectrometer (GCMS). Two approaches are described herein. The first approach uses a custom water pre-concentrator for performing trap and purge of VOCs from water. The second approach uses a custom micro-volume, split-splitless injector that is compatible with air and water. These water sampling systems will enable a single GC-based instrument to analyze air and water samples for VOC content. As reduced mass, volume, and power is crucial for long-duration, manned space-exploration, these water sampling systems will demonstrate the ability of a GCMS to monitor both air and water quality of the astronaut environment, thereby reducing the amount of required instrumentation for long duration habitation. Laboratory prototypes of these water sampling systems have been constructed and tested with a quadrupole ion trap mass spectrometer as well as a thermal conductivity detector. Presented herein are details of these water sampling system with preliminary test results.

  18. Rapid planar chromatographic analysis of 25 water-soluble dyes used as food additives.

    Science.gov (United States)

    Morlock, Gertrud E; Oellig, Claudia

    2009-01-01

    A rapid planar chromatographic method for identification and quantification of 25 water-soluble dyes in food was developed. In a horizontal developing chamber, the chromatographic separation on silica gel 60F254 high-performance thin-layer chromatography plates took 12 min for 40 runs in parallel, using 8 mL ethyl acetate-methanol-water-acetic acid (65 + 23 + 11 + 1, v/v/v/v) mobile phase up to a migration distance of 50 mm. However, the total analysis time, inclusive of application and evaluation, took 60 min for 40 runs. Thus, the overall time/run can be calculated as 1.5 min with a solvent consumption of 200 microL. A sample throughput of 1000 runs/8 h day can be reached by switching between the working stations (application, development, and evaluation) in a 20 min interval, which triples the analysis throughput. Densitometry was performed by absorption measurement using the multiwavelength scan mode in the UV and visible ranges. Repeatabilities [relative standard deviation (RSD), 4 determinations] at the first or second calibration level showed precisions of mostly or = 0.9987) and RSD values ( or = 0.9996). If necessary for confirmation, online mass spectra were recorded within a minute.

  19. Stability indicating high performance thin layer chromatographic method for quantitation of venlafaxine in bulk and pharmaceutical dosage form

    Directory of Open Access Journals (Sweden)

    Sunil K Dubey

    2015-01-01

    Full Text Available Background: Venlafaxine (VEN is a phenethylamine bicyclic compound, chemically, 1-(2-[dimethyl amino]-1-[4-methoxy phenyl] ethyl cyclo-hexan-1ol hydrochloride. It is a antidepressant. It inhibits the reuptake of serotonin, nor adrenaline and dopamine to a lesser extent at the presynaptic membrane. Aim: A simple, rapid, precise, accurate, and economical high performance thin layer chromatographic (HPTLC method has been developed and validated for the determination of VEN both as a bulk drug and in formulation. Materials and Methods: The method uses aluminum plates precoated with silica gel 60 F254 as the stationary phase and dichloromethane:acetonitrile:N-hexane:triethylamine: 0.5:0.5:4:0.7 (v/v/v/v as mobile phase. Results: This system gave compact spots for VEN (R f = 0.46 ± 0.05. Forced degradation studies were done by subjecting VEN to acid and alkali hydrolysis, oxidation, and reduction. The peak of the degradation product was well resolved from that of the pure drug and had significant different R f values. Analysis of VEN was performed in the absorbance mode at 225 nm. The limit of detection and quantification were 12.48 and 37.81 ng/spot respectively. Conclusions: The developed method was validated and found to be simple, specific, accurate and precise and can be used for routine quality control analysis of VEN in bulk and pharmaceutical formulation.

  20. Two dimensional chromatographic analysis as a quality measure of ...

    African Journals Online (AJOL)

    Background: Homoeopathic mother tinctures and herbal extracts are used worldwide for medicinal purposes on the basis that the plant extract contains the active components essential for medicinal use. Quality analysis of samples ensures that the correct active components are present for medicinal use. Thin layer ...

  1. Derivatization reactions in the gas—liquid chromatographic analysis of drugs in biological fluids

    NARCIS (Netherlands)

    Hulshoff, A.; Lingeman, H.

    1984-01-01

    Alkylation, acylation, silylation and other derivatization reactions applied to the gas chromatographic analysis of drugs in biological matrices are reviewed. Reaction conditions are discussed in relation to reaction mechanisms. Detector-oriented labelling of drugs, and derivatization with chiral

  2. Acrylamide analysis in food by liquid chromatographic and gas chromatographic methods.

    Science.gov (United States)

    Elbashir, Abdalla A; Omar, Mei M Ali; Ibrahim, Wan Aini Wan; Schmitz, Oliver J; Aboul-Enein, Hassan Y

    2014-01-01

    Acrylamide (AA) is a compound classified as carcinogenic to humans by the International Agency for Research on Cancer. It was first discovered to be present in certain heated processed food by the Swedish National Food Administration (SNFA) and University of Stockholm in early 2002. The major pathway for AA formation in food is the Maillard reaction between reducing sugar and the amino acid asparagine at high temperature. Since the discovery of AA's presence in food, many analytical methods have been developed for determination of AA contents in different food matrices. Also, several studies have been conducted to develop extraction procedures for AA from difficult food matrices. AA is a small, highly polar molecule, which makes its extraction and analysis challenging. Many articles and reviews have been published dealing with AA in food. The aim of the review is to discuss AA formation in food, the factors affecting AA formation and removal, AA exposure assessment, AA extraction and cleanup from food samples, and analytical methods used in AA determination, such as high-performance liquid chromatography (HPLC) and gas chromatography (GC). Special attention is given to sample extraction and cleanup procedures and analytical techniques used for AA determination.

  3. Principal coordinate analysis assisted chromatographic analysis of bacterial cell wall collection: A robust classification approach.

    Science.gov (United States)

    Kumar, Keshav; Cava, Felipe

    2018-04-10

    In the present work, Principal coordinate analysis (PCoA) is introduced to develop a robust model to classify the chromatographic data sets of peptidoglycan sample. PcoA captures the heterogeneity present in the data sets by using the dissimilarity matrix as input. Thus, in principle, it can even capture the subtle differences in the bacterial peptidoglycan composition and can provide a more robust and fast approach for classifying the bacterial collection and identifying the novel cell wall targets for further biological and clinical studies. The utility of the proposed approach is successfully demonstrated by analysing the two different kind of bacterial collections. The first set comprised of peptidoglycan sample belonging to different subclasses of Alphaproteobacteria. Whereas, the second set that is relatively more intricate for the chemometric analysis consist of different wild type Vibrio Cholerae and its mutants having subtle differences in their peptidoglycan composition. The present work clearly proposes a useful approach that can classify the chromatographic data sets of chromatographic peptidoglycan samples having subtle differences. Furthermore, present work clearly suggest that PCoA can be a method of choice in any data analysis workflow. Copyright © 2018 Elsevier Inc. All rights reserved.

  4. Thin-layer chromatographic determination of erythromycin and other macrolide antibiotics in livestock products.

    Science.gov (United States)

    Petz, M; Solly, R; Lymburn, M; Clear, M H

    1987-01-01

    A method is described for determination of 4 macrolide antibiotics in livestock products. Erythromycin, tylosin, oleandomycin, and spiramycin were extracted from animal tissues, milk, and egg with acetonitrile at pH 8.5. Cleanup was done by adding sodium chloride and dichloromethane, evaporating the organic layer, and subsequent acid/base partitioning. After the antibiotics were separated by thin-layer chromatography (TLC), they were reacted with xanthydrol and could be detected as purple spots down to 0.02 mg/kg without interference by other commonly used therapeutic drugs (23 were tested). Anisaldehyde-sulfuric acid, cerium sulfate-molybdic acid, phosphomolybdic acid, and Dragendorff's reagent proved to be less sensitive as visualizing agents. For quantitation, TLC plates were scanned at 525 nm. Recoveries were between 71 and 96% for erythromycin and tylosin in liver, muscle, and egg at the 0.1-0.5 mg/kg level and 51% for erythromycin in milk at the 0.02 mg/kg level (coefficient of variation = 10-18%). Bioautography with Bacillus subtilis was used to confirm results, in addition to TLC analysis of derivatized antibiotics and liquid chromatography with electrochemical detection. Various derivatization procedures for erythromycin were investigated for improved ultra-violet or fluorescence detection in liquid chromatography.

  5. Hydrocarbon Fuel Thermal Performance Modeling based on Systematic Measurement and Comprehensive Chromatographic Analysis

    Science.gov (United States)

    2016-07-31

    distribution unlimited Hydrocarbon Fuel Thermal Performance Modeling based on Systematic Measurement and Comprehensive Chromatographic Analysis Matthew...vital importance for hydrocarbon -fueled propulsion systems: fuel thermal performance as indicated by physical and chemical effects of cooling passage... analysis . The selection and acquisition of a set of chemically diverse fuels is pivotal for a successful outcome since test method validation and

  6. [Sample preparation methods for chromatographic analysis of organic components in atmospheric particulate matter].

    Science.gov (United States)

    Hao, Liang; Wu, Dapeng; Guan, Yafeng

    2014-09-01

    The determination of organic composition in atmospheric particulate matter (PM) is of great importance in understanding how PM affects human health, environment, climate, and ecosystem. Organic components are also the scientific basis for emission source tracking, PM regulation and risk management. Therefore, the molecular characterization of the organic fraction of PM has become one of the priority research issues in the field of environmental analysis. Due to the extreme complexity of PM samples, chromatographic methods have been the chief selection. The common procedure for the analysis of organic components in PM includes several steps: sample collection on the fiber filters, sample preparation (transform the sample into a form suitable for chromatographic analysis), analysis by chromatographic methods. Among these steps, the sample preparation methods will largely determine the throughput and the data quality. Solvent extraction methods followed by sample pretreatment (e. g. pre-separation, derivatization, pre-concentration) have long been used for PM sample analysis, and thermal desorption methods have also mainly focused on the non-polar organic component analysis in PM. In this paper, the sample preparation methods prior to chromatographic analysis of organic components in PM are reviewed comprehensively, and the corresponding merits and limitations of each method are also briefly discussed.

  7. Gas chromatographic analysis of volatiles in fluid and gas inclusions

    Science.gov (United States)

    Andrawes, F.; Holzer, G.; Roedder, E.; Gibson, E.K.; Oro, John

    1984-01-01

    Most geological samples and some synthetic materials contain fluid inclusions. These inclusions preserve for us tiny samples of the liquid and/or the gas phase that was present during formation, although in some cases they may have undergone significant changes from the original material. Studies of the current composition of the inclusions provide data on both the original composition and the change since trapping.These inclusions are seldom larger than 1 millimeter in diameter. The composition varies from a single major compound (e.g., water) in a single phase to a very complex mixture in one or more phases. The concentration of some of the compounds present may be at trace levels.We present here some analyses of inclusions in a variety of geological samples, including diamonds. We used a sample crusher and a gas chromatography—mass spectrometry (GC—MS) system to analyze for organic and inorganic volatiles present as major to trace constituents in inclusions. The crusher is a hardened stainless-steel piston cylinder apparatus with tungsten carbide crusing surfaces, and is operated in a pure helium atmosphere at a controlled temperature.Samples ranging from 1 mg to 1 g were crushed and the released volatiles were analyzed using multi-chromatographic columns and detectors, including the sensitive helium ionization detector. Identification of the GC peaks was carried out by GC—MS. This combination of procedures has been shown to provide geochemically useful information on the process involved in the history of the samples analyzed.

  8. Chromatographic fingerprint analysis of yohimbe bark and related dietary supplements using UHPLC/UV/MS.

    Science.gov (United States)

    Sun, Jianghao; Chen, Pei

    2012-03-05

    A practical ultra high-performance liquid chromatography (UHPLC) method was developed for fingerprint analysis of and determination of yohimbine in yohimbe barks and related dietary supplements. Good separation was achieved using a Waters Acquity BEH C(18) column with gradient elution using 0.1% (v/v) aqueous ammonium hydroxide and 0.1% ammonium hydroxide in methanol as the mobile phases. The study is the first reported chromatographic method that separates corynanthine from yohimbine in yohimbe bark extract. The chromatographic fingerprint analysis was applied to the analysis of 18 yohimbe commercial dietary supplement samples. Quantitation of yohimbine, the traditional method for analysis of yohimbe barks, were also performed to evaluate the results of the fingerprint analysis. Wide variability was observed in fingerprints and yohimbine content among yohimbe dietary supplement samples. For most of the dietary supplements, the yohimbine content was not consistent with the label claims. Copyright © 2011. Published by Elsevier B.V.

  9. Improvement of gas chromatographic analysis for organic acids and ...

    African Journals Online (AJOL)

    Yomi

    2010-08-27

    Aug 27, 2010 ... and ethanol fermentation by using the anaerobic bacterium. Clostridium ... GC analysis. Standard solution for GC analysis consisted of acetic acid (Sigma-. Aldrich ... Microorganism and inoculum preparation. C. beijerinckii ...

  10. Chromatographic and Spectrophotometric Analysis of Phenolic Compounds from Fruits of Libidibia ferrea Martius.

    Science.gov (United States)

    Ferreira, Magda R A; Fernandes, Mônica T M; da Silva, Wliana A V; Bezerra, Isabelle C F; de Souza, Tatiane P; Pimentel, Maria F; Soares, Luiz A L

    2016-05-01

    Libidibia ferrea (Mart. ex Tul.) L.P. Queiroz (Fabaceae) is a tree which is native to Brazil, widely known as "Jucá," where its herbal derivatives are used in folk medicine with several therapeutic properties. The constituents, which have already been described in the fruit, are mainly hydrolysable tannins (gallic acid [GA] and ellagic acid [EA]). The aim of this study was to investigate the phenolic variability in the fruit of L. ferrea by ultraviolet/visible (UV/VIS) and chromatographic methods (high-performance liquid chromatography [HPLC]/high-performance thin layer chromatography [HPTLC]). Several samples were collected from different regions of Brazil and the qualitative (fingerprints by HPTLC and HPLC) and quantitative analysis (UV/VIS and HPLC) of polyphenols were performed. The HPTLC and HPLC profiles allowed separation and identification of both major analytical markers: EA and GA. The chemical profiles were similar in a number of spots or peaks for the samples, but some differences could be observed in the intensity or area of the analytical markers for HPTLC or HPLC, respectively. Regarding the quantitative analysis, the polyphenolic content by UV/VIS ranged from 13.99 to 37.86 g% expressed as GA or from 10.75 to 29.09 g% expressed as EA. The contents of EA and GA by liquid chromatography-reversed phase (LC-RP) method ranged from 0.57 to 2.68 g% and from 0.54 to 3.23 g%, respectively. The chemical profiles obtained by HPTLC or HPLC, as well as the quantitative analysis by spectrophotometry or LC-RP method, were suitable for discrimination of each herbal sample and can be used as tools for the comparative analysis of the fruits from L. ferrea. The polyphenols of fruits of Libidibia ferrea can be quantified by UV/VIS and HPLCThe HPLC method was able to detect the gallic and ellagic acids in several samples of fruits of Libidibia ferreaThe phenolic profiles of fruits from Libidibia ferrea by HPTLC and HPLC were reproductible. Abbreviations used: HPTLC

  11. Thin-layer chromatographic technique for rapid detection of bacterial phospholipases.

    Science.gov (United States)

    Legakis, N J; Papavassiliou, J

    1975-11-01

    Silica gel thin-layer chromatography was employed to detect lecithinase activity induced from bacterial resting cell preparations induced from bacterial resting cell preparations incubated at 37 C for 4 h in the presence of purified egg yolk lecithin. Bacillus subtilis, Bacillus cereus, Serratia marcescens, and Pseudomonas aeruginosa hydrolyzed lecithin with the formation of free fatty acids as the sole lipid-soluble product. In none of the Escherichia coli and Citrobacter freundii strains tested could lecithinase activity be detected. Four among eight strains of Enterobacter aerogenes and one among 12 strains of Proteus tested produced negligible amounts of free fatty acid.

  12. Improvement of gas chromatographic analysis for organic acids and ...

    African Journals Online (AJOL)

    Yomi

    2010-08-27

    Aug 27, 2010 ... short retention time and fair recognition peak of the compounds were obtained under the ... GC for acid and solvent analysis from ABE fermentation ... FID was kept at 230°C. Nitrogen gas was used as a carrier gas at a.

  13. Gas Chromatographic-Mass Spectrometric Analysis of Essential Oil ...

    African Journals Online (AJOL)

    Purpose: To analyze the essential oil composition of the flower of Jasminum officinale L. var. grandifloroum L. (Jasminum grandiflorum) by gas chromatography-mass spectrometry (GC-MS). Methods: The optimum GC-MS conditions used for the analysis were 250 oC inlet temperature, 150 oC MSD detector temperature, ...

  14. Chromatographic-mass spectrometric analysis of ethanol extract of ...

    African Journals Online (AJOL)

    Methods: The dried root of Maesa perlaria var. formosana was extracted with 95 % ethanol for composition analysis under the following optimum GC-MS conditions: 250 °C inlet temperature, 250 °C MSD detector temperature, and GC oven temperature programmed as follows: initial temperature held at 70 °C for 15 min, ...

  15. The adaptive internet application for interpretation of the transformer oil gas chromatographic analysis results

    Directory of Open Access Journals (Sweden)

    Polužanski Vladimir

    2015-01-01

    Full Text Available This paper describes an adaptive Internet application for the interpretation of the transformer oil gas chromatographic analysis results. The first version of the application is developed by following an evolutionary software development concept. The most important software development risks and the appropriate solutions are described. An open-source web framework named Bootstrap is used for an application implementation. The application is developed by using ASP.NET and MS SQL server.

  16. Thin layer chromatographic method for the detection of uric acid: collaborative study.

    Science.gov (United States)

    Thrasher, J J; Abadie, A

    1978-07-01

    A collaborative study has been completed on an improved method for the detection and confirmation of uric acid from bird and insect excreta. The proposed method involves the lithium carbonate solubilization of the suspect excreta material, followed by butanol-methanol-water-acetic acid thin layer chromatography, and trisodium phosphate-phosphotungstic acid color development. The collaborative tests resulted in 100% detection of uric acid standard at the 50 ng level and 75% detection at the 20-25 ng level. No false positives were reported during tests of compounds similar to uric acid. The proposed method has been adopted official first action; the present official final action method, 44.161, will be retained for screening purposes.

  17. Gas chromatographic analysis of extractive solvent in reprocessing plants

    International Nuclear Information System (INIS)

    Marlet, B.

    1984-01-01

    Operation of a reprocessing plant using the Purex process is recalled and analytical controls for optimum performance are specified. The aim of this thesis is the development of analytical methods using gas chromatography required to follow the evolution of the extraction solvent during spent fuel reprocessing. The solvent at different concentrations, is analysed along the reprocessing lines in organic or aqueous phases. Solvent degradation interferes with extraction and decomposition products are analysed. The solvent becomes less and less efficient, also it is distilled and quality is checked. Traces of solvent should also be checked in waste water. Analysis are made as simple as possible to facilitate handling of radioactive samples [fr

  18. Stability indicating high performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in combined dosage form.

    Science.gov (United States)

    Bageshwar, Deepak; Khanvilkar, Vineeta; Kadam, Vilasrao

    2011-11-01

    A specific, precise and stability indicating high-performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in pharmaceutical formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F 254 as the stationary phase. The solvent system consisted of methanol:water:ammonium acetate; 4.0:1.0:0.5 (v/v/v). This system was found to give compact and dense spots for both itopride hydrochloride ( R f value of 0.55±0.02) and pantoprazole sodium ( R f value of 0.85±0.04). Densitometric analysis of both drugs was carried out in the reflectance-absorbance mode at 289 nm. The linear regression analysis data for the calibration plots showed a good linear relationship with R 2 =0.9988±0.0012 in the concentration range of 100-400 ng for pantoprazole sodium. Also, the linear regression analysis data for the calibration plots showed a good linear relationship with R 2 =0.9990±0.0008 in the concentration range of 200-1200 ng for itopride hydrochloride. The method was validated for specificity, precision, robustness and recovery. Statistical analysis proves that the method is repeatable and selective for the estimation of both the said drugs. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating method.

  19. Further Validation of a Rapid Screening Semiquantitative Thin-Layer Chromatographic Method for Marketed Antimalarial Medicines for Adoption in Malawi

    Directory of Open Access Journals (Sweden)

    Dorcas Osei-Safo

    2018-01-01

    Full Text Available A recently developed semiquantitative thin-layer chromatographic (SQ-TLC assay has been employed in postmarketing surveillance of antimalarial medicines used in Malawi prior to HPLC assay. Both methods gave analogous results in a significant majority of the samples, with a good correlation (r = 0.9012 for the active pharmaceutical ingredients of the dosage forms assayed. Artemether-containing medicines had the highest percentage (92.67% of samples with comparable results for both assays. The lowest percentage (66.67% was observed in artesunate-containing medicines. The SQ-TLC method was validated for specificity, accuracy, precision, linearity, and stability according to the International Conference on Harmonisation guidelines, with the results falling within acceptable limits. For specificity, retention factor values of the test samples and reference standards were comparable, while accuracy and precision of 91.1 ± 5.7% were obtained for all samples. The method was linear in the range 1.0–2.0 µg/spot with a correlation coefficient of r = 0.9783. Stability tests also fell within acceptable limits. In this study, we present the validation of the SQ-TLC method and propose its adoption as a rapid screening tool for field estimation of the quality of antimalarial and other essential medicines in Malawi and other parts of the developing world prior to a more accurate HPLC assay.

  20. Automation of an ion chromatograph for precipitation analysis with computerized data reduction

    Science.gov (United States)

    Hedley, Arthur G.; Fishman, Marvin J.

    1982-01-01

    Interconnection of an ion chromatograph, an autosampler, and a computing integrator to form an analytical system for simultaneous determination of fluoride, chloride, orthophosphate, bromide, nitrate, and sulfate in precipitation samples is described. Computer programs provided with the integrator are modified to implement ionchromatographic data reduction and data storage. The liquid-flow scheme for the ion chromatograph is changed by addition of a second suppressor column for greater analytical capacity. An additional vave enables selection of either suppressor column for analysis, as the other column is regenerated and stabilized with concentrated eluent.Minimum limits of detection and quantitation for each anion are calculated; these limits are a function of suppressor exhaustion. Precision for replicate analyses of six precipitation samples for fluoride, chloride, orthophosphate, nitrate, and sulfate ranged from 0.003 to 0.027 milligrams per liter. To determine accuracy of results, the same samples were spiked with known concentrations of the above mentioned anions. Average recovery was 108 percent.

  1. Spectroscopic and chromatographic analysis of oil from an oil shale flash pyrolysis unit

    Energy Technology Data Exchange (ETDEWEB)

    Khraisha, V.H.; Irqsousi, N.A. [University of Jordan, Amman (Jordan). Dept. of Chemical Engineering; Shabib, I.M. [Applied Science Univ., Amman (Jordan). Dept. of Chemistry

    2003-01-01

    In this investigation, spectroscopic (FT-IR, UV-Vis, {sup 1}H NMR) and chromatographic (GC) techniques were used to analyze two Jordanian shale oils, Sultani and El-Lajjun. The oils were extracted at different pyrolysis temperatures (400-500{sup o}C) using a fluidized bed reactor. The spectroscopic and chromatographic analyses show that the variation of pyrolysis temperature has no significant effect on the composition of the produced oil. The {sup 1}H NMR results indicate that the protons of methyl and methelyene represent the bulk of the hydrogen ({approx}90%) in most shale oil samples. GC analysis reveals that the oil samples contain n-alkanes with a predominant proportion of n-C{sub 25}. (Author)

  2. Use of the Keele injector for sample introduction for gas chromatographic analysis of vinclozolin in lettuces.

    Science.gov (United States)

    Shim, J H; Lee, Y S; Kim, M R; Lee, C J; Kim, I S

    2003-10-10

    We examined a Keele injector for sample introduction for gas chromatographic analysis of vinclozolin treated in lettuces. Samples in milligram quantity were introduced into a glass tube in a Keele injector at a gas chromatograph injection port. The glass tube was then crushed to allow the sample to carry onto a capillary column in a normal manner. The standard calibration curve for quantitative detection of vinclozolin was obtained by determining vinclozolin spiked in samples at variable concentrations. The calibration curve showed a linear response to vinclozolin ranging from 0.05 to 1.0 microg/g, giving a slope value of 174.8, the y-intercept value of -2.8146 and the mean r2-value of 0.9994. Limit of quantification for vinclozolin was 0.05 microg/g by this method, comparable to 0.01 microg/g by a normal injector. When samples treated previously with vinclozolin were determined by the Keele injector, vinclozolin was found to be about 30% lower as compared to a normal method, suggesting about 70% recovery of the spiked vinclozolin by the Keele injector. From these results, the Keele injector was suggested to be potential for sample introduction in gas chromatographic analysis of vinclozolin in lettuce samples.

  3. Analysis of electrocautery generated smoke by chromatographic-mass spectrometry.

    Science.gov (United States)

    Kalil, Jefferson; Pessine, Francisco B T; Fidelis, Carlos H V; Menezes, Fabio H; Palma, Paulo Cesar Rodrigues

    2016-01-01

    to analyze the chemical components of the smoke from electrocautery from coagulating muscle and liver tissues of pigs. we collected smoke produced by electrocautery applied to porcine tissue in previously evacuated bottles, with qualitative and quantitative analysis of the compounds present through the hyphenated technique gas chromatography / mass spectrometry. there was a majority of decanal aldehyde in the fumes from the subcutaneous, muscle and liver tissues. Fumes of subcutaneous and muscular tissues also showed the presence of hexanal and phenol. In the fumes of subcutaneous and liver tissues we also found toluene and limonene and, finally, nonanal smoke was present in the muscle and liver tissues. there is increasing evidence showing that smoke from electrocautery used in subcutaneous, muscle and liver tissue is harmful to human health. Thus, there is need to reduce exposure to it or wear masks with filters capable of retaining these particles. analisar quimicamente os componentes da fumaça do eletrocautério, provenientes da coagulação de tecidos, muscular e hepático de suino. coleta de fumaça produzida por eletrocauterização de tecido porcino em frascos previamente evacuados com análise qualitativa e quantitativa dos compostos presentes, através de técnica hifenada, cromatografia a gás/espectrometria de massas. houve presença majoritária do aldeído decanal nas fumaças provenientes dos tecidos subcutâneo, muscular e hepático. Fumaças dos tecidos subcutâneo e muscular mostraram também a presença de hexanal e fenol. Nas fumaças dos tecidos subcutâneo e hepático foram encontrados ainda tolueno e limoneno e, por fim, nonanal estava presente nas fumaças dos tecidos muscular e hepático. há número crescente de evidências mostrando que fumaça proveniente de eletrocauterização de tecidos subcutâneo, muscular e hepático é nociva à saúde de seres humanos. Portanto, há necessidade de reduzir a exposição a ela ou usar máscara com

  4. Stability indicating high performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in combined dosage form

    Directory of Open Access Journals (Sweden)

    Deepak Bageshwar

    2011-11-01

    Full Text Available A specific, precise and stability indicating high-performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in pharmaceutical formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F254 as the stationary phase. The solvent system consisted of methanol:water:ammonium acetate; 4.0:1.0:0.5 (v/v/v. This system was found to give compact and dense spots for both itopride hydrochloride (Rf value of 0.55±0.02 and pantoprazole sodium (Rf value of 0.85±0.04. Densitometric analysis of both drugs was carried out in the reflectance–absorbance mode at 289 nm. The linear regression analysis data for the calibration plots showed a good linear relationship with R2=0.9988±0.0012 in the concentration range of 100–400 ng for pantoprazole sodium. Also, the linear regression analysis data for the calibration plots showed a good linear relationship with R2=0.9990±0.0008 in the concentration range of 200–1200 ng for itopride hydrochloride. The method was validated for specificity, precision, robustness and recovery. Statistical analysis proves that the method is repeatable and selective for the estimation of both the said drugs. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating method. Keywords: Gastroesophageal reflux disease (GERD, Itopride hydrochloride, Pantoprazole sodium, High performance thin layer chromatography (HPTLC, Stability indicating, Forced degradation

  5. Chromatographic analysis of irradiated medicinal herbs: Rhamnus purshiana D.C. and Paulinia cupana Kunth

    International Nuclear Information System (INIS)

    Koseki, Paula M; Rela, Paulo R.; Villavicencio, Anna Lucia C.H.

    2001-01-01

    Full text: Introduction: Nowadays the interest in phytotherapeutics is increasing; therefore the consumer attention to the medicinal active plants is growing. The rich Brazilian flora, represents more than 20% of the plant species know in the world as raw materials for pharmaceutical preparations. Since the last decade microbiological decontamination of medicinal herbs by irradiation has been carried out and presented in many scientific articles. The microbial contamination in these raw plant materials is the issue of several studies, which propose appropriate techniques for the reduction of micro-organisms. One of these techniques is radiation processing by gamma source industrial plants. Other is the utilisation of accelerators. In order to safeguard consumers, treatment by ionizing radiation is allowed now in Brazil to medicinal herbs and pharmaceutical products. The radiation process is known as safe for a large variety of products and applications as well as a effective in the reduction of pathogenic micro-organisms. The aim of our study is observe if flavonoids and alkaloids will be influenced by irradiation. Experimental: Samples - Local herbs companies in Sao Paulo, Brazil, provided dehydrated samples of Rhamnus purshiana D.C. and Paulinia cupana Kunth. Irradiation. The powdered samples were irradiated in on plastic package in a electron beam accelerator facility of Radiation Dynamics Inc., USA (E=1,5 MeV, l=25 mA, installed in IPEN Sao Paulo, Brazil. The irradiation doses were 10,20 and 30 kGy at room temperature. The thickness of samples was less than 0,5 cm. Sample analysis -flavonoids and alkaloids analysis was performed in a Thin Layer Chromatography according to Wagner (1995). Results and discussion: No alterations in the flavonoids and alkaloids, after irradiation treatment in that herbs was observed. Chromatographic analysis of the different extracts irradiated at increasing doses indicated that there were no great differences in the chemical

  6. Chromatographic background drift correction coupled with parallel factor analysis to resolve coelution problems in three-dimensional chromatographic data: quantification of eleven antibiotics in tap water samples by high-performance liquid chromatography coupled with a diode array detector.

    Science.gov (United States)

    Yu, Yong-Jie; Wu, Hai-Long; Fu, Hai-Yan; Zhao, Juan; Li, Yuan-Na; Li, Shu-Fang; Kang, Chao; Yu, Ru-Qin

    2013-08-09

    Chromatographic background drift correction has been an important field of research in chromatographic analysis. In the present work, orthogonal spectral space projection for background drift correction of three-dimensional chromatographic data was described in detail and combined with parallel factor analysis (PARAFAC) to resolve overlapped chromatographic peaks and obtain the second-order advantage. This strategy was verified by simulated chromatographic data and afforded significant improvement in quantitative results. Finally, this strategy was successfully utilized to quantify eleven antibiotics in tap water samples. Compared with the traditional methodology of introducing excessive factors for the PARAFAC model to eliminate the effect of background drift, clear improvement in the quantitative performance of PARAFAC was observed after background drift correction by orthogonal spectral space projection. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Analysis of turbulent boundary layers

    CERN Document Server

    Cebeci, Tuncer

    1974-01-01

    Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculati

  8. Stochastic resonance is applied to quantitative analysis for weak chromatographic signal of glyburide in plasma

    International Nuclear Information System (INIS)

    Zhang Wei; Xiang Bingren; Wu Yanwei; Shang Erxin

    2005-01-01

    Based on the theory of stochastic resonance, a new method carried on the quantitive analysis to weak chromatographic signal of glyburide in plasma, which was embedded in the noise background and the signal-to-noise ratio (SNR) of HPLC-UV is enhanced remarkably. This method enhances the quantification limit to 1 ng ml -1 , which is the same as HPLC-MS, and makes it possible to detect the weak signal accurately by HPLC-UV, which was not suitable before. The results showed good recovery and linear range from 1 to 50 ng ml -1 of glyburide in plasma and the method can be used for quantitative analysis of glyburide

  9. Chromatographic enhancement techniques for the analysis of persistent organic pollutants in environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Reiner, E.; Boden, A.; MacPherson, K.; Kolic, T. [Ontario Ministry of the Environment, Ottawa, Ontario (Canada); Dorman, F. [Restek Corporation, Belefonte, PA (United States); Cochran, J. [LECO Corporation, Las Vegas, NV (United States)

    2004-09-15

    A number of chromatographic enhancements can be made to improve resolution, reduce analysis times and increase peak capacity. Fast GC with TOFMS is able to deconvolute coeluting peaks with unique mass spectra separated by at least 150 ms. Analyte specific columns like Rtx-Dioxin2 can resolve all the 2,3,7,8 containing congeners except 1,2,3,7,8,9-HxCDF. This compound is typically present at the lowest concentration or not detected and makes up less than 1% of the TEQ. Comprehensive 2D GC can be used to separate a number of difficult coelutions for PCBs and other halogenated organics.

  10. Multivariate analysis of chromatographic retention data as a supplementary means for grouping structurally related compounds.

    Science.gov (United States)

    Fasoula, S; Zisi, Ch; Sampsonidis, I; Virgiliou, Ch; Theodoridis, G; Gika, H; Nikitas, P; Pappa-Louisi, A

    2015-03-27

    In the present study a series of 45 metabolite standards belonging to four chemically similar metabolite classes (sugars, amino acids, nucleosides and nucleobases, and amines) was subjected to LC analysis on three HILIC columns under 21 different gradient conditions with the aim to explore whether the retention properties of these analytes are determined from the chemical group they belong. Two multivariate techniques, principal component analysis (PCA) and discriminant analysis (DA), were used for statistical evaluation of the chromatographic data and extraction similarities between chemically related compounds. The total variance explained by the first two principal components of PCA was found to be about 98%, whereas both statistical analyses indicated that all analytes are successfully grouped in four clusters of chemical structure based on the retention obtained in four or at least three chromatographic runs, which, however should be performed on two different HILIC columns. Moreover, leave-one-out cross-validation of the above retention data set showed that the chemical group in which an analyte belongs can be 95.6% correctly predicted when the analyte is subjected to LC analysis under the same four or three experimental conditions as the all set of analytes was run beforehand. That, in turn, may assist with disambiguation of analyte identification in complex biological extracts. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Determination of drugs in biological fluids by direct injection of samples for liquid-chromatographic analysis.

    Science.gov (United States)

    Mullett, Wayne M

    2007-03-10

    The analysis of drugs in various biological fluids is an important criterion for the determination of the physiological performance of a drug. After sampling of the biological fluid, the next step in the analytical process is sample preparation. The complexity of biological fluids adds to the challenge of direct determination of the drug by chromatographic analysis, therefore demanding a sample preparation step that is often time-consuming, tedious, and frequently overlooked. However, direct on-line injection methods offer the advantage of reducing sample preparation steps and enabling effective pre-concentration and clean-up of biological fluids. These procedures can be automated and therefore reduce the requirements for handling potentially infectious biomaterial, improve reproducibility, and minimize sample manipulations and potential contamination. The objective of this review is to present an overview of the existing literature with emphasis on advances in automated sample preparation methods for liquid-chromatographic methods. More specifically, this review concentrates on the use of direct injection techniques, such as restricted-access materials, turbulent-flow chromatography and other automated on-line solid-phase extraction (SPE) procedures. It also includes short overviews of emerging automated extraction-phase technologies, such as molecularly imprinted polymers, in-tube solid-phase micro-extraction, and micro-extraction in a packed syringe for a more selective extraction of analytes from complex samples, providing further improvements in the analysis of biological materials. Lastly, the outlook for these methods and potential new applications for these technologies are briefly discussed.

  12. Chromatographic methods

    International Nuclear Information System (INIS)

    Marhol, M.; Stary, J.

    1975-01-01

    The characteristics are given of chromatographic separation and the methods are listed. Methods and data on materials used in partition, adsorption, precipitation and ion exchange chromatography are listed and conditions are described under which ion partition takes place. Special attention is devoted to ion exchange chromatography where tables are given to show the course of values of the partition coefficients of different ions in dependence on the concentration of agents and the course of equilibrium sorptions on different materials in dependence on the solution pH. A theoretical analysis is given and the properties of the most widely used ion exchangers are listed. Experimental conditions and apparatus used for each type of chromatography are listed. (L.K.)

  13. Validated high-performance thin-layer chromatographic (HPTLC method for simultaneous determination of nadifloxacin, mometasone furoate, and miconazole nitrate cream using fractional factorial design

    Directory of Open Access Journals (Sweden)

    Kalpana G. Patel

    2016-07-01

    Full Text Available A high-performance thin-layer chromatographic method for simultaneous determination of nadifloxacin, mometasone furoate, and miconazole nitrate was developed and validated as per International Conference on Harmonization guidelines. High-performance thin-layer chromatographic separation was performed on aluminum plates precoated with silica gel 60F254 and methanol:ethyl acetate:toluene: acetonitrile:3M ammonium formate in water (1:2.5:6.0:0.3:0.2, % v/v as optimized mobile phase at detection wavelength of 224 nm. The retardation factor (Rf values for nadifloxacin, mometasone furoate, and miconazole nitrate were 0.23, 0.70, and 0.59, respectively. Percent recoveries in terms of accuracy for the marketed formulation were found to be 98.35–99.76%, 99.36–99.65%, and 99.16–100.25% for nadifloxacin, mometasone furoate, and miconazole nitrate, respectively. The pooled percent relative standard deviation for repeatability and intermediate precision studies was found to be < 2% for three target analytes. The effect of four independent variables, methanol content in total mobile phase, wavelength, chamber saturation time, and solvent front, was evaluated by fractional factorial design for robustness testing. Amongst all four factors, volume of methanol in mobile phase appeared to have a possibly significant effect on retention factor of miconazole nitrate compared with the other two drugs nadifloxacin and mometasone furoate, and therefore it was important to be carefully controlled. In summary, a novel, simple, accurate, reproducible, and robust high-performance thin-layer chromatographic method was developed, which would be of use in quality control of these cream formulations.

  14. Headspace solid-phase microextraction procedures for gas chromatographic analysis of biological fluids and materials.

    Science.gov (United States)

    Mills, G A; Walker, V

    2000-12-01

    Solid-phase microextraction (SPME) is a new solventless sample preparation technique that is finding wide usage. This review provides updated information on headspace SPME with gas chromatographic separation for the extraction and measurement of volatile and semivolatile analytes in biological fluids and materials. Firstly the background to the technique is given in terms of apparatus, fibres used, extraction conditions and derivatisation procedures. Then the different matrices, urine, blood, faeces, breast milk, hair, breath and saliva are considered separately. For each, methods appropriate for the analysis of drugs and metabolites, solvents and chemicals, anaesthetics, pesticides, organometallics and endogenous compounds are reviewed and the main experimental conditions outlined with specific examples. Then finally, the future potential of SPME for the analysis of biological samples in terms of the development of new devices and fibre chemistries and its coupling with high-performance liquid chromatography is discussed.

  15. Dynamic Headspace Sampling as an Initial Step for Sample Preparation in Chromatographic Analysis.

    Science.gov (United States)

    Wojnowski, Wojciech; Majchrzak, Tomasz; Dymerski, Tomasz; Gębicki, Jacek; Namieśnik, Jacek

    2017-11-01

    This work represents a brief summary of the use of dynamic headspace (DHS) as a technique for sample preparation in chromatographic analysis. Despite numerous developments in the area of analyte isolation and enrichment, DHS remains one of the fundamental methods used with GC. In our opinion, interest in this technique will not diminish significantly because it conforms to stipulations of green analytical chemistry. Moreover, DHS fulfills the need for methods that facilitate detection and determination of analytes present at ultratrace levels in complex matrixes. The main focus of this work was placed on the theoretical fundamentals of this method. Also described herein were DHS development, the advantages and disadvantages of this technique compared with other headspace sampling techniques, and selected examples of its applications in food and environmental analyses.

  16. High-performance liquid chromatographic analysis of anthraquinone compounds in the Laurera benguelensis

    Science.gov (United States)

    Manojlović, N.; Marković, Z.; Gritsanapan, W.; Boonpragob, K.

    2009-09-01

    A high-performance liquid chromatographic (HPLC) method has been developed for the characterization of anthraquinone metabolites in extracts of the lichen Laurera benguelensis. With this method four anthraquinone derivatives 1,8-dihydroxy-3-methoxy-6-methylanthraquinone, 1,8-dihydroxy-3-formyl-6-methoxyanthraquinone, 1,8-dihydroxy-3-hydroxymethyl-6-methoxy-anthraquinone and 1,3,8-trihyroxy-6-methylanthraquinone can be analyzed. Components of lichen were detected by characteristic ultraviolet spectra and relative retention times. This is first report of phytochemical analysis of L. benguelensis. Importance of this research is in recognizing some new source (lichen and its extracts) as a natural emplacement of antioxidants because oxidation with free radicals or autooxidation is big problem for preservation of food products.

  17. Formation of hydrocarbons in irradiated Brazilian beans: gas chromatographic analysis to detect radiation processing

    International Nuclear Information System (INIS)

    Villavicencio, A.L.C.H.; Mancini-Filho, J.; Hartmann, M.; Ammon, J.; Delincee, H.

    1997-01-01

    Radiation processing of beans, which are a major source of dietary protein in Brazil, is a valuable alternative to chemical fumigation to combat postharvest losses due to insect infestation. To ensure free consumer choice, irradiated food will be labeled as such, and to enforce labeling, analytical methods to detect the irradiation treatment in the food product itself are desirable. In two varieties of Brazilian beans, Carioca and Macacar beans, the radiolytic formation of hydrocarbons formed after alpha and beta cleavage, with regard to the carbonyl group in triglycerides, have been studied. Using gas chromatographic analysis of these radiolytic hydrocarbons, different yields per precursor fatty acid are observed for the two types of beans. However, the typical degradation pattern allows the identification of the irradiation treatment in both bean varieties, even after 6 months of storage

  18. Identification of homemade inorganic explosives by ion chromatographic analysis of post-blast residues.

    Science.gov (United States)

    Johns, Cameron; Shellie, Robert A; Potter, Oscar G; O'Reilly, John W; Hutchinson, Joseph P; Guijt, Rosanne M; Breadmore, Michael C; Hilder, Emily F; Dicinoski, Greg W; Haddad, Paul R

    2008-02-29

    Anions and cations of interest for the post-blast identification of homemade inorganic explosives were separated and detected by ion chromatographic (IC) methods. The ionic analytes used for identification of explosives in this study comprised 18 anions (acetate, benzoate, bromate, carbonate, chlorate, chloride, chlorite, chromate, cyanate, fluoride, formate, nitrate, nitrite, perchlorate, phosphate, sulfate, thiocyanate and thiosulfate) and 12 cations (ammonium, barium(II), calcium(II), chromium(III), ethylammonium, magnesium(II), manganese(II), methylammonium, potassium(I), sodium(I), strontium(II), and zinc(II)). Two IC separations are presented, using suppressed IC on a Dionex AS20 column with potassium hydroxide as eluent for anions, and non-suppressed IC for cations using a Dionex SCS 1 column with oxalic acid/acetonitrile as eluent. Conductivity detection was used in both cases. Detection limits for anions were in the range 2-27.4ppb, and for cations were in the range 13-115ppb. These methods allowed the explosive residue ions to be identified and separated from background ions likely to be present in the environment. Linearity (over a calibration range of 0.05-50ppm) was evaluated for both methods, with r(2) values ranging from 0.9889 to 1.000. Reproducibility over 10 consecutive injections of a 5ppm standard ranged from 0.01 to 0.22% relative standard deviation (RSD) for retention time and 0.29 to 2.16%RSD for peak area. The anion and cation separations were performed simultaneously by using two Dionex ICS-2000 chromatographs served by a single autoinjector. The efficacy of the developed methods was demonstrated by analysis of residue samples taken from witness plates and soils collected following the controlled detonation of a series of different inorganic homemade explosives. The results obtained were also confirmed by parallel analysis of the same samples by capillary electrophoresis (CE) with excellent agreement being obtained.

  19. Asymptotic analysis and boundary layers

    CERN Document Server

    Cousteix, Jean

    2007-01-01

    This book presents a new method of asymptotic analysis of boundary-layer problems, the Successive Complementary Expansion Method (SCEM). The first part is devoted to a general comprehensive presentation of the tools of asymptotic analysis. It gives the keys to understand a boundary-layer problem and explains the methods to construct an approximation. The second part is devoted to SCEM and its applications in fluid mechanics, including external and internal flows. The advantages of SCEM are discussed in comparison with the standard Method of Matched Asymptotic Expansions. In particular, for the first time, the theory of Interactive Boundary Layer is fully justified. With its chapter summaries, detailed derivations of results, discussed examples and fully worked out problems and solutions, the book is self-contained. It is written on a mathematical level accessible to graduate and post-graduate students of engineering and physics with a good knowledge in fluid mechanics. Researchers and practitioners will estee...

  20. Batch-to-batch quality consistency evaluation of botanical drug products using multivariate statistical analysis of the chromatographic fingerprint.

    Science.gov (United States)

    Xiong, Haoshu; Yu, Lawrence X; Qu, Haibin

    2013-06-01

    Botanical drug products have batch-to-batch quality variability due to botanical raw materials and the current manufacturing process. The rational evaluation and control of product quality consistency are essential to ensure the efficacy and safety. Chromatographic fingerprinting is an important and widely used tool to characterize the chemical composition of botanical drug products. Multivariate statistical analysis has showed its efficacy and applicability in the quality evaluation of many kinds of industrial products. In this paper, the combined use of multivariate statistical analysis and chromatographic fingerprinting is presented here to evaluate batch-to-batch quality consistency of botanical drug products. A typical botanical drug product in China, Shenmai injection, was selected as the example to demonstrate the feasibility of this approach. The high-performance liquid chromatographic fingerprint data of historical batches were collected from a traditional Chinese medicine manufacturing factory. Characteristic peaks were weighted by their variability among production batches. A principal component analysis model was established after outliers were modified or removed. Multivariate (Hotelling T(2) and DModX) control charts were finally successfully applied to evaluate the quality consistency. The results suggest useful applications for a combination of multivariate statistical analysis with chromatographic fingerprinting in batch-to-batch quality consistency evaluation for the manufacture of botanical drug products.

  1. Abnormal tyrosine and phenylalanine metabolism in patients with tyrosyluria and phenylketonuria; gas-liquid chromatographic analysis of urinary metabolites

    NARCIS (Netherlands)

    Wadman, S.K.; Heiden, C. van der; Ketting, D.; Sprang, F.J. van

    Gas-liquid chromatographic methods have been developed for the analysis of: urinary phenylalanine metabolites (I) in patients with phenylketonuria, tyrosine metabolites (II) in patients with a disturbed tyrosine metabolism at the level of p-hydroxyphenylpyruvate hydroxylase, and homogentisic acid in

  2. Current applications of miniaturized chromatographic and electrophoretic techniques in drug analysis.

    Science.gov (United States)

    Aturki, Zeineb; Rocco, Anna; Rocchi, Silvia; Fanali, Salvatore

    2014-12-01

    In the last decade, miniaturized separation techniques have become greatly popular in pharmaceutical analysis. Miniaturized separation methods are increasingly utilized in all processes of drug discovery as well as quality control of pharmaceutical preparation. The great advantages presented by the analytical miniaturized techniques, including high separation efficiency and resolution, rapid analysis and minimal consumption of reagents and samples, make them an attractive alternative to the conventional chromatographic methods for drug analysis. The purpose of this review is to give a general overview of the applicability of capillary electrophoresis (CE), capillary electrochromatography (CEC) and micro/capillary/nano-liquid chromatography (micro-LC/CLC/nano-LC) for the analysis of pharmaceutical formulations, active pharmaceutical ingredients (API), drug impurity testing, chiral drug separation, determination of drugs and metabolites in biological fluids. The results concerning the use of CEC, micro-LC, CLC, and nano-LC in the period 2009-2013, while for CE, those from 2012 up to the review draft are here summarized and some specific examples are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Chromatographic analysis of methylglyoxal and other α-dicarbonyls using gas-diffusion microextraction.

    Science.gov (United States)

    Santos, Christiane M; Valente, Inês M; Gonçalves, Luís M; Rodrigues, José A

    2013-12-07

    Many α-dicarbonyl compounds such as methylglyoxal, diacetyl and pentane-2,3-dione are important quality markers of processed foods. They are produced by enzymatic and chemical processes, the Maillard reaction is the most known chemical route for α-dicarbonyl formation. In the case of methylglyoxal, there are obstacles to be overcome when analysing this compound due to its high reactivity, low volatility and low concentration. The use of extraction techniques based on the volatilization of methylglyoxal (like solid-phase microextraction) showed to be ineffective for the methylglyoxal extraction from aqueous solutions. Therefore, derivatization is typically applied to increase analyte's volatility. In this work a new methodology for the extraction and analysis of methylglyoxal and also diacetyl and pentane-2,3-dione from selected food matrices is presented. It is based on a gas-diffusion microextraction step followed by high performance liquid chromatographic analysis. It was successfully applied to port wines, black tea and soy sauce. Methylglyoxal, diacetyl and pentane-2,3-dione were quantified in the following concentration ranges: 0.24-1.74 mg L(-1), 0.1-1.85 mg L(-1) and 0.023-0.15 mg L(-1), respectively. The main advantages over existing methodologies are its simplicity in terms of sample handling, not requiring any chemical modification of the α-dicarbonyls prior to the extraction, low reagent consumption and short time of analysis.

  4. Gas chromatographic analysis of simmondsins and simmondsin ferulates in jojoba meal.

    Science.gov (United States)

    Van Boven, M; Holser, R; Cokelaere, M; Flo, G; Decuypere, E

    2000-09-01

    A capillary gas chromatographic method was developed for the simultaneous determination of simmondsins and simmondsin ferulates in jojoba meal, in detoxified jojoba meal, in jojoba meal extracts, and in animal food mixtures.

  5. Antimicrobial Activity and Chromatographic Analysis of Extracts from Tropaeolum pentaphyllum Lam. Tubers

    Directory of Open Access Journals (Sweden)

    Ritiel Corrêa da Cruz

    2016-04-01

    Full Text Available Background: Tropaeolum pentaphyllum Lam. tubers (Tropaeolaceae are known and used as a condiment and for the treatment of skin infections in Southern Brazil. However, its activity and composition has not yet been investigated. Thus, different extracts and the essential oil from the tubers were tested against a range of microorganisms. The most active extracts were submitted to chromatographic analysis. Methods: Hydroalcoholic extract (70%, fractions of it, and the essential oil from the tubers were tested against several bacteria, yeasts and molds, furnishing the corresponding inhibitory, bactericidal and fungicidal minimal concentration values. The most active extracts were submitted to GC-MS investigation. Results: The strongest effects against different strains of microorganisms, such as Gram-positive and negative bacteria, Candida spp. and dermatophytes were observed for the essential oil and the chloroform fraction, with minimal inhibitory concentrations (MICs well below 200 µg/mL. GC-MS analysis revealed that the major essential oil constituent is benzyl isothiocyanate (BITC, while the chloroform fraction is constituted of BITC, amides, sulfur, fatty acids and its esters, all compounds that may be related to the demonstrated activity. Conclusions: Overall, the results support the popular use of the plant for the treatment of skin infections, and revealed the main active compounds.

  6. Multiplex gas chromatography: an alternative concept for gas chromatographic analysis of planetary atmospheres

    Science.gov (United States)

    Valentin, J. R.

    1989-01-01

    Gas chromatography (GC) is a powerful technique for analyzing gaseous mixtures. Applied to the earth's atmosphere, GC can be used to determine the permanent gases--such as carbon dioxide, nitrogen, and oxygen--and to analyze organic pollutants in air. The U.S. National Aeronautics and Space Administration (NASA) has used GC in spacecraft missions to Mars (the Viking Biology Gas Exchange Experiment [GEX] and the Viking Gas Chromatograph-Mass Spectrometer [GC-MS]) and to Venus (the Pioneer Venus Gas Chromatograph [PVGC] on board the Pioneer Venus sounder probe) for determining the atmospheric constituents of these two planets. Even though conventional GC was very useful in the Viking and Pioneer missions, spacecraft constraints and limitations intrinsic to the technique prevented the collection of more samples. With the Venus probe, for instance, each measurement took a relatively long time to complete (10 min), and successive samples could not be introduced until the previous samples had left the column. Therefore, while the probe descended through the Venusian atmosphere, only three samples were acquired at widely separated altitudes. With the Viking mission, the sampling rate was not a serious problem because samples were acquired over a period of one year. However, the detection limit was a major disadvantage. The GC-MS could not detect simple hydrocarbons and simple alcohols below 0.1 ppm, and the GEX could not detect them below 1 ppm. For more complex molecules, the detection limits were at the parts-per-billion level for both instruments. Finally, in both the Viking and Pioneer missions, the relatively slow rate of data acquisition limited the number of analyses, and consequently, the amount of information returned. Similar constraints are expected in future NASA missions. For instance, gas chromatographic instrumentation is being developed to collect and analyze organic gases and aerosols in the atmosphere of Titan (one of Saturn's satellites). The Titan

  7. Direct chromatographic analysis of metabolites of lipophilic tracers in whole blood by ISRP chromatography

    International Nuclear Information System (INIS)

    Rosenspire, K.C.; Hirth, W.; Jurisson, S.; Nowotnik, D.P.; Eckelman, W.C.; Nunn, A.D.

    1991-01-01

    HPLC using columns packed with 5 μ Internal Surface Reverse Phase (ISRP) resin have shown utility in the analysis of lipophilic drugs and their metabolites by direct injection of serum or plasma samples. We have developed a method for rapid on-line separation of small hydrophobic components from cellular whole blood components. This is achieved through the use of 75 μ GFF (glycine-phenylalanine-phenylalanine) glass bead ISRP chromatographic material packed into a small HPLC column, and used in conjunction with an HPLC system containing a switching valve and a second analytical column. When heparinized whole blood is applied to a 75 μ GFF ISRP column, and the column eluted with an isotonic eluent, lipophilic compounds free in plasma are retained by the column, while plasma proteins, blood cells, and compounds bound to these blood components pass through the ISRP column. Following the elution of these components, the lipophilic compounds retained on the ISRP column are eluted by increasing the percentage of organic solvent in the eluent, and are further resolved (if required) by the analytical column. We have applied this analytical method to the study of metabolism of the 99m Tc-BATO (Boronic acid Adducts of Technetium diOxime) cerebral and myocardial perfusion tracers. (author)

  8. Simultaneous column chromatographic extraction and purification of abscisic acid in peanut plants for direct HPLC analysis.

    Science.gov (United States)

    Zhang, Ya-Wen; Fan, Wei-Wei; Li, Hui; Ni, He; Han, Han-Bing; Li, Hai-Hang

    2015-10-01

    Abscisic acid (ABA), a universal signaling molecule, plays important roles in regulating plant growth, development and stress responses. The low contents and complex components in plants make it difficult to be accurately analyzed. A novel one-step sample preparation method for ABA in plants was developed. Fresh peanut (Arachis hypogaea) plant materials were fixed by oven-drying, microwave drying, boiling or Carnoy's fixative, and loaded onto a mini-preparing column. After washed the impurities, ABA was eluted with a small amount of solvent. ABA in plant materials was completely extracted and purified in 2mL solution and directly analyzed by HPLC, with a 99.3% recovery rate. Multiple samples can be simultaneously prepared. Analyses using this method indicated that the endogenous ABA in oven-dried peanut leaves increased 20.2-fold from 1.01 to 20.37μgg(-1) dry weight within 12h and then decreased in 30% polyethylene glycol 6000 treated plants, and increased 3.34-fold from 0.85 to 2.84μgg(-1) dry weight in 5 days and then decreased in soil drought treated plants. The method combined the column chromatographic extraction and solid-phase separation technologies in one step and can completely extracted plant endogenous ABA in a purified and highly concentrated form for direct HPLC analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Application of Gas Chromatographic analysis to RPC detectors in the ATLAS experiment at CERN-LHC

    CERN Document Server

    De Asmundis, R

    2007-01-01

    Starting from 2007 a large number (1200) Resistive Plate Chambers (RPC) detectors will be used as muon trigger detectors in the ATLAS Experiment at CERN-LHC accelerator. RPC are gaseous detector in which the quality and the stability of the gas mixture as well as the design of the gas supplying system, play a fundamental role in their functioning. RPC are foreseen to work more than ten years in the high radiation environment of ATLAS and the gas mixture acts really as a "lifeguard" for the detectors. For this reason a great attention has been devoted to the gas studies in order to optimize RPC performance, robustness and reliability in a high radiation environment. In this paper we describe the work done to decide how to supply and control in an optimal way the gas to the detectors, in order to ensure their best performance for a long time. The activity, based on Gas Chromatographic (GC) analysis, has been carried on a sample of final RPC working in radiation conditions much more intense than those foreseen f...

  10. Automatic settlement analysis of single-layer armour layers

    NARCIS (Netherlands)

    Hofland, B.; van gent, Marcel

    2016-01-01

    A method to quantify, analyse, and present the settlement of single-layer concrete armour layers of coastal structures is presented. The use of the image processing technique for settlement analysis is discussed based on various modelling
    studies performed over the years. The accuracy of the

  11. Batch-to-Batch Quality Consistency Evaluation of Botanical Drug Products Using Multivariate Statistical Analysis of the Chromatographic Fingerprint

    OpenAIRE

    Xiong, Haoshu; Yu, Lawrence X.; Qu, Haibin

    2013-01-01

    Botanical drug products have batch-to-batch quality variability due to botanical raw materials and the current manufacturing process. The rational evaluation and control of product quality consistency are essential to ensure the efficacy and safety. Chromatographic fingerprinting is an important and widely used tool to characterize the chemical composition of botanical drug products. Multivariate statistical analysis has showed its efficacy and applicability in the quality evaluation of many ...

  12. Storing of Extracts in Polypropylene Microcentrifuge Tubes Yields Contaminant Peak During Ultra-flow Liquid Chromatographic Analysis

    OpenAIRE

    Kshirsagar, Parthraj R.; Hegde, Harsha; Pai, Sandeep R.

    2016-01-01

    Background and Aim: This study was designed to understand the effect of storage in polypropylene microcentrifuge tubes and glass vials during ultra-flow liquid chromatographic (UFLC) analysis. Materials and Methods: One ml of methanol was placed in polypropylene microcentrifuge tubes (PP material, Autoclavable) and glass vials (Borosilicate) separately for 1, 2, 4, 8, 10, 20, 40, and 80 days intervals stored at ?4?C. Results: Contaminant peak was detected in methanol stored in polypropylene m...

  13. Multivariate analysis of FTIR and ion chromatographic data for the quality control of tequila.

    Science.gov (United States)

    Lachenmeier, Dirk W; Richling, Elke; López, Mercedes G; Frank, Willi; Schreier, Peter

    2005-03-23

    Principal component analysis (PCA) was applied to the chromatographic and spectroscopic data of authentic Mexican tequilas (n = 14) and commercially available samples purchased in Mexico and Germany (n = 24). The scores scatter plot of the first two principal components (PC) of the anions chloride, nitrate, sulfate, acetate, and oxalate accounting for 78% of the variability allowed a classification between tequilas bottled in Mexico and overseas; however, no discrimination between tequila categories was possible. Mexican products had a significantly (p = 0.0014) lower inorganic anion concentration (range = 1.5-5.1 mg/L; mean = 2.5 mg/L) than the products bottled in the importing countries (range = 3.3-62.6 mg/L; mean = 26.3 mg/L). FTIR allowed a rapid screening of density and ethanol as well as the volatile compounds methanol, ethyl acetate, propanol-1, isobutanol, and 2-/3-methyl-1-butanol using partial least-squares regression (precisions = 5.3-29.3%). Using PCA of the volatile compounds, a differentiation between tequila derived from "100% agave" (Agave tequilana Weber var. azul, Agavaceae) and tequila produced with other fermentable sugars ("mixed"tequila) was possible. The first two PCs describe 89% of the total variability of the data. Methanol and isobutanol influenced the variability in PC1, which led to discrimination. The concentrations of methanol and isobutanol were significantly higher (methanol, p = 0.004; isobutanol, p = 0.005) in the 100% agave (methanol, 297.9 +/- 49.5; isobutanol, 251.3 +/- 34.9) than in the mixed tequilas (methanol, 197.8 +/- 118.5; isobutanol, 151.4 +/- 52.8).

  14. High Performance Liquid Chromatographic Analysis of Phytoplankton Pigments Using a C16-Amide Column

    Science.gov (United States)

    A reverse-phase high performance liquid chromatographic (RP-HPLC) method was developed to analyze in a single run, most polar and non-polar chlorophylls and carotenoids from marine phytoplankton. The method is based on a RP-C16-Amide column and a ternary gradient system consistin...

  15. Full second order chromatographic/spectrometric data matrices for automated sample identification and component analysis by non-data-reducing image analysis

    DEFF Research Database (Denmark)

    Nielsen, Niles-Peter Vest; Smedsgaard, Jørn; Frisvad, Jens Christian

    1999-01-01

    A data analysis method is proposed for identification and for confirmation of classification schemes, based on single- or multiple-wavelength chromatographic profiles. The proposed method works directly on the chromatographic data without data reduction procedures such as peak area or retention...... classes from the reference chromatograms, This feature is a valuable aid in selecting components for further analysis, The identification method is demonstrated on two data sets: 212 isolates from 41 food-borne Penicillium species and 61 isolates from 6 soil-borne Penicillium species. Both data sets...

  16. Chromatographic analysis of cis- and trans-mevinphos in poisoned wildlife.

    Science.gov (United States)

    Allender, W J; Keegan, J

    1992-09-18

    A method is described for the analysis of the cis- and trans-isomers of mevinphos in baits and avian tissues. The procedure involves extraction of the mevinphos isomers with acetone-dichloromethane (1:1) followed by clean-up on alumina. Bait samples were initially screened by thin-layer chromatography and identity of extracts confirmed by infrared spectrophotometry and gas chromatography-mass spectrometry.

  17. Piper nigrum: micropropagation, antioxidative enzyme activities, and chromatographic fingerprint analysis for quality control.

    Science.gov (United States)

    Ahmad, Nisar; Abbasi, Bilal Haider; Rahman, Inayat ur; Fazal, Hina

    2013-04-01

    A reliable in vitro regeneration system for the economical and medicinally important Piper nigrum L. has been established. Callus and shoot regeneration was encouraged from leaf portions on Murashige and Skoog (MS) medium augmented with varied concentrations of plant growth regulators. A higher callus production (90 %) was observed in explants incubated on MS medium incorporated with 1.0 mg L(-1) 6-benzyladenine (BA) along with 0.5 mg L(-1) gibberellic acid after 4 weeks of culture. Moreover, a callogenic response of 85 % was also recorded for 1.0 mg L(-1) BA in combination with 0.25 mg L(-1) α-naphthalene acetic acid (NAA) and 0.25 mg L(-1) 2,4-dichlorophenoxyacetic acid or 0.5 mg L(-1) indole butyric acid (IBA) along with 0.25 mg L(-1) NAA and indole acetic acid. Subsequent sub-culturing of callus after 4 weeks of culture onto MS medium supplemented with 1.5 mg L(-1) thiodiazoran or 1.5 mg L(-1) IBA induced 100 % shoot response. Rooted plantlets were achieved on medium containing varied concentrations of auxins. The antioxidative enzyme activities [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)] revealed that significantly higher SOD was observed in regenerated plantlets than in other tissues. However, POD, CAT, and APX were higher in callus than in other tissues. A high-performance liquid chromatography (HPLC) fingerprint analysis protocol was established for quality control in different in vitro-regenerated tissues of P. nigrum L. During analysis, most of the common peaks represent the active principle "piperine." The chemical contents, especially piperine, showed variation from callus culture to whole plantlet regeneration. Based on the deviation in chromatographic peaks, the in vitro-regenerated plantlets exhibit a nearly similar piperine profile to acclimated plantlets. The in vitro regeneration system and HPLC fingerprint analysis established here brought a novel approach to the quality control of in vitro

  18. Chromatographic efficiency of polar capillary columns applied for the analysis of fatty acid methyl esters by gas chromatography.

    Science.gov (United States)

    Waktola, Habtewold D; Mjøs, Svein A

    2018-04-01

    The chromatographic efficiency that could be achieved in temperature-programmed gas chromatography was compared for four capillary columns that are typically applied for analysis of fatty acid methyl esters (FAME). Three different carrier gases, hydrogen, helium and nitrogen, were applied. For each experiment, the carrier gas velocities and the temperature rates were varied with a full 9 × 3 design, with nine levels on the carrier gas velocity and temperature rates of 1, 2 or 3°C/min. Response surface methodology was used to create models of chromatographic efficiency as a function of temperature rate and carrier gas velocity. The chromatographic efficiency was defined as the inverse of peak widths measured in retention index units. The final results were standardized so that the efficiencies that could be achieved within a certain time frame, defined by the retention time of the last compound in the chromatogram, could be compared. The results show that there were clear differences in the efficiencies that could be achieved with the different columns and that the efficiency decreased with increasing polarity of the stationary phase. The differences can be explained by higher resistance to mass transfer in the stationary phase in the most polar columns. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Time-resolved chromatographic analysis and mechanisms in adsorption and catalysis.

    Science.gov (United States)

    Roubani-Kalantzopoulou, Fani

    2009-03-06

    The main object of this review is the study of fundamentals of adsorption and heterogeneous catalysis, a benefit for the understanding of adsorptive and catalytic properties. This work aims to define and record, with the utmost accuracy, the phenomena and the possible reactions. A new methodology for the study of the adsorption is presented, which is a version of the well-known inverse gas chromatography. This reversed-flow inverse gas chromatography (RF-IGC) is technically very simple, and it is combined with a mathematical analysis that gives the possibility for the estimation of various physicochemical parameters related to adsorbent or catalyst characterization, under conditions compatible with the operation of real adsorbents and catalysts. On this base, this methodology has been successfully applied to the study of the impact of air pollutants, volatile organic and/or inorganic, on many solids such as marbles, ceramics, oxide-pigments of works of art, building materials, authentic statues of the Greek Archaeological Museums. Moreover, this methodology proved to be a powerful tool for studying the topography of active sites of heterogeneous surfaces in the nano-scale domain. Thus, some very important local quantities for the surface chemistry have been determined experimentally for many solids including thin films. These physicochemical local quantities (among which adsorption energy and entropy, surface diffusion coefficient, probability density function) have been determined from the experimental pairs of height of extra chromatographic peaks and time by a nonlinear least-squares method, through personal computer programs written in GW BASIC and lately in FORTRAN. Through the time-resolved analysis the surface characterization of the examined materials took place. In addition, the kinetic constants responsible for adsorption/desorption and surface chemical reactions have also been calculated. Thus, important answers have been provided to the following

  20. Coffee contains cholinomimetic compound distinct from caffeine. I: Purification and chromatographic analysis.

    Science.gov (United States)

    Tse, S Y

    1991-07-01

    Both regular and decaffeinated coffees were found to have cholinomimetic actions when tested in urethane-anesthetized rats. These actions were distinct from those of caffeine and reversible by atropine. The bioactive fraction was purified from alcoholic extracts of instant decaffeinated coffee by liquid column chromatography and preparative TLC. The purified compound showed similar pharmacological actions as the starting material. Chromatographic behavior was further characterized by analytical TLC and HPLC. Chromatographic analyses of extracts of green coffee beans and roasted ground coffees showed that the cardioactive compound was only present in roasted coffees. Similar analyses of other commonly consumed beverages, including teas and cocoa, showed that this compound was not present in beverages besides coffee.

  1. Microstructure-based analysis and simulation of flow and mass transfer in chromatographic stationary phases

    Science.gov (United States)

    Koku, Harun

    Limitations of mass transfer in chromatographic bioseparations employing traditional packed particles have fuelled the inception and development of alternative stationary phases with improved performance characteristics. This work investigates case studies in two categories of these alternative media, namely polymer-modified packed particles and continuous monolithic phases, for insight into their enhanced properties. Specifically, high-resolution microscopy techniques and image-based analysis algorithms were implemented to extract morphology information for these materials, in an attempt to elucidate the relation between microstructure and performance. For the monolith, mesoscopic simulation methods were also employed for a more rigorous analysis of the flow and dispersion behavior. Scanning and transmission electron microscopy images of the commercial polymer-modified, agarose-based particle Sepharose XL were compared to those for its unmodified counterpart, Sepharose FF. Local regions in the composite dextran-agarose Sepharose XL particles were noted to exhibit a denser network of fibers and smaller pore sizes overall, compared to those in the traditional Sepharose FF particles. Images of particles equilibrated with high concentrations of protein revealed a significant difference in protein localization patterns, with the stained protein in XL occupying a markedly higher area fraction of the images. This suggests a higher volume available for adsorption and provides visual clues into how the consistently higher static capacity of these polymer-modified particles is manifested. Treatment of the XL particles with dextranase, an enzyme that breaks down dextran, resulted in a reduction of protein coverage, providing evidence that it is indeed the dextran that is responsible for the improved static capacity in this polymer-modified stationary phase. Imaging and image analysis techniques were also used to analyze the commercial CIM(TM) disk monolith. Two- and three

  2. High-performance thin-layer chromatographic fingerprints of isoflavonoids for distinguishing between Radix Puerariae Lobate and Radix Puerariae Thomsonii.

    Science.gov (United States)

    Chen, Si-Bao; Liu, He-Ping; Tian, Run-Tao; Yang, Da-Jian; Chen, Shi-Lin; Xu, Hong-Xi; Chan, Albert S C; Xie, Pei-Shan

    2006-07-14

    The roots of Pueraria lobata (Wild.) Ohwi and Pueraria thomsonii Benth have been officially recorded in all editions of Chinese Pharmacopoeia under the same monograph 'Gegen' (Radix Puerariae, RP). However, in its 2005 edition, the two species were separated into both individual monographs, namely 'Gegen' (Radix Puerariae Lobatae, RPL) and 'Fenge' (Radix Puerariae Thomsonii, RPT), respectively, due to their obvious content discrepancy of puerarin, the major active constituent. In present paper, the fingerprint of high-performance thin-layer chromatography (HPTLC) combining digital scanning profiling was developed to identify and distinguish the both species in detail. The unique properties of the HPTLC fingerprints were validated by analyzing ten batches of Pueraria lobata and P. thomsonii samples, respectively. The common pattern of the HPTLC images of the roots of Pueraria spp. and the respective different ratios of the chemical distribution can directly discern the two species. The corresponding digital scanning profiles provided an easy way for quantifiable comparison among the samples. Obvious difference in ingredient content and HPTLC patterns of the two species questioned their bio-equivalence and explained that recording both species separately in the current edition of Chinese Pharmacopoeia (2005 edition) is reasonable due to not only the content of major constituent, puerarin, but also the peak-to-peak distribution in the fingerprint and integration value of the total components. Furthermore, the HPTLC fingerprint is also suitable for rapid and simple authentication and comparison of the subtle difference among samples with identical plant resource but different geographic locations.

  3. Detection limits in the chromatographic element trace analysis - quantitative TLC, HPLC and GC with the example of beryllium acetylacetonate

    International Nuclear Information System (INIS)

    Schwedt, G.

    1981-01-01

    Chromatographic analyses of beryllium acetylacetonate are carried out in synthetic solutions within the nano- and picogram range of beryllium. For thin-layer chromatography (TLC) normal and silanized silica gel is used, for high-performance liquid chromatography (HPLC) silica gel of 7 μm particles, for gas chromatography (GC) silicone SE-30 as stationary phase. Visual evaluation and remission measurements in TLC, UV-254 nm absorption measurements in HPLC and measurements with a FID in GC are employed for the determination of the calibration curves. A calibration curve through the origin and a detection limit of 150 pg Be determinable form are received by HPLC only. For trace analyses by GC a new definition of a detection limit for the evaluation of substance peaks on a solvent tailing is suggested. (orig.) [de

  4. Storing of Extracts in Polypropylene Microcentrifuge Tubes Yields Contaminant Peak During Ultra-flow Liquid Chromatographic Analysis.

    Science.gov (United States)

    Kshirsagar, Parthraj R; Hegde, Harsha; Pai, Sandeep R

    2016-05-01

    This study was designed to understand the effect of storage in polypropylene microcentrifuge tubes and glass vials during ultra-flow liquid chromatographic (UFLC) analysis. One ml of methanol was placed in polypropylene microcentrifuge tubes (PP material, Autoclavable) and glass vials (Borosilicate) separately for 1, 2, 4, 8, 10, 20, 40, and 80 days intervals stored at -4°C. Contaminant peak was detected in methanol stored in polypropylene microcentrifuge tubes using UFLC analysis. The contaminant peak detected was prominent, sharp detectable at 9.176 ± 0.138 min on a Waters 250-4.6 mm, 4 μ, Nova-Pak C18 column with mobile phase consisting of methanol:water (70:30). It was evident from the study that long-term storage of biological samples prepared using methanol in polypropylene microcentrifuge tubes produce contaminant peak. Further, this may mislead in future reporting an unnatural compound by researchers. Long-term storage of biological samples prepared using methanol in polypropylene microcentrifuge tubes produce contaminant peakContamination peak with higher area under the curve (609993) was obtained in ultra-flow liquid chromatographic run for methanol stored in PP microcentrifuge tubesContamination peak was detected at retention time 9.113 min with a lambda max of 220.38 nm and 300 mAU intensity on the given chromatographic conditionsGlass vials serve better option over PP microcentrifuge tubes for storing biological samples. Abbreviations used: UFLC: Ultra Flow Liquid Chromatography; LC: Liquid Chromatography; MS: Mass spectrometry; AUC: Area Under Curve.

  5. High-pressure liquid chromatographic analysis of pramoxine hydrochloride in high lipoid aerosol foam dosage form.

    Science.gov (United States)

    Weinberger, R; Mann, B; Posluszny, J

    1980-04-01

    A rapid and quantitative method for the determination of pramoxine hydrochloride by high-pressure liquid chromatography is presented. The drug is extracted as the salt from a preparation with a high lipoid composition by partitioning it to the aqueous phase of an ether-methanol-water-acetic acid system. The extract is chromatographed on an octadecylsilane bonded packing with a methanol-water-acetic acid-methanesulfonic acid mobile phase. The time required for each separation is approximately 6 min. Analytical recoveries of 100.4 +/- 1.5% were obtained.

  6. Characterization of crude oils and petroleum products: (I Elution liquid chromatographic separation and gas chromatographic analysis of crude oils and petroleum products

    Directory of Open Access Journals (Sweden)

    E.O. Odebunmi

    2002-12-01

    Full Text Available Some physical and chemical properties of samples of light, medium and heavy Nigerian crude oils and petroleum products including gasoline, kerosene and engine oil have been measured and are reported in this paper. The crude oils and petroleum products have also been characterized by fractional distillation and elution liquid chromatography. The fractions obtained from elution liquid chromatography were analyzed using gas chromatography (GC. The GC fractions were identified by comparing the retention time of peaks in the unknown samples with those of components of calibration standard mixtures. The importance of the physico-chemical properties and the significance of the fractional distillation and chromatographic separation methods to industrial process operations have been discussed.

  7. Preparation and characterization of micro-cell membrane chromatographic column with N-hydroxysuccinimide group-modified silica-based porous layer open tubular capillary.

    Science.gov (United States)

    Xu, Liang; Xu, Bei; Zhao, Zhi-Yu; Yang, Hui-Ping; Tang, Cheng; Dong, Lin-Yi; Liu, Kun; Fu, Li; Wang, Xian-Hua

    2017-09-22

    Cell membrane chromatography (CMC) is an effective tool in screening active compounds from natural products and studying membrane protein interactions. Nevertheless, it always consumes a large amount of cells (e.g. 10 7 -10 8 ) for column preparation. To overcome this, micro-CMC (mCMC), that employs a silica capillary as membrane carrier, was developed. However, both CMC and mCMC suffer from short column life span (e.g. 3days), mainly due to the falling-off of cellular membranes (CMs). This has greatly limited further application of CMC and mCMC, especially when the cells are hard to obtain. To solve this, N-hydroxysuccinimide (NHS)-modified silica-based porous layer open tubular capillary was first prepared for mCMC. The NHS groups can easily react with amino groups on CMs to form a stable covalent bond under a mild condition. So, CMs immobilized on the NHS-modified capillary are less likely to fall off. To verify this, SKBR3/mCMC (Her2 positive) and BALL1/mCMC (CD20 positive) columns were prepared. Two monoclonal antibody drugs, trastuzumab (anti-Her2) and rituximab (anti-CD20), were selected as analytes to characterize the columns. As a result, NHS-modified column for mCMC can afford higher chromatographic retention than non-modified column. Besides, the column life span was significantly improved to more than 16days for SKBR3/mCMC and 14days for BALL1/mCMC, while the compared column showed a sharp decline in retention factor in first 3days. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Development of sampling method and chromatographic analysis of volatile organic compounds emitted from human skin.

    Science.gov (United States)

    Grabowska-Polanowska, Beata; Miarka, Przemysław; Skowron, Monika; Sułowicz, Joanna; Wojtyna, Katarzyna; Moskal, Karolina; Śliwka, Ireneusz

    2017-10-01

    The studies on volatile organic compounds emitted from skin are an interest for chemists, biologists and physicians due to their role in development of different scientific areas, including medical diagnostics, forensic medicine and the perfume design. This paper presents a proposal of two sampling methods applied to skin odor collection: the first one uses a bag of cellulose film, the second one, using cellulose sachets filled with active carbon. Volatile organic compounds were adsorbed on carbon sorbent, removed via thermal desorption and analyzed using gas chromatograph with mass spectrometer. The first sampling method allowed identification of more compounds (52) comparing to the second one (30). Quantitative analyses for acetone, butanal, pentanal and hexanal were done. The skin odor sampling method using a bag of cellulose film, allowed the identification of many more compounds when compared with the method using a sachet filled with active carbon.

  9. Comparing monolithic and fused core HPLC columns for fast chromatographic analysis of fat-soluble vitamins.

    Science.gov (United States)

    Kurdi, Said El; Muaileq, Dina Abu; Alhazmi, Hassan A; Bratty, Mohammed Al; Deeb, Sami El

    2017-06-27

    HPLC stationary phases of monolithic and fused core type can be used to achieve fast chromatographic separation as an alternative to UPLC. In this study, monolithic and fused core stationary phases are compared for fast separation of four fat-soluble vitamins. Three new methods on the first and second generation monolithic silica RP-18e columns and a fused core pentafluoro-phenyl propyl column were developed. Application of three fused core columns offered comparable separations of retinyl palmitate, DL-α-tocopheryl acetate, cholecalciferol and menadione in terms of elution speed and separation efficiency. Separation was achieved in approx. 5 min with good resolution (Rs > 5) and precision (RSD ≤ 0.6 %). Monolithic columns showed, however, a higher number of theoretical plates, better precision and lower column backpressure than the fused core column. The three developed methods were successfully applied to separate and quantitate fat-soluble vitamins in commercial products.

  10. Comparing monolithic and fused core HPLC columns for fast chromatographic analysis of fat-soluble vitamins

    Directory of Open Access Journals (Sweden)

    Kurdi Said El

    2017-06-01

    Full Text Available HPLC stationary phases of monolithic and fused core type can be used to achieve fast chromatographic separation as an alternative to UPLC. In this study, monolithic and fused core stationary phases are compared for fast separation of four fat-soluble vitamins. Three new methods on the first and second generation monolithic silica RP-18e columns and a fused core pentafluoro-phenyl propyl column were developed. Application of three fused core columns offered comparable separations of retinyl palmitate, DL-α-tocopheryl acetate, cholecalciferol and menadione in terms of elution speed and separation efficiency. Separation was achieved in approx. 5 min with good resolution (Rs > 5 and precision (RSD ≤ 0.6 %. Monolithic columns showed, however, a higher number of theoretical plates, better precision and lower column backpressure than the fused core column. The three developed methods were successfully applied to separate and quantitate fat-soluble vitamins in commercial products.

  11. Liquid-chromatographic analysis for cyclosporine with use of a microbore column and small sample volume.

    Science.gov (United States)

    Annesley, T; Matz, K; Balogh, L; Clayton, L; Giacherio, D

    1986-07-01

    This liquid-chromatographic assay requires 0.2 to 0.5 mL of whole blood, avoids the use of diethyl ether, and consumes only 10 to 20% of the solvents used in prior methods. Sample preparation involves an acidic extraction with methyl-t-butyl ether, performed in a 13 X 100 mm disposable glass tube, then a short second extraction of the organic phase with sodium hydroxide. After evaporation of the methyl-t-butyl ether, chromatography is performed on an "Astec" 2.0-mm (i.d.) octyl column. We compared results by this procedure with those by use of earlier larger-scale extractions and their respective 4.6-mm (i.d.) columns; analytical recoveries of cyclosporins A and D were comparable with previous findings and results for patients' specimens were equivalent, but the microbore columns provided greatly increased resolution and sensitivity.

  12. High-performance liquid chromatographic analysis of methadone hydrochloride oral solution.

    Science.gov (United States)

    Beasley, T H; Ziegler, H W

    1977-12-01

    A direct and rapid high-performance liquid chromatographic assay for methadone hydrochloride in a flavored oral solution dosage form is described. A syrup sample, one part diluted with three parts of water, is introduced onto a column packed with octadecylsilane bonded on 10 micrometer porous silica gel (reversed phase). A formic acid-ammonium formate-buffered mobile phase is linear programmed with acetonitrile. The absorbance is monitored continuously at 280 or 254 nm, using a flow-through, UV, double-beam photometer. An aqueous methadone hydrochloride solution is used for external standardization. The relative standard deviation was not more than 1.0%. Drug recovery from a syrup base was better than 99.8%.

  13. RBS analysis of electrochromic layers

    Energy Technology Data Exchange (ETDEWEB)

    Green, D C; Bell, J M [University of Technology, Sydney, NSW (Australia); Kenny, M J; Wielunski, L S [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics

    1994-12-31

    Tungsten oxide thin films produced by dip-coating from tungsten alkoxide solutions are of interest for their application in large area switchable windows. The application consists of a layer of electrochromic tungsten oxide (W0{sub 3}) on indium tin oxide (ITO) coated glass in contact with a complementary structure. Electrochromic devices are switchable between states of high and low transparency by the application of a small voltage. The mechanism relies on the dual injection of ions and electrons into the W0{sub 3} layer from adjacent layers in the device. Electrochromic tungsten oxide can be deposited using standard techniques (eg. sputtering and evaporation) but also using sol-gel deposition. Sol-gel processing has an advantage over conventional preparation techniques because of the simplicity of the equipment. The scaling up to large area coatings is also feasible. RBS and forward recoil has been used to obtain profiles for individual elements in the structure of electrochromic films. 3 refs., 3 figs.

  14. RBS analysis of electrochromic layers

    Energy Technology Data Exchange (ETDEWEB)

    Green, D.C.; Bell, J.M. [University of Technology, Sydney, NSW (Australia); Kenny, M.J.; Wielunski, L.S. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics

    1993-12-31

    Tungsten oxide thin films produced by dip-coating from tungsten alkoxide solutions are of interest for their application in large area switchable windows. The application consists of a layer of electrochromic tungsten oxide (W0{sub 3}) on indium tin oxide (ITO) coated glass in contact with a complementary structure. Electrochromic devices are switchable between states of high and low transparency by the application of a small voltage. The mechanism relies on the dual injection of ions and electrons into the W0{sub 3} layer from adjacent layers in the device. Electrochromic tungsten oxide can be deposited using standard techniques (eg. sputtering and evaporation) but also using sol-gel deposition. Sol-gel processing has an advantage over conventional preparation techniques because of the simplicity of the equipment. The scaling up to large area coatings is also feasible. RBS and forward recoil has been used to obtain profiles for individual elements in the structure of electrochromic films. 3 refs., 3 figs.

  15. Chromatographic and biological aspects of organomercurials

    Energy Technology Data Exchange (ETDEWEB)

    Fishbein, L

    1970-01-01

    A thorough review on the biological and chromatographic aspects of methylmercury, phenylmercurials, and miscellaneous organomercurials is presented. Areas covered include ecology, epidemiology, paper chromatography, thin-layer chromatography, gas chromatography, metabolism and toxicity, and environmental degradation. 183 references.

  16. The development of a high performance liquid chromatograph with a sensitive on-stream radioactivity monitor for the analysis of 3H- and 14C-labelled gibberellins

    International Nuclear Information System (INIS)

    Reeve, D.R.; Yokota, T.; Nash, L.; Crozier, A.

    1976-01-01

    The development of a high performance liquid chromatograph for the separation of gibberellins is described. The system combines high efficiency, peak capacity, and sample capacity with rapid speed of analysis. In addition, the construction details of a sensitive on-stream radioactivity monitor are outlined. The overall versatility of the chromatograph has been demonstrated by the separation of a range of 3 H- and 14 C-labelled gibberellins and gibberellin precursors. The system also has considerable potential for the analysis of abscisic acid and acidic and neutral indoles. (author)

  17. Second-order Data by Flow Injection Analysis with Spectrophotometric Diode-array Detection and Incorporated Gel-filtration Chromatographic Column

    DEFF Research Database (Denmark)

    Bechmann, Iben Ellegaard

    1997-01-01

    A flow injection analysis (FIA) system furnished with a gel-filtration chromatographic column and with photodiode-array detection was used for the generation of second-order data. The system presented is a model system in which the analytes are blue dextran, potassium hexacyanoferrate(III) and he......A flow injection analysis (FIA) system furnished with a gel-filtration chromatographic column and with photodiode-array detection was used for the generation of second-order data. The system presented is a model system in which the analytes are blue dextran, potassium hexacyanoferrate...

  18. Mass spectrometric protein characterization in proteome analysis using GELoader tip micro-columns packed with various chromatographic material

    International Nuclear Information System (INIS)

    Larsen, M.R.

    2001-01-01

    In the early 90'ies mass spectrometry (MS) was introduced as a tool for identifying proteins in protein sequence databases. Since then it has become an integrated tool in protein characterization and is today routinely used to identify proteins separated by gel electrophoresis. A two-tiered mass spectrometric protein identification strategy has recently been proposed. In the first strategy peptide mass maps obtained from the protein of interest are compared with theoretically derived peptide mass maps from proteins in protein sequence databases. If the protein cannot be identified by this strategy, tandem mass spectrometric sequencing is used to generate enough sequence data to identify the protein in protein sequence databases or expressed sequence tag (EST) databases. However, the above strategies primarily identify a protein relatively to the DNA sequence, in which no information about e.g. post-translational modifications (PTMs) is stored. PTMs are known to modify the function, location, solubility and activity of proteins in the cell, and they are therefore very important for understanding living cells. More than 200 different PTMs are known, of which glycosylation, phosphorylation and proteolytic processing are the most common ones. Mass spectrometric analysis of PTMs on gel-separated proteins requires a higher amount of protein than for identification only. In addition, higher sequence coverage from the peptide mass maps or pre-purification of the modified peptides prior to MS analysis, is necessary for detection of putative modified peptides. In this study a multi-tiered strategy, in which GELoader tip micro-columns packed with increasingly more hydrophobic chromatographic material are used in combination with mass spectrometry, is described. The ultimate aim was to gain increased sequence coverage from peptide mixtures derived from gel-separated proteins, in order to locate modified peptides. Graphite powder is described as an alternative to traditional

  19. Development and Validation of High Performance Thin-Layer Chromatographic Method for Determination of α-Mangostin in Fruit Pericarp of Mangosteen Plant (Garcinia mangostana L. using Ultraviolet – Visible Detection

    Directory of Open Access Journals (Sweden)

    Himanshu Misra

    2009-10-01

    Full Text Available A simple, fast and precise quantitative high performance thin-layer chromatographic method has been developed for quantitative estimation of α-mangostin in fruit pericarp of Garcinia mangostana L. (Hypericaceae. Best solvent for extraction of a-mangostin optimized after screening with five solvents under same conditions using hot solid-liquid extraction through soxhlet apparatus. Methanol and chloroform gave highest and second highest recovery of a-mangostin, respectively. Plates were developed in chloroform-methanol in the ratio of 27-3 (v/v. Post-chromatographic derivatization performed using anisaldehyde-sulphuric acid reagent and scanned at 382 nm in ultraviolet-visible mode. The developed method was found to be linear in the range 1.0 to 5.0 mg spot-1, limits of detection and quantitation were 150 and 450 ng spot-1. The developed method was validated in terms of system suitability, specificity and robustness.

  20. High Performance Liquid Chromatographic Analysis of Almotriptan Malate in Bulk and Tablets

    Directory of Open Access Journals (Sweden)

    Chandra Bala Sekaran

    2013-02-01

    Full Text Available Purpose: A simple RP-HPLC method has been developed and validated for the determination of almotriptan malate (ATM in bulk and tablets. Methods: Chromatographic separation of ATM was achieved by using a Thermo Scientific C18 column. A Mobile phase containing a mixture of methanol, water and acetic acid (4:8:0.1 v/v was pumped at the flow rate of 1 mL/min. Detection was performed at 227 nm. According to ICH guidelines, the method was validated. Results: The calibration curve was linear in the concentration range 5–60 μg/mL for the ATM with regression coefficient 0.9999. The method was precise with RSD <1.2%. Excellent recoveries of 99.60 - 100.80% proved the accuracy of the method. The limits of detection and quantification were found to be 0.025 and 0.075 μg/mL, respectively. Conclusion: The method was successfully applied for the quantification of ATM in tablets with acceptable accuracy and precision.

  1. Integrated Analysis of the Wood Oil from Xanthocyparis vietnamensis Farjon & Hiep. by Chromatographic and Spectroscopic Techniques.

    Science.gov (United States)

    Bazzali, Ophélie; Thai, Tran Huy; Hoi, Tran Minh; Khang, Nguyen Sinh; Hien, Nguyen Thi; Casanova, Joseph; Bighelli, Ange; Tomi, Félix

    2016-06-27

    In order to get better knowledge about the volatiles produced by Xanthocyparis vietnamensis, a species recently discovered in Vietnam, its wood oil has been analyzed by a combination of chromatographic (GC, CC) and spectroscopic (GC-MS, (13)C-NMR) techniques. Forty components that accounted for 87.9% of the oil composition have been identified. The composition is dominated by nootkatene (20.7%), 11,12,13-tri-nor-eremophil-1(10)-en-7-one (17.2%), γ-eudesmol (5.1%), nootkatone (4.7%), valencene (3.5%) and 13-nor-eremophil-1(10)-en-11-one (2.6%). The structure of two new compounds-10-epi-nor-γ-eudesmen-11-one and 12-hydroxy-isodihydroagarofuran-has been elucidated, while 11,12,13-tri-nor-eremophil-1(10)-en-7-ol is reported as a natural product for the first time. The composition of X. vietnamensis wood oil varied drastically from those of leaf oils, dominated by hedycaryol (34.4%), phyllocladene (37.8%) or by pimara-6(14)-15-diene (19.4%).

  2. Integrated Analysis of the Wood Oil from Xanthocyparis vietnamensis Farjon & Hiep. by Chromatographic and Spectroscopic Techniques

    Directory of Open Access Journals (Sweden)

    Ophélie Bazzali

    2016-06-01

    Full Text Available In order to get better knowledge about the volatiles produced by Xanthocyparis vietnamensis, a species recently discovered in Vietnam, its wood oil has been analyzed by a combination of chromatographic (GC, CC and spectroscopic (GC-MS, 13C-NMR techniques. Forty components that accounted for 87.9% of the oil composition have been identified. The composition is dominated by nootkatene (20.7%, 11,12,13-tri-nor-eremophil-1(10-en-7-one (17.2%, γ-eudesmol (5.1%, nootkatone (4.7%, valencene (3.5% and 13-nor-eremophil-1(10-en-11-one (2.6%. The structure of two new compounds—10-epi-nor-γ-eudesmen-11-one and 12-hydroxy-isodihydroagarofuran—has been elucidated, while 11,12,13-tri-nor-eremophil-1(10-en-7-ol is reported as a natural product for the first time. The composition of X. vietnamensis wood oil varied drastically from those of leaf oils, dominated by hedycaryol (34.4%, phyllocladene (37.8% or by pimara-6(14-15-diene (19.4%.

  3. Capillary gas chromatographic analysis of nerve agents using large volume injections. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Deinum, T.; Nieuwenhuy, C.

    1994-11-01

    The procedure developed at TNO-Prins Maurits Laboratory (TNO-PML) for the verification of intact organophosphorus chemical warfare agents in water samples was improved. The last step in this procedure, the laborious and non-reproducible transfer of an ethyl acetate extract onto a Tenax-adsorption tube followed by thermal desorption of the Tenax-tube, was replaced by large volume injection of the extract onto a capillary gas chromatographic system. The parameters controlling the injection of a large volume of an extract (200 ul) were investigated and optimized. As ethyl acetate caused severe problems, potential new solvents were evaluated. With the improved procedure, the nerve agents sarin, tabun, soman, diisopropyl fluorophosphate (DFP) and VX could be determined in freshly prepared water samples at pg/ml (ppt) levels. The fate of the nerve agents under study in water at two pH`s (4.8 and 6) was investigated. For VX, the pH should be adjusted before extraction. Moreover, it is worthwhile to acidify water samples to diminish hydrolysis.

  4. Diterpenoic acids analysis using a coupled TLC-surface-enhanced Raman spectroscopy system

    NARCIS (Netherlands)

    Orinak, A.; Talian, I.; Efremov, E.V.; Ariese, F.; Oriaakova, R.

    2008-01-01

    Hyphenation of thin layer chromatography (TLC) with surface-based spectral methods requires a homogeneous surface for direct and quantitative analysis on the chromatographic plate after separation. Since most chromatographic materials do not produce strong background signals in Raman spectroscopy

  5. Development of chromatographic methods for analysis of sulfamethoxazole, trimethoprim, their degradation products and preservatives in syrup

    Directory of Open Access Journals (Sweden)

    Perović Ivana

    2014-01-01

    Full Text Available In this paper the experimental conditions for optimal reversed-phase liquid chromatographic (RP-HPLC determination of sulfamethoxazole, trimethoprim and preservatives, as well as degradation products of sulfamethoxazole and trimethoprim in syrup were defined. The determination of active compounds and preservatives was carried out on Zorbax Eclipse XDB-C18, 150 mm × 4.6 mm, 5 μm particle size column, mobile phase flow rate was 1.5 mL min-1, and detection at 235 nm for the active compounds and 254 nm for preservatives. Mobile phase A consisted of 150 mL of acetonitrile, 850 mL of water and 1 mL of triethanolamine (pH 5.90 adjusted with diluted acetic acid, while mobile phase B was acetonitrile. The mobile phase ratio was defined by the gradient program. For the determination of degradation products Zorbax Eclipse Plus C18, 100 mm x 4.6 mm, 3.5 μm particle size column was used, the mobile phase flow rate was 0.5 mL min-1 and detection at 210 nm for 3,4,5-trimethoxybenzoic acid and 254 nm for sulfanilic acid and sulfanilamide. Mobile phase A was 50 mM potassium dihydrogenphosphate (pH 5.60 adjusted with a 0.5 mol L-1 potassium hydroxide, while mobile phase B was acetonitrile. The mobile phase ratio was defined by the gradient program. Through the validation of the developed methods their efficiency and reliability is confirmed and consequently the adequacy for the routine control.

  6. Biomimetic chromatographic analysis of selenium species: Application for the estimation of their pharmacokinetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Tsopelas, Fotios [National Technical University of Athens, Laboratory of Inorganic and Analytical Chemistry, School of Chemical Engineering, Athens (Greece); University of Athens, Laboratory of Pharmaceutical Chemistry, School of Pharmacy, Athens (Greece); Tsantili-Kakoulidou, Anna [University of Athens, Laboratory of Pharmaceutical Chemistry, School of Pharmacy, Athens (Greece); Ochsenkuehn-Petropoulou, Maria [National Technical University of Athens, Laboratory of Inorganic and Analytical Chemistry, School of Chemical Engineering, Athens (Greece)

    2010-07-15

    The retention behavior of selenites, selenates, seleno-dl-methionine, selenocystine, selenocystamine, selenourea, dimethyl selenide, and dimethyl diselenide was investigated by means of biomimetic liquid chromatography. For this purpose, two immobilized artificial membrane (IAM) columns, namely, IAM.PC.DD2 and IAM.PC.MG, and two immobilized plasma protein columns, human serum albumin (HSA) and {alpha}{sub 1}-acid glycoprotein (AGP) columns, were employed using different mobile phase conditions in respect to pH and buffer composition. In general, satisfactory interrelations between retention factors obtained with the two IAM stationary phases and HSA/AGP columns were obtained. Large differences were observed between biomimetic retention factors and octanol-water logD values, since the latter fail to describe electrostatic interactions. In contrast, despite the column diversity, the net retention outcome on all four biomimetic columns was quite similar, especially in the presence of phosphate-buffered saline, which by its effective shielding alleviates the differences between the stationary phases. Of the two IAM columns, IAM.PC.DD2 showed better performance when compared with HSA and AGP columns as well as to octanol-water partitioning. Biomimetic chromatographic indices were further used to estimate the percentage of human oral absorption and plasma protein binding of the eight selenium species investigated, according to equations previously reported in the literature. The estimated values of human oral absorption imply moderate absorption only for dimethyl diselenide, which also may exhibit considerable plasma protein binding. Moderate affinity for plasma proteins should also be expected for dimethyl selenide and selenocystamine. (orig.)

  7. Quantitative HPLC-ICP-MS analysis of antimony redox speciation in complex sample matrices: new insights into the Sb-chemistry causing poor chromatographic recoveries

    DEFF Research Database (Denmark)

    Hansen, Claus; Schmidt, Bjørn; Larsen, Erik Huusfeldt

    2011-01-01

    In solution antimony exists either in the pentavalent or trivalent oxidation state. As Sb(III) is more toxic than Sb(V), it is important to be able to perform a quantitative speciation analysis of Sb’s oxidation state. The most commonly applied chromatographic methods used for this redox speciation...

  8. Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis

    DEFF Research Database (Denmark)

    Larsen, Kirsten Kolbjørn; Wielandt, Daniel Kim Peel; Schiller, Martin

    2016-01-01

    Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of ...

  9. Portfolio analysis of layered security measures.

    Science.gov (United States)

    Chatterjee, Samrat; Hora, Stephen C; Rosoff, Heather

    2015-03-01

    Layered defenses are necessary for protecting the public from terrorist attacks. Designing a system of such defensive measures requires consideration of the interaction of these countermeasures. In this article, we present an analysis of a layered security system within the lower Manhattan area. It shows how portfolios of security measures can be evaluated through portfolio decision analysis. Consideration is given to the total benefits and costs of the system. Portfolio diagrams are created that help communicate alternatives among stakeholders who have differing views on the tradeoffs between security and economic activity. © 2014 Society for Risk Analysis.

  10. Simple fluorimetric liquid chromatographic method for the analysis of undecylenic acid and zinc undecylenate in pharmaceutical preparations.

    Science.gov (United States)

    Lin, Ming-Chun; Wu, Hsin-Lung; Kou, Hwang-Shang; Wu, Shou-Mei

    2006-06-30

    A simple and selective liquid chromatographic method is described for the analysis of undecylenic acid (UA) and zinc undecylenate (ZnUA) in pharmaceutical preparations. The method is based on the derivatization of the analytes extracted from various samples with 2-(2-naphthoxy)ethyl 2-(piperidino)ethanesulfonate. The resulting derivative was analyzed by liquid chromatography with fluorimetric detection. The quantitation of the method is in the range of 3.0-50.0 microM UA with a detection limit of about 0.3 microM (S/N = 3 with 10 microl injection). We found that acetonitrile is a selective solvent for differentially dissolving UA from coexisted ZnUA in compound formulation. This results in the specific analysis of UA in the presence of ZnUA and simply analyzing the coexisted ZnUA by the value of total UA (UA+ZnUA) minus that of UA. Application of the method to the analysis of undecylenic acid and zinc undecylenate in ointment, powder and solution preparations proved feasible.

  11. Characterization of Chinese rice wine taste attributes using liquid chromatographic analysis, sensory evaluation, and an electronic tongue.

    Science.gov (United States)

    Yu, HaiYan; Zhao, Jie; Li, Fenghua; Tian, Huaixiang; Ma, Xia

    2015-08-01

    To evaluate the taste characteristics of Chinese rice wine, wine samples sourced from different vintage years were analyzed using liquid chromatographic analysis, sensory evaluation, and an electronic tongue. Six organic acids and seventeen amino acids were measured using high performance liquid chromatography (HPLC). Five monosaccharides were measured using anion-exchange chromatography. The global taste attributes were analyzed using an electronic tongue (E-tongue). The correlations between the 28 taste-active compounds and the sensory attributes, and the correlations between the E-tongue response and the sensory attributes were established via partial least square discriminant analysis (PLSDA). E-tongue response data combined with linear discriminant analysis (LDA) were used to discriminate the Chinese rice wine samples sourced from different vintage years. Sensory evaluation indicated significant differences in the Chinese rice wine samples sourced from 2003, 2005, 2008, and 2010 vintage years in the sensory attributes of harmony and mellow. The PLSDA model for the taste-active compounds and the sensory attributes showed that proline, fucose, arabinose, lactic acid, glutamic acid, arginine, isoleucine, valine, threonine, and lysine had an influence on the taste characteristic of Chinese rice wine. The Chinese rice wine samples were all correctly classified using the E-tongue and LDA. The electronic tongue was an effective tool for rapid discrimination of Chinese rice wine. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Forensic Analysis of Blue Ball point Pen Inks Using Ultraviolet-Visible Spectrometer and Ultra-Performance Liquid Chromatograph

    International Nuclear Information System (INIS)

    Lee, L.C.; Shandu, K.T.S.; Nor Syahirah Mohamad Razi; Ab Aziz Ishak; Khairul Osman

    2015-01-01

    Twelve varieties of blue ball point pens were selected and analyzed using UV-Vis spectrometer and ultra-performance liquid chromatography (UPLC). The aim of the study was to determine discrimination power (DP) of these methods in differentiating pen inks collected from the market in Malaysia. Discrimination analysis of 66 possible pen-pair of blue ball point pens was carried out via one-way ANOVA based on obtained chromatogram and spectra. A total of 18 peaks were determined as coming from inks based on the chromatographic data extracted at three different wavelengths (279, 370 and 400 nm). While for the UV-Vis spectrometer analysis, presence of peaks at 303, 545, 577 and 584 nm wavelengths were recorded. UV-Vis spectral data were mainly produced by the colorant components (for example, dyes) found in inks and UPLC may detect ink components other than dyes, for example, additives. As conclusion, the DP for UV-Vis and UPLC were determined to be 72.12 % and 98.48 %, respectively. This manuscript demonstrates the potential of UPLC for discriminating pen inks based on non-dye components. Additionally, the dye components in inks do not seem to play important role in discrimination of pen inks. (author)

  13. Interlaboratory tests to identify irradiation treatment of various foods via gas chromatographic detection of hydrocarbons, ESR spectroscopy and TL analysis

    Energy Technology Data Exchange (ETDEWEB)

    Schreiber, G.A.; Helle, N.; Schulzki, G.; Linke, B.; Spiegelberg, A.; Mager, M.; Boegl, K.W. [BgVV - Federal Inst. for Health Protection of Consumers and Veterinary Medicine, Berlin (Germany)

    1996-12-31

    The gas chromatographic (GC) analysis of radiation-induced volatile hydrocarbons (HC) and 2-alkylcyclobutanones, the ESR spectroscopic detection of radiation-specific radicals and the thermoluminescence (TL) analysis of silicate mineral are the most important methods for identification of irradiated foods. After successful performance in interlaboratory studies on meat products, fish, spices, herbs and shells of nuts, all or some of these methods have been approved by national authorities in Germany and the United Kingdom. Recently, draft European Standards have been elaborated for approval by member states of the European Committee for Standardization (CEN). Several research laboratories have shown that these methods can be applied to various foods not yet tested in collaborative studies. However, for an effective application in food control it is necessary to prove their suitability in interlaboratory studies. Therefore, in 1993/94, various interlaboratory tests were organised by the BgVV. In an ESR spectroscopic test, shrimps and paprika powder were examined. Shrimps were also the subject of examination in a TL test. Finally, GC detection of radiation-induced hydrocarbons in the fat fraction of foods was used in another test to identify irradiated Camembert, avocado, papaya and mango. In the following paper, results of the interlaboratory tests are summarised. Detailed reports are published by this institute. (author).

  14. Interlaboratory tests to identify irradiation treatment of various foods via gas chromatographic detection of hydrocarbons, ESR spectroscopy and TL analysis

    International Nuclear Information System (INIS)

    Schreiber, G.A.; Helle, N.; Schulzki, G.; Linke, B.; Spiegelberg, A.; Mager, M.; Boegl, K.W.

    1996-01-01

    The gas chromatographic (GC) analysis of radiation-induced volatile hydrocarbons (HC) and 2-alkylcyclobutanones, the ESR spectroscopic detection of radiation-specific radicals and the thermoluminescence (TL) analysis of silicate mineral are the most important methods for identification of irradiated foods. After successful performance in interlaboratory studies on meat products, fish, spices, herbs and shells of nuts, all or some of these methods have been approved by national authorities in Germany and the United Kingdom. Recently, draft European Standards have been elaborated for approval by member states of the European Committee for Standardization (CEN). Several research laboratories have shown that these methods can be applied to various foods not yet tested in collaborative studies. However, for an effective application in food control it is necessary to prove their suitability in interlaboratory studies. Therefore, in 1993/94, various interlaboratory tests were organised by the BgVV. In an ESR spectroscopic test, shrimps and paprika powder were examined. Shrimps were also the subject of examination in a TL test. Finally, GC detection of radiation-induced hydrocarbons in the fat fraction of foods was used in another test to identify irradiated Camembert, avocado, papaya and mango. In the following paper, results of the interlaboratory tests are summarised. Detailed reports are published by this institute. (author)

  15. Chromatographic analysis of phenol compounds in six natural populations of Anthyllis vulneraria (L.

    Directory of Open Access Journals (Sweden)

    Andzrej Kalinowski

    2015-01-01

    Full Text Available Thin-layer chromatography was used to study the phenol composition in individual plants from six natural populations of Anthyllis collected from three distinct geographic regions of Poland. The results showed a variability of the phenols in the examined populations. The populations from Wielkopolska region proved to be most variable, showing the greatest number of phenols. The lowest number of the phenols studies was found in the Tatry populations. Each population showed its own particular spectrum of phenolic compounds. It was found that the populations originating from similar habitats showed more common spots than those from different regions. Populations from the Tatra region were found to differ most from the rest.

  16. Influence of corrosion layers on quantitative analysis

    International Nuclear Information System (INIS)

    Denker, A.; Bohne, W.; Opitz-Coutureau, J.; Rauschenberg, J.; Roehrich, J.; Strub, E.

    2005-01-01

    Art historians and restorers in charge of ancient metal objects are often reluctant to remove the corrosion layer evolved over time, as this would change the appearance of the artefact dramatically. Therefore, when an elemental analysis of the objects is required, this has to be done by penetrating the corrosion layer. In this work the influence of corrosion was studied on Chinese and Roman coins, where removal of oxidized material was possible. Measurements on spots with and without corrosion are presented and the results discussed

  17. Impedance analysis on organic ultrathin layers

    Energy Technology Data Exchange (ETDEWEB)

    Bom, Sidhant; Wagner, Veit [Jacobs University Bremen, School of Engineering and Science, Campus Ring 8, 28759 Bremen (Germany)

    2008-07-01

    Impedance spectroscopy is a standard technique for thin film analysis to obtain important information as thicknesses, diffusion properties of mobile ions and leakage currents. The measured electrical impedance of a sample is modeled by a physical equivalent circuit of resistors and capacitors. In the present work this information is obtained as a function of frequency also for ultrathin organic layers in the monolayer regime. A series of semiconducting and insulating polymers (regioregular poly-3-hexylthiophene (rr-P3HT), polymethylmethacrylate (PMMA)) and self assembled monolayers (octadecyltrichlorosilane (OTS), hexamethyldisilazane (HMDS), thiolated phospholipids) were deposited either on highly n-doped silicon wafers or on gold surfaces. E.g. ultrathin layers were obtained by dip coating a silicon wafer in rr-P3HT solution in chloroform. The thickness of 2 nm determined for this system by impedance measurement agrees well with the atomic force microscopy analysis and corresponds to a single layer of polymer chains. The leakage current is seen as an ohmic contribution at low frequencies and allows a systematic optimization of process parameters. In summary, impedance spectroscopy allows very fast and convenient analysis of thin organic layers even down to the monolayer regime.

  18. Quantitative Mass spectrometric Analysis of Ropivacaine and Bupivacaine in Authentic, Pharmaceutical and Spiked Human Plasma without Chromatographic Separation

    Directory of Open Access Journals (Sweden)

    Nahla N. Salama

    2009-01-01

    Full Text Available The present study employs time of flight mass spectrometry for quantitative analysis of the local anesthetic drugs ropivacaine and bupivacaine in authentic, pharmaceutical and spiked human plasma as well as in the presence of their impurities 2,6-dimethylaniline and alkaline degradation product. The method is based on time of flight electron spray ionization mass spectrometry technique without preliminary chromatographic separation and makes use of bupivacaine as internal standard for ropivacaine, which is used as internal standard for bupivacaine. A linear relationship between drug concentrations and the peak intensity ratio of ions of the analyzed substances is established. The method is linear from 23.8 to 2380.0 ng mL-1 for both drugs. The correlation coefficient was ≥0.996 in authentic and spiked human plasma. The average percentage recoveries in the ranges of 95.39%–102.75% was obtained. The method is accurate (% RE < 5% and reproducible with intra- and inter-assay precision (RSD% < 8.0%. The quantification limit is 23.8 ng mL-1 for both drugs. The method is not only highly sensitive and selective, but also simple and effective for determination or identification of both drugs in authentic and biological fluids. The method can be applied in purity testing, quality control and stability monitoring for the studied drugs.

  19. Quantitative Mass Spectrometric Analysis of Ropivacaine and Bupivacaine in Authentic, Pharmaceutical and Spiked Human Plasma without Chromatographic Separation

    Directory of Open Access Journals (Sweden)

    Nahla N. Salama

    2009-01-01

    Full Text Available The present study employs time of flight mass spectrometry for quantitative analysis of the local anesthetic drugs ropivacaine and bupivacaine in authentic, pharmaceutical and spiked human plasma as well as in the presence of their impurities 2,6-dimethylaniline and alkaline degradation product. The method is based on time of flight electron spray ionization mass spectrometry technique without preliminary chromatographic separation and makes use of bupivacaine as internal standard for ropivacaine, which is used as internal standard for bupivacaine. A linear relationship between drug concentrations and the peak intensity ratio of ions of the analyzed substances is established. The method is linear from 23.8 to 2380.0 ng mL −1 for both drugs. The correlation coefficient was ≥0.996 in authentic and spiked human plasma. The average percentage recoveries in the ranges of 95.39%-102.75% was obtained. The method is accurate (% RE <; 5% and reproducible with intra- and inter-assay precision (RSD% <; 8.0%. The quantification limit is 23.8 ng mL −1 for both drugs. The method is not only highly sensitive and selective, but also simple and effective for determination or identification of both drugs in authentic and biological fluids. The method can be applied in purity testing, quality control and stability monitoring for the studied drugs.

  20. Rapid process development of chromatographic process using direct analysis in real time mass spectrometry as a process analytical technology tool.

    Science.gov (United States)

    Yan, Binjun; Chen, Teng; Xu, Zhilin; Qu, Haibin

    2014-06-01

    The concept of quality by design (QbD) is widely applied in the process development of pharmaceuticals. However, the additional cost and time have caused some resistance about QbD implementation. To show a possible solution, this work proposed a rapid process development method, which used direct analysis in real time mass spectrometry (DART-MS) as a process analytical technology (PAT) tool for studying the chromatographic process of Ginkgo biloba L., as an example. The breakthrough curves were fast determined by DART-MS at-line. A high correlation coefficient of 0.9520 was found between the concentrations of ginkgolide A determined by DART-MS and HPLC. Based on the PAT tool, the impacts of process parameters on the adsorption capacity were discovered rapidly, which showed a decreased adsorption capacity with the increase of the flow rate. This work has shown the feasibility and advantages of integrating PAT into QbD implementation for rapid process development. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Generation of accurate peptide retention data for targeted and data independent quantitative LC-MS analysis: Chromatographic lessons in proteomics.

    Science.gov (United States)

    Krokhin, Oleg V; Spicer, Vic

    2016-12-01

    The emergence of data-independent quantitative LC-MS/MS analysis protocols further highlights the importance of high-quality reproducible chromatographic procedures. Knowing, controlling and being able to predict the effect of multiple factors that alter peptide RP-HPLC separation selectivity is critical for successful data collection for the construction of ion libraries. Proteomic researchers have often regarded RP-HPLC as a "black box", while vast amount of research on peptide separation is readily available. In addition to obvious parameters, such as the type of ion-pairing modifier, stationary phase and column temperature, we describe the "mysterious" effects of gradient slope, column size and flow rate on peptide separation selectivity. Retention time variations due to these parameters are governed by the linear solvent strength (LSS) theory on a peptide level by the value of its slope S in the basic LSS equation-a parameter that can be accurately predicted. Thus, the application of shallower gradients, higher flow rates, or smaller columns will each increases the relative retention of peptides with higher S-values (long species with multiple positively charged groups). Simultaneous changes to these parameters that each drive shifts in separation selectivity in the same direction should be avoided. The unification of terminology represents another pressing issue in this field of applied proteomics that should be addressed to facilitate further progress. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Development and validation of a reversed phase liquid chromatographic method for analysis of oxytetracycline and related impurities.

    Science.gov (United States)

    Kahsay, Getu; Shraim, Fairouz; Villatte, Philippe; Rotger, Jacques; Cassus-Coussère, Céline; Van Schepdael, Ann; Hoogmartens, Jos; Adams, Erwin

    2013-03-05

    A simple, robust and fast high-performance liquid chromatographic method is described for the analysis of oxytetracycline and its related impurities. The principal peak and impurities are all baseline separated in 20 min using an Inertsil C₈ (150 mm × 4.6 mm, 5 μm) column kept at 50 °C. The mobile phase consists of a gradient mixture of mobile phases A (0.05% trifluoroacetic acid in water) and B (acetonitrile-methanol-tetrahydrofuran, 80:15:5, v/v/v) pumped at a flow rate of 1.3 ml/min. UV detection was performed at 254 nm. The developed method was validated for its robustness, sensitivity, precision and linearity in the range from limit of quantification (LOQ) to 120%. The limits of detection (LOD) and LOQ were found to be 0.08 μg/ml and 0.32 μg/ml, respectively. This method allows the separation of oxytetracycline from all known and 5 unknown impurities, which is better than previously reported in the literature. Moreover, the simple mobile phase composition devoid of non-volatile buffers made the method suitable to interface with mass spectrometry for further characterization of unknown impurities. The developed method has been applied for determination of related substances in oxytetracycline bulk samples available from four manufacturers. The validation results demonstrate that the method is reliable for quantification of oxytetracycline and its impurities. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Radioimmunoassay and liquid-chromatographic analysis for free cortisol in urine compared with isotope dilution-mass spectrometry

    International Nuclear Information System (INIS)

    Lantto, O.

    1982-01-01

    Three different routine methods for analysis for urinary cortisol with those by a highly specific reference method based on isotope dilution-mass spectrometry (I) were compared. A ''high-performance'' liquid-chromatographic method (II) gave the most comparable results (regression coefficient 0.86, intercept 9 nmol/L). For some urines much lower values were obtained by I than by II. Two radioimmunoassay (III) methods, one involving direct assay and one involving extraction, gave less-accurate results (regression coefficients of 1.87 and 1.52 and intercepts of 86 and 12 nmol/L, respectively), although values obtained by III and by I correlated well (r = 0.95-0.99), indicating a relation between the free cortisol and the compounds interfering in III. The apparent accuracy for the extraction method was improved by using as calibration standards urine samples previously assayed by I (regression coefficient 0.90, intercept 6 nmol/L). All four methods investigated showed a statistically significant sex-related difference in 24-h urinary cortisol excretion; evidently such a finding should be a prerequisite in any such method proposed for routine use

  4. Supercritical fluid extraction (SFE) and gas chromatographic (GC) analysis of products from irradiated foods containing fat

    International Nuclear Information System (INIS)

    Adam, S.T.

    1993-01-01

    Official analytical methods specify the use of organic liquid solvents which may be hazardous to human health. Non-toxic chlorinated fluorocarbons (CFC) which are still recommended for extracting soil samples are known to be detrimental to the stratospheric ozone layer and therefore subject to the ''FCKW-Halon-Verbots-Verordnung''. Therefore, alternative extraction methods using solvents in the supercritical state are currently being developed (Supercritical Fluid Extraction (SFE)). Their low viscosity and the high diffusivity of solutes in the fluids allow selective, efficient and timesaving extractions. Carbon dioxide (CO 2 ) is the fluid of choice in many applications because its critical parameters permit mild operating conditions. CO 2 of high purity is available at low cost, it is neither inflammable nor explosive, physiologically harmless and part of natural cycle processes. Furthermore, it is simply removed from the matrix without any residues left. The combination of SFE and sorptive collection of the extracted substances has been found to lead to high enrichment factors for the analytes. Distillative concentration and solid phase elution steps, required in the classical solvent extraction procedure, are no longer necessary. Loss of analytes occurring in cryogenic or solvent traps is completeley avoided. Plugging of the restrictor as a consequence of the Joule Thomson effect was not observed in the presented method. (orig./vhe)

  5. Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis.

    Science.gov (United States)

    Larsen, K K; Wielandt, D; Schiller, M; Bizzarro, M

    2016-04-22

    Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr(3+), CrCl(2+) and CrCl2(+)) with equilibrium mass-dependent isotope fractionation spanning a range of ∼1‰/amu and consistent with theory. The heaviest isotopes partition into Cr(3+), intermediates in CrCl(2+) and the lightest in CrCl2(+)/CrCl3°. Thus, for a typical reported loss of ∼25% Cr (in the form of Cr(3+)) through chromatographic purification, this translates into 185 ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected (53)Cr/(52)Cr (μ(53)Cr* of 5.2 ppm) and (54)Cr/(52)Cr (μ(54)Cr* of 13.5 ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr(3+) by >5 days exposure to HNO3H2O2 solutions at room temperature, resulting in >∼98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120 °C) for several hours, resulting in >97.5% Cr recovery using a

  6. Comparative analysis of ciprofloxacin in different pharmaceutical products by high performance liquid chromatograph

    International Nuclear Information System (INIS)

    Qureshi, M.N.; Rahman, I.U.

    2012-01-01

    Pharmaceutical products with different trade names having ciprofloxacin as an active ingredient were collected from the market. The products were assayed under similar conditions for active ingredient applying HPLC technique. Results obtained from quantification of ciprofloxacin contents of each product were compared with their label claims. Comparative analysis of these products was performed based on the quantity of ciprofloxacin. (author)

  7. High-resolution gas chromatographic analysis of polycyclic aromatic hydrocarbons and aliphatic hydrocarbons

    International Nuclear Information System (INIS)

    Perez, M.; Gonzalez, D.

    1988-01-01

    A study of the analysis by gas chromatography of aromatic polycyclic hydrocarbons and aliphatic hydrocarbons is presented. The separation has been carried out by glass and fused silica capillary column in two different polar stationary phases OV-1 and SE-54. The limitation and the advantages of the procedure are discussed in terms of separation, sensitivity and precision. (Author) 20 refs

  8. Improved Chromatographic Bioavailability Estimations

    National Research Council Canada - National Science Library

    Dorsey, John

    1996-01-01

    .... Since the inception of reversed phase liquid chromatography there have been many attempts to correlate chromatographic retention with bioavailability and the most often used bulk measure, the octanol...

  9. Recent advances in metal-organic frameworks and covalent organic frameworks for sample preparation and chromatographic analysis.

    Science.gov (United States)

    Wang, Xuan; Ye, Nengsheng

    2017-12-01

    In the field of analytical chemistry, sample preparation and chromatographic separation are two core procedures. The means by which to improve the sensitivity, selectivity and detection limit of a method have become a topic of great interest. Recently, porous organic frameworks, such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), have been widely used in this research area because of their special features, and different methods have been developed. This review summarizes the applications of MOFs and COFs in sample preparation and chromatographic stationary phases. The MOF- or COF-based solid-phase extraction (SPE), solid-phase microextraction (SPME), gas chromatography (GC), high-performance liquid chromatography (HPLC) and capillary electrochromatography (CEC) methods are described. The excellent properties of MOFs and COFs have resulted in intense interest in exploring their performance and mechanisms for sample preparation and chromatographic separation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. A study of cider distillates using sensory and chromatographic data and chemometric analysis

    OpenAIRE

    Picinelli, Anna; Rodríguez, Roberto; Mangas, J.J. (Juan)

    2016-01-01

    Twenty-one samples of cider distillates have been analyzed for sensory characteristics, volatile and furanic compounds, and low-molecular mass polyphenols. Principal Component Analysis established relationships between sensory attributes and the cider distillates on the basis of the raw material used in their manufacture and aging level. Three sensory descriptors (smoothness, nutty, and toasty) were predicted with good accuracy using 7 aromas as predictor variables and a Partial L...

  11. Development of a chromatographic micro-system for radionuclides analysis in nitric acid media

    International Nuclear Information System (INIS)

    Losno, Marion

    2017-01-01

    Radionuclides analysis is a key point for nuclear waste management and nuclear material control. Several steps of sample modification have to be carried out before measurements in order to avoid any interferences and improve measurement precision. However those different steps are long, irradiating and difficult to achieve in gloveboxes. Moreover they produce liquid and solid waste. The goal of the study is to offer a new alternative to the use of solid phase extraction column for radionuclides separation in hard nitric acid medium. The system will decrease the amount of nuclear waste due to the analysis and automatize the different steps of the analysis. A plastic device made of COC containing a micro solid phase extraction column is first designed. Stationary phase is a poly(AMA-co-EDMA) monolith synthesized in situ. Its structure is adjustable and its functionalization versatile with a high resistance to nitric acid medium. Exchange capacity is 150 mg/g of monolith for TBP and TBP/CMPO column and up to 280 mg/g of monolith in case of DAAP. Exchange coefficients are determined for U(VI), Th(IV), Eu(III) and Nd(III) for 3 different extractants (and Pu(IV) in case of TBP column). Monolith synthesis is transferred in centrifugal device and hydrodynamic behavior studied. U,Th/Eu separation was finally carried out in both classic and centrifugal micro-system on TBP column. (author) [fr

  12. Fluorescence, electrophoretic and chromatographic fingerprints of herbal medicines and their comparative chemometric analysis.

    Science.gov (United States)

    Mazina, Jekaterina; Vaher, Merike; Kuhtinskaja, Maria; Poryvkina, Larisa; Kaljurand, Mihkel

    2015-07-01

    The aim of the present study was to compare the polyphenolic compositions of 47 medicinal herbs (HM) and four herbal tea mixtures from Central Estonia by rapid, reliable and sensitive Spectral Fluorescence Signature (SFS) method in a front face mode. The SFS method was validated for the main identified HM representatives including detection limits (0.037mgL(-1) for catechin, 0.052mgL(-1) for protocatechuic acid, 0.136mgL(-1) for chlorogenic acid, 0.058mgL(-1) for syringic acid and 0.256mgL(-1) for ferulic acid), linearity (up to 5.0-15mgL(-1)), intra-day precision (RSDs=6.6-10.6%), inter-day precision (RSDs=6.4-13.8%), matrix effect (-15.8 to +5.5) and recovery (85-107%). The phytochemical fingerprints were differentiated by parallel factor analysis (PARAFAC) combined with hierarchical cluster analysis (CA) and principal component analysis (PCA). HM were clustered into four main clusters (catechin-like, hydroxycinnamic acid-like, dihydrobenzoic acid-like derivatives containing HM and HM with low/very low content of fluorescent constituents) and 14 subclusters (rich, medium, low/very low contents). The average accuracy and precision of CA for validation HM set were 97.4% (within 85.2-100%) and 89.6%, (within 66.7-100%), respectively. PARAFAC-PCA/CA has improved the analysis of HM by the SFS method. The results were verified by two separation methods CE-DAD and HPLC-DAD-MS also combined with PARAFAC-PCA/CA. The SFS-PARAFAC-PCA/CA method has potential as a rapid and reliable tool for investigating the fingerprints and predicting the composition of HM or evaluating the quality and authenticity of different standardised formulas. Moreover, SFS-PARAFAC-PCA/CA can be implemented as a laboratory and/or an onsite method. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. The application of HP-GFC chromatographic method for the analysis of oligosaccharides in bioactive complexes

    Directory of Open Access Journals (Sweden)

    Savić Ivan

    2009-01-01

    Full Text Available The aim of this work was to optimize a GFC method for the analysis of bioactive metal (Cu, Co and Fe complexes with olygosaccharides (dextran and pullulan. Bioactive metal complexes with olygosaccharides were synthesized by original procedure. GFC was used to study the molecular weight distribution, polymerization degree of oligosaccharides and bioactive metal complexes. The metal bounding in complexes depends on the ligand polymerization degree and the presence of OH groups in coordinative sphere of the central metal ion. The interaction between oligosaccharide and metal ions are very important in veterinary medicine, agriculture, pharmacy and medicine.

  14. Gas chromatographic analysis of reactive carbonyl compounds formed from lipids upon UV-irradiation

    International Nuclear Information System (INIS)

    Dennis, K.J.; Shibamoto, T.

    1990-01-01

    Peroxidation of lipids produces carbonyl compounds; some of these, e.g., malonaldehyde and 4-hydroxynonenal, are genotoxic because of their reactivity with biological nucleophiles. Analysis of the reactive carbonyl compounds is often difficult. The methylhydrazine method developed for malonaldehyde analysis was applied to simultaneously measure the products formed from linoleic acid, linolenic acid, arachidonic acid, and squalene upon ultraviolet-irradiation (UV-irradiation). The photoreaction products, saturated monocarbonyl, alpha,beta-unsaturated carbonyls, and beta-dicarbonyls, were derivatized with methylhydrazine to give hydrazones, pyrazolines, and pyrazoles, respectively. The derivatives were analyzed by gas chromatography and gas chromatography-mass spectrometry. Lipid peroxidation products identified included formaldehyde, acetaldehyde, acrolein, malonaldehyde, n-hexanal, and 4-hydroxy-2-nonenal. Malonaldehyde levels formed upon 4 hr of irradiation were 0.06 micrograms/mg from squalene, 2.4 micrograms/mg from linolenic acid, and 5.7 micrograms/mg from arachidonic acid. Significant levels of acrolein (2.5 micrograms/mg) and 4-hydroxy-2-nonenal (0.17 micrograms/mg) were also produced from arachidonic acid upon 4 hr irradiation

  15. Chromatographic and spectroscopic analysis of heavy crude oil mixtures with emphasis in nuclear magnetic resonance spectroscopy: A review

    International Nuclear Information System (INIS)

    Silva, Sandra L.; Silva, Artur M.S.; Ribeiro, Jorge C.; Martins, Fernando G.; Da Silva, Francisco A.; Silva, Carlos M.

    2011-01-01

    Graphical abstract: The chromatographic and spectroscopic techniques used to characterize heavy crude oils, although more focused in the nuclear magnetic resonance spectroscopy as the technique of choice, due to its capability to provide great information on the chemical nature of individual types of proton and carbon atoms in different and complex mixtures of crude oils are described. This review is based on 65 references and describes in a critical and interpretative ways the advantages of the NMR spectroscopy as a main technique to be used in crude oil refining industries that want to characterize crude oil fractions and the obtained refined products. Highlights: ► Chromatogrfaphic and spectroscopic techniques used to characterize heavy crude oils have been reviewed. ► This review describes in a critical and interpretative ways the advantages of the NMR spectroscopy as a main technique to be used in crude oil refining industries. ► The progress in the interpretation of the NMR spectra and of different multivariate data analyses and their potential in the identification and characterization of hydrocarbons and their physical and chemical properties have also been reviewed. - Abstract: The state of the art in the characterization of heavy crude oil mixtures is presented. This characterization can be done by different techniques, such as gas chromatography (GC), high performance liquid chromatography (HPLC), thin layer chromatography (TLC), infrared spectroscopy (IR), Raman spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). Nuclear magnetic resonance spectroscopy is the technique of choice due to its capability to provide information on the chemical nature of individual types of hydrogen and carbon atoms in different and complex mixtures of crude oils. The progress made in the interpretation of the NMR spectra with the development of new NMR techniques and different multivariate data analyses could give relevant

  16. Liquid chromatographic analysis of a formulated ester from a gas-turbine engine test

    Science.gov (United States)

    Jones, W. R., Jr.; Morales, W.

    1983-01-01

    Size exclusion chromatography (SEC) utilizing mu-Bondagel and mu-Styragel columns with a tetrahydrofuran mobile phase was used to determine the chemical degradation of lubricant samples from a gas-turbine engine test. A MIL-L-27502 candidate, ester-based lubricant was run in a J57-29 engine at a bulk oil temperature of 216 C. In general, the analyses indicated a progressive loss of primary ester, additive depletion, and formation of higher molecular weight material. An oil sample taken at the conclusion of the test showed a reversal of this trend because of large additions of new oil. The high-molecular-weight product from the degraded ester absorbed strongly in the ultraviolet region at 254 nanometers. This would indicate the presence of chromophoric groups. An analysis of a similar ester lubricant from a separate high-temperature bearing test yielded qualitatively similar results.

  17. Sample preparation for liquid chromatographic analysis of phytochemicals in biological fluids.

    Science.gov (United States)

    Oh, Ju-Hee; Lee, Young-Joo

    2014-01-01

    Natural products have been used traditionally for the treatment and prevention of diseases for thousands of years and are nowadays consumed as dietary supplements and herbal medicine. To ensure the safe and effective use of these herbal products, information about bioavailability of active compounds in plasma or target tissues should be provided via validated analytical methods combined with appropriate sampling methods. To provide comprehensive and abridged information about sample preparation methods for the quantification of phytochemicals in biological samples using liquid chromatography analysis. Sample pre-treatment procedures used in analytical methods for in vivo pharmacokinetic studies of natural compounds or herbal medicines were reviewed. These were categorised according to the biological matrices (plasma, bile, urine, faeces and tissues) and sample clean-up processes (protein precipitation, liquid-liquid extraction and solid-phase extraction). Although various kinds of sample pre-treatment methods have been developed, liquid-liquid extraction is still widely used and solid-phase extraction is becoming increasingly popular because of its efficiency for extensive clean up of complex matrix samples. However, protein precipitation is still favoured due to its simplicity. Sample treatment for phytochemical analysis in biological fluids is an indispensable and critical step to obtain high quality results. This step could dominate the overall analytical process because both the duration of the process as well as the reliability of the data depend in large part on its efficiency. Thus, special attention should be given to the choice of a proper sample treatment method that targets analytes and their biomatrix. Copyright © 2013 John Wiley & Sons, Ltd.

  18. Plant regeneration of Erigeron breviscapus (vant.) Hand. Mazz. and its chromatographic fingerprint analysis for quality control.

    Science.gov (United States)

    Liu, Chun-Zhao; Gao, Min; Guo, Bin

    2008-01-01

    An efficient micropropagation system for Erigeron breviscapus (vant.) Hand. Mazz., an important medicinal plant for heart disease, has been developed. Shoot organogenesis occurred from E. breviscapus leaf explants inoculated on a medium supplemented with a combination of plant growth regulators. On average, 17 shoots per leaf explant were produced after 30 days when they were cultured on MS basal salts and vitamin medium containing 5 microM 6-benzylaminopurine (BAP) and 5 microM 1-naphthaleneacetic acid (NAA). All the regenerated shoots formed complete plantlets on a medium containing 2.5-10 microM indole-3-butyric acid (IBA) within 30 days, and 80.2% of the regenerated plantlets survived and grew vigorously in field conditions. Based on the variation in common peaks and the produced amount of the most important bioactive component, scutellarin, a high performance liquid chromatography (HPLC) fingerprinting system was developed for quality control of these micropropagated plants. Chemical constituents in E. breviscapus micropropagated plants varied during plant development from regeneration to maturation, the latter of which showed the most similar phytochemical profile in comparison with mother plants. The regeneration protocol and HPLC fingerprint analysis developed here provided a new approach to quality control of micropropagated plants producing secondary metabolites with significant implications for germplasm conservation.

  19. Chemical fingerprinting of terpanes and steranes by chromatographic alignment and principal component analysis

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, J.H. [Royal Veterinary and Agricultural Univ., Thorvaldsensvej (Denmark). Dept. of Natural Sciences; Hansen, A.B. [National Environmental Research Inst., Roskilde (Denmark). Dept. of Environmental Chemistry and Microbiology; Andersen, O. [Roskilde Univ., Roskilde (Denmark). Dept. of Life Sciences and Chemistry

    2005-07-01

    Biomarkers such as steranes and terpanes are abundant in crude oils, particularly in heavy distillate petroleum products. They are useful for matching highly weathered oil samples when other groups of petroleum hydrocarbons fail to distinguish oil samples. In this study, time warping and principal component analysis (PCA) were applied for oil hydrocarbon fingerprinting based on relative amounts of terpane and sterane isomers analyzed by gas chromatography and mass spectrometry. The 4 principal components were boiling point range, clay content, marine or organic terrestrial matter, and maturity based on differences in the terpane and sterane isomer patterns. This study is an extension of a previous fingerprinting study for identifying the sources of oil spill samples based only on the profiles of sterane isomers. Spill samples from the Baltic Carrier oil spill were correctly identified by inspection of score plots. The interpretation of the loading and score plots offered further chemical information about correlations between changes in the amounts of sterane and terpane isomers. It was concluded that this method is an objective procedure for analyzing chromatograms with more comprehensive data usage compared to other fingerprinting methods. 20 refs., 4 figs.

  20. Chemical fingerprinting of terpanes and steranes by chromatographic alignment and principal component analysis

    International Nuclear Information System (INIS)

    Christensen, J.H.; Hansen, A.B.; Andersen, O.

    2005-01-01

    Biomarkers such as steranes and terpanes are abundant in crude oils, particularly in heavy distillate petroleum products. They are useful for matching highly weathered oil samples when other groups of petroleum hydrocarbons fail to distinguish oil samples. In this study, time warping and principal component analysis (PCA) were applied for oil hydrocarbon fingerprinting based on relative amounts of terpane and sterane isomers analyzed by gas chromatography and mass spectrometry. The 4 principal components were boiling point range, clay content, marine or organic terrestrial matter, and maturity based on differences in the terpane and sterane isomer patterns. This study is an extension of a previous fingerprinting study for identifying the sources of oil spill samples based only on the profiles of sterane isomers. Spill samples from the Baltic Carrier oil spill were correctly identified by inspection of score plots. The interpretation of the loading and score plots offered further chemical information about correlations between changes in the amounts of sterane and terpane isomers. It was concluded that this method is an objective procedure for analyzing chromatograms with more comprehensive data usage compared to other fingerprinting methods. 20 refs., 4 figs

  1. Liquid Chromatographic Method for the Analysis of Brimonidine in Ophthalmic Formulations

    Directory of Open Access Journals (Sweden)

    A. Narendra

    2012-01-01

    Full Text Available A reverse phase LC method was developed for the determination of Brimonidine in eye drops. Chromatography was carried on an Inertsil ODS 3V column (C18 using a mixture of Octane 1- sulfonic acid sodium salt (0.02M (pH 3.5 ± 0.05 and acetonitrile (64:36 v/v as mobile phase at a flow rate of 1 mL/min with UV detection at 254 nm. The drug was eluted at 4.636 min. The detector response was linear in the concentration range of 0.4–72 μg/mL. The limit of detection and limit of quantification were found to be 0.0561 and 0.1848 μg/mL respectively. The proposed method was validated as per the ICH guidelines and can be applied for the routine analysis of Brimonidine in eye drops.

  2. Validation of high-performance liquid chromatographic method for analysis of fluconazole in microemulsions and liquid crystals

    Directory of Open Access Journals (Sweden)

    Hilris Rocha e Silva

    2014-04-01

    Full Text Available In recent decades, there has been a significant increase in the incidence of fungal diseases. Certain fungal diseases cause cutaneous lesions and in the usual treatment, generally administred orally, the drug reaches the site of action with difficulty and its concentration is too low. An approach much explored in recent years is the development of nanotechnology-based drug delivery systems, and microemulsions (ME and liquid crystals (LC are promising. ME and LC were developed with oleic acid or copaiba oil as the oil phase, propoxyl (5OP ethoxyl (20 OE cetyl alcohol as surfactant and water. An analytical method to assess the incorporation of fluconazole (FLU in the systems under study was validated according to guidelines of the International Conference on Harmonization (ICH guidelines and the Brazilian Food, Drug and Sanitation Agency (ANVISA. The method was conducted on a C18-RP column (250 × 4.6 mm i.d., maintained at room temperature. The mobile phase consisted of acetonitrile and water (50:50, v/v, run at a flow rate of 1.0mL/min and using ultraviolet detection at 210nm. The chromatographic separation was obtained with a retention time of 6.3min, and was linear in the range of 20-400 µg/mL (r2=0.9999. The specificity showed no interference of the excipients. The accuracy was 100.76%. The limits of detection and quantitation were 0.057 and 0.172 µg.mL-1, respectively. Moreover, method validation demonstrated satisfactory results for precision and robustness. The proposed method was applied for the analysis of the incorporation of FLU in ME and LC, contributing to improve the quality control and to assure the therapeutic efficacy.

  3. Non-Destructive X-ray Spectrometric and Chromatographic Analysis of Metal Containers and Their Contents, from Ancient Macedonia

    Directory of Open Access Journals (Sweden)

    Christos S. Katsifas

    2018-06-01

    Full Text Available This work describes a holistic archaeometric approach to ancient Macedonian specimens. In the region of the ancient city Lete, the deceased members of a rich and important family were interred in a cluster of seven tombs (4th century BC. Among the numerous grave goods, there was also a set of metal containers preserving their original content. The physico-chemical analysis of the containers and their contents was performed in order to understand the purpose of their use. For the containers, Energy Dispersive micro-X-Ray Fluorescence (EDμXRF spectroscopy was implemented taking advantage of its non-invasive character. The case (B35 and the small pyxis (B37 were made of a binary Cu-Sn alloy accompanied by a slight amount of impurities (Fe, Pb, As and the two miniature bowls were made of almost pure Cu. For the study of the contents, a combination of EDμXRF, X-Ray Diffraction (XRD, and Gas Chromatography—Mass Spectrometry (GC-MS was carried out. Especially for the extraction of the volatile compounds, the Solid Phase Micro-Extraction (SPME technique was used in the headspace mode. Because of the detection of Br, High Pressure Liquid Chromatography coupled to a Diode-Array-Detector (HPLC-DAD was implemented, confirming the existence of the ancient dye shellfish purple (porphyra in Greek. The analytical results of the combined implementation of spectrometric and chromatographic analytical techniques of the metal containers and their contents expand our knowledge about the pharmaceutical practices in Macedonia during the 4th century BC.

  4. Gas chromatographic-mass spectrometric analysis of di(2-ethylhexyl) phthalate and its metabolites in hepatic microsomal incubations

    Energy Technology Data Exchange (ETDEWEB)

    Pietrogrande, M.C.; Rossi, D.; Paganetto, G

    2003-03-17

    A method is reported for the determination of di(2-ethylhexyl) phthalate (DEHP) and its metabolites in in vitro metabolism studies. Gas chromatography-mass spectrometry (GC-MS) analysis allows separation of 18 by-products of DEHP metabolism. On the basis of retention time and specific mass spectra m/z values, three classes of compounds can be identified: (i) alcohols as hydrolysis product; (ii) acids produced by alcohol oxidation; (iii) compounds retaining phthalic moiety. The chromatogram can also be acquired in SIM mode at m/z 149 resulting in 13 well-separated chromatographic peaks: from retention time and mass spectra it can be inferred that the main peaks correspond to mono(2-ethylhexyl) phthalate (MEHP) and ({omega}-1)-hydroxyl-MEHP. The kinetics of DEHP metabolism was studied using an S9 Aroclor-induced liver fraction as in vitro model and following incubation assay after 20, 40, 60 and 90 min. The composition of incubation mixtures can be quantitatively evaluated from selected ion monitoring chromatograms at m/z 149: the by-product concentration increases during the incubation time, as a consequence of DEHP degradation. During the incubation test a significant conversion of DEHP into MEHP is observed: a conversion yield of 10, 13, 16 and 20% of the original DEHP is obtained after 20, 40, 60 and 90 min, respectively. The metabolic conversion of DEHP to MEHP explains the endocrine-disrupting activity of the original DEHP; moreover, it has been demonstrated that MEHP and its ({omega}-1)-oxidation metabolite induce peroxisome proliferation. This result strengthens the suggestion that the study of DEHP metabolic pathway is fundamental to better understanding its toxicological behavior.

  5. Chromatographic analysis with different detectors in the chemical characterisation and dereplication of African propolis.

    Science.gov (United States)

    Zhang, Tong; Omar, Ruwida; Siheri, Weam; Al Mutairi, Sultan; Clements, Carol; Fearnley, James; Edrada-Ebel, RuAngelie; Watson, David

    2014-03-01

    Propolis or bee glue has very diverse composition and is potentially a source of biologically active compounds. Comprehensive chemical profiling was performed on 22 African propolis samples collected from the sub-Saharan region of Africa by using various hyphenated analytical techniques including Liquid Chromatography (LC)-UltraViolet Detection (UV)-Evaporative Light Scattering Detection (ELSD), LC-High Resolution Mass Spectrometry (HRMS), Gas Chromatography (GC)-MS and LC-Diode Array Detector (DAD)-HRMS/MS. The diversity of the composition of these African propolis samples could be observed by heat mapping the LC-UV and ELSD data. The characteristic chemical components were uncovered by applying Principal Component Analysis (PCA) to the LC-HRMS data and a preliminary dereplication was carried out by searching their accurate masses in the Dictionary of Natural Products (DNP). A further identification was achieved by comparing their GC-MS or LC-DAD-HRMS/MS spectra with previously published data. Generally no clear geographic delineation was observed in the classification of these African propolis samples. Triterpenoids were found as the major chemical components in more than half of the propolis samples analysed in this study and some others were classified as temperate and Eastern Mediterranean type of propolis. Based on the comparative chemical profiling and dereplication studies one uncommon propolis from southern Nigeria stood out from others by presenting prenylated isoflavonoids, which indicated that it was more like Brazilian red propolis, and more significantly a high abundance of stilbenoid compounds which could be novel in propolis. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. High-performance Thin-layer Chromatographic-densitometric Quantification and Recovery of Bioactive Compounds for Identification of Elite Chemotypes of Gloriosa superba L. Collected from Sikkim Himalayas (India).

    Science.gov (United States)

    Misra, Ankita; Shukla, Pushpendra Kumar; Kumar, Bhanu; Chand, Jai; Kushwaha, Poonam; Khalid, Md; Singh Rawat, Ajay Kumar; Srivastava, Sharad

    2017-10-01

    Gloriosa superba L. (Colchicaceae) is used as adjuvant therapy in gout for its potential antimitotic activity due to high colchicine(s) alkaloids. This study aimed to develop an easy, cheap, precise, and accurate high-performance thin-layer chromatographic (HPTLC) validated method for simultaneous quantification of bioactive alkaloids (colchicine and gloriosine) in G. superba L. and to identify its elite chemotype(s) from Sikkim Himalayas (India). The HPTLC chromatographic method was developed using mobile phase of chloroform: acetone: diethyl amine (5:4:1) at λ max of 350 nm. Five germplasms were collected from targeted region, and on morpho-anatomical inspection, no significant variation was observed among them. Quantification data reveal that content of colchicine ( R f : 0.72) and gloriosine ( R f : 0.61) varies from 0.035%-0.150% to 0.006%-0.032% (dry wt. basis). Linearity of method was obtained in the concentration range of 100-400 ng/spot of marker(s), exhibiting regression coefficient of 0.9987 (colchicine) and 0.9983 (gloriosine) with optimum recovery of 97.79 ± 3.86 and 100.023% ± 0.01%, respectively. Limit of detection and limit of quantification were analyzed, respectively, as 6.245, 18.926 and 8.024, 24.316 (ng). Two germplasms, namely NBG-27 and NBG-26, were found to be elite chemotype of both the markers. The developed method is validated in terms of accuracy, recovery, and precision studies as per the ICH guidelines (2005) and can be adopted for the simultaneous quantification of colchicine and gloriosine in phytopharmaceuticals. In addition, this study is relevant to explore the chemotypic variability in metabolite content for commercial and medicinal purposes. An easy, cheap, precise, and accurate high performance thin layer chromatographic (HPTLC) validated method for simultaneous quantification of bioactive alkaloids (colchicine and gloriosine) in G. superba L.Five germplasms were collected from targeted region, and on morpho anatomical

  7. The use of dissolvable layered double hydroxide components in an in situ solid-phase extraction for chromatographic determination of tetracyclines in water and milk samples.

    Science.gov (United States)

    Phiroonsoontorn, Nattaphorn; Sansuk, Sira; Santaladchaiyakit, Yanawath; Srijaranai, Supalax

    2017-10-13

    This research presents a simple and green in situ solid phase extraction (is-SPE) combined with high-performance liquid chromatography (HPLC) for the simultaneous analysis of tetracyclines (TCs) including tetracycline, oxytetracycline, and chlortetracycline. In is-SPE, TCs were efficiently extracted through the precipitation formation of dissolvable layered double hydroxides (LDHs) by mixing the LDH components such as magnesium and aluminum ions (both in metal chloride salts) thoroughly in an alkaline sample solution. After the centrifugation, the precipitate was completely dissolved with trifluoroacetic acid to release the enriched TCs, and then analyzed by HPLC. Under optimized conditions, this method gave good enrichment factors (EFs) of 41-93 with low limits of detection (LODs) of 0.7-6μg/L and limits of quantitation (LOQs) of 3-15μg/L. Also, the proposed method was successfully applied for the determination of TCs in water and milk samples with the recoveries ranging from 81.7-108.1% for water and 55.7-88.7% for milk. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. OpenChrom: a cross-platform open source software for the mass spectrometric analysis of chromatographic data.

    Science.gov (United States)

    Wenig, Philip; Odermatt, Juergen

    2010-07-30

    Today, data evaluation has become a bottleneck in chromatographic science. Analytical instruments equipped with automated samplers yield large amounts of measurement data, which needs to be verified and analyzed. Since nearly every GC/MS instrument vendor offers its own data format and software tools, the consequences are problems with data exchange and a lack of comparability between the analytical results. To challenge this situation a number of either commercial or non-profit software applications have been developed. These applications provide functionalities to import and analyze several data formats but have shortcomings in terms of the transparency of the implemented analytical algorithms and/or are restricted to a specific computer platform. This work describes a native approach to handle chromatographic data files. The approach can be extended in its functionality such as facilities to detect baselines, to detect, integrate and identify peaks and to compare mass spectra, as well as the ability to internationalize the application. Additionally, filters can be applied on the chromatographic data to enhance its quality, for example to remove background and noise. Extended operations like do, undo and redo are supported. OpenChrom is a software application to edit and analyze mass spectrometric chromatographic data. It is extensible in many different ways, depending on the demands of the users or the analytical procedures and algorithms. It offers a customizable graphical user interface. The software is independent of the operating system, due to the fact that the Rich Client Platform is written in Java. OpenChrom is released under the Eclipse Public License 1.0 (EPL). There are no license constraints regarding extensions. They can be published using open source as well as proprietary licenses. OpenChrom is available free of charge at http://www.openchrom.net.

  9. Chromatographic separations of stereoisomers

    Energy Technology Data Exchange (ETDEWEB)

    Souter, R.W.

    1985-01-01

    This text covers both diastereomers and enantiomers; describes techniques for GC, HPLC, and other chromatographic methods; and tabulates results of various applications by both techniques and compound class. It provides current knowledge about separation mechanisms and interactions of asymmetric molecules, as well as experimental and commercial materials such as columns, instruments, and derivatization reagents. The contents also include stereoisomer separations by gas chromatography. Stereoisomer separations by high-performance liquid chromatography. Stereoisomer separations by other chromatographic techniques.

  10. Suspect screening of large numbers of emerging contaminants in environmental waters using artificial neural networks for chromatographic retention time prediction and high resolution mass spectrometry data analysis.

    Science.gov (United States)

    Bade, Richard; Bijlsma, Lubertus; Miller, Thomas H; Barron, Leon P; Sancho, Juan Vicente; Hernández, Felix

    2015-12-15

    The recent development of broad-scope high resolution mass spectrometry (HRMS) screening methods has resulted in a much improved capability for new compound identification in environmental samples. However, positive identifications at the ng/L concentration level rely on analytical reference standards for chromatographic retention time (tR) and mass spectral comparisons. Chromatographic tR prediction can play a role in increasing confidence in suspect screening efforts for new compounds in the environment, especially when standards are not available, but reliable methods are lacking. The current work focuses on the development of artificial neural networks (ANNs) for tR prediction in gradient reversed-phase liquid chromatography and applied along with HRMS data to suspect screening of wastewater and environmental surface water samples. Based on a compound tR dataset of >500 compounds, an optimized 4-layer back-propagation multi-layer perceptron model enabled predictions for 85% of all compounds to within 2min of their measured tR for training (n=344) and verification (n=100) datasets. To evaluate the ANN ability for generalization to new data, the model was further tested using 100 randomly selected compounds and revealed 95% prediction accuracy within the 2-minute elution interval. Given the increasing concern on the presence of drug metabolites and other transformation products (TPs) in the aquatic environment, the model was applied along with HRMS data for preliminary identification of pharmaceutically-related compounds in real samples. Examples of compounds where reference standards were subsequently acquired and later confirmed are also presented. To our knowledge, this work presents for the first time, the successful application of an accurate retention time predictor and HRMS data-mining using the largest number of compounds to preliminarily identify new or emerging contaminants in wastewater and surface waters. Copyright © 2015 Elsevier B.V. All rights

  11. Quantitative determination of 14C(-)-epicatechin and 14C-rutin on the Uncaria plant by a two-step heterogeneous thin-layer chromatographic-liquid scintillation counting procedure

    International Nuclear Information System (INIS)

    Das, N.P.; Law, K.H.

    1987-01-01

    A simple, rapid, precise and relatively inexpensive thin-layer chromatographic method coupled to heterogeneous liquid scintillation counting procedure was used for the quantitation of radioactivity of biologically synthesized ( 14 C) flavonoids and other phenolic plant constituents. The two flavonoids, namely ( 14 C) rutin and ( 14 C) (-) -epicatechin, extracted from the plant Uncaria elliptica Roxb were separated on plastic thin-layer plates coated with silica gel using the two solvent systems : acetonitrile-acetic acid-water (8.5:0.5:1.5) and ethyl acetate-acetic acid-water (3:1:3). The respective spots on the plates that corresponded to the two flavonoids were cut out and eluted with 3 ml aliquots of methanol followed by direct addition of scintillation flour. This method gave 99 +- 2 per cent of the total count indicating the excellent elution procedure. The results were reproducible and showed linearity over the range of 0 - 35000 dpm. The elution efficiency by several other organic solvents were also investigated. (author). 19 refs., 4 tables

  12. Layer by layer: complex analysis with OCT technology

    Science.gov (United States)

    Florin, Christian

    2017-03-01

    three-dimensional tomographic image. For 3D measuring technique specially designed ASP- arrays with a very high image rate are available. If ASP- Arrays are coupled with the OCT method, layer thicknesses can be determined without contact, sealing seams can be inspected or geometrical shapes can be measured. From a stack of hundreds of single OCT images, interesting images can be selected and fed to the computer to analyse them.

  13. High performance liquid chromatographic separation of polycyclic aromatic hydrocarbons on microparticulate pyrrolidone and application to the analysis of shale oil

    International Nuclear Information System (INIS)

    Mourey, T.H.; Siggia, S.; Uden, P.C.; Crowley, R.J.

    1980-01-01

    A chemically bonded pyrrolidone substrate is used for the high performance liquid chromatographic separation of polycyclic aromatic hydrocarbons. The cyclic amide phase interacts electronically with the polycyclic aromatic hydrocarbons in both the normal and reversed phase modes. Separation is effected according to the number of aromatic rings and the type of ring condensation. Information obtained is very different from that observed on hydrocarbon substrates, and thus these phases can be used in a complementary fashion to give a profile of polycyclic aromatics in shale oil samples. 7 figures, 1 table

  14. Improved method for the extraction and chromatographic analysis on a fused-core column of ellagitannins found in oak-aged wine.

    Science.gov (United States)

    Navarro, María; Kontoudakis, Nikolaos; Canals, Joan Miquel; García-Romero, Esteban; Gómez-Alonso, Sergio; Zamora, Fernando; Hermosín-Gutiérrez, Isidro

    2017-07-01

    A new method for the analysis of ellagitannins observed in oak-aged wine is proposed, exhibiting interesting advantages with regard to previously reported analytical methods. The necessary extraction of ellagitannins from wine was simplified to a single step of solid phase extraction (SPE) using size exclusion chromatography with Sephadex LH-20 without the need for any previous SPE of phenolic compounds using reversed-phase materials. The quantitative recovery of wine ellagitannins requires a combined elution with methanol and ethyl acetate, especially for increasing the recovery of the less polar acutissimins. The chromatographic method was performed using a fused-core C18 column, thereby avoiding the coelution of main ellagitannins, such as vescalagin and roburin E. However, the very polar ellagitannins, namely, the roburins A, B and C, still partially coeluted, and their quantification was assisted by the MS detector. This methodology also enabled the analysis of free gallic and ellagic acids in the same chromatographic run. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Chromatographic hydrogen isotope separation

    International Nuclear Information System (INIS)

    Aldridge, F.T.

    1983-01-01

    Intermetallic compounds with the CaCu5 type of crystal structure, particularly LaNiCo and CaNi5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation column. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale multi-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors

  16. Chromatographic hydrogen isotope separation

    International Nuclear Information System (INIS)

    Aldridge, F.T.

    1981-01-01

    Intermetallic compounds with the CaCu5 type of crystal structure , particularly LaNiCo and CaNi5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors

  17. Quality analysis of commercial samples of Ziziphi spinosae semen (suanzaoren by means of chromatographic fingerprinting assisted by principal component analysis

    Directory of Open Access Journals (Sweden)

    Shuai Sun

    2014-06-01

    Full Text Available Due to the scarcity of resources of Ziziphi spinosae semen (ZSS, many inferior goods and even adulterants are generally found in medicine markets. To strengthen the quality control, HPLC fingerprint common pattern established in this paper showed three main bioactive compounds in one chromatogram simultaneously. Principal component analysis based on DAD signals could discriminate adulterants and inferiorities. Principal component analysis indicated that all samples could be mainly regrouped into two main clusters according to the first principal component (PC1, redefined as Vicenin II and the second principal component (PC2, redefined as zizyphusine. PC1 and PC2 could explain 91.42% of the variance. Content of zizyphusine fluctuated more greatly than that of spinosin, and this result was also confirmed by the HPTLC result. Samples with low content of jujubosides and two common adulterants could not be used equivalently with authenticated ones in clinic, while one reference standard extract could substitute the crude drug in pharmaceutical production. Giving special consideration to the well-known bioactive saponins but with low response by end absorption, a fast and cheap HPTLC method for quality control of ZSS was developed and the result obtained was commensurate well with that of HPLC analysis. Samples having similar fingerprints to HPTLC common pattern targeting at saponins could be regarded as authenticated ones. This work provided a faster and cheaper way for quality control of ZSS and laid foundation for establishing a more effective quality control method for ZSS. Keywords: Adulterant, Common pattern, Principal component analysis, Quality control, Ziziphi spinosae semen

  18. Chromatographical Analysis of Amino Acids in Sepia Mutant of Drosophila melanogaster under Stress of Cypermethrin and Alphamethrin

    Directory of Open Access Journals (Sweden)

    Namrata Rana

    2014-07-01

    Full Text Available Insects are invertebrates that are taxonomically referred to as the class Insecta. They are the most numerous and most widespread terrestrial taxon within the phylum Arthropoda, and indeed the most diverse group of animals on the earth, with around 925,000 species described—more than all other animal groups combined. Insects may be found in nearly all environments on the planet, although only a small number of species have adapted to life in the oceans where crustaceans tend to predominate instead. HPTLC is a method commonly applied for the identification, assay and the testing for purity, stability, dissolution or content uniformity of raw materials (herbal and animal extracts, fermentation mixtures, drugs and excipients and formulated products (pharmaceuticals, cosmetics, nutrients. These flexible and cost-effective techniques present the advantage of the simultaneous processing of standards and samples with versatile detection possibilities, including a great variety of post-chromatographic derivatization reagents.

  19. Two-dimensional chromatographic analysis using three second-dimension columns for continuous comprehensive analysis of intact proteins.

    Science.gov (United States)

    Zhu, Zaifang; Chen, Huang; Ren, Jiangtao; Lu, Juan J; Gu, Congying; Lynch, Kyle B; Wu, Si; Wang, Zhe; Cao, Chengxi; Liu, Shaorong

    2018-03-01

    We develop a new two-dimensional (2D) high performance liquid chromatography (HPLC) approach for intact protein analysis. Development of 2D HPLC has a bottleneck problem - limited second-dimension (second-D) separation speed. We solve this problem by incorporating multiple second-D columns to allow several second-D separations to be proceeded in parallel. To demonstrate the feasibility of using this approach for comprehensive protein analysis, we select ion-exchange chromatography as the first-dimension and reverse-phase chromatography as the second-D. We incorporate three second-D columns in an innovative way so that three reverse-phase separations can be performed simultaneously. We test this system for separating both standard proteins and E. coli lysates and achieve baseline resolutions for eleven standard proteins and obtain more than 500 peaks for E. coli lysates. This is an indication that the sample complexities are greatly reduced. We see less than 10 bands when each fraction of the second-D effluents are analyzed by sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE), compared to hundreds of SDS-PAGE bands as the original sample is analyzed. This approach could potentially be an excellent and general tool for protein analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. High-performance thin-layer chromatographic methods in the evaluation of the antioxidant and anti-hyperglycemic activity of Myrmecodia platytyrea as a promising opportunity in diabetes treatment.

    Science.gov (United States)

    Agatonovic-Kustrin, S; Morton, D W; Adam, A; Mizaton, H H; Zakaria, H

    2017-12-29

    The steady increase of diabetes is becoming a major burden on health care systems. As diabetic complications arise from oxidative stress, an antioxidant therapy along with anti-diabetic drugs is recommended. Myrmecodia or ant plant is highly valued as a traditional medicine in West Papua. It is used as an alternative treatment for diabetes, as the substances produced by ants can reduce blood sugar levels. The aim of this study was to develop and establish high-performance thin-layer chromatographic (HPTLC)-bioautographic methods to measure the antioxidant and hypoglycemic effects in different extracts from Myrmecodia platytyrea and to compare them with sterol content. Antioxidant activity in methanol, ethanol, dichloromethane (DCM) and ethyl acetate (EA) extracts were measured with a direct HPTLC-2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) assay, while hypoglycemic effects were assessed using a newly developed α-amylase inhibitory activity assay. Stigmasterol is observed, after derivatization with anisaldehyde, as purple colored zones under visible light at hRF values of 0.66. The highest antioxidant activity was observed in the ethanol extract which is rich in polyphenols and flavonoids, while the DCM extract did not show antioxidant activity, but had significant α-amylase inhibitory activity. The highest α-amylase inhibitory activity was observed in the EA and DCM extracts and was related to their stigmasterol content. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

  1. Qualitative and quantitative analysis of specific polysaccharides in Dendrobium huoshanense by using saccharide mapping and chromatographic methods.

    Science.gov (United States)

    Deng, Yong; Chen, Ling-Xiao; Han, Bang-Xing; Wu, Ding-Tao; Cheong, Kit-Leong; Chen, Nai-Fu; Zhao, Jing; Li, Shao-Ping

    2016-09-10

    Qualitative and quantitative analysis of specific polysaccharides from ten batches of Dendrobium huoshanense were performed using high performance size exclusion chromatography coupled with multi-angle laser light scattering and refractive index detector (HPSEC-MALLS-RID), gas chromatography-mass spectrometry (GC-MS), nuclear magnetic resonance (NMR) and saccharide mapping based on polysaccharides analysis by using carbohydrate gel electrophoresis (PACE) and high performance thin layer chromatography (HPTLC). Results showed that molecular weights, the radius of gyrations, and contents of specific polysaccharides in D. huoshanense were ranging from 1.16×10(5) to 2.17×10(5)Da, 38.8 to 52.1nm, and 9.9% to 19.9%, respectively. Furthermore, the main monosaccharide compositions were Man and Glc. Indeed, the main glycosidic linkages were β-1,4-Manp and β-1,4-Glcp, and substituted with acetyl groups at O-2 and O-3 of 1,4-linked Manp. Moreover, results showed that PACE and HPTLC fingerprints of partial acidic and enzymatic hydrolysates of specific polysaccharides were similar, which are helpful to better understand the specific polysaccharides in D. huoshanense and beneficial to improve their quality control. These approaches could also be routinely used for quality control of polysaccharides in other medicinal plants. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Characterization of organic and conventional sweet basil leaves using chromatographic and flow-injection mass spectrometric (FIMS) fingerprints combined with principal component analysis

    Science.gov (United States)

    Lu, Yingjian; Gao, Boyan; Chen, Pei; Charles, Denys; Yu, Liangli (Lucy)

    2014-01-01

    Sweet basil, Ocimum basilicum., is one of the most important and wildly used spices and has been shown to have antioxidant, antibacterial, and anti-diarrheal activities. In this study, high performance liquid chromatographic (HPLC) and flow-injection mass spectrometric (FIMS) fingerprinting techniques were used to differentiate organic and conventional sweet basil leaf samples. Principal component analysis (PCA) of the fingerprints indicated that both HPLC and FIMS fingerprints could effectively detect the chemical differences in the organic and conventional sweet basil leaf samples. This study suggested that the organic basil sample contained greater concentrations of almost all the major compounds than its conventional counterpart on a per same botanical weight basis. The FIMS method was able to rapidly differentiate the organic and conventional sweet basil leaf samples (1 min analysis time), whereas the HPLC fingerprints provided more information about the chemical composition of the basil samples with a longer analytical time. PMID:24518341

  3. Thin Layer Chromatographic Resolution of Some β-adrenolytics and a β2-Agonist Using Bovine Serum Albumin as Chiral Additive in Stationary Phase.

    Science.gov (United States)

    Malik, Poonam; Bhushan, Ravi

    2018-01-01

    Direct enantiomeric resolution of commonly used five racemic β-adrenolytics, namely, bisoprolol, atenolol, propranolol, salbutamol and carvedilol has been achieved by thin layer chromatography using bovine serum albumin (BSA) as chiral additive in stationary phase. Successful resolution of the enantiomers of all racemic β-adrenolytics was achieved by use of different composition of simple organic solvents having no buffer or inorganic ions. The effect of variation in pH, temperature, amount of BSA as the additive, and composition of mobile phase on resolution was systematically studied. Spots were visualized in iodine vapors. Native enantiomers for each of the five analytes were isolated and identified and their elution order was determined. The limit of detection was found to be 0.7, 1.2, 0.84, 1.6 and 0.9 μg (per spot) for each enantiomer of bisoprolol, atenolol, propranolol, salbutamol and carvedilol, respectively. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  4. Liquid chromatographic separation of terpenoid pigments in foods and food products.

    Science.gov (United States)

    Cserháti, T; Forgács, E

    2001-11-30

    The newest achievements in the use of various liquid chromatographic techniques such as adsorption and reversed-phase thin-layer chromatography and HPLC employed for the separation and quantitative determination of terpenoid-based color substances in foods and food products are reviewed. The techniques applied for the analysis of individual pigments and pigments classes are surveyed and critically evaluated. Future trends in the separation and identification of pigments in foods and food products are delineated.

  5. Vibrational Spectroscopy of Chromatographic Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jeanne E. Pemberton

    2011-03-10

    Chromatographic separations play a central role in DOE-supported fundamental research related to energy, biological systems, the environment, and nuclear science. The overall portfolio of research activities in the Separations and Analysis Program within the DOE Office of Basic Energy Sciences includes support for activities designed to develop a molecular-level understanding of the chemical processes that underlie separations for both large-scale and analytical-scale purposes. The research effort funded by this grant award was a continuation of DOE-supported research to develop vibrational spectroscopic methods to characterize the interfacial details of separations processes at a molecular level.

  6. The gas-chromatographic and gas-chromatographic-mass-spectrometric identification of halogen-containing organic compounds

    Science.gov (United States)

    Gidaspov, B. V.; Zenkevich, I. G.; Rodin, A. A.

    1989-09-01

    The problem of identifying halogen-containing organic compounds in their gas-chromatographic and gas-chromatographic-mass-spectrometric (GC-MS) determination in different materials has been examined. Particular attention has been paid not to the complete characterisation of methods for carrying out this analysis but to the most important problem of increasing the selectivity at the stages of sampling, separation, and interpretation of the gas-chromatographic and GC-MS information. The bibliography contains 292 references.

  7. 2nd international conference on ion beam surface layer analysis

    International Nuclear Information System (INIS)

    1975-01-01

    The papers of this conference are concerned with the fundamental aspects and with the application of surface layer analysis. It is reported amongst others about backscattering analysis, Auger electron spectroscopy, channelling and microprobe. (HPOE) [de

  8. In situ alcoholysis of triacylglycerols by application of switchable-polarity solvents. A new derivatization procedure for the gas-chromatographic analysis of vegetable oils.

    Science.gov (United States)

    Saliu, Francesco; Orlandi, Marco

    2013-10-01

    We describe a new use of switchable-polarity solvents for the simultaneous derivatization and extraction of triacylglycerols from vegetable oils before gas-chromatographic analysis. Different equimolecular mixtures of the commercially available amidine 1,8-diazabicyclo[5.4.0]undec-7-ene and n-alkyl alcohols were tested. Triolein was used as a model compound. Very good results were achieved by using butanol (recovery of butyl oleate was 89 ± 4%). The procedure was applied for the characterization of the fatty acid profile of different vegetable oils. No statistically significant differences from the results obtained with the application of two traditional methods were evidenced. Moreover, the use of switchable-polarity solvents showed many advantages: owing to the basicity of the amidines, no catalyst was required; the transterification reaction was conducted under mild conditions, one step and in situ; no particular matrix interferences were evidenced; the solvent was recovered.

  9. Multivariate curve-resolution analysis of pesticides in water samples from liquid chromatographic-diode array data.

    Science.gov (United States)

    Maggio, Rubén M; Damiani, Patricia C; Olivieri, Alejandro C

    2011-01-30

    Liquid chromatographic-diode array detection data recorded for aqueous mixtures of 11 pesticides show the combined presence of strongly coeluting peaks, distortions in the time dimension between experimental runs, and the presence of potential interferents not modeled by the calibration phase in certain test samples. Due to the complexity of these phenomena, data were processed by a second-order multivariate algorithm based on multivariate curve resolution and alternating least-squares, which allows one to successfully model both the spectral and retention time behavior for all sample constituents. This led to the accurate quantitation of all analytes in a set of validation samples: aldicarb sulfoxide, oxamyl, aldicarb sulfone, methomyl, 3-hydroxy-carbofuran, aldicarb, propoxur, carbofuran, carbaryl, 1-naphthol and methiocarb. Limits of detection in the range 0.1-2 μg mL(-1) were obtained. Additionally, the second-order advantage for several analytes was achieved in samples containing several uncalibrated interferences. The limits of detection for all analytes were decreased by solid phase pre-concentration to values compatible to those officially recommended, i.e., in the order of 5 ng mL(-1). Copyright © 2010 Elsevier B.V. All rights reserved.

  10. Gas chromatographic analysis of dimethyltryptamine and beta-carboline alkaloids in ayahuasca, an Amazonian psychoactive plant beverage.

    Science.gov (United States)

    Pires, Ana Paula Salum; De Oliveira, Carolina Dizioli Rodrigues; Moura, Sidnei; Dörr, Felipe Augusto; Silva, Wagner Abreu E; Yonamine, Mauricio

    2009-01-01

    Ayahuasca is obtained by infusing the pounded stems of Banisteriopsis caapi in combination with the leaves of Psychotria viridis. P. viridis is rich in the psychedelic indole N,N-dimethyltryptamine, whereas B. caapi contains substantial amounts of beta-carboline alkaloids, mainly harmine, harmaline and tetrahydroharmine, which are monoamine-oxidase inhibitors. Because of differences in composition in ayahuasca preparations, a method to measure their main active constituents is needed. To develop a gas chromatographic method for the simultaneous determination of dimethyltryptamine and the main beta-carbolines found in ayahuasca preparations. The alkaloids were extracted by means of solid phase extraction (C(18)) and detected by gas chromatography with nitrogen/phosphorous detector. The lower limit of quantification (LLOQ) was 0.02 mg/mL for all analytes. The calibration curves were linear over a concentration range of 0.02-4.0 mg/mL (r(2 )> 0.99). The method was also precise (RSD ayahuasca was developed and validated. The method can be useful to estimate administered doses in animals and humans for further pharmacological and toxicological investigations of ayahuasca. Copyright (c) 2009 John Wiley & Sons, Ltd.

  11. High-performance liquid chromatographic analysis of cyclosporin A in rat blood and liver using a commercially available internal standard.

    Science.gov (United States)

    Chimalakonda, Anjaneya P; Shah, Rakhi B; Mehvar, Reza

    2002-05-25

    All the available HPLC assays of cyclosporin A (CyA) use internal standards that are not commercially available. Our purpose was to develop an HPLC assay for measurements of CyA in rat blood and liver using a commercially available internal standard (I.S.). After the addition of tamoxifen (I.S.), blood (0.25 ml) or the liver homogenate (1 ml) samples were extracted into a mixture of ether:methanol (95:5). The residue after evaporation of the organic layer was dissolved in 200 microl of an injection solution and washed with 1 ml of hexane before analysis. The separation was achieved using an LC-1 column (70 degrees C) with a mobile phase of methanol-acetonitrile-0.01 M KH(2)PO(4) (50:25:25, v/v) and a flow-rate of 1 ml/min. Detection was at 205 nm. Cyclosporin A and I.S. eluted at 5 and 7 min, respectively, free from endogenous peaks. Linear relationships (r>0.98) were observed between the CyA:I.S. peak area ratios and the CyA concentrations within the range of 0.2-10 microg/ml for blood and 0.1-4 microg/ml for the liver homogenates. The intra- and inter-run C.V.s and errors for both the blood and liver samples were <15%. The extraction efficiency (n=5) was close to 100% for both CyA and I.S. in both blood and liver homogenates. The lower limit of quantitation of the assay was 0.2 or 0.1 microg/ml based on 250 microl of blood or 1 ml of liver homogenate, respectively. The assay was capable of measuring blood and liver concentrations of CyA in a rat injected intravenously with a single 5-mg/kg dose of the drug.

  12. Antioxidant and Antiangiogenic Properties, and Gas Chromatographic-Time of Flight Analysis of Sonchus arvensis Leaves Extracts

    International Nuclear Information System (INIS)

    Itam, A.; Shah, A. M.; Majid, A.; Ismail, Z.

    2015-01-01

    Sonchus arvensis L. (Asteraceae) is one of the medicinal herbs used in traditional medicines, in which the leaf extract was used as a diuretic, lithotriptic and antiurolithiasis agent. The leaves of S. arvensis reported contain several compounds, including a variety of flavonoids, terpenoids and sterol, even this plant also contain silica and potassium. Flavonoids are secondary metabolite compound which have ability as antioxidant. In this study, the aims are to determine of antioxidants and antiangiogenic properties, and phytoconstituents quantitative of aqueous and methanol extracts of S. arvensis leaves. The antioxidant properties were studied using 1,1-Diphenyl-2-picrylhydrazyl (DPPH) free radical, xanthine oxidase and beta-carotene-linoleate models system. Furthermore, the antiangiogenic property was evaluated using ex vivo rat aorta ring assay. Quantitative determination of extracts phytoconstituents were carried out by using Gas Chromatographic-Time of Flight (GC-TOF) mass spectrophotometric methods. The results showed that the aqueous and methanol extracts have ability as antioxidant which is antioxidant activities of aqueous extracts on DPPH radical and inhibition of xanthine oxidase activity are higher than that of methanol extracts. Meanwhile antioxidant activity using beta-carotene-linoleate model system of S. arvensis aqueous extract is lower than that of methanol extracts. Nevertheless, the differences of these antioxidant activities are not significant. Antiangiogenic property of aqueous extract is also higher than that of methanol extract which is measured at 100 meu g mL/sup -1/ of extracts. This indicates that there is correlation between antioxidant activity and antiangigenic property, exhibiting that this plant possesses the potential to prevent or cure the diseases that related to angiogenesis such as cancer. (author)

  13. Reductive amination of glutaraldehyde 2,4-dinitrophenylhydrazone using 2-picoline borane and high-performance liquid chromatographic analysis.

    Science.gov (United States)

    Uchiyama, Shigehisa; Sakamoto, Hironari; Ohno, Akiko; Inaba, Yohei; Nakagome, Hideki; Kunugita, Naoki

    2012-09-21

    A typical method for the measurement of glutaraldehyde (GLA) employs 2,4-dinitrophenylhydrazine (DNPH) to form GLA-DNPhydrazone derivatives. However, this method is subject to analytical errors because GLA-DNPhydrazone is a quaternary bis-derivative and forms three geometric isomers (E-E, E-Z and Z-Z) as a result of the two C[double bond, length as m-dash]N double bonds. To overcome this issue, a method for transforming the C[double bond, length as m-dash]N double bond into a C-N single bond, using reductive amination of DNPhydrazone derivatives, has been applied. The amination reaction of GLA-DNPhydrazones with 2-picoline borane is accelerated with catalytic amounts of acid and is completed within 10 minutes in the presence of 100 mmol L(-1) phosphoric acid. Reduction of GLA-DNPhydrazone by 2-picoline borane is unique and results in the formation of N-(2,4-dinitrophenyl)-1-piperidinamine (DNPPA). NMR and LC-APCI-MS data confirmed the product identification. DNPPA is very stable and did not change when stored for at least four weeks at room temperature. DNPPA has excellent solubility of 14.6 g L(-1) at 20 °C in acetonitrile. The absorption maximum wavelength and the molar absorptivity of DNPPA were 351 nm and 4.2 × 10(4) L mol(-1) cm(-1) respectively. Complete separation between the reduced forms of C1-C10 aldehyde DNPhydrazones, including DNPPA, can be achieved by operating the reversed-phase high-performance liquid chromatograph at 351 nm in gradient mode using a C18 amide column. The reductive amination method for GLA overcomes analytical errors caused by E-E, E-Z and Z-Z geometrical isomers.

  14. Analysis of the Younger Dryas Impact Layer

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, Richard B.; West, Allen; Revay, Zsolt; Hagstrum, Jonathon T,; Belgya, Thomas; Hee, Shane S. Que; Smith, Alan R.

    2010-02-27

    We have uncovered a thin layer of magnetic grains and microspherules, carbon spherules, and glass-like carbon at nine sites across North America, a site in Belgium, and throughout the rims of 16 Carolina Bays. It is consistent with the ejecta layer from an impact event and has been dated to 12.9 ka BP coinciding with the onset of Younger Dryas (YD) cooling and widespread megafaunal extinctions in North America. At many locations the impact layer is directly below a black mat marking the sudden disappearance of the megafauna and Clovis people. The distribution pattern of the Younger Dryas boundary (YDB) ejecta layer is consistent with an impact near the Great Lakes that deposited terrestrial-like ejecta near the impact site and unusual, titanium-rich projectile-like ejecta further away. High water content associated with the ejecta, up to 28 at. percent hydrogen (H), suggests the impact occurred over the Laurentide Ice Sheet. YDB microspherules and magnetic grains are highly enriched in TiO{sub 2}. Magnetic grains from several sites are enriched in iridium (Ir), up to 117 ppb. The TiO{sub 2}/FeO, K/Th, TiO{sub 2}/Zr, Al{sub 2}O{sub 3}/FeO+MgO, CaO/Al{sub 2}O{sub 3}, REE/ chondrite, FeO/MnO ratios and SiO{sub 2}, Na{sub 2}O, K{sub 2}O, Cr{sub 2}O{sub 3}, Ni, Co, U, Th and other trace element abundances are inconsistent with all terrestrial and extraterrestrial (ET) sources except for KREEP, a lunar igneous rock rich in potassium (K), rare-earth elements (REE), phosphorus (P), and other incompatible elements including U and Th. Normal Fe, Ti, and {sup 238}U/{sup 235}U isotopic abundances were found in the magnetic grains, but {sup 234}U was enriched over equilibrium values by 50 percent in Murray Springs and by 130 percent in Belgium. 40K abundance is enriched by up to 100 percent in YDB sediments and Clovis chert artifacts. Highly vesicular carbon spherules containing nanodiamonds, glass-like carbon, charcoal and soot found in large quantities in the YDB layer are

  15. SIMULTANEOUS ANALYSIS OF AZIDOTHYMIDINE AND ITS MONOPHOSPHATE, DIPHOSPHATE AND TRIPHOSPHATE DERIVATIVES IN BIOLOGICAL-FLUIDS, TISSUE AND CULTURED-CELLS BY A RAPID HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC METHOD

    NARCIS (Netherlands)

    MOLEMA, G; JANSEN, RW; Visser, Jan; MEIJER, DKF

    1992-01-01

    A rapid high-performance liquid chromatographic (HPLC) method for the simultaneous analysis of the antiviral drug azidothymidine (AZT), AZT monophosphate, AZT diphosphate and AZT triphosphate, with ultraviolet detection in the nanomolar range, is described. Determination of these compounds in vitro

  16. Optimization of the gas chromatographic separations

    International Nuclear Information System (INIS)

    Gasco Sanchez, L.

    1973-01-01

    A review and a critical study on the optimization of the gas chromatographic separations are made. After dealing with the fundamental gas chromatographic equations, some methods of expressing column performances are discussed: performance indices, performance parameters, resolution and effective plate number per unit time. This is completed with a comparative study on performances of various types of columns. Moreover, optimization methods for operating chromatographic conditions are extensively dealt with: as resolution optimization, separation time, and normalization techniques for the time of analysis in order to achieve the maximum resolution at constant time. Finally, some others non operating parameters such as: selectivity of stationary phases, column preparation and optimization methods by means of computers are studied. (Author) 68 refs

  17. An analysis for crack layer stability

    Science.gov (United States)

    Sehanobish, K.; Botsis, J.; Moet, A.; Chudnovsky, A.

    1986-01-01

    The problem of uncontrolled crack propagation and crack arrest is considered with respect to crack layer (CL) translational stability. CL propagation is determined by the difference between the energy release rate and the amount of energy required for material transformation, and necessary and sufficient conditions for CL instability are derived. CL propagation in polystyrene is studied for two cases. For the case of remotely applied fixed load fatigue, the sufficient condition of instability is shown to be met before the necessary condition, and the necessary condition controls the stability. For the fixed displacement case, neither of the instability conditions are met, and CL propagation remains stable, resulting in crack arrest.

  18. Thin layer chromatographic analysis of pteridine-like pigments in the migratory locust, Locusta migratoria migratorioides (Orthoptera: Oedipodidae)

    Czech Academy of Sciences Publication Activity Database

    Němec, Václav; Breuer, M.; De Loof, A.

    2003-01-01

    Roč. 19, - (2003), s. 19-23 ISSN 1210-5759 Institutional research plan: CEZ:AV0Z5007907 Keywords : Pterines * phase-transition * juvenile hormone Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.741, year: 2003

  19. Capillary gas chromatographic analysis of mycolic acid cleavage products, cellular fatty acids, and alcohols of Mycobacterium xenopi.

    OpenAIRE

    Luquin, M; Lopez, F; Ausina, V

    1989-01-01

    The fatty acids, alcohols, and mycolic acids of 26 strains of Mycobacterium xenopi were studied by capillary gas chromatography and thin-layer chromatography. All strains contained alpha-, keto-, and omega-carboxymycolates. The primary mycolic acid cleavage product was hexacosanoic acid. The fatty acid patterns and, especially, the presence of 2-docosanol are characteristic markers of M. xenopi.

  20. Isotope separations using chromatographic methods

    International Nuclear Information System (INIS)

    Leseticky, L.

    1985-01-01

    A survey is given of chromatographic separations of compounds only differing in isotope composition. Isotope effects on physical properties which allow chromatographic separation (vapour tension, adsorption heat, partition coefficient) are very small, with the exception of the simplest molecules. Therefore, separation factors only assume the value of several per cent. From this ensues the necessity of using columns which are specially and very carefully prepared and have a separation efficiency of the order of 10 4 theoretical plates. Briefly discussed is liquid chromatography on ion exchangers which with a varied degree of success was used for separating simple inorganic compounds or ions. Ion exchange chromatography of amino acids labelled with tritium, and chromatography of tritium labelled steroids also provided only a certain degree of separation. A detailed analysis is presented of gas chromatography separation of various deuterium and tritium labelled low-molecular compounds, to which a number of studies has been devoted in the literature. Very promising is the method of complexation gas chromatography based on the reversible formation of a complex of the ligand (the compound being separated) and the compound of the (transition) metal as the steady-state phase. (author)

  1. Dual-layer ultrathin film optics: I. Theory and analysis

    International Nuclear Information System (INIS)

    Wang, Qian; Lim, Kim Peng

    2015-01-01

    This paper revisits dual-layer ultrathin film optics, which can be used for functional graded refractive index thin film stack. We present the detailed derivation including s-polarized and p-polarized light under arbitrary incidence angle showing the equivalence between the dual-layer ultrathin films and a negative birefringent thin film and also the approximations made during the derivation. Analysis of the approximations shows the influence of thickness of dual-layer thin films, the incidence angle and desired refractive index of the birefringent film. Numerical comparison between the titanium dioxide/aluminum oxide based dual-layer ultrathin film stack and the equivalent birefringent film verifies the theoretical analysis. The detailed theoretical study and numerical comparison provide a physical insight and design guidelines for dual-layer ultrathin film based optical devices. (paper)

  2. Chromatographic characterisation, in vitro antioxidant and free ...

    African Journals Online (AJOL)

    Chromatographic fractionation and spectroscopic analysis of the ME4 fraction revealed the presence of four compounds namely garcinia biflavonoids GB1 and GB2, garcinal and garcinoic acid. These findings show that these four compounds are partly responsible for the great antioxidant potential of G. kola seeds.

  3. Rapid Analysis Procedures for Triglycerides and Fatty Acids as Pentyl and Phenethyl Esters for the Detection of Butter Adulteration Using Chromatographic Techniques

    Directory of Open Access Journals (Sweden)

    Daniele Naviglio

    2017-01-01

    Full Text Available This paper presents the development of three methods for quality control, fraud detection, and authentication of butter fat and other oils/fats using chromatographic techniques, with one method for triglycerides and two methods for fatty acids (FAs. The procedure for the analysis of triglycerides requires only dissolution of the sample in n-hexane and gas chromatography (GC analysis using a capillary column. The second method is based on the transesterification of triglycerides as pentyl esters in a single-step reaction using sodium pentanoate in pentanol. The reaction proceeds at room temperature and is similar to the potassium hydroxide-catalysed transesterification of triglycerides with methanol and even more similar to the sodium methoxide method and sodium butanoate method. The advantage of using pentyl esters includes reducing the volatility of short-chain FAs, and substantial recoveries were obtained compared with methyl ester analysis. The third method involves the transesterification of triglycerides in fat through reaction with 2-phenylethanol in a single step; 2-phenylethanol possesses a chromophore, and the phenethyl esters formed are analysed by high-performance liquid chromatography (HPLC with UV detection.

  4. Chiral high-performance liquid chromatographic analysis of fluoxetine and norfluoxetine in rabbit plasma, urine, and vitreous humor using an acetylated beta-cyclodextrin column.

    Science.gov (United States)

    Yee, L; Wong, S H; Skrinska, V A

    2000-10-01

    Fluoxetine (Prozac) is a potent selective serotonin reuptake inhibitor used for the treatment of major depression. Both fluoxetine (F) and its demethylated metabolite, norfluoxetine (NF), are racemic. S-Fluoxetine (SF) and S-norfluoxetine (SNF) are more potent inhibitors of serotonin reuptake than R-fluoxetine (RF) and R-norfluoxetine (RNF). Quantitation of individual enantiomers may provide a greater understanding of pharmacokinetic properties. The objective of this study was to perform a limited chiral selectivity study using rabbit plasma, urine, and vitreous humor analyzed by a solid-phase extraction protocol and a newly developed chiral analysis with an acetylated beta-cyclodextrin (CD) column. Liquid chromatographic parameters for CD were as follows: a mobile phase composition of methanol/0.3% triethylamine buffer, pH 5.6, (30:70), a flow rate of 1 mL/min, detection at 214 nm, and a temperature of 40 degrees C. Elution order was SNF, SF, RNF, and RF with capacity factors of 6, 7, 8, and 9, respectively. The corresponding resolution factors were as follows: R1,2 = 0.8, R2,3 = 1.2, and R3,4 = 0.9. The conditions for solid-phase extraction were optimized for Varian Bond Elut Certify columns. Following sample application, the column was rinsed with water, acetic acid, and then with methanol. Drug enantiomers were eluted with methylene chloride, isopropanol, and ammonium hydroxide (78:20:2). After extract evaporation, the extract residue was reconstituted for high-performance liquid chromatographic analysis. To investigate chiral pharmacology, a biodistribution study was performed by administering 2 mg/kg of F to five rabbits. Blood, urine, and vitreous specimens were collected. Plasma samples collected 45 min postinjection showed nearly equal concentrations of RF and SE After 24 h, the only metabolite detected in plasma was RNF. Drugs were not detectable in vitreous humor. Urine concentrations of SNF, SF, RNF, and RF were 51, 76, 34, and 8 microg/L, respectively

  5. Ion beam analysis of aluminium in thin layers

    International Nuclear Information System (INIS)

    Healy, M.J.F.; Pidduck, A.J.; Dollinger, G.; Gorgens, L.; Bergmaier, A.

    2002-01-01

    This work quantifies aluminium in thin surface and near surface layers. In one example, the layer overlies a thin gallium nitride layer on an aluminium oxide substrate and in a second example the aluminium exists just below the surface of an indium arsenide substrate. The technique of non-Rutherford elastic backscattering of protons was used for the samples where aluminum in the layer of interest needed to be resolved from aluminium in the sapphire substrate and the results were corroborated at the Technische Universitaet Muenchen using heavy ion elastic recoil detection analysis. In the second example, where it was unnecessary to isolate the signal of aluminium in the layer of interest (as the substrate contained no aluminium), then the 27 Al(d,p 01 ) 28 Al nuclear reaction was used. The elastic proton scattering cross section of aluminum was found to vary very rapidly over the energy range of interest

  6. Comparison of the phenolic composition of fruit juices by single step gradient HPLC analysis of multiple components versus multiple chromatographic runs optimised for individual families.

    Science.gov (United States)

    Bremner, P D; Blacklock, C J; Paganga, G; Mullen, W; Rice-Evans, C A; Crozier, A

    2000-06-01

    After minimal sample preparation, two different HPLC methodologies, one based on a single gradient reversed-phase HPLC step, the other on multiple HPLC runs each optimised for specific components, were used to investigate the composition of flavonoids and phenolic acids in apple and tomato juices. The principal components in apple juice were identified as chlorogenic acid, phloridzin, caffeic acid and p-coumaric acid. Tomato juice was found to contain chlorogenic acid, caffeic acid, p-coumaric acid, naringenin and rutin. The quantitative estimates of the levels of these compounds, obtained with the two HPLC procedures, were very similar, demonstrating that either method can be used to analyse accurately the phenolic components of apple and tomato juices. Chlorogenic acid in tomato juice was the only component not fully resolved in the single run study and the multiple run analysis prior to enzyme treatment. The single run system of analysis is recommended for the initial investigation of plant phenolics and the multiple run approach for analyses where chromatographic resolution requires improvement.

  7. Analysis of Reaction between α-Lipoic Acid and 2-Chloro-1-methylquinolinium Tetrafluoroborate Used as a Precolumn Derivatization Technique in Chromatographic Determination of α-Lipoic Acid

    Directory of Open Access Journals (Sweden)

    Magdalena Godlewska

    2015-01-01

    Full Text Available The present study offers results of analysis concerning the course of reaction between reduced α-lipoic acid (LA and 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT. In water environments, the reaction between CMQT and hydrophilic thiols proceeds very rapidly and the resultant products are stable. For the described analysis, optimum reaction conditions, such as concentration of the reducing agent, environment pH, and concentration of the reagent were carefully selected. The spectrophotometric assay was carried out measuring absorbance at λ=348 nm (i.e., the spectral band of the obtained reaction product. Furthermore, the calibration curve of lipoic acid was registered. It was concluded that the Lambert-Beer law was observed within the range 1–10 μmol L−1. Later, the reaction between LA and CMQT was used as precolumn derivatization in a chromatographic determination of the lipoic acid in the range 2.5–50 μmol L−1. Practical applicability of the designed methods was evaluated by determining lipoic acid in Revitanerv pharmaceutical preparation which contains 300 mg LA in a single capsule. The error of the determination did not exceed 0.5% in relation to the declared value.

  8. Layer-by-layer and intrinsic analysis of molecular and thermodynamic properties across soft interfaces

    International Nuclear Information System (INIS)

    Sega, Marcello; Fábián, Balázs; Jedlovszky, Pál

    2015-01-01

    Interfaces are ubiquitous objects, whose thermodynamic behavior we only recently started to understand at the microscopic detail. Here, we borrow concepts from the techniques of surface identification and intrinsic analysis, to provide a complementary point of view on the density, stress, energy, and free energy distribution across liquid (“soft”) interfaces by analyzing the respective contributions coming from successive layers

  9. Layer-by-layer and intrinsic analysis of molecular and thermodynamic properties across soft interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sega, Marcello [Computational Physics Group, University of Vienna, Sensengasse 8/9, 1090 Vienna (Austria); Fábián, Balázs [Institut UTINAM (CNRS UMR 6213), Université de Franche-Comté, 16 route de Gray, F-25030 Besançon (France); Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest (Hungary); Jedlovszky, Pál [Laboratory of Interfaces and Nanosize Systems, Institute of Chemistry, Eötvös Loránd University, Pázmány P. Stny 1/A, H-1117 Budapest (Hungary); MTA-BME Research Group of Technical Analytical Chemistry, Szt. Gellért tér 4, H-1111 Budapest (Hungary); Department of Chemistry, EKF, Leányka u. 6, H-3300 Eger (Hungary)

    2015-09-21

    Interfaces are ubiquitous objects, whose thermodynamic behavior we only recently started to understand at the microscopic detail. Here, we borrow concepts from the techniques of surface identification and intrinsic analysis, to provide a complementary point of view on the density, stress, energy, and free energy distribution across liquid (“soft”) interfaces by analyzing the respective contributions coming from successive layers.

  10. Stress Analysis in Polymeric Coating Layer Deposited on Rigid Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Soon Lee [Korea University of Technology and Education, School of Mechatronics Engineering, Chonan (Korea, Republic of)

    2015-08-15

    This paper presents an analysis of thermal stress induced along the interface between a polymeric coating layer and a steel substrate as a result of uniform temperature change. The epoxy layer is assumed to be a linear viscoelastic material and to be theromorheologically simple. The viscoelastic boundary element method is employed to investigate the behavior of interface stresses. The numerical results exhibit relaxation of interface stresses and large stress gradients, which are observed in the vicinity of the free surface. Since the exceedingly large stresses cannot be borne by the polymeric coating layer, local cracking or delamination can occur at the interface corner.

  11. Separation of Berberine Hydrochloride and Tetrahydropalmatine and Their Quantitative Analysis with Thin Layer Chromatography Involved with Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Jing Lu

    2015-01-01

    Full Text Available [BMIM]OH was used in mobile and stationary phase of thin layer chromatography (TLC to analyze berberine hydrochloride and tetrahydropalmatine for the first time. Supported imidazole ionic liquid with hydroxide ion on silica gel (SiO2·Im+·OH− was synthesized through simple procedure and characterized by Fourier transform infrared spectroscopy (FT-IR, elemental analysis, and scanning electron microscope (SEM. Moreover, on the plates prepared by SiO2·Im+·OH−, the contents of the above alkaloids in the Chinese patent medicine (CPM of “Stomacheasy” capsule were successfully determined by TLC scanner. The key conditions and chromatographic behaviors were also investigated in detail. According to similar ways, ionic liquids (ILs also can be used in other planar chromatographies in two modes. This study is expected to be helpful in expanding the application of IL and its bonded silica gel in TLC separation field.

  12. Incorporating high-pressure electroosmotic pump and a nano-flow gradient generator into a miniaturized liquid chromatographic system for peptide analysis.

    Science.gov (United States)

    Chen, Apeng; Lynch, Kyle B; Wang, Xiaochun; Lu, Joann J; Gu, Congying; Liu, Shaorong

    2014-09-24

    We integrate a high-pressure electroosmotic pump (EOP), a nanoflow gradient generator, and a capillary column into a miniaturized liquid chromatographic system that can be directly coupled with a mass spectrometer for proteomic analysis. We have recently developed a low-cost high-pressure EOP capable of generating pressure of tens of thousands psi, ideal for uses in miniaturized HPLC. The pump worked smoothly when it was used for isocratic elutions. When it was used for gradient elutions, generating reproducible gradient profiles was challenging; because the pump rate fluctuated when the pump was used to pump high-content organic solvents. This presents an issue for separating proteins/peptides since high-content organic solvents are often utilized. In this work, we solve this problem by incorporating our high-pressure EOP with a nano-flow gradient generator so that the EOP needs only to pump an aqueous solution. With this combination, we develop a capillary-based nano-HPLC system capable of performing nano-flow gradient elution; the pump rate is stable, and the gradient profiles are reproducible and can be conveniently tuned. To demonstrate its utility, we couple it with either a UV absorbance detector or a mass spectrometer for peptide separations. Copyright © 2014. Published by Elsevier B.V.

  13. Applying Hierarchical Task Analysis Method to Discovery Layer Evaluation

    Directory of Open Access Journals (Sweden)

    Marlen Promann

    2015-03-01

    Full Text Available Libraries are implementing discovery layers to offer better user experiences. While usability tests have been helpful in evaluating the success or failure of implementing discovery layers in the library context, the focus has remained on its relative interface benefits over the traditional federated search. The informal site- and context specific usability tests have offered little to test the rigor of the discovery layers against the user goals, motivations and workflow they have been designed to support. This study proposes hierarchical task analysis (HTA as an important complementary evaluation method to usability testing of discovery layers. Relevant literature is reviewed for the discovery layers and the HTA method. As no previous application of HTA to the evaluation of discovery layers was found, this paper presents the application of HTA as an expert based and workflow centered (e.g. retrieving a relevant book or a journal article method to evaluating discovery layers. Purdue University’s Primo by Ex Libris was used to map eleven use cases as HTA charts. Nielsen’s Goal Composition theory was used as an analytical framework to evaluate the goal carts from two perspectives: a users’ physical interactions (i.e. clicks, and b user’s cognitive steps (i.e. decision points for what to do next. A brief comparison of HTA and usability test findings is offered as a way of conclusion.

  14. Assessment of chromatographic methods for the chemical stability of a new miconazole nitrate cream

    International Nuclear Information System (INIS)

    Garcia Pulpeiro, Oscar; Calzadilla Aguiar, Wendy; Rodriguez Bencomo, Wendy

    2013-01-01

    To assess the chromatographic methods for the chemical stability of a new 2 % miconazol nitrate cream. arious degradation conditions were firstly used in the raw material miconazole nitrate in order to obtain the possible degradation products of this drug and to evaluate them by thin layer chromatography-based method, which was validated to identify the degradation products in the new cream. The performance of the official method based on high resolution liquid chromatography and reported in British Pharmacopoeia 2010 was evaluated, and its selectivity against the possible degradation products were also analyzed. Both chromatographic methods were applied to the analysis of cream samples from the three pilot batches under heat stress for 30 days

  15. Evaluation of advanced gas chromatographs for on-site analysis. Final CRADA report for number Y-1295-0374

    Energy Technology Data Exchange (ETDEWEB)

    Wise, M.B.; Guerin, M.R.; Palausky, A.; Merriweather, R. [Lockheed Martin Energy Research, Oak Ridge, TN (United States); Forsberg, R.E. [Mine Safety Appliances-Baseline Industries, Lyons, CO (United States)

    1997-02-21

    The EKHO gas chromatography (GC) is being marketed by Mine Safety Appliances as an instrument for on-site environmental analysis and for process applications. This GC utilizes a unique bundled capillary column produced in Russia that provides very fast analysis and a wide linear dynamic range. Oak Ridge National Laboratory (ORNL) has been involved in a CRADA with Mine Safety Appliances in order to evaluate the analytical performance of the EKHO GC and is suitability for on-site environmental applications. Tests that were performed at ORNL included the analysis of air, water, and soil samples for aromatic hydrocarbons including benzene, toluene, xylene, and ethylbenzene (BTEX). These compounds were selected in order to simulate contamination by gasoline and other petroleum fuels. Performance factors that were studied included the instrument detection limits, the linearity, dynamic range, and precision for replicate samples. Other factors that were evaluated include the ease of set-up and operation.

  16. Matrix effect and correction by standard addition in quantitative liquid chromatographic-mass spectrometric analysis of diarrhetic shellfish poisoning toxins.

    Science.gov (United States)

    Ito, Shinya; Tsukada, Katsuo

    2002-01-11

    An evaluation of the feasibility of liquid chromatography-mass spectrometry (LC-MS) with atmospheric pressure ionization was made for quantitation of four diarrhetic shellfish poisoning toxins, okadaic acid, dinophysistoxin-1, pectenotoxin-6 and yessotoxin in scallops. When LC-MS was applied to the analysis of scallop extracts, large signal suppressions were observed due to coeluting substances from the column. To compensate for these matrix signal suppressions, the standard addition method was applied. First, the sample was analyzed and then the sample involving the addition of calibration standards is analyzed. Although this method requires two LC-MS runs per analysis, effective correction of quantitative errors was found.

  17. Optimisation and characterisation of silica-based reversed-phase liquid chromatographic systems for the analysis of basic pharmaceuticals

    NARCIS (Netherlands)

    Vervoort, R.J.M.; Debets, A.J.J.; Claessens, H.A.; Cramers, C.A.M.G.; Jong, de G.J.

    2000-01-01

    Reversed-phase liquid chromatography using silica-based columns is successfully applied in many separations. However, also some drawbacks exist, i.e. the analysis of basic compounds is often hampered by ionic interaction of the basic analytes with residual silanols present on the silica surface,

  18. Method for the routine quantitative gas chromatographic analysis of major free fatty acids in butter and cream.

    Science.gov (United States)

    Woo, A H; Lindsay, R C

    1980-07-01

    A rapid quantiative method was developed for routine analysis of the major, even carbon-numbered free fatty acids in butter and cream. Free fatty acids were isolated directly from intact samples by a modified silicic acid-potassium hydroxide arrestant column and were separated by gas chromatography with a 1.8 m x 2 mm inner diameter glass column packed with 10% neopentyl glycol adipate on 80/100 Chromosorb W. Purified, formic acid-saturated carrier gas was required for minimal peak tailing and extended column life. The accuracy and reproducibility of the mmethod was established through quantitative recovery studies of free fatty acid mixtures, free fatty acids added to butter, and replicate analysis of butter and cream samples.

  19. Application of chemometric analysis based on physicochemical and chromatographic data for the differentiation origin of plant protection products containing chlorpyrifos.

    Science.gov (United States)

    Miszczyk, Marek; Płonka, Marlena; Bober, Katarzyna; Dołowy, Małgorzata; Pyka, Alina; Pszczolińska, Klaudia

    2015-01-01

    The aim of this study was to investigate the similarities and dissimilarities between the pesticide samples in form of emulsifiable concentrates (EC) formulation containing chlorpyrifos as active ingredient coming from different sources (i.e., shops and wholesales) and also belonging to various series. The results obtained by the Headspace Gas Chromatography-Mass Spectrometry method and also some selected physicochemical properties of examined pesticides including pH, density, stability, active ingredient and water content in pesticides tested were compared using two chemometric methods. Applicability of simple cluster analysis and also principal component analysis of obtained data in differentiation of examined plant protection products coming from different sources was confirmed. It would be advantageous in the routine control of originality and also in the detection of counterfeit pesticides, respectively, among commercially available pesticides containing chlorpyrifos as an active ingredient.

  20. Quality assessment of raw and processed Arctium lappa L. through multicomponent quantification, chromatographic fingerprint, and related chemometric analysis.

    Science.gov (United States)

    Qin, Kunming; Wang, Bin; Li, Weidong; Cai, Hao; Chen, Danni; Liu, Xiao; Yin, Fangzhou; Cai, Baochang

    2015-05-01

    In traditional Chinese medicine, raw and processed herbs are used to treat different diseases. Suitable quality assessment methods are crucial for the discrimination between raw and processed herbs. The dried fruit of Arctium lappa L. and their processed products are widely used in traditional Chinese medicine, yet their therapeutic effects are different. In this study, a novel strategy using high-performance liquid chromatography and diode array detection coupled with multivariate statistical analysis to rapidly explore raw and processed Arctium lappa L. was proposed and validated. Four main components in a total of 30 batches of raw and processed Fructus Arctii samples were analyzed, and ten characteristic peaks were identified in the fingerprint common pattern. Furthermore, similarity evaluation, principal component analysis, and hierachical cluster analysis were applied to demonstrate the distinction. The results suggested that the relative amounts of the chemical components of raw and processed Fructus Arctii samples are different. This new method has been successfully applied to detect the raw and processed Fructus Arctii in marketed herbal medicinal products. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Quality by Design approach in the development of hydrophilic interaction liquid chromatographic method for the analysis of iohexol and its impurities.

    Science.gov (United States)

    Jovanović, Marko; Rakić, Tijana; Tumpa, Anja; Jančić Stojanović, Biljana

    2015-06-10

    This study presents the development of hydrophilic interaction liquid chromatographic method for the analysis of iohexol, its endo-isomer and three impurities following Quality by Design (QbD) approach. The main objective of the method was to identify the conditions where adequate separation quality in minimal analysis duration could be achieved within a robust region that guarantees the stability of method performance. The relationship between critical process parameters (acetonitrile content in the mobile phase, pH of the water phase and ammonium acetate concentration in the water phase) and critical quality attributes is created applying design of experiments methodology. The defined mathematical models and Monte Carlo simulation are used to evaluate the risk of uncertainty in models prediction and incertitude in adjusting the process parameters and to identify the design space. The borders of the design space are experimentally verified and confirmed that the quality of the method is preserved in this region. Moreover, Plackett-Burman design is applied for experimental robustness testing and method is fully validated to verify the adequacy of selected optimal conditions: the analytical column ZIC HILIC (100 mm × 4.6 mm, 5 μm particle size); mobile phase consisted of acetonitrile-water phase (72 mM ammonium acetate, pH adjusted to 6.5 with glacial acetic acid) (86.7:13.3) v/v; column temperature 25 °C, mobile phase flow rate 1 mL min(-1), wavelength of detection 254 nm. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Analysis of anti-neoplastic drug in bacterial ghost matrix, w/o/w double nanoemulsion and w/o nanoemulsion by a validated 'green' liquid chromatographic method.

    Science.gov (United States)

    Youssof, Abdullah M E; Salem-Bekhit, Mounir M; Shakeel, Faiyaz; Alanazi, Fars K; Haq, Nazrul

    2016-07-01

    The objective of the present investigation was to develop and validate a 'green' reversed phase high-performance liquid chromatography (RP-HPLC) method for rapid analysis of a cytotoxic drug 5-fluorouracil (5-FU) in bulk drug, marketed injection, water-in-oil (w/o) nanoemulsion, double water-in-oil-in-water (w/o/w) nanoemulsion and bacterial ghost (BG) matrix. The chromatography study was carried out at room temperature (25±1°C) using an HPLC system with the help of ultraviolet (UV)-visible detector. The chromatographic performance was achieved with a Nucleodur 150mm×4.6mm RP C8 column filled with 5µm filler as a static phase. The mobile phase consisted of ethyl acetate: methanol (7:3% v/v) which was delivered at a flow rate of 1.0mLmin(-1) and the drug was detected in UV mode at 254nm. The developed method was validated in terms of linearity (r(2)=0.998), accuracy (98.19-102.09%), precision (% RSD=0.58-1.17), robustness (% RSD=0.12-0.53) and sensitivity with satisfactory results. The efficiency of the method was demonstrated by the assay of the drug in marketed injection, w/o nanoemulsion, w/o/w nanoemulsion and BG with satisfactory results. The successful resolution of the drug along with its degradation products clearly established the stability-indicating nature of the proposed method. Overall, these results suggested that the proposed analytical method could be effectively applied to the routine analysis of 5-FU in bulk drug, various pharmaceutical dosage forms and BG. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Direct coupling of a liquid chromatograph to a continuous flow hydrogen nuclear magnetic resonance detector for analysis of petroleum and synthetic fuels

    International Nuclear Information System (INIS)

    Haw, J.F.; Glass, T.E.; Hausler, D.W.; Motell, E.; Dorn, H.C.

    1980-01-01

    Initial results obtained for a flow 1 H nuclear magnetic resonance (NMR) detector directly coupled to a liquid chromatography unit are described. Results achieved for a model mixture and several jet fuel samples are discussed. Chromatographic separation of alkanes, alkylbenzenes, and substituted naphthalenes present in the jet fuel samples are easily identified with the 1 H NMR detector. Results with our present flow 1 H NMR insert indicate that 5-Hz linewidths are readily obtainable for typical chromatographic flow rates. The limitations and advantages of this liquid chromatography detector are compared with more commonly employed detectors (e.g., refractive index detectors). 11 figures

  4. Isolation and identification of phytoestrogens and flavonoids in an Ayurvedic proprietary medicine using chromatographic and Mass Spectroscopic analysis

    Institute of Scientific and Technical Information of China (English)

    Sulaiman CT; Arun A; Anandan EM; Sandhya CR; Indira Balachandran

    2015-01-01

    Objective: To develop analytical methods for the isolation and structural identification of poly phenols including phytoestrogens in Mensokot tablet, a herbal proprietary medicine. Methods:Isolation consisted of an ultrasound-assisted extraction, followed by acid hydrolysis and a final liquid-liquid extraction step in diethyl ether. Identification and structural characterisation was done by liquid chromatography coupled with Q-TOF-ESI-MS/MS analysis. Results:Phytoestrogens such as Coumestrol, Genistein and Glycitein have been identified in Mensokot tablet along with several other flavonoids. Conclusion: In the present research, a rapid HPLC-MS/MS method has been developed for the identification of phytoestrogens and other flavonoids from an Ayurvedic proprietary medicine. Phytoestrogens are considered to play an important role in the prevention of cancers, heart disease, menopausal symptoms and osteoporosis.

  5. Development and validation of a rapid chromatographic method for the analysis of flunarizine and its main production impurities

    Directory of Open Access Journals (Sweden)

    Niamh O’Connor

    2013-06-01

    Full Text Available A rapid selective method for the analysis of flunarizine and its associated impurities was developed and validated according to ICH guidelines. The separation was carried out using a Thermo Scientific Hypersil Gold C18 column (50mm×4.6mm i.d., 1.9μm particle size with a gradient mobile phase of acetonitrile–ammonium acetate–tetrabutylammoniumhydrogen sulfate buffer, at a flow rate of 1.8mL/min and UV detection at 230nm. Naturally aged samples were also tested to determine sample stability. A profile of sample and impurity breakdown was also presented. Keywords: Flunarizine, Sub 2μm column, Active pharmaceutical ingredient, HPLC

  6. Pesticide residues in canned foods, fruits, and vegetables: the application of Supercritical Fluid Extraction and chromatographic techniques in the analysis.

    Science.gov (United States)

    El-Saeid, Mohamed H

    2003-12-11

    Multiple pesticide residues have been observed in some samples of canned foods, frozen vegetables, and fruit jam, which put the health of the consumers at risk of adverse effects. It is quite apparent that such a state of affairs calls for the need of more accurate, cost-effective, and rapid analytical techniques capable of detecting the minimum concentrations of the multiple pesticide residues. The aims of this paper were first, to determine the effectiveness of the use of Supercritical Fluid Extraction (SFE) and Supercritical Fluid Chromatography (SFC) techniques in the analysis of the levels of pesticide residues in canned foods, vegetables, and fruits; and second, to contribute to the promotion of consumer safety by excluding pesticide residue contamination from markets. Fifteen different types of imported canned and frozen fruits and vegetables samples obtained from the Houston local food markets were investigated. The major types of pesticides tested were pyrethroids, herbicides, fungicides, and carbamates. By using these techniques, the overall data showed 60.82% of the food samples had no detection of any pesticide residues under this investigation. On the other hand, 39.15% different food samples were contaminated by four different pyrethroid residues +/- RSD% ranging from 0.03 +/- 0.005 to 0.05 +/- 0.03 ppm, of which most of the pyrethroid residues were detected in frozen vegetables and strawberry jam. Herbicide residues in test samples ranged from 0.03 +/- 0.005 to 0.8 +/- 0.01 ppm. Five different fungicides, ranging from 0.05 +/- 0.02 to 0.8 +/- 0.1 ppm, were found in five different frozen vegetable samples. Carbamate residues were not detected in 60% of investigated food samples. It was concluded that SFE and SFC techniques were accurate, reliable, less time consuming, and cost effective in the analysis of imported canned foods, fruits, and vegetables and are recommended for the monitoring of pesticide contaminations.

  7. Pesticide Residues in Canned Foods, Fruits, and Vegetables: The Application of Supercritical Fluid Extraction and Chromatographic Techniques in the Analysis

    Directory of Open Access Journals (Sweden)

    Mohamed H. EL-Saeid

    2003-01-01

    Full Text Available Multiple pesticide residues have been observed in some samples of canned foods, frozen vegetables, and fruit jam, which put the health of the consumers at risk of adverse effects. It is quite apparent that such a state of affairs calls for the need of more accurate, cost-effective, and rapid analytical techniques capable of detecting the minimum concentrations of the multiple pesticide residues. The aims of this paper were first, to determine the effectiveness of the use of Supercritical Fluid Extraction (SFE and Supercritical Fluid Chromatography (SFC techniques in the analysis of the levels of pesticide residues in canned foods, vegetables, and fruits; and second, to contribute to the promotion of consumer safety by excluding pesticide residue contamination from markets. Fifteen different types of imported canned and frozen fruits and vegetables samples obtained from the Houston local food markets were investigated. The major types of pesticides tested were pyrethroids, herbicides, fungicides, and carbamates.By using these techniques, the overall data showed 60.82% of the food samples had no detection of any pesticide residues under this investigation. On the other hand, 39.15% different food samples were contaminated by four different pyrethroid residues ± RSD% ranging from 0.03 ± 0.005 to 0.05 ± 0.03 ppm, of which most of the pyrethroid residues were detected in frozen vegetables and strawberry jam. Herbicide residues in test samples ranged from 0.03 ± 0.005 to 0.8 ± 0.01 ppm. Five different fungicides, ranging from 0.05 ± 0.02 to 0.8 ±0.1 ppm, were found in five different frozen vegetable samples. Carbamate residues were not detected in 60% of investigated food samples. It was concluded that SFE and SFC techniques were accurate, reliable, less time consuming, and cost effective in the analysis of imported canned foods, fruits, and vegetables and are recommended for the monitoring of pesticide contaminations.

  8. Conserved variable analysis of the marine boundary layer and air

    Indian Academy of Sciences (India)

    The present study is based on the observed features of the MBL (Marine Boundary Layer) during the Bay of Bengal and Monsoon Experiment (BOBMEX) - Pilot phase. Conserved Variable Analysis (CVA) of the conserved variables such as potential temperature, virtual potential temperature, equivalent potential temperature ...

  9. Surface reactivity and layer analysis of chemisorbed reaction films in ...

    Indian Academy of Sciences (India)

    Administrator

    Surface reactivity and layer analysis of chemisorbed reaction films in ... in the nitrogen environment. Keywords. Surface reactivity ... sium (Na–K) compounds in the coating or core of the ..... Barkshire I R, Pruton M and Smith G C 1995 Appl. Sur.

  10. Sloshing analysis of tanks containing multiple fluid layers

    International Nuclear Information System (INIS)

    Uras, R.A.; Tang, Yu.

    1994-01-01

    The effect of liquid density changes in high level radioactive liquid waste storage tanks is studied. The density variations with the liquid depth is modeled by layers of piece wise constant densities. A computational formulation based on the finite element method is presented. The computer code FLUSTR-ANL has been modified for the analysis of the sloshing response under seismic excitation

  11. Development and validation of reversed-phase high performance liquid chromatographic method for analysis of cephradine in human plasma samples

    International Nuclear Information System (INIS)

    Ahmad, M.; Usman, M.; Madni, A.; Akhtar, N.; Khalid, N.; Asghar, W.

    2010-01-01

    An HPLC method with high precision, accuracy and selectivity was developed and validated for the assessment of cephradine in human plasma samples. The extraction procedure was simple and accurate with single step followed by direct injection of sample into HPLC system. The extracted cephradine in spiked human plasma was separated and quantitated using reversed phase C/sub 18/ column and UV detection wavelength of 254 nm. The optimized mobile phase of new composition of 0.05 M potassium dihydrogen phosphate (pH 3.4)-acetonitrile (88: 12) was pumped at an optimum flow rate of 1 mL.min/sup 1/. The method resulted linearity in the concentration range 0.15- 20 micro g mL/sup -1/. The limit of detection (LOD) and limit of quantification (LOQ) were 0.05 and 0.150 Microg.mL/sup -1/, respectively. The accuracy of method was 98.68 %. This method can 1>e applied for bioequivalence studies and therapeutic drug monitoring as well as for the routine analysis of cephradine. (author)

  12. Simultaneous high performance liquid chromatographic analysis of vitamins B1, B2 and B6 in royal jelly

    Directory of Open Access Journals (Sweden)

    Presoto Ana Elisa F

    2004-01-01

    Full Text Available Royal jelly is used as a food supplement, popularly known as rich in B vitamins. The present work has two objectives: firstly, to apply simultaneous quantitative determination by High Performance Liquid Chromatography of thiamin (vitamin B1, riboflavin (vitamin B2 and pyridoxine (vitamin B6 and secondly to compare the obtained data with the Dietary Reference Intake (DRI values. The values obtained showed no thiamin, a range from 20 to 171 ng g-1 of riboflavin and from 408 to 2 188 ng g-1 of pyridoxine in royal jelly. According to the Food and Nutrition Board (2000, the DRI of these vitamins varies from 0.2-1.4 mg for thiamin; 0.3-1.6 mg for riboflavin and 0.1-2.0 mg for pyridoxine, depending on age and sex. According to these recommendations, royal jelly is not a good source of vitamins B1, B2 or B6 as these vitamins appear only on order of ng g-1. The proposed method can be used in routine analysis for royal jelly, having the advantage of being simple, fast and reliable.

  13. Application of Chromatographic and Electrophoretic Methods for the Analysis of Imidazolium and Pyridinium Cations as Used in Ionic Liquids

    Directory of Open Access Journals (Sweden)

    P. Stepnowski

    2006-11-01

    Full Text Available Interest in ionic liquids for their potential in different chemical processes isconstantly increasing, as they are claimed to be environmentally benign – excellent, non-volatile solvents for a wide range of applications. The wide applicability of thesecompounds also demands reliable, relatively simple and reproducible analytical techniques.These methods must be applicable not only to different technical or natural matrices but alsoto the very low concentrations that are likely to be present in biological and environmentalsystems. In this review, therefore, methods for separating and analysing imidazolium- andpyridinium-type ionic liquids in aqueous matrices using high performance liquidchromatography (HPLC and capillary electrophoresis (CE are examined. The techniquesfor identifying ionic liquids are meant primarily to track the concentrations of ionic liquidsas residues not only in products and wastes but also in biological or environmental samples.The application of hyphenated techniques in this field is intended to selectively separate thequaternary entity from other cationic and non-ionic species present in the matrix, and toenable its fine-scale quantification. Nowadays, methods developed for cation analysis arebased mostly on reversed-phase high-performance liquid chromatography, ionchromatography, ion-pair chromatography and capillary electrophoresis, where variousbuffered mobile phases are used.

  14. Non-chromatographic speciation analysis of mercury by flow injection on-line preconcentration in combination with chemical vapor generation atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Wu Hong [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China); Department of Chemistry, Xuzhou Normal University, Xuzhou 221116 (China); Jin Yan [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China); Han Weiying [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China); Miao, Qiang [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China); Bi Shuping [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China)]. E-mail: bisp@nju.edu.cn

    2006-07-15

    A novel non-chromatographic approach for direct speciation of mercury, based on the selective retention inorganic mercury and methylmercury on the inner wall of a knotted reactor by using ammonium diethyl dithiophosphate and dithizone as complexing agents respectively, was developed for flow injection on-line sorption preconcentration coupled with chemical vapor generation non-dispersive atomic fluorescence spectrometry. With the sample pH kept at 2.0, the preconcentration of inorganic mercury on the inner walls of the knotted reactor was carried out based on the exclusive retention of Hg-DDP complex in the presence of methylmercury via on-line merging the sample solution with ammonium diethyl dithiophosphate solution, and selective preconcentration methylmercury was achieved with dithizone instead of ammonium diethyl dithiophosphate. A 15% (v/v) HCl was introduced to elute the retained mercury species and merge with KBH{sub 4} solution for atomic fluorescence spectrometry detection. Under the optimal experimental conditions, the sample throughputs of inorganic mercury and methylmercury were 30 and 20 h{sup -1} with the enhancement factors of 13 and 24. The detection limits were found to be 3.6 ng l{sup -1} for Hg{sup 2+} and 2.0 ng l{sup -1} for CH{sub 3}Hg{sup +}. The precisions (RSD) for the 11 replicate measurements of each 0.2 {mu}g l{sup -1} of Hg{sup 2+} and CH{sub 3}Hg{sup +} were 2.2% and 2.8%, respectively. The developed method was validated by the analysis of certified reference materials (simulated natural water, rice flour and pork) and by recovery measurements on spiked samples, and was applied to the determination of inorganic mercury and methylmercury in biological and environmental water samples.

  15. Non-chromatographic screening procedure for arsenic speciation analysis in fish-based baby foods by using electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Garcia, Ignacio; Briceno, Marisol [Department of Analytical Chemistry, Faculty of Chemistry, University of Murcia, E-30071 Murcia (Spain); Hernandez-Cordoba, Manuel, E-mail: hcordoba@um.es [Department of Analytical Chemistry, Faculty of Chemistry, University of Murcia, E-30071 Murcia (Spain)

    2011-08-05

    Highlights: {yields} Arsenic in fish-based food samples can be determined without the need of a dissolution stage. {yields} Speciation of the main forms of arsenic in fish-based baby foods does not require chromatography. {yields} The behavior of arsenic compounds in ETAAS strongly depends on the chemical modifier used. - Abstract: A procedure for the speciation analysis of arsenic in fish-based baby foods is presented. Inorganic arsenic, methylarsonic acid (MA), dimethylarsinic acid (DMA) and arsenobetaine (AB) were determined by electrothermal atomic absorption spectrometry (ETAAS) using suspensions prepared in a 0.01 mol L{sup -1} tetramethylammonium hydroxide (TMAH) solution. Speciation is based on the use of three different chemically modified ETAAS atomizers to obtain the analytical signals. Using a palladium salt as the chemical modifier, the signal corresponding to the total arsenic concentration is obtained. When palladium is replaced by Ce(IV), the signal is solely due to inorganic arsenic (III and V) + MA. If no signal is obtained in this latter case, it is possible to distinguish between DMA and AB using a zirconium coated atomizer. The signal obtained in this way is due solely to DMA, and the concentration of AB can be obtained by the difference with the total arsenic content. Determinations by ETAAS require the use of the standard additions method. The limits of detection for the determination of AB, DMA and inorganic arsenic (+MA) are 15, 25 and 50 ng g{sup -1} expressed as arsenic, respectively. These detection limits are good enough for the procedure to be appropriate for the rapid determination of these compounds, avoiding extraction processes and/or chromatographic separations. Data for commercial samples, as well as for four standard reference materials, are given.

  16. Non-chromatographic screening procedure for arsenic speciation analysis in fish-based baby foods by using electrothermal atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Lopez-Garcia, Ignacio; Briceno, Marisol; Hernandez-Cordoba, Manuel

    2011-01-01

    Highlights: → Arsenic in fish-based food samples can be determined without the need of a dissolution stage. → Speciation of the main forms of arsenic in fish-based baby foods does not require chromatography. → The behavior of arsenic compounds in ETAAS strongly depends on the chemical modifier used. - Abstract: A procedure for the speciation analysis of arsenic in fish-based baby foods is presented. Inorganic arsenic, methylarsonic acid (MA), dimethylarsinic acid (DMA) and arsenobetaine (AB) were determined by electrothermal atomic absorption spectrometry (ETAAS) using suspensions prepared in a 0.01 mol L -1 tetramethylammonium hydroxide (TMAH) solution. Speciation is based on the use of three different chemically modified ETAAS atomizers to obtain the analytical signals. Using a palladium salt as the chemical modifier, the signal corresponding to the total arsenic concentration is obtained. When palladium is replaced by Ce(IV), the signal is solely due to inorganic arsenic (III and V) + MA. If no signal is obtained in this latter case, it is possible to distinguish between DMA and AB using a zirconium coated atomizer. The signal obtained in this way is due solely to DMA, and the concentration of AB can be obtained by the difference with the total arsenic content. Determinations by ETAAS require the use of the standard additions method. The limits of detection for the determination of AB, DMA and inorganic arsenic (+MA) are 15, 25 and 50 ng g -1 expressed as arsenic, respectively. These detection limits are good enough for the procedure to be appropriate for the rapid determination of these compounds, avoiding extraction processes and/or chromatographic separations. Data for commercial samples, as well as for four standard reference materials, are given.

  17. Non-chromatographic speciation analysis of mercury by flow injection on-line preconcentration in combination with chemical vapor generation atomic fluorescence spectrometry

    International Nuclear Information System (INIS)

    Wu Hong; Jin Yan; Han Weiying; Miao, Qiang; Bi Shuping

    2006-01-01

    A novel non-chromatographic approach for direct speciation of mercury, based on the selective retention inorganic mercury and methylmercury on the inner wall of a knotted reactor by using ammonium diethyl dithiophosphate and dithizone as complexing agents respectively, was developed for flow injection on-line sorption preconcentration coupled with chemical vapor generation non-dispersive atomic fluorescence spectrometry. With the sample pH kept at 2.0, the preconcentration of inorganic mercury on the inner walls of the knotted reactor was carried out based on the exclusive retention of Hg-DDP complex in the presence of methylmercury via on-line merging the sample solution with ammonium diethyl dithiophosphate solution, and selective preconcentration methylmercury was achieved with dithizone instead of ammonium diethyl dithiophosphate. A 15% (v/v) HCl was introduced to elute the retained mercury species and merge with KBH 4 solution for atomic fluorescence spectrometry detection. Under the optimal experimental conditions, the sample throughputs of inorganic mercury and methylmercury were 30 and 20 h -1 with the enhancement factors of 13 and 24. The detection limits were found to be 3.6 ng l -1 for Hg 2+ and 2.0 ng l -1 for CH 3 Hg + . The precisions (RSD) for the 11 replicate measurements of each 0.2 μg l -1 of Hg 2+ and CH 3 Hg + were 2.2% and 2.8%, respectively. The developed method was validated by the analysis of certified reference materials (simulated natural water, rice flour and pork) and by recovery measurements on spiked samples, and was applied to the determination of inorganic mercury and methylmercury in biological and environmental water samples

  18. Development and validation of a dissolution test with reversed-phase high performance liquid chromatographic analysis for Candesartan cilexetil in tablet dosage forms

    Directory of Open Access Journals (Sweden)

    Vairappan Kamalakkannan

    2016-09-01

    Full Text Available A simple, rapid, selective and reproducible reversed-phase high performance liquid chromatographic (RP-HPLC method has been developed and validated for the estimation of release of Candesartan cilexetil (CC in tablets. Analysis was performed on an Agilent, Zorbax C8 column (150mm × 4.6mm, 5μm with the mobile phase consisting of phosphate buffer (pH2.5–acetonitrile (15:85, v/v at a flow rate of 1.0mL/min. UV detection was performed at 215nm and the retention time for CC was 2.2. The calibration curve was linear (correlation coefficient = 1.000 in the selected range of analyte. The optimized dissolution conditions include the USP apparatus 2 at a paddle rotation rate of 50rpm and 900mL of phosphate buffer (pH7.2 with 0.03% of polysorbate 80 as dissolution medium, at 37.0 ± 0.5°C. The method was validated for precision, linearity, specificity, accuracy, limit of quantitation and ruggedness. The system suitability parameters, such as theoretical plate, tailing factor and relative standard deviation (RSD between six standard replicates were well within the limits. The stability result shows that the drug is stable in the prescribed dissolution medium. Three different batches (A, B and C of the formulation containing 8mg of Candesartan cilexetil was performed with the developed method and the results showed no significant differences among the batches.

  19. Two-step microextraction combined with high performance liquid chromatographic analysis of pyrethroids in water and vegetable samples.

    Science.gov (United States)

    Mukdasai, Siriboon; Thomas, Chunpen; Srijaranai, Supalax

    2014-03-01

    Dispersive liquid microextraction (DLME) combined with dispersive µ-solid phase extraction (D-µ-SPE) has been developed as a new approach for the extraction of four pyrethroids (tetramethrin, fenpropathrin, deltamethrin and permethrin) prior to the analysis by high performance liquid chromatography (HPLC) with UV detection. 1-Octanol was used as the extraction solvent in DLME. Magnetic nanoparticles (Fe3O4) functionalized with 3-aminopropyl triethoxysilane (APTS) were used as the dispersive in DLME and as the adsorbent in D-µ-SPE. The extracted pyrethroids were separated within 30 min using isocratic elution with acetonitrile:water (72:28). The factors affecting the extraction efficiency were investigated. Under the optimum conditions, the enrichment factors were in the range of 51-108. Linearity was obtained in the range 0.5-400 ng mL(-1) (tetramethrin) and 5-400 ng mL(-1) (fenpropathrin, deltamethrin and permethrin) with the correlation coefficients (R(2)) greater than 0.995. Detection limits were 0.05-2 ng mL(-1) (water samples) and 0.02-2.0 ng g(-1) (vegetable samples). The relative standard deviations of peak area varied from 1.8 to 2.5% (n=10). The extraction recoveries of the four pyrethroids in field water and vegetable samples were 91.7-104.5%. The proposed method has high potential for use as a sensitive method for determination of pyrethroid residues in water and vegetable samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Validation for chromatographic and electrophoretic methods

    OpenAIRE

    Ribani, Marcelo; Bottoli, Carla Beatriz Grespan; Collins, Carol H.; Jardim, Isabel Cristina Sales Fontes; Melo, Lúcio Flávio Costa

    2004-01-01

    The validation of an analytical method is fundamental to implementing a quality control system in any analytical laboratory. As the separation techniques, GC, HPLC and CE, are often the principal tools used in such determinations, procedure validation is a necessity. The objective of this review is to describe the main aspects of validation in chromatographic and electrophoretic analysis, showing, in a general way, the similarities and differences between the guidelines established by the dif...

  1. Gas chromatographic-mass spectrometric analysis of biomarkers related to folate and cobalamin status in human serum after dimercaptopropanesulfonate reduction and heptafluorobutyl chloroformate derivatization

    Czech Academy of Sciences Publication Activity Database

    Šimek, Petr; Hušek, Petr; Zahradníčková, Helena

    2008-01-01

    Roč. 80, č. 15 (2008), s. 5776-5782 ISSN 0003-2700 R&D Projects: GA ČR GA303/06/1674 Institutional research plan: CEZ:AV0Z50070508 Keywords : biomarkers * gas chromatographic * chloroformate derivatization Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 5.712, year: 2008

  2. Vibrational analysis of single-layered graphene sheets

    Energy Technology Data Exchange (ETDEWEB)

    Sakhaee-Pour, A; Ahmadian, M T [Center of Excellence in Design, Robotics and Automation (CEDRA), Department of Mechanical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Naghdabadi, R [Department of Mechanical Engineering and Institute for Nano Science and Technology, Sharif University of Technology, Tehran (Iran, Islamic Republic of)], E-mail: sakhaee@alum.sharif.edu, E-mail: naghdabd@sharif.edu

    2008-02-27

    A molecular structural mechanics method has been implemented to investigate the vibrational behavior of single-layered graphene sheets. By adopting this approach, mode shapes and natural frequencies are obtained. Vibrational analysis is performed with different chirality and boundary conditions. Numerical results from the atomistic modeling are employed to develop predictive equations via a statistical nonlinear regression model. With the proposed equations, fundamental frequencies of single-layered graphene sheets with considered boundary conditions can be predicted within 3% difference with respect to the atomistic simulation.

  3. Study of matrix effects on the direct trace analysis of acidic pesticides in water using various liquid chromatographic modes coupled to tandem mass spectrometric detection.

    Science.gov (United States)

    Dijkman, E; Mooibroek, D; Hoogerbrugge, R; Hogendoorn, E; Sancho, J V; Pozo, O; Hernández, F

    2001-08-10

    This study investigated the effects of matrix interferences on the analytical performance of a triple quadrupole mass spectrometric (MS-MS) detector coupled to various reversed-phase liquid chromatographic (LC) modes for the on-line determination of various types of acidic herbicides in water using external calibration for quantification of the analytes tested at a level of 0.4 microg/l. The LC modes included (i) a single-column configuration (LC), (ii) precolumn switching (PC-LC) and (iii) coupled-column LC (LC-LC). As regards detection, electrospray (ESI) and atmospheric pressure chemical ionization (APCI) in both positive (PI) and negative (NI) ionization modes were examined. Salinity and dissolved organic carbon (DOC) were selected as interferences to study matrix effects in this type of analysis. Therefore, Milli-Q and tap water samples both fortified with 12 mg/l DOC and spiked with sulfometuron-methyl, bentazone, bromoxynil, 2-methyl-4-chlorophenoxyacetic acid, and 2-methyl-4-chlorophenoxypropionic acid at a level of about 0.4 microg/l were analyzed with the various LC-MS approaches. Direct sample injection was performed with volumes of 0.25 ml or 2.0 ml on a column of 2.1 mm I.D. or 4.6 mm I.D. for the ESI and APCI modes, respectively. The recovery data were used to compare and evaluate the analytical performance of the various LC approaches. As regards matrix effects, the salinity provided a dramatic decrease in response for early eluting analytes (k value of about 1) when using the LC mode. Both PC-LC and LC-LC efficiently eliminated this problem. The high DOC content hardly effected the responses of analytes in the ESI mode, while in most cases the responses increased when using APCI-MS-MS detection. Of all the tested configurations, LC-LC-ESI-MS-MS with the column combination Discovery C18/ABZ+ was the most favorable as regards elimination of matrix effects and provided reliable quantification of all compounds using external calibration at the tested

  4. Use of graphite layer open tubular (GLOT) in environmental analysis

    International Nuclear Information System (INIS)

    Bruner, F.; Lattanzi, L.; Borghesi, P.

    1996-01-01

    Recently it has been developed a series of new capillary columns characterised by the use of graphitized carbon black modified from different amount of liquid phase. The characteristics of these columns, called graphite layer open tubular (GLOT), are described together with their application to the environmental analysis. A specific application of GLOT columns is for the direct analysis of aqueous solutions avoiding solvent extraction procedure. A comparison between a GLOT column and a traditional capillary column, estimating their behaviour after repeated direct injections of aqueous solution sample is written. Some applications regarding the analysis of the atmosphere pollutants, as aliphatic and aromatic hydrocarbons, and their compounds are written too

  5. An aircraft gas chromatograph-mass spectrometer System for Organic Fast Identification Analysis (SOFIA): design, performance and a case study of Asian monsoon pollution outflow

    Science.gov (United States)

    Bourtsoukidis, Efstratios; Helleis, Frank; Tomsche, Laura; Fischer, Horst; Hofmann, Rolf; Lelieveld, Jos; Williams, Jonathan

    2017-12-01

    Volatile organic compounds (VOCs) are important for global air quality and oxidation processes in the troposphere. In addition to ground-based measurements, the chemical evolution of such species during transport can be studied by performing in situ airborne measurements. Generally, aircraft instrumentation needs to be sensitive, robust and sample at higher frequency than ground-based systems while their construction must comply with rigorous mechanical and electrical safety standards. Here, we present a new System for Organic Fast Identification Analysis (SOFIA), which is a custom-built fast gas chromatography-mass spectrometry (GC-MS) system with a time resolution of 2-3 min and the ability to quantify atmospheric mixing ratios of halocarbons (e.g. chloromethanes), hydrocarbons (e.g isoprene), oxygenated VOCs (acetone, propanal, butanone) and aromatics (e.g. benzene, toluene) from sub-ppt to ppb levels. The relatively high time resolution is the result of a novel cryogenic pre-concentration unit which rapidly cools (˜ 6 °C s-1) the sample enrichment traps to -140 °C, and a new chromatographic oven designed for rapid cooling rates (˜ 30 °C s-1) and subsequent thermal stabilization. SOFIA was installed in the High Altitude and Long Range Research Aircraft (HALO) for the Oxidation Mechanism Observations (OMO) campaign in August 2015, aimed at investigating the Asian monsoon pollution outflow in the tropical upper troposphere. In addition to a comprehensive instrument characterization we present an example monsoon plume crossing flight as a case study to demonstrate the instrument capability. Hydrocarbon, halocarbon and oxygenated VOC data from SOFIA are compared with mixing ratios of carbon monoxide (CO) and methane (CH4), used to define the pollution plume. By using excess (ExMR) and normalized excess mixing ratios (NEMRs) the pollution could be attributed to two air masses of distinctly different origin, identified by back-trajectory analysis. This work

  6. Multiplex real-time quantitative PCR, microscopy and rapid diagnostic immuno-chromatographic tests for the detection of Plasmodium spp: performance, limit of detection analysis and quality assurance

    Directory of Open Access Journals (Sweden)

    Ralevski Filip

    2009-12-01

    Full Text Available Abstract Background Accurate laboratory diagnosis of malaria species in returning travelers is paramount in the treatment of this potentially fatal infectious disease. Materials and methods A total of 466 blood specimens from returning travelers to Africa, Asia, and South/Central America with suspected malaria infection were collected between 2007 and 2009 at the reference public health laboratory. These specimens were assessed by reference microscopy, multipex real-time quantitative polymerase chain reaction (QPCR, and two rapid diagnostic immuno-chromatographic tests (ICT in a blinded manner. Key clinical laboratory parameters such as limit of detection (LOD analysis on clinical specimens by parasite stage, inter-reader variability of ICTs, staffing implications, quality assurance and cost analysis were evaluated. Results QPCR is the most analytically sensitive method (sensitivity 99.41%, followed by CARESTART (sensitivity 88.24%, and BINAXNOW (sensitivity 86.47% for the diagnosis of malaria in returning travelers when compared to reference microscopy. However, microscopy was unable to specifically identify Plasmodia spp. in 18 out of 170 positive samples by QPCR. Moreover, the 17 samples that were negative by microscopy and positive by QPCR were also positive by ICTs. Quality assurance was achieved for QPCR by exchanging a blinded proficiency panel with another reference laboratory. The Kappa value of inter-reader variability among three readers for BINAXNOW and CARESTART was calculated to be 0.872 and 0.898 respectively. Serial dilution studies demonstrated that the QPCR cycle threshold correlates linearly with parasitemia (R2 = 0.9746 in a clinically relevant dynamic range and retains a LOD of 11 rDNA copies/μl for P. falciparum, which was several log lower than reference microscopy and ICTs. LOD for QPCR is affected not only by parasitemia but the parasite stage distribution of each clinical specimen. QPCR was approximately 6-fold more

  7. Evaluation of pesticide adsorption in gas chromatographic injector and column

    Directory of Open Access Journals (Sweden)

    Gevany Paulino de Pinho

    2012-01-01

    Full Text Available Components in complex matrices can cause variations in chromatographic response during analysis of pesticides by gas chromatography. These variations are related to the competition between analytes and matrix components for adsorption sites in the chromatographic system. The capacity of the pesticides chlorpyrifos and deltamethrin to be adsorbed in the injector and chromatographic column was evaluated by constructing three isotherms and changing the column heating rate to 10 and 30 ºC min-1. By using ANCOVA to compare the slope of calibration graphs, results showed that the higher the injector temperature (310 ºC the lower the pesticide adsorption. Also, deltamethrin influenced the adsorption of chlorpyrifos on the column chromatographic.

  8. Preparation and evaluation of 99mTc-cefuroxime, a potential infection specific imaging agent: A reliable thin layer chromatographic system to delineate impurities from the 99mTc-antibiotic

    International Nuclear Information System (INIS)

    Chattopadhyay, Sankha; Ghosh, Mayuri; Sett, Sucharita; Das, Malay Kanti; Chandra, Susmita; De, Kakali; Mishra, Mridula; Sinha, Samarendu; Ranjan Sarkar, Bharat; Ganguly, Shantanu

    2012-01-01

    Technetium-99m labelled cefuroxime, a second-generation cephalosporin antibiotic and potential bacteria specific infection imaging agent was evaluated. A good radiochemical purity (95%) of the labelled product was obtained after filtering the reaction mixture through a 0.22 μm filter. Scintigraphy study of the purified product showed uptake in infectious lesions 45 min after injection and abscess-to-muscle ratios were found to be 1.80, 1.85 and 1.88 at 45 min, 1.5 hr and 3 hr, respectively. A versatile and reliable chromatographic technique to assess the radiochemical purity of 99m Tc-cefuroxime has also been described. - Highlights: ► Preparation of 99m Tc-cefuroxime in presence of Sn-tartrate as reducing agent. ► Physiochemical and biological evaluation of 99m Tc-cefuroxime. ► A versatile and reliable chromatographic technique to assess the radiochemical purity of 99m Tc-cefuroxime.

  9. Assessment of the chromatographic lipophilicity of eight cephalosporins on different stationary phases.

    Science.gov (United States)

    Dąbrowska, Monika; Starek, Małgorzata; Komsta, Łukasz; Szafrański, Przemysław; Stasiewicz-Urban, Anna; Opoka, Włodzimierz

    2017-04-01

    The retention behaviors were investigated for a series of eight cephalosporins in thin-layer chromatography (TLC) using stationary phases of RP-2, RP-8, RP-18, NH 2 , DIOL, and CN chemically bonded silica gel. Additionally, various binary mobile phases (water/methanol and water/acetone) were used in different volume proportions. The retention behavior of the analyzed molecules was defined by R M0 constant. In addition, reversed phase high performance liquid chromatography (RP-HPLC) was performed in lipophilicity studies by using immobilized artificial membrane (IAM) stationary phase. Obtained chromatographic data (R M0 and logk' IAM ) were correlated with the lipophilicity, expressed as values of the log calculated (logP calc ) and experimental (logP exp(shake-flask) ) partition coefficient. Principal component analysis (PCA) was applied in order to obtain an overview of similarity or dissimilarity among the analyzed compounds. Hierarchical cluster analysis (HCA) was performed to compare the separation characteristics of the applied stationary phases. This study was undertaken to identify the best chromatographic system and chromatographic data processing method to enable the prediction of logP values. A comprehensive chromatographic investigation into the retention of the analyzed cephalosporins revealed a similar behavior on RP-18, RP-8 and CN stationary phases. The weak correlations obtained between experimental and certain computed lipophilicity indices revealed that R M0 and PC1/RM are relevant lipophilicity parameters and the RP-8, CN and RP-18 plates are appropriate stationary phases for lipophilicity investigation, whereas computational approaches still cannot fully replace experimentation. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Dual liquid and gas chromatograph system

    Science.gov (United States)

    Gay, D.D.

    A chromatographic system is described that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a nontransparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extreme low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  11. Pareto distance for multi-layer network analysis

    DEFF Research Database (Denmark)

    Magnani, Matteo; Rossi, Luca

    2013-01-01

    services, e.g., Facebook, Twitter, LinkedIn and Foursquare. As a result, the analysis of on-line social networks requires a wider scope and, more technically speaking, models for the representation of this fragmented scenario. The recent introduction of more realistic layered models has however determined......Social Network Analysis has been historically applied to single networks, e.g., interaction networks between co-workers. However, the advent of on-line social network sites has emphasized the stratified structure of our social experience. Individuals usually spread their identities over multiple...

  12. Packer Detection for Multi-Layer Executables Using Entropy Analysis

    Directory of Open Access Journals (Sweden)

    Munkhbayar Bat-Erdene

    2017-03-01

    Full Text Available Packing algorithms are broadly used to avoid anti-malware systems, and the proportion of packed malware has been growing rapidly. However, just a few studies have been conducted on detection various types of packing algorithms in a systemic way. Following this understanding, we elaborate a method to classify packing algorithms of a given executable into three categories: single-layer packing, re-packing, or multi-layer packing. We convert entropy values of the executable file loaded into memory into symbolic representations, for which we used SAX (Symbolic Aggregate Approximation. Based on experiments of 2196 programs and 19 packing algorithms, we identify that precision (97.7%, accuracy (97.5%, and recall ( 96.8% of our method are respectively high to confirm that entropy analysis is applicable in identifying packing algorithms.

  13. Radioimmunoassay of methaqualone in human urine compared with chromatographic methods

    International Nuclear Information System (INIS)

    Mule, S.J.; Kogan, M.; Jukofsky, D.

    1978-01-01

    The 125 I-radioimmunoassay for methaqualone in human urine was evaluated by a comparison with newly modified gas-liquid chromatographic and thin-layer chromatographic methods. The statistically significant sensitivity value for the radioimmunoassay was at 2 μg of methaqualone per liter of urine. The coefficient of variation was 2.88 -+ 0.16% intraassay. There was cross-reactivity only with metabolites of methaqualone, 4'-hydroxymethaqualone being twice as sensitively measured as methaqualone. There was complete agreement between results by radioimmunoassay and by gas-liquid chromatography in 96.7% of the samples analyzed. Only 1.2% of the radioimmunoassay values were false positives, and 2.1% false negatives (phi = 0.8917, P < 0.001). Comparisons between the thin-layer chromatographic data and the gas--liquid chromatographic or radioimmunoassay data showed less agreement because of the 50- to 200-fold higher sensitivity of the latter techniques. Gas--liquid chromatography therefore appears to represent the best reference method for the evaluation of the radioimmunoassay, which appears to be a very sensitive and reliable technique for detecting methaqualone and its metabolites in human urine

  14. On stress analysis of a crack-layer

    Science.gov (United States)

    Chudnovsky, A.; Dolgopolsky, A.; Kachanov, M.

    1984-01-01

    This work considers the problem of elastic interaction of a macrocrack with an array of microcracks in the vicinity of the macrocrack tip. Using the double layer potential techniques, the solution to the problem within the framework of the plane problem of elastostatics has been obtained. Three particular problems of interest to fracture mechanics have been analyzed. It follows from analysis that microcrack array can either amplify or reduce the resulting stress field of the macrocrack-microcrack array system depending on the array's configuration. Using the obtained elastic solution the energy release rate associated with the translational motion of the macrocrack-microcrack array system has been evaluated.

  15. Titan atmospheric composition by hypervelocity shock layer analysis

    International Nuclear Information System (INIS)

    Nelson, H.F.; Park, C.; Whiting, E.E.

    1989-01-01

    The Cassini Mission, a NASA/ESA cooperative project which includes a deployment of probe into the atmosphere of Titan, is described, with particular attention given to the shock radiometer experiment planned for the Titan probe for the analysis of Titan's atmosphere. Results from a shock layer analysis are presented, demonstrating that the mole fractions of the major species (N2, CH4, and, possibly Ar) in the Titan atmosphere can be successfully determined by the Titan-probe radiometer, by measuring the intensity of the CN(violet) radiation emitted in the shock layer during the high velocity portion of the probe entry between 200 and 400 km altitude. It is shown that the sensitivity of the CN(violet) radiation makes it possible to determine the mole fractions of N2, CH4, and Ar to about 0.015, 0.003, and 0.01, respectively, i.e., much better than the present uncertainties in the composition of Titan atmosphere. 29 refs

  16. Partition/Ion-Exclusion Chromatographic Ion Stacking for the Analysis of Trace Anions in Water and Salt Samples by Ion Chromatography.

    Science.gov (United States)

    Akter, Fouzia; Saito, Shingo; Tasaki-Handa, Yuiko; Shibukawa, Masami

    2018-01-01

    A new analytical methodology for a simple and efficient on-line preconcentration of trace inorganic anions in water and salt samples prior to ion chromatographic determination is proposed. The preconcentration method is based on partition/ion-exclusion chromatographic ion stacking (PIEC ion stacking) with a hydrophilic polymer gel column containing a small amount of fixed anionic charges. The developed on-line PIEC ion stacking-ion chromatography method was validated by recovery experiments for the determination of nitrate in tap water in terms of both accuracy and precision, and the results showed the reliability of the method. The method proposed was also successfully applied to the determination of trace impurity nitrite and nitrate in reagent-grade salts of sodium sulfate. A low background level can be achieved since pure water is used as the eluant for the PIEC ion stacking. It is possible to reach sensitive detection at sub-μg L -1 levels by on-line PIEC ion stacking-ion chromatography.

  17. Simultaneous derivatisation and preconcentration of parabens in food and other matrices by isobutyl chloroformate and dispersive liquid-liquid microextraction followed by gas chromatographic analysis.

    Science.gov (United States)

    Jain, Rajeev; Mudiam, Mohana Krishna Reddy; Chauhan, Abhishek; Ch, Ratnasekhar; Murthy, R C; Khan, Haider A

    2013-11-01

    A simple, rapid and economical method has been proposed for the quantitative determination of parabens (methyl, ethyl, propyl and butyl paraben) in different samples (food, cosmetics and water) based on isobutyl chloroformate (IBCF) derivatisation and preconcentration using dispersive liquid-liquid microextraction in single step. Under optimum conditions, solid samples were extracted with ethanol (disperser solvent) and 200 μL of this extract along with 50 μL of chloroform (extraction solvent) and 10 μL of IBCF was rapidly injected into 2 mL of ultra-pure water containing 150 μL of pyridine to induce formation of a cloudy state. After centrifugation, 1 μL of the sedimented phase was analysed using gas chromatograph-flame ionisation detector (GC-FID) and the peaks were confirmed using gas chromatograph-positive chemical ionisation-mass spectrometer (GC-PCI-MS). Method was found to be linear over the range of 0.1-10 μg mL(-1) with square of correlation coefficient (R(2)) in the range of 0.9913-0.9992. Limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.029-0.102 μg mL(-1) and 0.095-0.336 μg mL(-1) with a signal to noise ratio of 3:1 and 10:1, respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Aeromechanics Analysis of a Boundary Layer Ingesting Fan

    Science.gov (United States)

    Bakhle, Milind A.; Reddy, T. S. R.; Herrick, Gregory P.; Shabbir, Aamir; Florea, Razvan V.

    2013-01-01

    Boundary layer ingesting propulsion systems have the potential to significantly reduce fuel burn but these systems must overcome the challe nges related to aeromechanics-fan flutter stability and forced response dynamic stresses. High-fidelity computational analysis of the fan a eromechanics is integral to the ongoing effort to design a boundary layer ingesting inlet and fan for fabrication and wind-tunnel test. A t hree-dimensional, time-accurate, Reynolds-averaged Navier Stokes computational fluid dynamics code is used to study aerothermodynamic and a eromechanical behavior of the fan in response to both clean and distorted inflows. The computational aeromechanics analyses performed in th is study show an intermediate design iteration of the fan to be flutter-free at the design conditions analyzed with both clean and distorte d in-flows. Dynamic stresses from forced response have been calculated for the design rotational speed. Additional work is ongoing to expan d the analyses to off-design conditions, and for on-resonance conditions.

  19. Layers of protection analysis in the framework of possibility theory.

    Science.gov (United States)

    Ouazraoui, N; Nait-Said, R; Bourareche, M; Sellami, I

    2013-11-15

    An important issue faced by risk analysts is how to deal with uncertainties associated with accident scenarios. In industry, one often uses single values derived from historical data or literature to estimate events probability or their frequency. However, both dynamic environments of systems and the need to consider rare component failures may make unrealistic this kind of data. In this paper, uncertainty encountered in Layers Of Protection Analysis (LOPA) is considered in the framework of possibility theory. Data provided by reliability databases and/or experts judgments are represented by fuzzy quantities (possibilities). The fuzzy outcome frequency is calculated by extended multiplication using α-cuts method. The fuzzy outcome is compared to a scenario risk tolerance criteria and the required reduction is obtained by resolving a possibilistic decision-making problem under necessity constraint. In order to validate the proposed model, a case study concerning the protection layers of an operational heater is carried out. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Choice of optimal conditions for layer-by-layer analysis of semiconductor structures on spark mass spectrometer

    International Nuclear Information System (INIS)

    Gerasimov, V.A.; Saprykin, A.I.; Shelpakova, I.R.; Yudelevich, I.G.

    1978-01-01

    Criteria of choosing counter-electrode-configuration, size and material have been determined. A tantalum counter-electrode with rectangular cross-section (3.5-4.5) mmx(0.05-0.08) mm 2 is proposed for layer-by-layer analysis of Si, Ge, GaAs, InSb. A scanning velocity has been chosen and spark generator operating conditions have been optimized which ensure the surface roughness of 0.5-0.8 μ after sparking. A systematic study has been made of the effect of ballast elements in the discharge circuit on the basic characteristics of the layer-by-layer analysis: ionic current intensity, counter-electrode contribution to the total ionic current, intensity of dicharged ions and surface roughness. A ballast ohmic resistance inside the ion source decreases a correction for the blank by one order of magnitude and the sparked surface roughness by 2-3 times

  1. Chromatographic monitoring procedures in laboratory practice

    Energy Technology Data Exchange (ETDEWEB)

    Kaplina, E G; Belova, O I; Lasunina, N A

    1976-01-01

    The Moscow Coke and Chemical Works consist of three plants in combination, viz., the coking plant, the synthetic ammonia plant using coke-oven-gas hydrogen and the oxygen plant. The plant requirements include daily analyses not only of the coke-oven gas but also of a rich gas and an ethylene fraction. The analyses are carried out in VTI-2 apparatus. The analytical data are used to calculate the calorific values and densities of the gases. The time requirements are very considerable and the laboratory has long been engaged in developing and introducing chromatographic procedures for the major constituents of coke-oven gas, rich gas and ethylene fraction. The procedure developed for the coke-oven and rich gases uses two parallel columns, one packed with molecular sieves and the other with grade KSM silica gel. Hydrogen was determined with argon as the carrier gas, and all other constituents with helium. The procedure was time-consuming and complicated. An attempt was made to separate the gases in an LKhM-7a chromatograph with a programme-controlled 50 to 250/sup 0/C heating cycle, but the procedure still had a number of serious defects and could not be recommended for regular quality control. The final variant involved two parallel columns and a procedure based on that in GOST 14920 (''Dry gas. Proximate analysis''). The chromatograph was a type KhL-69 with a 6-way cock in the gas line so that each of the columns could be brought on stream in succession. The analytical column packings were zeolite (in a 2 m column) and diatomaceous brick with 25% n-hexadecane (in a 6 m column).

  2. Cross-Layer Design and Analysis of Downlink Communications in Cellular CDMA Systems

    Directory of Open Access Journals (Sweden)

    Sun Jin Yuan

    2006-01-01

    Full Text Available A cellular CDMA network with voice and data communications is considered. Focusing on the downlink direction, we seek for the overall performance improvement which can be achieved by cross-layer analysis and design, taking physical layer, link layer, network layer, and transport layer into account. We are concerned with the role of each single layer as well as the interaction among layers, and propose algorithms/schemes accordingly to improve the system performance. These proposals include adaptive scheduling for link layer, priority-based handoff strategy for network admission control, and an algorithm for the avoidance of TCP spurious timeouts at the transport layer. Numerical results show the performance gain of each proposed scheme over independent performance of an individual layer in the wireless mobile network. We conclude that the system performance in terms of capacity, throughput, dropping probability, outage, power efficiency, delay, and fairness can be enhanced by jointly considering the interactions across layers.

  3. Single-step preparation of selected biological fluids for the high performance liquid chromatographic analysis of fat-soluble vitamins and antioxidants.

    Science.gov (United States)

    Lazzarino, Giacomo; Longo, Salvatore; Amorini, Angela Maria; Di Pietro, Valentina; D'Urso, Serafina; Lazzarino, Giuseppe; Belli, Antonio; Tavazzi, Barbara

    2017-12-08

    Fat-soluble vitamins and antioxidants are of relevance in health and disease. Current methods to extract these compounds from biological fluids mainly need use of multi-steps and multi organic solvents. They are time-consuming and difficult to apply to treat simultaneously large sample number. We here describe a single-step, one solvent extraction of fat-soluble vitamins and antioxidants from biological fluids, and the chromatographic separation of all-trans-retinoic acid, 25-hydroxycholecalciferol, all-trans-retinol, astaxanthin, lutein, zeaxanthin, trans-β-apo-8'-carotenal, γ-tocopherol, β-cryptoxanthin, α-tocopherol, phylloquinone, lycopene, α-carotene, β-carotene and coenzyme Q 10 . Extraction is obtained by adding one volume of biological fluid to two acetonitrile volumes, vortexing for 60s and incubating for 60min at 37°C under agitation. HPLC separation occurs in 30min using Hypersil C18, 100×4.6mm, 5μm particle size column, gradient from 70% methanol+30% H 2 O to 100% acetonitrile, flow rate of 1.0ml/min and 37°C column temperature. Compounds are revealed using highly sensitive UV-VIS diode array detector. The HPLC method suitability was assessed in terms of sensitivity, reproducibility and recovery. Using the present extraction and chromatographic conditions we obtained values of the fat-soluble vitamins and antioxidants in serum from 50 healthy controls similar to those found in literature. Additionally, the profile of these compounds was also measured in seminal plasma from 20 healthy fertile donors. Results indicate that this simple, rapid and low cost sample processing is suitable to extract fat-soluble vitamins and antioxidants from biological fluids and can be applied in clinical and nutritional studies. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Numerical Analysis of Deflections of Multi-Layered Beams

    Science.gov (United States)

    Biliński, Tadeusz; Socha, Tomasz

    2015-03-01

    The paper concerns the rheological bending problem of wooden beams reinforced with embedded composite bars. A theoretical model of the behaviour of a multi-layered beam is presented. The component materials of this beam are described with equations for the linear viscoelastic five-parameter rheological model. Two numerical analysis methods for the long-term response of wood structures are presented. The first method has been developed with SCILAB software. The second one has been developed with the finite element calculation software ABAQUS and user subroutine UMAT. Laboratory investigations were conducted on sample beams of natural dimensions in order to validate the proposed theoretical model and verify numerical simulations. Good agreement between experimental measurements and numerical results is observed.

  5. Numerical Analysis of Deflections of Multi-Layered Beams

    Directory of Open Access Journals (Sweden)

    Biliński Tadeusz

    2015-03-01

    Full Text Available The paper concerns the rheological bending problem of wooden beams reinforced with embedded composite bars. A theoretical model of the behaviour of a multi-layered beam is presented. The component materials of this beam are described with equations for the linear viscoelastic five-parameter rheological model. Two numerical analysis methods for the long-term response of wood structures are presented. The first method has been developed with SCILAB software. The second one has been developed with the finite element calculation software ABAQUS and user subroutine UMAT. Laboratory investigations were conducted on sample beams of natural dimensions in order to validate the proposed theoretical model and verify numerical simulations. Good agreement between experimental measurements and numerical results is observed.

  6. Hygrothermal analysis of surface layers of historical masonry

    Science.gov (United States)

    Kočí, Václav; Maděra, Jiří; Keppert, Martin; Černý, Robert

    2017-11-01

    The paper deals with the hygrothermal analysis of surface layers of historical masonry. Solid brick provided with a traditional and two modified lime-based plasters is studied. The heat and moisture transport in the envelope is induced by an exposure of the wall from the exterior side to dynamic climatic conditions of Olomouc, Czech Republic. The transport processes are described using diffusion type of mathematical model based on experimentally determined material properties. The computational results indicate that hygric transport and accumulation properties of exterior plasters affect the hygrothermal performance of the underlying solid brick in a very significant way, being able to regulate the amount of transported moisture. The modified lime plasters are not found generally superior to the traditional lime plasters in that respect. Therefore, their suitability for historical masonry should be assessed case by case, with a particular attention to the climatic conditions and to the properties of the load bearing structure.

  7. High-pressure liquid chromatographic assay of Bay n 7133 in human serum.

    OpenAIRE

    Fasching, C E; Hughes, C E; Hector, R F; Peterson, L R

    1984-01-01

    A high-pressure liquid chromatographic method that includes a Sep-Pak (Waters Associates, Inc., Milford , Mass.) preparation of human serum was employed for the quantitative assay of Bay n 7133. Drug levels of 0.1 to 20 micrograms/ml could be detected. No interference from amphotericin B was found in the chromatographic analysis of Bay n 7133.

  8. Analysis of low active-pharmaceutical-ingredient signal drugs based on thin layer chromatography and surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Li, Xiao; Chen, Hui; Zhu, Qingxia; Liu, Yan; Lu, Feng

    2016-11-30

    Active pharmaceutical ingredients (API) embedded in the excipients of the formula can usually be unravelled by normal Raman spectroscopy (NRS). However, more and more drugs with low API content and/or low Raman scattering coefficient were insensitive to NRS analysis, which was for the first time defined as Low API-Signal Drugs (LASIDs) in this paper. The NRS spectra of these LASIDs were similar to their dominant excipients' profiles, such as lactose, starch, microcrystalline cellulose (MCC), etc., and were classified into three types as such. 21 out of 100 kinds of drugs were screened as LASIDs and characterized further by Raman microscopic mapping. Accordingly, we proposed a tailored solution to the qualitation and quantitation problem of these LASIDs, using surface-enhanced Raman spectroscopic (SERS) detection on the thin layer chromatographic (TLC) plate both in situ and after-separation. Experimental conditions and parameters including TLC support matrix, SERS substrate, detection mode, similarity threshold, internal standard, etc., were optimized. All LASIDs were satisfactorily identified and the quantitation results agreed well with those of high performance liquid chromatography (HPLC). For some structural analogues of LASIDs, although they presented highly similar SERS spectra and were tough to distinguish even with Raman microscopic mapping, they could be successfully discriminated from each other by coupling SERS (with portable Raman spectrometer) with TLC. These results demonstrated that the proposed solution could be employed to detect the LASIDs with high accuracy and cost-effectiveness. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Supercritical Fluid Chromatographic Separation of Dimethylpolysiloxane Polymer

    Energy Technology Data Exchange (ETDEWEB)

    Pyo, Dong Jin; Lim, Chang Hyun [Kangwon National University, Chuncheon (Korea, Republic of)

    2005-02-15

    Water was used as a polar modifier and a μ-porasil column as a saturator column. The μ-porasil column was inserted between the pump outlet and the injection valve. During the passage of the supercritical fluid mobile phase through the silica column, a polar modifier (water) can be dissolved in the pressurized supercritical fluid. Dimethylpolysiloxane polymer has been known as more polar polymer than polystyrene polymer. Dimethylpolysiloxane polymer has never been separated using water modified mobile phase. In this paper, using a μ-porasil column as a saturator column, excellent supercritical fluid chromatograms of dimethylpolysiloxane oligomers were obtained. The use of compressed (dense) gases and supercritical fluids as chromatographic mobile phases in conjunction with liquid chromatographic (LC)-type packed columns was first reported by Klesper et al. in 1962. During its relatively short history, supercritical fluid chromatography (SFC) has become an attractive alternative to GC and LC in certain industrially important applications. SFC gives the advantage of high efficiency and allows the analysis of nonvolatile or thermally labile mixtures.

  10. Supercritical Fluid Chromatographic Separation of Dimethylpolysiloxane Polymer

    International Nuclear Information System (INIS)

    Pyo, Dong Jin; Lim, Chang Hyun

    2005-01-01

    Water was used as a polar modifier and a μ-porasil column as a saturator column. The μ-porasil column was inserted between the pump outlet and the injection valve. During the passage of the supercritical fluid mobile phase through the silica column, a polar modifier (water) can be dissolved in the pressurized supercritical fluid. Dimethylpolysiloxane polymer has been known as more polar polymer than polystyrene polymer. Dimethylpolysiloxane polymer has never been separated using water modified mobile phase. In this paper, using a μ-porasil column as a saturator column, excellent supercritical fluid chromatograms of dimethylpolysiloxane oligomers were obtained. The use of compressed (dense) gases and supercritical fluids as chromatographic mobile phases in conjunction with liquid chromatographic (LC)-type packed columns was first reported by Klesper et al. in 1962. During its relatively short history, supercritical fluid chromatography (SFC) has become an attractive alternative to GC and LC in certain industrially important applications. SFC gives the advantage of high efficiency and allows the analysis of nonvolatile or thermally labile mixtures

  11. Purification of 3H-dihydroalprenolol by two dimensional thin layer chromatography

    International Nuclear Information System (INIS)

    Smisterova, J.; Soltes, L.; Kallay, Z.

    1989-01-01

    A two dimensional thin-layer chromatographic method was developed for the purification and analysis of (-)-[ 3 H]dihydroalprenolol by using an acidic mobile phase (butanol/water/acetic acid 25:10:4, v/v) in one direction and a basic eluent (chloroform/acetone/triethylamine 50:40:10, v/v) in another direction. (author)

  12. Layered Metal Hydroxides Containing Calcium and Their Structural Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Hyun; Heo, Il; Lee, Sung Han; Oh, Jae Min [College of Science and Technology, Yonsei University, Wonju (Korea, Republic of); Paek, Seung Min [Kyungpook National University, Daegu (Korea, Republic of); Park, Chung Berm; Choi, Ae Jin [National Institute of Horticultural and Herbal Science of R and D Eumseong (Korea, Republic of); Choy, Jin Ho [Ewha Womans University, Seoul (Korea, Republic of)

    2012-06-15

    Layered metal hydroxides (LMHs) containing calcium were synthesized by coprecipitation in solution having two different trivalent metal ions, iron and aluminum. Two mixed metal solutions (Ca{sup 2+}/Al{sup 3+} and Ca{sup 2+}/Fe{sup 3+} = 2/1) were added to sodium hydroxide solution and the final pH was adjusted to {approx}11.5 and {approx}13 for CaAl-and CaFe-LMHs. Powder X-ray diffraction (XRD) for the two LMH samples showed well developed (00l) diffractions indicating 2-dimensional crystal structure of the synthesized LMHs. Rietveld refinement of the X-ray diffraction pattern, the local structure analysis through X-ray absorption spectroscopy, and thermal analysis also confirmed that the synthesized precipitates show typical structure of LMHs. The chemical formulae, Ca{sub 2.04}Al{sub 1}(OH){sub 6}(NO{sub 3}){center_dot}5.25H{sub 2}O and Ca{sub 2.01}Fe{sub 1}(OH){sub 6}(NO{sub 3}){center_dot}4.75H{sub 2}O were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Particle morphology and thermal behavior for the synthesized LMHs were examined by field emission scanning electron microscopy and thermogravimetric differential scanning calorimetry

  13. Design and analysis of three-layer-core optical fiber

    Science.gov (United States)

    Zheng, Siwen; Liu, Yazhuo; Chang, Guangjian

    2018-03-01

    A three-layer-core single-mode large-mode-area fiber is investigated. The three-layer structure in the core, which is composed of a core-index layer, a cladding-index layer, and a depression-index layer, could achieve a large effective area Aeff while maintaining an ultralow bending loss without deteriorating cutoff behaviors. The single-mode large mode area of 100 to 330 μm2 could be achieved in the fiber. The effective area Aeff can be further enlarged by adjusting the layer parameters. Furthermore, the bending property could be improved in this three-layer-core structure. The bending loss could decrease by 2 to 4 orders of magnitude compared with the conventional step-index fiber with the same Aeff. These characteristics of three-layer-core fiber suggest that it can be used in large-mode-area wide-bandwidth high-capacity transmission or high-power optical fiber laser and amplifier in optical communications, which could be used for the basic physical layer structure of big data storage, reading, calculation, and transmission applications.

  14. Chromatographic analysis of phytochemicals components present in mangifera indica leaves for the synthesis of silver nanoparticles by AgNO3 reduction

    International Nuclear Information System (INIS)

    Martínez-Bernett, D; Silva-Granados, A; Herrera, A; Correa-Torres, S N

    2016-01-01

    It was studied the green synthesis of silver nanoparticles (AgNPs) from the reduction of a silver nitrate solution (1 and 10mM) in the presence of an extract of mangifera indica leaves. Phytochemicals components present in extracts of mango leaves were determined using a GC-MS chromatograph. The results showed the presence of the phenolic compound pyrogallol (26.9% wt/5mL of extract) and oleic acid (29.1% wt/5mL of extract), which are useful for the reduction of the metallic salt AgNO 3 and the stabilization of silver nanoparticles. The synthesized nanoparticles were characterized by UV visible spectroscopy (UV-vis), evidencing absorbances at wavelengths of 417nm (AgNPs-1) and 414nm (AgNPs- 10), which are characteristic peaks of this metallic nanoparticles. Scanning Electron Microscopy (SEM) was used to determine the size of the synthesized nanoparticles. A particle size of about 28±7nm was observed for the AgNPs-1 sample and 26±5nm for the AgNPs-10. This suggests the advantages of green chemistry to obtain silver nanoparticles with a narrow size distribution. (paper)

  15. Chromatographic analysis of phytochemicals components present in mangifera indica leaves for the synthesis of silver nanoparticles by AgNO3 reduction

    Science.gov (United States)

    Martínez-Bernett, D.; Silva-Granados, A.; Correa-Torres, S. N.; Herrera, A.

    2016-02-01

    It was studied the green synthesis of silver nanoparticles (AgNPs) from the reduction of a silver nitrate solution (1 and 10mM) in the presence of an extract of mangifera indica leaves. Phytochemicals components present in extracts of mango leaves were determined using a GC-MS chromatograph. The results showed the presence of the phenolic compound pyrogallol (26.9% wt/5mL of extract) and oleic acid (29.1% wt/5mL of extract), which are useful for the reduction of the metallic salt AgNO3 and the stabilization of silver nanoparticles. The synthesized nanoparticles were characterized by UV visible spectroscopy (UV-vis), evidencing absorbances at wavelengths of 417nm (AgNPs-1) and 414nm (AgNPs- 10), which are characteristic peaks of this metallic nanoparticles. Scanning Electron Microscopy (SEM) was used to determine the size of the synthesized nanoparticles. A particle size of about 28±7nm was observed for the AgNPs-1 sample and 26±5nm for the AgNPs-10. This suggests the advantages of green chemistry to obtain silver nanoparticles with a narrow size distribution.

  16. Thermal Analysis of Low Layer Density Multilayer Insulation Test Results

    Science.gov (United States)

    Johnson, Wesley L.

    2011-01-01

    Investigation of the thermal performance of low layer density multilayer insulations is important for designing long-duration space exploration missions involving the storage of cryogenic propellants. Theoretical calculations show an analytical optimal layer density, as widely reported in the literature. However, the appropriate test data by which to evaluate these calculations have been only recently obtained. As part of a recent research project, NASA procured several multilayer insulation test coupons for calorimeter testing. These coupons were configured to allow for the layer density to be varied from 0.5 to 2.6 layer/mm. The coupon testing was completed using the cylindrical Cryostat-l00 apparatus by the Cryogenics Test Laboratory at Kennedy Space Center. The results show the properties of the insulation as a function of layer density for multiple points. Overlaying these new results with data from the literature reveals a minimum layer density; however, the value is higher than predicted. Additionally, the data show that the transition region between high vacuum and no vacuum is dependent on the spacing of the reflective layers. Historically this spacing has not been taken into account as thermal performance was calculated as a function of pressure and temperature only; however the recent testing shows that the data is dependent on the Knudsen number which takes into account pressure, temperature, and layer spacing. These results aid in the understanding of the performance parameters of MLI and help to complete the body of literature on the topic.

  17. Reflectance analysis of porosity gradient in nanostructured silicon layers

    Science.gov (United States)

    Jurečka, Stanislav; Imamura, Kentaro; Matsumoto, Taketoshi; Kobayashi, Hikaru

    2017-12-01

    In this work we study optical properties of nanostructured layers formed on silicon surface. Nanostructured layers on Si are formed in order to reach high suppression of the light reflectance. Low spectral reflectance is important for improvement of the conversion efficiency of solar cells and for other optoelectronic applications. Effective method of forming nanostructured layers with ultralow reflectance in a broad interval of wavelengths is in our approach based on metal assisted etching of Si. Si surface immersed in HF and H2O2 solution is etched in contact with the Pt mesh roller and the structure of the mesh is transferred on the etched surface. During this etching procedure the layer density evolves gradually and the spectral reflectance decreases exponentially with the depth in porous layer. We analyzed properties of the layer porosity by incorporating the porosity gradient into construction of the layer spectral reflectance theoretical model. Analyzed layer is splitted into 20 sublayers in our approach. Complex dielectric function in each sublayer is computed by using Bruggeman effective media theory and the theoretical spectral reflectance of modelled multilayer system is computed by using Abeles matrix formalism. Porosity gradient is extracted from the theoretical reflectance model optimized in comparison to the experimental values. Resulting values of the structure porosity development provide important information for optimization of the technological treatment operations.

  18. Silicate glasses corrosion. Texture analysis of the corrosion layer

    International Nuclear Information System (INIS)

    Portal, Sabine

    2001-01-01

    We have studied the kinetic and the texture evolution of the corroded layer that forms on glass surfaces exposed to acidic solutions. The corroded layer is depleted in alkali cations and is produced by an ion exchange mechanism. It is porous and shows a lower refractive index than the one of the bulk glass. Spectroscopic ellipsometry allows determining the thickness of the layer and its refractive index. Several other techniques have been developed for characterizing the corrosion behaviour of glass surfaces: porosity is thus investigated by adsorption-desorption of nitrogen; the thickness and the composition of the layer are studied by secondary ion mass spectroscopy (S.I.M.S.); sodium concentration in the solution has been analyzed by atomic absorption. This study shows the importance of leaching conditions and glass preparation. The type of drying employed is susceptible to modify the texture and the structure of the layer. The layers produced in the early stages of the leaching process are not easily detectable. The different results lead however to the same conclusion: after a strong increase of porosity, a densification of the layer is observed with increasing time. The evolution of the layer texture could therefore modify the kinetic of the glass corrosion. (author) [fr

  19. Validação em métodos cromatográficos para análises de pequenas moléculas em matrizes biológicas Chromatographic methods validation for analysis of small molecules in biological matrices

    Directory of Open Access Journals (Sweden)

    Neila Maria Cassiano

    2009-01-01

    Full Text Available Chromatographic methods are commonly used for analysis of small molecules in different biological matrices. An important step to be considered upon a bioanalytical method's development is the capacity to yield reliable and reproducible results. This review discusses validation procedures adopted by different governmental agencies, such as Food and Drug Administration (USA, European Union (EU and Agência Nacional de Vigilância Sanitária (BR for quantification of small molecules by bioanalytical chromatographic methods. The main parameters addressed in this review are: selectivity, linearity, precision, accuracy, quantification and detection limits, recovery, dilution integrity, stability and robustness. Also, the acceptance criterions are clearly specified.

  20. Analysis and Modeling of Boundary Layer Separation Method (BLSM).

    Science.gov (United States)

    Pethő, Dóra; Horváth, Géza; Liszi, János; Tóth, Imre; Paor, Dávid

    2010-09-01

    Nowadays rules of environmental protection strictly regulate pollution material emission into environment. To keep the environmental protection laws recycling is one of the useful methods of waste material treatment. We have developed a new method for the treatment of industrial waste water and named it boundary layer separation method (BLSM). We apply the phenomena that ions can be enriched in the boundary layer of the electrically charged electrode surface compared to the bulk liquid phase. The main point of the method is that the boundary layer at correctly chosen movement velocity can be taken out of the waste water without being damaged, and the ion-enriched boundary layer can be recycled. Electrosorption is a surface phenomenon. It can be used with high efficiency in case of large electrochemically active surface of electrodes. During our research work two high surface area nickel electrodes have been prepared. The value of electrochemically active surface area of electrodes has been estimated. The existence of diffusion part of the double layer has been experimentally approved. The electrical double layer capacity has been determined. Ion transport by boundary layer separation has been introduced. Finally we have tried to estimate the relative significance of physical adsorption and electrosorption.

  1. Vibration analysis of thin-wall structures containing piezoactive layers

    International Nuclear Information System (INIS)

    Guz, I A; Kashtalyan, M; Zhuk, Y A

    2010-01-01

    A coupled dynamic problem of electro-mechanics for a layered beam is formulated based on the Kirchhoff-Love hypotheses. In the case of harmonic loading, a simplified formulation is given using the single frequency approximation and the concept of complex moduli. As an example, the problem of forced vibration of a three-layer sandwich beam (aluminium alloy core covered with piezoelectric layers) with hinged ends is solved in order to investigate the accuracy and applicability of the approximate monoharmonic approach. Different aspects of the beam response to the mechanical and electric excitation are studied.

  2. Comparative Analysis of Profitability of Layers Production in Esan ...

    African Journals Online (AJOL)

    MICHAEL HORSFALL

    KEY WORDS: Day old Chicks, Gross Margin, old layers, Point of lay, Profitability, Rate of return, Viability. ABSTRACT: This ... People depend on poultry for food and poultry farming serves as an additional ..... Wholesales Marketing of Tomato.

  3. Analysis of Thomsen parameters for finely layered VTI media

    International Nuclear Information System (INIS)

    Berryman, J.G.; Berge, P.A.

    1997-01-01

    The range of Thomsen's anisotropy parameters ε and δ for vertical transversely isotropic (VTI) media when the anisotropy is due to fine layering of isotropic elas-tic materials is considered. We show that ε lies in the range -3/8 ≤ ε ≤ 1/2 v p 2 > p-2 >-1 for finely layered media having constant density; smaller positive and all negative values of ε occur for media with large fluctuations in the Lamacute e parameter λ We show that sign(δ) = sign ( p -2 > - s -2 > s 2 /v p 2 >) for constant density media, so δ can be either positive or negative. Among all theoretically possible random media, posi-tive and negative δ are equally likely in finely layered media limited to two types of constituent layers. Lay-ered media having large fluctuations in Lamacute e λ are the ones most likely to have positive δ. Since Gassmann's results for fluid-saturated porous media show that the effects of fluids influence only the λ Lamacute e constant, not the shear modulus μ, these results suggest that positive δ occurring together with positive but small ε may be indicative of changing fluid content in layered earth

  4. Use of laminar chromatographic methods for determination of separation conditions in column extraction chromatography

    International Nuclear Information System (INIS)

    Ghersini, G.; Cerrai, E.

    1978-01-01

    Possibilities of using laminar chromatographic methods (paper and thin-layer chromatography) to determine optimal separation conditions in column extraction chromatography are analysed. Most of the given laminar methods are presented as Rf-spectra, i.e. as dependences of Rf found experimentally on eluating solution component concentration. Interrelation between Rf and distribution coefficients of corresponding liquid extraction systems and retention volumes of chromatographic columns is considered. Literature data on extraction paper and thin-layer chromatography of elements with various immovable phases are presented

  5. Chemometric strategy for automatic chromatographic peak detection and background drift correction in chromatographic data.

    Science.gov (United States)

    Yu, Yong-Jie; Xia, Qiao-Ling; Wang, Sheng; Wang, Bing; Xie, Fu-Wei; Zhang, Xiao-Bing; Ma, Yun-Ming; Wu, Hai-Long

    2014-09-12

    Peak detection and background drift correction (BDC) are the key stages in using chemometric methods to analyze chromatographic fingerprints of complex samples. This study developed a novel chemometric strategy for simultaneous automatic chromatographic peak detection and BDC. A robust statistical method was used for intelligent estimation of instrumental noise level coupled with first-order derivative of chromatographic signal to automatically extract chromatographic peaks in the data. A local curve-fitting strategy was then employed for BDC. Simulated and real liquid chromatographic data were designed with various kinds of background drift and degree of overlapped chromatographic peaks to verify the performance of the proposed strategy. The underlying chromatographic peaks can be automatically detected and reasonably integrated by this strategy. Meanwhile, chromatograms with BDC can be precisely obtained. The proposed method was used to analyze a complex gas chromatography dataset that monitored quality changes in plant extracts during storage procedure. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Plasmon analysis and homogenization in plane layered photonic crystals and hyperbolic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Davidovich, M. V., E-mail: davidovichmv@info.sgu.ru [Saratov State University (Russian Federation)

    2016-12-15

    Dispersion equations are obtained and analysis and homogenization are carried out in periodic and quasiperiodic plane layered structures consisting of alternating dielectric layers, metal and dielectric layers, as well as graphene sheets and dielectric (SiO{sub 2}) layers. Situations are considered when these structures acquire the properties of hyperbolic metamaterials (HMMs), i.e., materials the real parts of whose effective permittivity tensor have opposite signs. It is shown that the application of solely dielectric layers is more promising in the context of reducing losses.

  7. Analysis of diabatic flow modification in the internal boundary layer

    DEFF Research Database (Denmark)

    Floors, Rogier; Gryning, Sven-Erik; Pena Diaz, Alfredo

    2011-01-01

    Measurements at two meteorological masts in Denmark, Horns Rev in the sea and Høvsøre near the coastline on land, are used to analyze the behaviour of the flow after a smooth-to-rough change in surface conditions. The study shows that the wind profile within the internal boundary layer is control......Measurements at two meteorological masts in Denmark, Horns Rev in the sea and Høvsøre near the coastline on land, are used to analyze the behaviour of the flow after a smooth-to-rough change in surface conditions. The study shows that the wind profile within the internal boundary layer...

  8. Defect analysis of NiMnSb epitaxial layers

    Energy Technology Data Exchange (ETDEWEB)

    Nowicki, L. [Andrzej SoItan Institute for Nuclear Studies, ul. Hoza 69, 00-681 Warsaw (Poland)]. E-mail: lech.nowicki@fuw.edu.pl; Turos, A. [Andrzej SoItan Institute for Nuclear Studies, ul. Hoza 69, 00-681 Warsaw (Poland); Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw (Poland); Stonert, A. [Andrzej SoItan Institute for Nuclear Studies, ul. Hoza 69, 00-681 Warsaw (Poland); Garrido, F. [Centre de Spectrometrie Nucleaire et Spectrometrie de Masse, CNRS-IN2P3-Universite Paris-Sud, 91405 Orsay (France); Molenkamp, L.W. [Department of Physics, University Wuerzburg, Am Hubland, 97074 Wuerzburg (Germany); Bach, P. [Department of Physics, University Wuerzburg, Am Hubland, 97074 Wuerzburg (Germany); Schmidt, G. [Department of Physics, University Wuerzburg, Am Hubland, 97074 Wuerzburg (Germany); Karczewski, G. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Muecklich, A. [Forschungszentrum Rossendorf, Institut fuer Ionenstrahlphysik und Materialforschung, POB 510119, 01314 Dresden (Germany)

    2005-10-15

    NiMnSb layers grown on InP substrates with InGaAs buffer were studied by the backscattering/channeling spectrometry (RBS/C) with He beams. The nature of predominant defects observed in the layers was studied by determination of incident-energy dependence of the relative channeling yield. The defects are described as a combination of large amount of interstitial atoms and of stacking faults or grain boundaries. The presence of grains was confirmed by transmission electron microscopy.

  9. Measurement Uncertainty of Liquid Chromatographic Analyses Visualized by Ishikawa Diagrams

    OpenAIRE

    Meyer, Veronika R.

    2017-01-01

    Ishikawa, or cause-and-effect diagrams, help to visualize the parameters that influence a chromatographic analysis. Therefore, they facilitate the set up of the uncertainty budget of the analysis, which can then be expressed in mathematical form. If the uncertainty is calculated as the Gaussian sum of all uncertainty parameters, it is necessary to quantitate them all, a task that is usually not practical. The other possible approach is to use the intermediate precision as a base for the uncer...

  10. Conditional analysis near strong shear layers in DNS of isotropic turbulence at high Reynolds number

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, Takashi; Kaneda, Yukio [Graduate School of Engineering, Nagoya University (Japan); Hunt, Julian C R, E-mail: ishihara@cse.nagoya-u.ac.jp [University College of London (United Kingdom)

    2011-12-22

    Data analysis of high resolution DNS of isotropic turbulence with the Taylor scale Reynolds number R{sub {lambda}} = 1131 shows that there are thin shear layers consisting of a cluster of strong vortex tubes with typical diameter of order 10{eta}, where {eta} is the Kolmogorov length scale. The widths of the layers are of the order of the Taylor micro length scale. According to the analysis of one of the layers, coarse grained vorticity in the layer are aligned approximately in the plane of the layer so that there is a net mean shear across the layer with a mean velocity jump of the order of the root-mean-square of the fluctuating velocity, and energy dissipation averaged over the layer is larger than ten times the average over the whole flow. The mean and the standard deviation of the energy transfer T(x, {kappa}) from scales larger than 1/{kappa} to scales smaller than 1/{kappa} at position x are largest within the layers (where the most intense vortices and dissipation occur), but are also large just outside the layers (where viscous stresses are weak), by comparison with the average values of T over the whole region. The DNS data are consistent with exterior fluctuation being damped/filtered at the interface of the layer and then selectively amplified within the layer.

  11. Chromatographic Separations of Enantiomers and Underivatized Oligosaccharides

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    My graduate research has focused on separation science and bioanalytical analysis, which emphasized in method development. It includes three major areas: enantiomeric separations using high performance liquid chromatography (HPLC), Super/subcritical fluid chromatography (SFC), and capillary electrophoresis (CE); drug-protein binding behavior studies using CE; and carbohydrate analysis using liquid chromatograph-electrospray ionization mass spectrometry (LC-ESI-MS). Enantiomeric separations continue to be extremely important in the pharmaceutical industry. An in-depth evaluation of the enantiomeric separation capabilities of macrocyclic glycopeptides CSPs with SFC mobile phases was investigated using a set of over 100 chiral compounds. It was found that the macrocyclic based CSPs were able to separate enantiomers of various compounds with different polarities and functionalities. Seventy percent of all separations were achieved in less than 4 min due to the high flow rate (4.0 ml/min) that can be used in SFC. Drug-protein binding is an important process in determining the activity and fate of a drug once it enters the body. Two drug/protein systems have been studied using frontal analysis CE method. More sensitive fluorescence detection was introduced in this assay, which overcame the problem of low sensitivity that is common when using UV detection for drug-protein studies. In addition, the first usage of an argon ion laser with 257 nm beam coupled with CCD camera as a frontal analysis detection method enabled the simultaneous observation of drug fluorescence as well as the protein fluorescence. LC-ESI-MS was used for the separation and characterization of underivatized oligosaccharide mixtures. With the limits of detection as low as 50 picograms, all individual components of oligosaccharide mixtures (up to 11 glucose-units long) were baseline resolved on a Cyclobond I 2000 column and detected using ESI-MS. This system is characterized by high chromatographic

  12. Chromatographic Separations of Enantiomers and Underivatized Oligosaccharides

    International Nuclear Information System (INIS)

    Ying Liu

    2004-01-01

    My graduate research has focused on separation science and bioanalytical analysis, which emphasized in method development. It includes three major areas: enantiomeric separations using high performance liquid chromatography (HPLC), Super/subcritical fluid chromatography (SFC), and capillary electrophoresis (CE); drug-protein binding behavior studies using CE; and carbohydrate analysis using liquid chromatograph-electrospray ionization mass spectrometry (LC-ESI-MS). Enantiomeric separations continue to be extremely important in the pharmaceutical industry. An in-depth evaluation of the enantiomeric separation capabilities of macrocyclic glycopeptides CSPs with SFC mobile phases was investigated using a set of over 100 chiral compounds. It was found that the macrocyclic based CSPs were able to separate enantiomers of various compounds with different polarities and functionalities. Seventy percent of all separations were achieved in less than 4 min due to the high flow rate (4.0 ml/min) that can be used in SFC. Drug-protein binding is an important process in determining the activity and fate of a drug once it enters the body. Two drug/protein systems have been studied using frontal analysis CE method. More sensitive fluorescence detection was introduced in this assay, which overcame the problem of low sensitivity that is common when using UV detection for drug-protein studies. In addition, the first usage of an argon ion laser with 257 nm beam coupled with CCD camera as a frontal analysis detection method enabled the simultaneous observation of drug fluorescence as well as the protein fluorescence. LC-ESI-MS was used for the separation and characterization of underivatized oligosaccharide mixtures. With the limits of detection as low as 50 picograms, all individual components of oligosaccharide mixtures (up to 11 glucose-units long) were baseline resolved on a Cyclobond I 2000 column and detected using ESI-MS. This system is characterized by high chromatographic

  13. Development of a chromatographic separation method hyphenated to electro-spray ionization mass spectrometry (ESI-MS) and inductively coupled plasma mass spectrometry (ICP-MS): application to the lanthanides speciation analysis

    International Nuclear Information System (INIS)

    Beuvier, Ludovic

    2015-01-01

    This work focuses on the development of a chromatographic separation method coupled to both ESI-MS and ICP-MS in order to achieve the comprehensive speciation analysis of lanthanides in aqueous phase representative of back-extraction phases of advanced spent nuclear fuel treatment processes. This analytical method allowed the separation, the characterization and the quantitation of lanthanides complexes holding poly-aminocarboxylic ligands, such as DTPA and EDTA, used as complexing agents in these processes. A HILIC separation method of lanthanides complexes has been developed with an amide bonded stationary phase. A screening of a wide range of mobile phase compositions demonstrated that the adsorption mechanism was predominant. This screening allowed also obtaining optimized separation conditions. Faster analysis conditions with shorter amide column packed with sub 2 μm particles reduced analysis time by 2.5 and 25% solvent consumption. Isotopic and structural characterization by HILIC ESI-MS was performed as well as the development of external calibration quantitation method. Analytical performances of quantitation method were determined. Finally, the development of the HILIC coupling to ESI-MS and ICP-MS was achieved. A simultaneous quantitation method by ESI-MS and ICP-MS was performed to determine the species quantitative distribution in solution. Analytical performances of quantitation method were also determined. (author) [fr

  14. Multi-scale structural analysis of gas diffusion layers

    Science.gov (United States)

    Göbel, Martin; Godehardt, Michael; Schladitz, Katja

    2017-07-01

    The macroscopic properties of materials are strongly determined by their micro structure. Here, transport properties of gas diffusion layers (GDL) for fuel cells are considered. In order to simulate flow and thermal properties, detailed micro structural information is essential. 3D images obtained by high-resolution computed tomography using synchrotron radiation and scanning electron microscopy (SEM) combined with focused ion beam (FIB) serial slicing were used. A recent method for reconstruction of porous structures from FIB-SEM images and sophisticated morphological image transformations were applied to segment the solid structural components. The essential algorithmic steps for segmenting the different components in the tomographic data-sets are described and discussed. In this paper, two types of GDL, based on a non-woven substrate layer and a paper substrate layer were considered, respectively. More than three components are separated within the synchrotron radiation computed tomography data. That is, fiber system, polytetrafluoroethylene (PTFE) binder/impregnation, micro porous layer (MPL), inclusions within the latter, and pore space are segmented. The usage of the thus derived 3D structure data in different simulation applications can be demonstrated. Simulations of macroscopic properties such as thermal conductivity, depending on the flooding state of the GDL are possible.

  15. Neutron activation analysis of baths forming conversion layer on aluminium

    International Nuclear Information System (INIS)

    Szilagyi, Istvan; Maleczki, Emil; Bodizs, Denes

    1988-01-01

    Chromate layers were formed on the surface of aluminium using yellow and green chromating solutions. For the determination of the aluminium content neutron activation method was used. Nuclear effects disturbing the determination were eliminated by double irradiation technique. (author) 8 refs.; 4 figs

  16. Experimental analysis of drainage and water storage of litter layers

    Science.gov (United States)

    Guevara-Escobar, A.; Gonzalez-Sosa, E.; Ramos-Salinas, M.; Hernandez-Delgado, G. D.

    2007-06-01

    Leaf litter overlying forested floors are important for erosion control and slope stability, but also reduces pasture growth in silvopastoral systems. Little information exists regarding the value of percolation and storage capacity parameters for litter layers. These estimates are needed for modelling better management practices for leaf litter. Therefore, this work measured the effect of four rainfall intensities: 9.8, 30.2, 40.4 and 70.9 mm h-1 on the hydrological response of layers of three materials: recently senesced poplar leaves, fresh grass and woodchips. Maximum storage (Cmax), defined as the detention of water immediately before rainfall cessation, increased with rainfall intensity. The magnitude of the increment was 0.2 mm between the lowest and highest rainfall intensities. Mean values of Cmax were: 1.27, 1.51, 1.67 and 1.65 mm for poplar leaves; 0.63 0.77, 0.73 and 0.76 for fresh grass and; 1.64, 2.23, 2.21 and 2.16 for woodchips. Drainage parameters were: 9.9, 8.8 and 2.2 mm-1 for poplar, grass and woodchips layers. An underlying soil matrix influenced the drainage flow from poplar leaf layers producing pseudo-Hortonian overland flow, but this occurred only when the rainfall intensity was 40.4 and 70.9 mm h-1 and accounted for 0.4 and 0.8‰ of total drainage. On the other hand, the presence of a poplar leaf layer had a damping effect on the drainage rate from the underlying soil matrix, particularly at intermediate rainfall intensities: 30.2 or 40.4 mm h-1.

  17. Modeling Aquatic Toxicity through Chromatographic Systems.

    Science.gov (United States)

    Fernández-Pumarega, Alejandro; Amézqueta, Susana; Farré, Sandra; Muñoz-Pascual, Laura; Abraham, Michael H; Fuguet, Elisabet; Rosés, Martí

    2017-08-01

    Environmental risk assessment requires information about the toxicity of the growing number of chemical products coming from different origins that can contaminate water and become toxicants to aquatic species or other living beings via the trophic chain. Direct toxicity measurements using sensitive aquatic species can be carried out but they may become expensive and ethically questionable. Literature refers to the use of chromatographic measurements that correlate to the toxic effect of a compound over a specific aquatic species as an alternative to get toxicity information. In this work, we have studied the similarity in the response of the toxicity to different species and we have selected eight representative aquatic species (including tadpoles, fish, water fleas, protozoan, and bacteria) with known nonspecific toxicity to chemical substances. Next, we have selected four chromatographic systems offering good perspectives for surrogation of the eight selected aquatic systems, and thus prediction of toxicity from the chromatographic measurement. Then toxicity has been correlated to the chromatographic retention factor. Satisfactory correlation results have been obtained to emulate toxicity in five of the selected aquatic species through some of the chromatographic systems. Other aquatic species with similar characteristics to these five representative ones could also be emulated by using the same chromatographic systems. The final aim of this study is to model chemical products toxicity to aquatic species by means of chromatographic systems to reduce in vivo testing.

  18. Chromatographic properties PLOT multicapillary columns.

    Science.gov (United States)

    Nikolaeva, O A; Patrushev, Y V; Sidelnikov, V N

    2017-03-10

    Multicapillary columns (MCCs) for gas chromatography make it possible to perform high-speed analysis of the mixtures of gaseous and volatile substances at a relatively large amount of the loaded sample. The study was performed using PLOT MCCs for gas-solid chromatography (GSC) with different stationary phases (SP) based on alumina, silica and poly-(1-trimethylsilyl-1-propyne) (PTMSP) polymer as well as porous polymers divinylbenzene-styrene (DVB-St), divinylbenzene-vinylimidazole (DVB-VIm) and divinylbenzene-ethylene glycol dimethacrylate (DVB-EGD). These MCCs have the efficiency of 4000-10000 theoretical plates per meter (TP/m) and at a column length of 25-30cm can separate within 10-20s multicomponent mixtures of substances belonging to different classes of chemical compounds. The sample amount not overloading the column is 0.03-1μg and depends on the features of a porous layer. Examples of separations on some of the studied columns are considered. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Analysis of carbonyl compounds via headspace solid-phase microextraction with on-fiber derivatization and gas chromatographic-ion trap tandem mass spectrometric determination of their O-(2,3,4,5,6-pentafluorobenzyl)oxime derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Schmarr, Hans-Georg [Dienstleistungszentrum Laendlicher Raum (DLR) Rheinpfalz, Breitenweg 71, D-67435 Neustadt an der Weinstrasse (Germany)], E-mail: hans-georg.schmarr@dlr.rlp.de; Potouridis, Theodoros; Ganss, Sebastian; Sang, Wei; Koepp, Benedikt; Bokuz, Ursula; Fischer, Ulrich [Dienstleistungszentrum Laendlicher Raum (DLR) Rheinpfalz, Breitenweg 71, D-67435 Neustadt an der Weinstrasse (Germany)

    2008-06-09

    An improved method for the analysis of carbonyls is described utilizing a headspace solid-phase microextraction (HS-SPME) step and on-fiber derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) hydrochloride. Thermal desorption of the oxime derivatives formed on the fiber is followed by gas chromatographic separation coupled to an ion trap tandem mass spectrometer (GC-ITMS). Selecting specific fragment ions within the electron ionization (EI{sup +}) mass spectra of these oxime derivatives as precursor ions for MS-MS fragmentation provides a suitable method for the target analysis of individual carbonyl classes, such as alkanals, (E)-2-alkenals, (E,E)-2,4-alkadienals, and others. Retention indices on polar as well as on apolar stationary phases along with EI{sup +} mass spectra patterns are presented for a large set of oxime derivatives, giving valuable information needed for unambiguous assignment of substances in complex sample matrices. The fast sample preparation and derivatization step via HS-SPME can be automated and is applicable to a variety of biological samples and foodstuffs, allowing rapid and sensitive screening analyses of important aldehydic biomarkers and aroma active compounds.

  20. Analysis of Windward Side Hypersonic Boundary Layer Transition on Blunted Cones at Angle of Attack

    Science.gov (United States)

    2017-01-09

    correlated with PSE/LST N-Factors. 15. SUBJECT TERMS boundary layer transition, hypersonic, ground test 16. SECURITY CLASSIFICATION OF: 17. LIMITATION ...Maccoll) solution e condition at boundary layer edge w condition at wall, viscous ∞ condition in freestream Conventions LST Linear Stability Theory PSE...STATES AIR FORCE AFRL-RQ-WP-TP-2017-0169 ANALYSIS OF WINDWARD SIDE HYPERSONIC BOUNDARY LAYER TRANSITION ON BLUNTED CONES AT ANGLE OF ATTACK Roger

  1. Blocking layer modeling for temperature analysis of electron transfer ...

    African Journals Online (AJOL)

    In this article, we simulate thermal effects on the electron transfer rate from three quantum dots CdSe, CdS and CdTe to three metal oxides TiO2, SnO2 and ZnO2 in the presence of four blocking layers ZnS, ZnO, TiO2 and Al2O3, in a porous quantum dot sensitized solar cell (QDSSC) structure, using Marcus theory.

  2. Asymptotic spectral analysis in colliding leaky quantum layers

    Czech Academy of Sciences Publication Activity Database

    Kondej, S.; Krejčiřík, David

    2017-01-01

    Roč. 446, č. 2 (2017), s. 1328-1355 ISSN 0022-247X R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : quantum layers * leaky graphs * Delta interaction supported on hypersurfaces * Norm-resolvent convergence * non-self-adjoint interaction Subject RIV: BE - Theoretical Physics OBOR OECD: Applied mathematics Impact factor: 1.064, year: 2016

  3. Analysis of the transfer function for layered piezoelectric ultrasonic sensors

    Directory of Open Access Journals (Sweden)

    E. Gutiérrrez-Reyes

    2017-06-01

    Full Text Available We model theoretically the voltage response to an acoustic pulse of a multilayer system forming a low noise capacitive sensor including a Polyvinylidene Fluoride piezoelectric film. First we model a generic piezoelectric detector consisting of a piezoelectric film between two metallic electrodes that are the responsible to convert the acoustic signal into a voltage signal. Then we calculate the pressure-to-voltage transfer function for a N-layer piezo-electric capacitor detector, allowing to study the effects of the electrode and protective layers thickness in typical layered piezoelectric sensors. The derived transfer function, when multiplied by the Fourier transform of the incident acoustic pulse, gives the voltage electric response in the frequency domain. An important concern regarding the transfer function is that it may have zeros at specific frequencies, and thus inverting the voltage Fourier transform of the pulse to recover the pressure signal in the time domain is not always, in principle, possible. Our formulas can be used to predict the existence and locations of such zeroes. We illustrate the use of the transfer function by predicting the electric signal generated at a multilayer piezoelectric sensor to an ultrasonic pulse generated photoacoustically by a laser pulse at a three media system with impedance mismatch. This theoretical calculations are compared with our own experimental measurements.

  4. Gas-chromatographic separation of hydrogen isotopic mixtures

    International Nuclear Information System (INIS)

    Preda, Anisoara; Bidica, Nicolae

    2005-01-01

    Full text: Gas chromatographic separation of hydrogen isotopes have been reported in the literature since late of 1950's. Gas chromatography is primarily an analytical method, but because of its properties it may be used in many other fields with excellent results. A simple method is proposed for the gas-chromatographic analysis of complex gas mixtures containing hydrogen isotopes; the method is based on the substantial difference in the thermal conductivity of these isotopes. One of the main disadvantages of the conventional gas chromatography is the long retention times required for the analysis of hydrogen gas mixtures while the column is operated at very low temperature. The method described in this paper was based on using a capillary molecular sieve 5A column operated for this kind of separation at 173 K. The carrier gas was Ne and the detector was TCD. In the paper chromatograms for various carrier flow rates and various hydrogen isotope mixtures are presented. (authors)

  5. A Quantitative Gas Chromatographic Ethanol Determination.

    Science.gov (United States)

    Leary, James J.

    1983-01-01

    Describes a gas chromatographic experiment for the quantitative determination of volume percent ethanol in water ethanol solutions. Background information, procedures, and typical results are included. Accuracy and precision of results are both on the order of two percent. (JN)

  6. Surface analysis of uranyl fluoride layers with a glow discharge lamp

    International Nuclear Information System (INIS)

    Nel, J.T.; Stander, C.M.; Boehmer, R.G.

    1991-01-01

    Surface analysis with a Grimm-type glow discharge lamp was used to analyse uranyl fluoride layers that had formed on a nickel substrate after exposure to UF 6 . Narrow-band optical filters were used to isolate the intensities of three fluorine emission lines. An in-depth profile of layer composition was obtained. (author)

  7. Thermal analysis of a double layer phase change material floor

    International Nuclear Information System (INIS)

    Jin Xing; Zhang Xiaosong

    2011-01-01

    Phase change materials (PCMs) can be used to shift the cooling or heating load from the peak period to the off-peak period. In this paper, a new double layer phase change material (PCM) floor is put forward. The two layers of PCM have different melting temperature. The system is used to store heat or cold energy in the off-peak period and release them in the peak period during heating or cooling. According to the numerical model built in this paper, the thermal performances of the floor are analyzed. The results show that the optimal melting temperatures of PCMs exist. The fluctuations of the floor surface temperatures and the heat fluxes will be reduced and the system still can provide a certain amount of heat or cold energy after the heat pump or chiller has been turned off for a long time. Compared to the floor without PCM, the energy released by the floor with PCM in peak period will be increased by 41.1% and 37.9% during heating and cooling when the heat of fusion of PCM is 150 kJ/kg. - Highlights: → A new double layer phase change material floor is put forward. → The system is used to store heat or cold energy in the off-peak period and release them in the peak period during heating or cooling. → The optimal melting temperatures of PCMs in the system exist. → The heat and cold energy released by the floor with PCM in peak period can be increased by 41.1% and 37.9%.

  8. Analysis of a PDF model in a mixing layer case

    International Nuclear Information System (INIS)

    Minier, J.P.; Pozorski, J.

    1996-04-01

    A recent turbulence model put forward by Pope (1991) in the context of PDF modeling has been applied to a mixing layer case. This model solves the one-point joint velocity-dissipation pdf equation by simulating the instantaneous behaviour of a large number of Lagrangian fluid particles. Closure of the evolution equations of these Lagrangian particles is based on diffusion stochastic processes. The paper reports numerical results and tries to analyse the physical meaning of some variables, in particular the dissipation-weighted kinetic energy and its relation with external intermittency. (authors). 14 refs., 7 figs

  9. Mars Solar Balloon Landed Gas Chromatograph Mass Spectrometer

    Science.gov (United States)

    Mahaffy, P.; Harpold, D.; Niemann, H.; Atreya, S.; Gorevan, S.; Israel, G.; Bertaux, J. L.; Jones, J.; Owen, T.; Raulin, F.

    1999-01-01

    payload based Micromissions, it is essential to implement an even broader chemical analysis and to enable a significant extension of previous isotope measurements. Such a development would enhance the presently very active study of questions of atmospheric evolution and loss and past climatic conditions. The method selected to implement this program can be based on well-established mass spectrometry techniques. Sampled gas is chemically and physically processed to separate the gas mixture into components using gas chromatograph and related enrichment techniques. This allows trace species to be identified and reveals isotopic distributions in many cases with improved precision. Samples of interest, such as organic molecules, may lie deep below the highly oxidized surface layer and the suggested program includes enhanced sampling techniques to measure volatiles preserved in solid phase material deep below the surface as well as gas from the well mixed atmosphere.

  10. Detection and size analysis of proteins with switchable DNA layers.

    Science.gov (United States)

    Rant, Ulrich; Pringsheim, Erika; Kaiser, Wolfgang; Arinaga, Kenji; Knezevic, Jelena; Tornow, Marc; Fujita, Shozo; Yokoyama, Naoki; Abstreiter, Gerhard

    2009-04-01

    We introduce a chip-compatible scheme for the label-free detection of proteins in real-time that is based on the electrically driven conformation switching of DNA oligonucleotides on metal surfaces. The switching behavior is a sensitive indicator for the specific recognition of IgG antibodies and antibody fragments, which can be detected in quantities of less than 10(-18) mol on the sensor surface. Moreover, we show how the dynamics of the induced molecular motion can be monitored by measuring the high-frequency switching response. When proteins bind to the layer, the increase in hydrodynamic drag slows the switching dynamics, which allows us to determine the size of the captured proteins. We demonstrate the identification of different antibody fragments by means of their kinetic fingerprint. The switchDNA method represents a generic approach to simultaneously detect and size target molecules using a single analytical platform.

  11. Determination of multiresidue analysis of β-agonists in muscle and viscera using liquid chromatograph/tandem mass spectrometry with Quick, Easy, Cheap, Effective, Rugged, and Safe methodologies

    Directory of Open Access Journals (Sweden)

    Yen-Ping Lin

    2017-04-01

    Full Text Available The official analytical method of the Taiwan Food and Drug Administration, Ministry of Health and Welfare for testing for veterinary drug residues in foods is the multiresidue analysis of β-agonists. Samples are pretreated through liquid–liquid extraction and solid-phase extraction. This method is time consuming and requires the intensive use of solvents. To improve analytical efficiency and reduce costs, our study incorporated QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe techniques to establish a new method of multiresidue analysis of β-agonists in animal muscle and viscera. The pretreatment time was shortened and solvent usage was minimized. The modified analysis was conducted using liquid chromatography/tandem mass spectrometry (LC–MS/MS and quantification was performed using multiple reaction monitoring. The results demonstrated that the correlation coefficients of the tissue calibration curve were higher than 0.99 and the limit of quantification (LOQ was 1 ppb. The average recoveries in spiked samples varied from 70% to 120%, and the relative difference between duplicated analysis results was lower than 10%. On the basis of the results, the proposed method was concluded to be an appropriate procedure for determining the presence of β-agonists, and demonstrated the advantages of high recovery rates in spiked samples, high precision, reduced analysis time and solvent usage, and lower costs.

  12. Two-step ion-exchange chromatographic purification combined with reversed-phase chromatography to isolate C-peptide for mass spectrometric analysis.

    Science.gov (United States)

    Kabytaev, Kuanysh; Durairaj, Anita; Shin, Dmitriy; Rohlfing, Curt L; Connolly, Shawn; Little, Randie R; Stoyanov, Alexander V

    2016-02-01

    A liquid chromatography with mass spectrometry on-line platform that includes the orthogonal techniques of ion exchange and reversed phase chromatography is applied for C-peptide analysis. Additional improvement is achieved by the subsequent application of cation- and anion-exchange purification steps that allow for isolating components that have their isoelectric points in a narrow pH range before final reversed-phase mass spectrometry analysis. The utility of this approach for isolating fractions in the desired "pI window" for profiling complex mixtures is discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. ONLINE SINGLE-COLUMN CAPILLARY GAS-CHROMATOGRAPHIC ANALYSIS OF ALL REACTANTS AND PRODUCTS IN THE SYNTHESIS OF FUEL METHANOL FROM HYDROGEN AND OXIDES OF CARBON

    NARCIS (Netherlands)

    MARSMAN, JH; BREMAN, BB; BEENACKERS, AACM

    The main problems with complete analysis of the components of fuel methanol, or in Fischer-Tropsch studies, are the several classes of compound present in the sample (permanent gases, water, alcohols, hydrocarbons), its wide range of components, its boiling point range, and the wide range of

  14. Selective removal of water in purge and cold-trap capillary gas chromatographic analysis of volatile organic traces in aqueous samples

    NARCIS (Netherlands)

    Noij, T.H.M.; van Es, A.J.J.; Cramers, C.A.M.G.; Rijks, J.A.; Dooper, R.P.M.

    1987-01-01

    The design and features of an on-line purge and cold-trap pre-concentration device for rapid analysis of volatile organic compounds in aqueous samples are discussed. Excessive water is removed from the purge gas by a condenser or a water permeable membrane in order to avoid blocking of the capillary

  15. Validação em métodos cromatográficos para análises de pequenas moléculas em matrizes biológicas Chromatographic methods validation for analysis of small molecules in biological matrices

    OpenAIRE

    Neila Maria Cassiano; Juliana Cristina Barreiro; Lúcia Regina Rocha Martins; Regina Vincenzi Oliveira; Quezia Bezerra Cass

    2009-01-01

    Chromatographic methods are commonly used for analysis of small molecules in different biological matrices. An important step to be considered upon a bioanalytical method's development is the capacity to yield reliable and reproducible results. This review discusses validation procedures adopted by different governmental agencies, such as Food and Drug Administration (USA), European Union (EU) and Agência Nacional de Vigilância Sanitária (BR) for quantification of small molecules by bioanalyt...

  16. Application of acetone acetals as water scavengers and derivatization agents prior to the gas chromatographic analysis of polar residual solvents in aqueous samples.

    Science.gov (United States)

    van Boxtel, Niels; Wolfs, Kris; Van Schepdael, Ann; Adams, Erwin

    2015-12-18

    The sensitivity of gas chromatography (GC) combined with the full evaporation technique (FET) for the analysis of aqueous samples is limited due to the maximum tolerable sample volume in a headspace vial. Using an acetone acetal as water scavenger prior to FET-GC analysis proved to be a useful and versatile tool for the analysis of high boiling analytes in aqueous samples. 2,2-Dimethoxypropane (DMP) was used in this case resulting in methanol and acetone as reaction products with water. These solvents are relatively volatile and were easily removed by evaporation enabling sample enrichment leading to 10-fold improvement in sensitivity compared to the standard 10μL FET sample volumes for a selection of typical high boiling polar residual solvents in water. This could be improved even further if more sample is used. The method was applied for the determination of residual NMP in an aqueous solution of a cefotaxime analogue and proved to be considerably better than conventional static headspace (sHS) and the standard FET approach. The methodology was also applied to determine trace amounts of ethylene glycol (EG) in aqueous samples like contact lens fluids, where scavenging of the water would avoid laborious extraction prior to derivatization. During this experiment it was revealed that DMP reacts quantitatively with EG to form 2,2-dimethyl-1,3-dioxolane (2,2-DD) under the proposed reaction conditions. The relatively high volatility (bp 93°C) of 2,2-DD makes it possible to perform analysis of EG using the sHS methodology making additional derivatization reactions superfluous. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Analysis of buried etch-stop layers in silicon by nitrogen-ion implantation

    International Nuclear Information System (INIS)

    Acero, M.C.; Esteve, J.; Montserrat, J.; Perez-Rodriguez, A.; Garrido, B.; Romano-Rodriguez, A.; Morante, J.R.

    1993-01-01

    The analysis of the etch-stop properties of layers obtained by substoichiometric nitrogen-ion implantation and annealing in silicon has been performed as a function of the implantation conditions. The analysis of the etching efficiency has been tested in TMAH-IPA systems. The results obtained show the need to implant at doses higher than 2 x 10 17 cm -2 to obtain etch-stop layers stable under high-temperature annealing. So, for implantation doses of 5 x 10 17 cm -2 , layers stand unetched for times longer than 2 h. The preliminary structural analysis of the samples suggests the presence of an amorphous silicon nitride layer for higher implantation doses. (author)

  18. Analysis of buried etch-stop layers in silicon by nitrogen-ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Acero, M.C.; Esteve, J.; Montserrat, J. (Centro Nacional de Microelectronica (CNM-CSIC), Bellaterra (Spain)); Perez-Rodriguez, A.; Garrido, B.; Romano-Rodriguez, A.; Morante, J.R. (Barcelona Univ. (Spain). Dept. Fisica Aplicada i Electronica)

    1993-09-01

    The analysis of the etch-stop properties of layers obtained by substoichiometric nitrogen-ion implantation and annealing in silicon has been performed as a function of the implantation conditions. The analysis of the etching efficiency has been tested in TMAH-IPA systems. The results obtained show the need to implant at doses higher than 2 x 10[sup 17] cm[sup -2] to obtain etch-stop layers stable under high-temperature annealing. So, for implantation doses of 5 x 10[sup 17] cm[sup -2], layers stand unetched for times longer than 2 h. The preliminary structural analysis of the samples suggests the presence of an amorphous silicon nitride layer for higher implantation doses. (author).

  19. Gas Chromatographic-Ion Trap Mass Spectrometric Analysis of Volatile Organic Compounds by Ion-Molecule Reactions Using the Electron-Deficient Reagent Ion CCl{3/+}

    Science.gov (United States)

    Wang, Cheng-Zhong; Su, Yue; Wang, Hao-Yang; Guo, Yin-Long

    2011-10-01

    When using tetrachloromethane as the reagent gas in gas chromatography-ion trap mass spectrometry equipped with hybrid ionization source, the cation CCl{3/+} was generated in high abundance and further gas-phase experiments showed that such an electron-deficient reagent ion CCl{3/+} could undergo interesting ion-molecule reactions with various volatile organic compounds, which not only present some informative gas-phase reactions, but also facilitate qualitative analysis of diverse volatile compounds by providing unique mass spectral data that are characteristic of particular chemical structures. The ion-molecule reactions of the reagent ion CCl{3/+} with different types of compounds were studied, and results showed that such reactions could give rise to structurally diagnostic ions, such as [M + CCl3 - HCl]+ for aromatic hydrocarbons, [M - OH]+ for saturated cyclic ether, ketone, and alcoholic compounds, [M - H]+ ion for monoterpenes, M·+ for sesquiterpenes, [M - CH3CO]+ for esters, as well as the further fragment ions. The mechanisms of ion-molecule reactions of aromatic hydrocarbons, aliphatic ketones and alcoholic compounds with the reagent ion CCl{3/+} were investigated and proposed according to the information provided by MS/MS experiments and theoretical calculations. Then, this method was applied to study volatile organic compounds in Dendranthema indicum var. aromaticum and 20 compounds, including monoterpenes and their oxygen-containing derivatives, aromatic hydrocarbon and sesquiterpenes were identified using such ion-molecule reactions. This study offers a perspective and an alternative tool for the analysis and identification of various volatile compounds.

  20. A Sensitive Method Approach for Chromatographic Analysis of Gas Streams in Separation Processes Based on Columns Packed with an Adsorbent Material

    Directory of Open Access Journals (Sweden)

    I. A. A. C. Esteves

    2016-01-01

    Full Text Available A sensitive method was developed and experimentally validated for the in-line analysis and quantification of gaseous feed and product streams of separation processes under research and development based on column chromatography. The analysis uses a specific mass spectrometry method coupled to engineering processes, such as Pressure Swing Adsorption (PSA and Simulated Moving Bed (SMB, which are examples of popular continuous separation technologies that can be used in applications such as natural gas and biogas purifications or carbon dioxide sequestration. These processes employ column adsorption equilibria on adsorbent materials, thus requiring real-time gas stream composition quantification. For this assay, an internal standard is assumed and a single-point calibration is used in a simple mixture-specific algorithm. The accuracy of the method was found to be between 0.01% and 0.25% (-mol for mixtures of CO2, CH4, and N2, tested as case-studies. This makes the method feasible for streams with quality control levels that can be used as a standard monitoring and analyzing procedure.

  1. Nanofluid of zinc oxide nanoparticles in ionic liquid for single drop liquid microextraction of fungicides in environmental waters prior to high performance liquid chromatographic analysis.

    Science.gov (United States)

    Amde, Meseret; Tan, Zhi-Qiang; Liu, Rui; Liu, Jing-Fu

    2015-05-22

    Using a nanofluid obtained by dispersing ZnO nanoparticles (ZnO NPs) in 1-hexyl-3-methylimidazolium hexafluorophosphate, new single drop microextraction method was developed for simultaneous extraction of three fungicides (chlorothalonil, kresoxim-methyl and famoxadone) in water samples prior to their analysis by high performance liquid chromatography (HPLC-VWD). The parameters affecting the extraction efficiency such as amount of ZnO NPs in the nanofluid, solvent volume, extraction time, stirring rate, pH and ionic strength of the sample solution were optimized. Under the optimized conditions, the limits of detection were in the range of 0.13-0.19ng/mL, the precision of the method assessed with intra-day and inter-day relative standard deviations were water samples including lake water, river water, as well as effluent and influent of wastewater treatment plant, with recoveries in the range of 74.94-96.11% at 5ng/mL spiking level. Besides to being environmental friendly, the high enrichment factor and the data quality obtained with the proposed method demonstrated its potential for application in multi residue analysis of fungicides in actual water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Application of Finite Layer Method in Pavement Structural Analysis

    Directory of Open Access Journals (Sweden)

    Pengfei Liu

    2017-06-01

    Full Text Available The finite element (FE method has been widely used in predicting the structural responses of asphalt pavements. However, the three-dimensional (3D modeling in general-purpose FE software systems such as ABAQUS requires extensive computations and is relatively time-consuming. To address this issue, a specific computational code EasyFEM was developed based on the finite layer method (FLM for analyzing structural responses of asphalt pavements under a static load. Basically, it is a 3D FE code that requires only a one-dimensional (1D mesh by incorporating analytical methods and using Fourier series in the other two dimensions, which can significantly reduce the computational time and required resources due to the easy implementation of parallel computing technology. Moreover, a newly-developed Element Energy Projection (EEP method for super-convergent calculations was implemented in EasyFEM to improve the accuracy of solutions for strains and stresses over the whole pavement model. The accuracy of the program is verified by comparing it with results from BISAR and ABAQUS for a typical asphalt pavement structure. The results show that the predicted responses from ABAQUS and EasyFEM are in good agreement with each other. The EasyFEM with the EEP post-processing technique converges faster compared with the results derived from ordinary EasyFEM applications, which proves that the EEP technique can improve the accuracy of strains and stresses from EasyFEM. In summary, the EasyFEM has a potential to provide a flexible and robust platform for the numerical simulation of asphalt pavements and can easily be post-processed with the EEP technique to enhance its advantages.

  3. Theoretical basis of quantification for layer of protection analysis (LOPA)

    International Nuclear Information System (INIS)

    Jin, Jianghong; Shuai, Bing; Wang, Xiaodong; Zhu, Zuogang

    2016-01-01

    Highlights: • When there is an IPL and λ 0 ⩾ 1, λ(t) and λ 0 don’t have logarithm linear relation any more. • The equations of scenario frequency of the low and high demand mode are different. • As long as an initiating event contributes more than 50% to the overall frequency, maximum is better than summation. • There are shared IPLs of initial events, so maximum is better than summation. • The bigger dependence degree of initial event is, the better maximum method is. - Abstract: In order to guide the corrective application of LOPA, this paper tries to discuss the theoretical basis of quantification for LOPA by comparing the computing methods of event tree consequences. It also discusses the computing equations for scenario frequency of the high demand mode by taking the scenario frequency of an initial event with one independent layer of protection (IPL) as example. Based on the probability theory, the computing method for scenario frequency of multiple initial events is improved and the application principle of two methods, i.e. summation and maximum value are brought forth. Research results show that the scenario frequency of the low demand mode has a specific computing equation. But for the high demand mode, the IPLs should be analyzed one by one, and the computing equation should be selected according to the demand mode of an IPL. As long as a single initiating event contributes more than 50% to the overall frequency of a particular consequence or the accident scenario induced by each initial event has the shared IPL, maximum value method is appropriate; otherwise, summation method should be adopted.

  4. Ring-element analysis of layered orthotropic bodies

    DEFF Research Database (Denmark)

    Jørgensen, O.

    1993-01-01

    For the analysis of arbitrarily laminated circular bodies, a displacement-based ring-element is presented. The analysis is performed in a cylindrical coordinate system. The method of analysis requires the boundary conditions as well as the external forces to be pi-periodic. The element formulation...... accounts for a desired degree of approximation of the displacement field in the direction of the circumference. This is done by a truncated Fourier expansion of the angular dependence of the displacements in terms of trigonometric functions. Thus the Fourier expansion coefficients are the unknowns...... to that of solutions obtained by traditional 3D elements. A scheme for analytical integration of the angular dependence of the stiffness matrix is given....

  5. Correlations between chromatographic parameters and bioactivity predictors of potential herbicides.

    Science.gov (United States)

    Janicka, Małgorzata

    2014-08-01

    Different liquid chromatography techniques, including reversed-phase liquid chromatography on Purosphere RP-18e, IAM.PC.DD2 and Cosmosil Cholester columns and micellar liqud chromatography with a Purosphere RP-8e column and using buffered sodium dodecyl sulfate-acetonitrile as the mobile phase, were applied to study the lipophilic properties of 15 newly synthesized phenoxyacetic and carbamic acid derivatives, which are potential herbicides. Chromatographic lipophilicity descriptors were used to extrapolate log k parameters (log kw and log km) and log k values. Partitioning lipophilicity descriptors, i.e., log P coefficients in an n-octanol-water system, were computed from the molecular structures of the tested compounds. Bioactivity descriptors, including partition coefficients in a water-plant cuticle system and water-human serum albumin and coefficients for human skin partition and permeation were calculated in silico by ACD/ADME software using the linear solvation energy relationship of Abraham. Principal component analysis was applied to describe similarities between various chromatographic and partitioning lipophilicities. Highly significant, predictive linear relationships were found between chromatographic parameters and bioactivity descriptors. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. Ground subsidence information as a valuable layer in GIS analysis

    Science.gov (United States)

    Murdzek, Radosław; Malik, Hubert; Leśniak, Andrzej

    2018-04-01

    Among the technologies used to improve functioning of local governments the geographic information systems (GIS) are widely used. GIS tools allow to simultaneously integrate spatial data resources, analyse them, process and use them to make strategic decisions. Nowadays GIS analysis is widely used in spatial planning or environmental protection. In these applications a number of spatial information are utilized, but rarely it is an information about environmental hazards. This paper includes information about ground subsidence that occurred in USCB mining area into GIS analysis. Monitoring of this phenomenon can be carried out using the radar differential interferometry (DInSAR) method.

  7. Ground subsidence information as a valuable layer in GIS analysis

    Directory of Open Access Journals (Sweden)

    Murdzek Radosław

    2018-01-01

    Full Text Available Among the technologies used to improve functioning of local governments the geographic information systems (GIS are widely used. GIS tools allow to simultaneously integrate spatial data resources, analyse them, process and use them to make strategic decisions. Nowadays GIS analysis is widely used in spatial planning or environmental protection. In these applications a number of spatial information are utilized, but rarely it is an information about environmental hazards. This paper includes information about ground subsidence that occurred in USCB mining area into GIS analysis. Monitoring of this phenomenon can be carried out using the radar differential interferometry (DInSAR method.

  8. Covalent triazine framework-1 as adsorbent for inline solid phase extraction-high performance liquid chromatographic analysis of trace nitroimidazoles in porcine liver and environmental waters.

    Science.gov (United States)

    Zhong, Cheng; Chen, Beibei; He, Man; Hu, Bin

    2017-02-03

    In this study, covalent triazine framework-1 (CTF-1) was adopted as solid phase extraction (SPE) sorbents, and a method of SPE inline coupled with high performance liquid chromatography-ultraviolet (HPLC-UV) detection was developed for trace analysis of three nitroimidazolaes (including metronidazole, ronidazole and dimetridazole) in porcine liver and environmental water samples. CTF-1 has rich π-electron and N containing triazine, thus can form π-π interaction and intermolecular hydrogen bond with three target polar nitroimidazoles, resulting in high extraction efficiency (87%-98%). Besides, CTF-1 has large specific area, which benefits rapid mass transfer and low column pressure, leading to fast adsorption/desorption dynamics. Several parameters affecting inline SPE including pH, sample flow rate, sample volume, desorption reagents, elution flow rate, elution volume, and ionic strength were investigated. Under the optimal experimental conditions, the limits of detection (S/N=3) were found to be in the range of 0.11-0.13μg/L. The enrichment factors (EFs) ranged from 52 to 59 fold (theoretical EF was 60-fold). The relative standard deviations were in the range of 4.3-9.4% (n=7, c=1μg/L), and the linear range was 0.5-500μg/L for three target analytes. The sample throughput is 7/h. The proposed method was successfully applied to the analysis of nitroimidazoles in porcine liver and environmental water samples with good recoveries for the spiked samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. New insights into comparison between synthetic and practical municipal wastewater in cake layer characteristic analysis of membrane bioreactor.

    Science.gov (United States)

    Zhou, Lijie; Zhuang, Wei-Qin; Wang, Xin; Yu, Ke; Yang, Shufang; Xia, Siqing

    2017-11-01

    In previous studies, cake layer analysis in membrane bioreactor (MBR) was both carried out with synthetic and practical municipal wastewater (SMW and PMW), leading to different results. This study aimed to identify the comparison between SMW and PMW in cake layer characteristic analysis of MBR. Two laboratory-scale anoxic/oxic MBRs were operated for over 90days with SMW and PMW, respectively. Results showed that PMW led to rough cake layer surface with particles, and the aggravation of cake layer formation with thinner and denser cake layer. Additionally, inorganic components, especially Si and Al, in PMW accumulated into cake layer and strengthened the cake layer structure, inducing severer biofouling. However, SMW promoted bacterial metabolism during cake layer formation, thus aggravated the accumulation of organic components into cake layer. Therefore, SMW highlighted the organic components in cake layer, but weakened the inorganic functions in practical MBR operation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Front and back side SIMS analysis of boron-doped delta-layer in diamond

    Energy Technology Data Exchange (ETDEWEB)

    Pinault-Thaury, M.-A., E-mail: marie-amandine.pinault-thaury@uvsq.fr [Groupe d’Etude de la Matière Condensée, CNRS, University of Paris Saclay, University of Versailles St Quentin, 45 Avenue des Etats-Unis, 78035 Versailles Cedex (France); Jomard, F. [Groupe d’Etude de la Matière Condensée, CNRS, University of Paris Saclay, University of Versailles St Quentin, 45 Avenue des Etats-Unis, 78035 Versailles Cedex (France); Mer-Calfati, C.; Tranchant, N.; Pomorski, M.; Bergonzo, P.; Arnault, J.-C. [CEA, LIST, Diamond Sensors Laboratory, 91191 Gif-sur-Yvette (France)

    2017-07-15

    Highlights: • Front and back side SIMS analysis of delta-layer boron-doped is a first for diamond. • Combination of front and back side depth profiling improves delta-layer analyses. • Sharp interfaces are evidenced on both sides of the delta-layer boron-doped diamond. • The growth of delta-layer boron doped diamond is now well controlled. - Abstract: Nowadays the availability of very thin diamond layers in the range of nanometers as well as the possibility to characterize such delta-layer structures are required for the field of photonics and spintronics, but also for the development of next generation high power devices involving boron doping. The fabrication of diamond structures with abrupt interfaces such as superlattices and quantum wells has been recently improved. A very accurate characterization is then essential even though the analysis of such structures is arduous and challenging. SIMS analyses are commonly used to obtain depth profiles of dopants. However, below 10 nm in thickness, SIMS induced ion mixing effects which are no longer negligible. Then the raw SIMS profile might differ from the real dopant profile. In this study, we have analyzed a diamond structure containing a thin boron epilayer, especially synthesized to achieve SIMS analysis on both sides and to overcome the effects of ion mixing. We evidence the ion mixing induced by primary ions. Such a structure is a delta diamond layer, comparable to classical boron-doped delta-layer in silicon. Our results show that the growth of boron-doped delta-layer in diamond is now well controlled in terms of thickness and interfaces.

  11. Infrared reflectometry of skin: Analysis of backscattered light from different skin layers

    Science.gov (United States)

    Pleitez, Miguel A.; Hertzberg, Otto; Bauer, Alexander; Lieblein, Tobias; Glasmacher, Mathias; Tholl, Hans; Mäntele, Werner

    2017-09-01

    We have recently reported infrared spectroscopy of human skin in vivo using quantum cascade laser excitation and photoacoustic or photothermal detection for non-invasive glucose measurement . Here, we analyze the IR light diffusely reflected from skin layers for spectral contributions of glucose. Excitation of human skin by an external cavity tunable quantum cascade laser in the spectral region from 1000 to 1245 cm- 1, where glucose exhibits a fingerprint absorption, yields reflectance spectra with some contributions from glucose molecules. A simple three-layer model of skin was used to calculate the scattering intensities from the surface and from shallow and deeper layers using the Boltzmann radiation transfer equation. Backscattering of light at wavelengths around 10 μm from the living skin occurs mostly from the Stratum corneum top layers and the shallow layers of the living epidermis. The analysis of the polarization of the backscattered light confirms this calculation. Polarization is essentially unchanged; only a very small fraction (light is due to specular reflectance and to scattering from layers close to the surface. Diffusely reflected light from deeper layers undergoing one or more scattering processes would appear with significantly altered polarization. We thus conclude that a non-invasive glucose measurement based on backscattering of IR light from skin would have the drawback that only shallow layers containing some glucose at concentrations only weakly related to blood glucose are monitored.

  12. Chromatographic and Spectral Analysis of Two Main Extractable Compounds Present in Aqueous Extracts of Laminated Aluminum Foil Used for Protecting LDPE-Filled Drug Vials

    Science.gov (United States)

    Akapo, Samuel O.; Syed, Sajid; Mamangun, Anicia; Skinner, Wayne

    2009-01-01

    Laminated aluminum foils are increasingly being used to protect drug products packaged in semipermeable containers (e.g., low-density polyethylene (LDPE)) from degradation and/or evaporation. The direct contact of such materials with primary packaging containers may potentially lead to adulteration of the drug product by extractable or leachable compounds present in the closure system. In this paper, we described a simple and reliable HPLC method for analysis of an aqueous extract of laminated aluminum foil overwrap used for packaging LDPE vials filled with aqueous pharmaceutical formulations. By means of combined HPLC-UV, GC/MS, LC/MS/MS, and NMR spectroscopy, the two major compounds detected in the aqueous extracts of the representative commercial overwraps were identified as cyclic oligomers with molecular weights of 452 and 472 and are possibly formed from poly-condensation of the adhesive components, namely, isophthalic acid, adipic acid, and diethylene glycol. Lower molecular weight compounds that might be associated with the “building blocks” of these compounds were not detected in the aqueous extracts. PMID:20140083

  13. Gas chromatographic-mass spectrometric analysis of urinary volatile organic metabolites: Optimization of the HS-SPME procedure and sample storage conditions.

    Science.gov (United States)

    Živković Semren, Tanja; Brčić Karačonji, Irena; Safner, Toni; Brajenović, Nataša; Tariba Lovaković, Blanka; Pizent, Alica

    2018-01-01

    Non-targeted metabolomics research of human volatile urinary metabolome can be used to identify potential biomarkers associated with the changes in metabolism related to various health disorders. To ensure reliable analysis of urinary volatile organic metabolites (VOMs) by gas chromatography-mass spectrometry (GC-MS), parameters affecting the headspace-solid phase microextraction (HS-SPME) procedure have been evaluated and optimized. The influence of incubation and extraction temperatures and times, coating fibre material and salt addition on SPME efficiency was investigated by multivariate optimization methods using reduced factorial and Doehlert matrix designs. The results showed optimum values for temperature to be 60°C, extraction time 50min, and incubation time 35min. The proposed conditions were applied to investigate urine samples' stability regarding different storage conditions and freeze-thaw processes. The sum of peak areas of urine samples stored at 4°C, -20°C, and -80°C up to six months showed a time dependent decrease over time although storage at -80°C resulted in a slight non-significant reduction comparing to the fresh sample. However, due to the volatile nature of the analysed compounds, more than two cycles of freezing/thawing of the sample stored for six months at -80°C should be avoided whenever possible. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Simple protein precipitation extraction technique followed by validated chromatographic method for linezolid analysis in real human plasma samples to study its pharmacokinetics.

    Science.gov (United States)

    Mohammed, Samah A; Eissa, Maya S; Ahmed, Hytham M

    2017-02-01

    Fast and sensitive HPLC method was developed, optimized and validated for quantification of linezolid (LNZ) in human plasma using guaifenesin as an internal standard (IS). Analyte and IS were extracted from plasma by simple protein precipitation extraction technique using methanol as the precipitating solvent. The pretreated samples were injected in a mobile phase formed of acetonitrile:water:methanol (20:70:10v/v/v) in an isocratic mode at a flow rate of 1.5mL/min with UV detection at 251nm. Separation was done using Aglient ODS C 18 . The method showed linearity in the range of 0.75-50μg/mL with correlation coefficients equals to 0.9991. Precision and accuracy were in conformity with the criteria normally accepted in bio-analytical method validation. The RSDs for intra- and inter-day assays were <3.56 and 4.63%, respectively. The intra- and inter-day accuracies were 94.67-98.28% and 91.25-96.18%, respectively. The mean absolute recoveries ranged from 92.56±1.78 to 95.24±2.84. According to stability results, LNZ was stable in human plasma during the storage and analysis. LNZ a pharmacokinetic behavior was studied by applying the proposed analytical method. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Automated multi-plug filtration cleanup for liquid chromatographic-tandem mass spectrometric pesticide multi-residue analysis in representative crop commodities.

    Science.gov (United States)

    Qin, Yuhong; Zhang, Jingru; Zhang, Yuan; Li, Fangbing; Han, Yongtao; Zou, Nan; Xu, Haowei; Qian, Meiyuan; Pan, Canping

    2016-09-02

    An automated multi-plug filtration cleanup (m-PFC) method on modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) extracts was developed. The automatic device was aimed to reduce labor-consuming manual operation workload in the cleanup steps. It could control the volume and the speed of pulling and pushing cycles accurately. In this work, m-PFC was based on multi-walled carbon nanotubes (MWCNTs) mixed with other sorbents and anhydrous magnesium sulfate (MgSO4) in a packed tip for analysis of pesticide multi-residues in crop commodities followed by liquid chromatography with tandem mass spectrometric (LC-MS/MS) detection. It was validated by analyzing 25 pesticides in six representative matrices spiked at two concentration levels of 10 and 100μg/kg. Salts, sorbents, m-PFC procedure, automated pulling and pushing volume, automated pulling speed, and pushing speed for each matrix were optimized. After optimization, two general automated m-PFC methods were introduced to relatively simple (apple, citrus fruit, peanut) and relatively complex (spinach, leek, green tea) matrices. Spike recoveries were within 83 and 108% and 1-14% RSD for most analytes in the tested matrices. Matrix-matched calibrations were performed with the coefficients of determination >0.997 between concentration levels of 10 and 1000μg/kg. The developed method was successfully applied to the determination of pesticide residues in market samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Analytical evaluation of BEA zeolite for the pre-concentration of polycyclic aromatic hydrocarbons and their subsequent chromatographic analysis in water samples.

    Science.gov (United States)

    Wilson, Walter B; Costa, Andréia A; Wang, Huiyong; Dias, José A; Dias, Sílvia C L; Campiglia, Andres D

    2012-07-06

    The analytical performance of BEA - a commercial zeolite - is evaluated for the pre-concentration of fifteen Environmental Protection Agency - polycyclic aromatic hydrocarbons and their subsequent HPLC analysis in tap and lake water samples. The pre-concentration factors obtained with BEA have led to a method with excellent analytical figures of merit. One milliliter aliquots were sufficient to obtain excellent precision of measurements at the parts-per-trillion concentration level with relative standard deviations varying from 4.1% (dibenzo[a,h]anthracene) to 13.4% (pyrene). The limits of detection were excellent as well and varied between 1.1 (anthracene) and 49.9 ng L(-1) (indeno[1,2,3-cd]pyrene). The recovery values of all the studied compounds meet the criterion for regulated polycyclic aromatic hydrocarbons, which mandates relative standard deviations equal or lower than 25%. The small volume of organic solvents (100 μL per sample) and amount of BEA (2 mg per sample) makes sample pre-concentration environmentally friendly and cost effective. The extraction procedure is well suited for numerous samples as the small working volume (1 mL) facilitates the implementation of simultaneous sample extraction. These are attractive features when routine monitoring of numerous samples is contemplated. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Quali-quantitative characterization of the volatile constituents in Cordia verbenacea D.C. essential oil exploiting advanced chromatographic approaches and nuclear magnetic resonance analysis.

    Science.gov (United States)

    Sciarrone, Danilo; Giuffrida, Daniele; Rotondo, Archimede; Micalizzi, Giuseppe; Zoccali, Mariosimone; Pantò, Sebastiano; Donato, Paola; Rodrigues-das-Dores, Rosana Goncalves; Mondello, Luigi

    2017-11-17

    Cordia verbenacea D.C. (Boraginaceae, Varronia curassavica Jacq. synonym) is a medicinal plant, native from Brazil, especially the leaves are used in folk medicine. The aim of this study was to extend the characterization of the volatile fraction of the essential oil obtained from this plant, by using GC-FID, GC-MS, and chiral GC. Moreover, to further clarify the composition of the volatile fraction, preparative multidimensional-GC (prep-MDGC) was used to collect unknown compounds, followed by NMR characterization. Specifically, the chemical characterization, both qualitative and quantitative, of the volatile fraction of the essential oil obtained from Cordia verbenacea cultivated in the Minas Gerais area (central area of Brazil) was investigated for the first time. The principal components from a quantitative point of view were α-pinene (25.32%; 24.48g/100g) and α-santalene (17.90%; 17.30g/100g), belonging to the terpenes family. Chiral-GC data are reported for the enantiomeric distribution of 7 different components. Last, to obtain the complete characterization of the essential oil constituents, prep-MDGC analysis was used to attain the isolation of two compounds, not present in the principal MS databases, which were unambiguously identified by NMR investigation as (E)-α-santalal and (E)-α-bergamotenal, reported for the first time in Cordia verbenacea essential oil. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Reverse phase high performance liquid chromatographic method development based on ultravioletvisible detector for the analysis of 1-hydroxypyrene (PAH biomarker) in human urine.

    Science.gov (United States)

    Kamal, Atif; Gulfraz, Mohammad; Anwar, Mohammad Asad; Malik, Riffat Naseem

    2015-01-01

    1-hydroxypyrene is an important biomarker of exposure to polycyclic aromatic hydrocarbons (PAHs), which appears in the urine of exposed human subjects. In developing countries, where advanced instruments are not available, the importance of this biomarker demands convenient and sensitive methods for determination purposes. This study aimed at developing a methodology to quantify 1-hydroxypyrene (a biomarker of PAHs exposure) based on the UV-visible detector in the reverse phase high pressure liquid chromatography (HPLC). A 20 μl injection of sample was used for manual injection into the HPLC Shimadzu, equipped with the SPD-20 A UV-visible detector, the LC-20AT pump and the DGU-20A5 degasser. The C-18 column was used for the purpose of the analysis. The method showed a good linearity (the range: R2 = 0.979-0.989), and high detectability up to the nmol level. The average retention was 6.37, with the accuracy of 2%, and the percentage of recovery remained 108%. The overall performance of this method was comparable (in terms of detection sensitivity) and relatively better than previously reported studies using the HPLC system equipped with the UV-detector. This method is suitable and reliable for the detection/quantification of the 1-OHP in human urine samples, using the UV-detector, however, it is less sensitive as compared to the results of a florescence detector. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  19. Sensitivity enhancement by chromatographic peak concentration with ultra-high performance liquid chromatography-nuclear magnetic resonance spectroscopy for minor impurity analysis.

    Science.gov (United States)

    Tokunaga, Takashi; Akagi, Ken-Ichi; Okamoto, Masahiko

    2017-07-28

    High performance liquid chromatography can be coupled with nuclear magnetic resonance (NMR) spectroscopy to give a powerful analytical method known as liquid chromatography-nuclear magnetic resonance (LC-NMR) spectroscopy, which can be used to determine the chemical structures of the components of complex mixtures. However, intrinsic limitations in the sensitivity of NMR spectroscopy have restricted the scope of this procedure, and resolving these limitations remains a critical problem for analysis. In this study, we coupled ultra-high performance liquid chromatography (UHPLC) with NMR to give a simple and versatile analytical method with higher sensitivity than conventional LC-NMR. UHPLC separation enabled the concentration of individual peaks to give a volume similar to that of the NMR flow cell, thereby maximizing the sensitivity to the theoretical upper limit. The UHPLC concentration of compound peaks present at typical impurity levels (5.0-13.1 nmol) in a mixture led to at most three-fold increase in the signal-to-noise ratio compared with LC-NMR. Furthermore, we demonstrated the use of UHPLC-NMR for obtaining structural information of a minor impurity in a reaction mixture in actual laboratory-scale development of a synthetic process. Using UHPLC-NMR, the experimental run times for chromatography and NMR were greatly reduced compared with LC-NMR. UHPLC-NMR successfully overcomes the difficulties associated with analyses of minor components in a complex mixture by LC-NMR, which are problematic even when an ultra-high field magnet and cryogenic probe are used. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Decomposition Methods For a Piv Data Analysis with Application to a Boundary Layer Separation Dynamics

    Directory of Open Access Journals (Sweden)

    Václav URUBA

    2010-12-01

    Full Text Available Separation of the turbulent boundary layer (BL on a flat plate under adverse pressure gradient was studied experimentally using Time-Resolved PIV technique. The results of spatio-temporal analysis of flow-field in the separation zone are presented. For this purpose, the POD (Proper Orthogonal Decomposition and its extension BOD (Bi-Orthogonal Decomposition techniques are applied as well as dynamical approach based on POPs (Principal Oscillation Patterns method. The study contributes to understanding physical mechanisms of a boundary layer separation process. The acquired information could be used to improve strategies of a boundary layer separation control.

  1. Collisional boundary layer analysis for neoclassical toroidal plasma viscosity in tokamaks

    International Nuclear Information System (INIS)

    Shaing, K. C.; Cahyna, P.; Becoulet, M.; Park, J.-K.; Sabbagh, S. A.; Chu, M. S.

    2008-01-01

    It is demonstrated that the pitch angle integrals in the transport fluxes in the ν regime calculated in K. C. Shang [Phys. Plasmas 10, 1443 (2003)] are divergent as the trapped-circulating boundary is approached. Here, ν is the collision frequency. The origin of this divergence results from the logarithmic dependence in the bounce averaged radial drift velocity. A collisional boundary layer analysis is developed to remove the singularity. The resultant pitch angle integrals now include not only the original physics of the ν regime but also the boundary layer physics. The transport fluxes, caused by the particles inside the boundary layer, scale as √(ν)

  2. CFD Analysis of a Centrifugal Fan for Performance Enhancement using Converging Boundary Layer Suction Slots

    OpenAIRE

    K. Vasudeva Karanth; N. Yagnesh Sharma

    2009-01-01

    Generally flow behavior in centrifugal fan is observed to be in a state of instability with flow separation zones on suction surface as well as near the front shroud. Overall performance of the diffusion process in a centrifugal fan could be enhanced by judiciously introducing the boundary layer suction slots. With easy accessibility of CFD as an analytical tool, an extensive numerical whole field analysis of the effect of boundary layer suction slots in discrete regions ...

  3. Validated determination of losartan and valsartan in human plasma by stir bar sorptive extraction based on acrylate monolithic polymer, liquid chromatographic analysis and experimental design methodology.

    Science.gov (United States)

    Babarahimi, Vida; Talebpour, Zahra; Haghighi, Farideh; Adib, Nuoshin; Vahidi, Hamed

    2018-05-10

    In our previous work, a new monolithic coating based on vinylpyrrolidone-ethylene glycol dimethacrylate polymer was introduced for stir bar sorptive extraction. The formulation of the prepared vinylpyrrolidone-ethylene glycol dimethacrylate monolithic polymer was optimized and the satisfactory quality of prepared coated stir bar was demonstrated. In this work, the prepared stir bar was utilized in combination with ultrasound-assisted liquid desorption, followed by high-performance liquid chromatography with ultraviolet detection for the simultaneous determination of losartan (LOS) and valsartan (VAS) in human plasma samples. In a comparison study, the extraction efficiency of the prepared stir bar was accompanied much higher extraction efficiency than the two commercial stir bars (polydimethylsiloxand and polyacrylate) for both target compounds. In order to improve the desorption efficiency of LOS and VAS, the best values for effective parameters on desorption step were selected systematically. Also, the effective parameters on extraction step were optimized using a Box-Behnken design. Under the optimum conditions, the analytical performance of the proposed method displayed excellent linear dynamic ranges for LOS (24-1000 ng mL -1 ) and VAS (91-1000 ng mL -1 ), with correlation coefficients of 0.9998 and 0.9971 and detection limits of 7 and 27 ng mL -1 , respectively. The intra- and inter-day recovery ranged from 98 to 117%, and the relative standard deviations were less than 8%. Finally, the proposed technique was successfully applied to the analysis of LOS and VAS at their therapeutic levels in volunteer patient plasma sample. The obtained results were confirmed using liquid chromatography-mass spectrometry. The proposed technique was more rapid than previously reported stir bar sorptive extraction techniques based on monolithic coatings, and exhibited lower detection limits in comparison with similar methods for the determination of LOS and VLS in

  4. Enhancement of early cervical cancer diagnosis with epithelial layer analysis of fluorescence lifetime images.

    Directory of Open Access Journals (Sweden)

    Jun Gu

    Full Text Available This work reports the use of layer analysis to aid the fluorescence lifetime diagnosis of cervical intraepithelial neoplasia (CIN from H&E stained cervical tissue sections. The mean and standard deviation of lifetimes in single region of interest (ROI of cervical epithelium were previously shown to correlate to the gold standard histopathological classification of early cervical cancer. These previously defined single ROIs were evenly divided into layers for analysis. A 10-layer model revealed a steady increase in fluorescence lifetime from the inner to the outer epithelial layers of healthy tissue sections, suggesting a close association with cellular maturity. The shorter lifetime and minimal lifetime increase towards the epithelial surface of CIN-affected regions are in good agreement with the absence of cellular maturation in CIN. Mean layer lifetimes in the top-half cervical epithelium were used as feature vectors for extreme learning machine (ELM classifier discriminations. It was found that the proposed layer analysis technique greatly improves the sensitivity and specificity to 94.6% and 84.3%, respectively, which can better supplement the traditional gold standard cervical histopathological examinations.

  5. Low-dimensional analysis, using POD, for two mixing layer-wake interactions

    International Nuclear Information System (INIS)

    Braud, Caroline; Heitz, Dominique; Arroyo, Georges; Perret, Laurent; Delville, Joeel; Bonnet, Jean-Paul

    2004-01-01

    The mixing layer-wake interaction is studied experimentally in the framework of two flow configurations. For the first one, the initial conditions of the mixing layer are modified by using a thick trailing edge, a wake effect is therefore superimposed to the mixing layer from its beginning (blunt trailing edge). In the second flow configuration, a canonical mixing layer is perturbed in its asymptotic region by the wake of a cylinder arranged perpendicular to the plane of the mixing layer. These interactions are analyzed mainly by using two-point velocity correlations and the proper orthogonal decomposition (POD). These two flow configurations differ by the degree of complexity they involve: the former is mainly 2D while the latter is highly 3D. The blunt trailing edge configuration is analyzed by using rakes of hot wire probes. This flow configuration is found to be considerably different when compared to a conventional mixing layer. It appears in particular that the scale of the large structures depends only on the trailing edge thickness and does not grow in its downstream evolution. A criterion, based on POD, is proposed in order to separate wake-mixing layer dominant areas of the downstream evolution of the flow. The complex 3D dynamical behaviour resulting from the interaction between the canonical plane mixing layer and the wake of a cylinder is investigated using data arising from particle image velocimetry measurements. An analysis of the velocity correlations shows different length scales in the regions dominated by wake like structures and shear layer type structures. In order to characterize the particular organization in the plane of symmetry, a POD-Galerkin projection of the Navier-Stokes equations is performed in this plane. This leads to a low-dimensional dynamical system that allows the analysis of the relationship between the dominant frequencies to be performed. A reconstruction of the dominant periodic motion suspected from previous studies is

  6. Field portable low temperature porous layer open tubular cryoadsorption headspace sampling and analysis part I: Instrumentation.

    Science.gov (United States)

    Bruno, Thomas J

    2016-01-15

    Building on the successful application in the laboratory of PLOT-cryoadsorption as a means of collecting vapor (or headspace) samples for chromatographic analysis, in this paper a field portable apparatus is introduced. This device fits inside of a briefcase (aluminum tool carrier), and can be easily transported by vehicle or by air. The portable apparatus functions entirely on compressed air, making it suitable for use in locations lacking electrical power, and for use in flammable and explosive environments. The apparatus consists of four aspects: a field capable PLOT-capillary platform, the supporting equipment platform, the service interface between the PLOT-capillary and the supporting equipment, and the necessary peripherals. Vapor sampling can be done with either a hand piece (containing the PLOT capillary) or with a custom fabricated standoff module. Both the hand piece and the standoff module can be heated and cooled to facilitate vapor collection and subsequent vapor sample removal. The service interface between the support platform and the sampling units makes use of a unique counter current approach that minimizes loss of cooling and heating due to heat transfer with the surroundings (recuperative thermostatting). Several types of PLOT-capillary elements and sampling probes are described in this report. Applications to a variety of samples relevant to forensic and environmental analysis are discussed in a companion paper. Published by Elsevier B.V.

  7. Analysis of biodiesel and biodiesel-petrodiesel blends by high performance thin layer chromatography combined with easy ambient sonic-spray ionization mass spectrometry.

    Science.gov (United States)

    Eberlin, Livia S; Abdelnur, Patricia V; Passero, Alan; de Sa, Gilberto F; Daroda, Romeu J; de Souza, Vanderlea; Eberlin, Marcos N

    2009-08-01

    High performance thin layer chromatography (HPTLC) combined with on-spot detection and characterization via easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is applied to the analysis of biodiesel (B100) and biodiesel-petrodiesel blends (BX). HPTLC provides chromatographic resolution of major components whereas EASI-MS allows on-spot characterization performed directly on the HPTLC surface at ambient conditions. Constituents (M) are detected by EASI-MS in a one component-one ion fashion as either [M + Na](+) or [M + H](+). For both B100 and BX samples, typical profiles of fatty acid methyl esters (FAME) detected as [FAME + Na](+) ions allow biodiesel typification. The spectrum of the petrodiesel spot displays a homologous series of protonated alkyl pyridines which are characteristic for petrofuels (natural markers). The spectrum for residual or admixture oil spots is characterized by sodiated triglycerides [TAG + Na](+). The application of HPTLC to analyze B100 and BX samples and its combination with EASI-MS for on-spot characterization and quality control is demonstrated.

  8. Chromatographic separation of Iodine species for environmental studies

    Energy Technology Data Exchange (ETDEWEB)

    Machado, E.C. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Geoquimica]. E-mail: geoedin@vm.uff.br; Bellido, A.V.B. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Fisico-Quimica]. E-mail: alf@risc2.rmn.uff.br; Bellido, L.F. [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)]. E-mail: lbellido@cnen.gov.br

    1999-07-01

    In this work a experimental method was developed to separate iodine species from environmental samples by using adsorption chromatography. The radionuclide {sup 123} I which has a half-life of 13 h and a convenient gamma ray of 159 keV was used to investigate a fast and efficient procedure for the separation of iodide and iodate ions in seawater from mangrove samples. The radio-iodine tracer technique is very useful, particularly in kinetic studies because it is easy to detect without any interference of concentration due to the small amount of tracer that is spiked. It is also possible to add two tracers (I-123 and I-131) in different oxidation states. Three chromatographic methods were studied: paper, thin layer and adsorption chromatography with silica and alumina. It was found that paper chromatography is very useful for checking the valence adjustment of the radioiodine species. Initially, several coefficient distributions of iodine species by adsorption in silica and alumina from NaOH, NaHCO{sub 3} and NaNO{sub 3} solutions (in the range 05. - 0.0001 m) were determined. The best separation so far was achieved by loading the sample (after adjusting the concentration to 0.1 NNaNO{sub 3}) into a chromatographic column with Al{sub 2} O{sub 3}. The iodide passes through the column and after washing the column, the iodate was removed by eluting with 1.0 M NaHCO{sub 3} solution. (author)

  9. Chromatographic separation of Iodine species for environmental studies

    International Nuclear Information System (INIS)

    Machado, E.C.

    1999-01-01

    In this work a experimental method was developed to separate iodine species from environmental samples by using adsorption chromatography. The radionuclide 123 I which has a half-life of 13 h and a convenient gamma ray of 159 keV was used to investigate a fast and efficient procedure for the separation of iodide and iodate ions in seawater from mangrove samples. The radio-iodine tracer technique is very useful, particularly in kinetic studies because it is easy to detect without any interference of concentration due to the small amount of tracer that is spiked. It is also possible to add two tracers (I-123 and I-131) in different oxidation states. Three chromatographic methods were studied: paper, thin layer and adsorption chromatography with silica and alumina. It was found that paper chromatography is very useful for checking the valence adjustment of the radioiodine species. Initially, several coefficient distributions of iodine species by adsorption in silica and alumina from NaOH, NaHCO 3 and NaNO 3 solutions (in the range 05. - 0.0001 m) were determined. The best separation so far was achieved by loading the sample (after adjusting the concentration to 0.1 NNaNO 3 ) into a chromatographic column with Al 2 O 3 . The iodide passes through the column and after washing the column, the iodate was removed by eluting with 1.0 M NaHCO 3 solution. (author)

  10. A X-ray diffraction analysis on constituent distribution of heavy rust layer formed on weathering steel using synchrotron radiation

    International Nuclear Information System (INIS)

    Hara, Shuichi

    2008-01-01

    A local structural analysis of heavy rust layers with large swelling and laminated layers formed on weathering steel bridges using synchrotron radiation X-ray diffraction (SR-XRD) in SPring-8 have been performed. The main constituent in average composition of the whole layer was spinel-type iron oxide [mainly Magnetite (Fe 3 O 4 )] and the mass ratio was 30-40 mass%. In contrast the mass ratio of spinel in its local parts, i.e., outer layer, inter-layer and inner layer position was not higher in common but the mass ratio of β-FeOOH was higher. Therefore it indicates that these heavy rust layers have been composed of many layers of spinel poor, rich and poor - cell (SPRaP-cell). Thus SR-XRD is useful for the analysis of the constituent distribution in the rust layer. (author)

  11. Gas chromatographic analysis of plant sterols

    Science.gov (United States)

    Phytosterols are well-known for their ability to lower blood cholesterol by competing with absorption of cholesterol from the diet and reabsorption of bile cholesterol. Phytosterols as food ingredients are “Generally Recognized As Safe” (GRAS) by the FDA, and they are increasingly incorporated into ...

  12. Liquid Chromatographic Analysis of Hydraulic Fluids.

    Science.gov (United States)

    1979-11-01

    chemical mixtures of a petroleum- or nonpetroleum-base stock component formulated with various additives which may be present in trace amounts or...absorb UV radiation near the monitoring wavelength may swamp the detector signal and therefore should be avoided in 1JV detection. The recorder trace of...Also, organic phosphites , thiophosphates, and sulfides are used to inhibit oxidative catalysis by metal ions. The oxidation inhibitor in 6083D-0 is BPC

  13. Gas chromatographic and mass spectrometric analysis of ...

    Indian Academy of Sciences (India)

    Unknown

    Following oral administration three major metabolites of ... It is well established that the stimulating anabolic effect of ... oral application of a single dose of clostebol (dose,. 20 mg) ..... 17â and testosterone production by ovarian follicles of the.

  14. Determination of losartan potassium, quinapril hydrochloride and hydrochlorothiazide in pharmaceutical preparations using derivative spectrophotometry and chromatographic-densitometric method.

    Science.gov (United States)

    Stolarczyk, Mariusz; Maślanka, Anna; Apola, Anna; Krzek, Jan

    2013-01-01

    Two methods, spectrophotometric and chromatographic-densitometric ones, were developed for determination of losartan potassium, quinapril hydrochloride and hydrochlorothiazide in pharmaceutical preparations. Spectrophotometric method involved derivative spectrophotometry and zero order spectrophotometry. The measurements were carried out at lambda = 224.0 nm for quinapril, lambda = 261.0 nm for hydrochlorothiazide and lambda = 270.0 nm for losartan when the derivative spectrophotometry was applied and lambda = 317.0 nm when zero order spectrophotometry was applied for the determination of hydrochlorothiazide. In chromatographic-densitometric studies high performance thin layer chromatography (HPTLC) plates were used as stationary phase and a mixture of solvents n-butanol : acetic acid : water (15 : 5 : 1, v/v/v) as mobile phase. Under the established conditions good resolution of examined constituents was obtained. Retardation factor for quinapril hydrochloride was R(f) - 0.70, for losartan potassium R(f) - 0.85 and for hydrochlorothiazide R(f) - 0.78. The developed methods are characterized by high sensitivity and accuracy. For quantitative analysis, densitometric measurements were carried out at lambda = 218.0 nm for quinapril, lambda = 275.0 nm for hydrochlorothiazide and = 232.0 nm for losartan.

  15. Analysis of residual stress in subsurface layers after precision hard machining of forging tools

    Directory of Open Access Journals (Sweden)

    Czan Andrej

    2018-01-01

    Full Text Available This paper is focused on analysis of residual stress of functional surfaces and subsurface layers created by precision technologies of hard machining for progressive constructional materials of forging tools. Methods of experiments are oriented on monitoring of residual stress in surface which is created by hard turning (roughing and finishing operations. Subsequently these surfaces were etched in thin layers by electro-chemical polishing. The residual stress was monitored in each etched layer. The measuring was executed by portable X-ray diffractometer for detection of residual stress and structural phases. The results significantly indicate rise and distribution of residual stress in surface and subsurface layers and their impact on functional properties of surface integrity.

  16. Liquid chromatographic-mass spectrometric method for ...

    African Journals Online (AJOL)

    Tropical Journal of Pharmaceutical Research ... Purpose: To develop and validate a simple, efficient and reliable Liquid chromatographic-mass spectrometric (LC-MS/MS) method for the quantitative determination of two dermatological drugs, ... By Country · List All Titles · Free To Read Titles This Journal is Open Access.

  17. Validated high performance liquid chromatographic (HPLC) method ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-02-22

    Feb 22, 2010 ... specific and accurate high performance liquid chromatographic method for determination of ZER in micro-volumes ... tional medicine as a cure for swelling, sores, loss of appetite and ... Receptor Activator for Nuclear Factor κ B Ligand .... The effect of ... be suitable for preclinical pharmacokinetic studies. The.

  18. A Small-Scale Low-Cost Gas Chromatograph

    Science.gov (United States)

    Gros, Natasa; Vrtacnik, Margareta

    2005-01-01

    The design and application of a small-scale portable gas chromatograph for learning of the basic concepts of chromatography is described. The apparatus consists of two basic separable units, which includes a chromatographic unit and an electronic unit.

  19. Composite Beam Cross-Section Analysis by a Single High-Order Element Layer

    DEFF Research Database (Denmark)

    Couturier, Philippe; Krenk, Steen

    2015-01-01

    An analysis procedure of general cross-section properties is presented. The formulation is based on the stress-strain states in the classic six equilibrium modes of a beam by considering a finite thickness slice modelled by a single layer of 3D finite elements. The theory is illustrated by applic......An analysis procedure of general cross-section properties is presented. The formulation is based on the stress-strain states in the classic six equilibrium modes of a beam by considering a finite thickness slice modelled by a single layer of 3D finite elements. The theory is illustrated...

  20. Simple setup for gas-phase H/D exchange mass spectrometry coupled to electron transfer dissociation and ion mobility for analysis of polypeptide structure on a liquid chromatographic time scale.

    Science.gov (United States)

    Mistarz, Ulrik H; Brown, Jeffery M; Haselmann, Kim F; Rand, Kasper D

    2014-12-02

    Gas-phase hydrogen/deuterium exchange (HDX) is a fast and sensitive, yet unharnessed analytical approach for providing information on the structural properties of biomolecules, in a complementary manner to mass analysis. Here, we describe a simple setup for ND3-mediated millisecond gas-phase HDX inside a mass spectrometer immediately after ESI (gas-phase HDX-MS) and show utility for studying the primary and higher-order structure of peptides and proteins. HDX was achieved by passing N2-gas through a container filled with aqueous deuterated ammonia reagent (ND3/D2O) and admitting the saturated gas immediately upstream or downstream of the primary skimmer cone. The approach was implemented on three commercially available mass spectrometers and required no or minor fully reversible reconfiguration of gas-inlets of the ion source. Results from gas-phase HDX-MS of peptides using the aqueous ND3/D2O as HDX reagent indicate that labeling is facilitated exclusively through gaseous ND3, yielding similar results to the infusion of purified ND3-gas, while circumventing the complications associated with the use of hazardous purified gases. Comparison of the solution-phase- and gas-phase deuterium uptake of Leu-Enkephalin and Glu-Fibrinopeptide B, confirmed that this gas-phase HDX-MS approach allows for labeling of sites (heteroatom-bound non-amide hydrogens located on side-chains, N-terminus and C-terminus) not accessed by classical solution-phase HDX-MS. The simple setup is compatible with liquid chromatography and a chip-based automated nanoESI interface, allowing for online gas-phase HDX-MS analysis of peptides and proteins separated on a liquid chromatographic time scale at increased throughput. Furthermore, online gas-phase HDX-MS could be performed in tandem with ion mobility separation or electron transfer dissociation, thus enabling multiple orthogonal analyses of the structural properties of peptides and proteins in a single automated LC-MS workflow.

  1. A validated high performance thin layer chromatography method for determination of yohimbine hydrochloride in pharmaceutical preparations

    OpenAIRE

    Jihan M Badr

    2013-01-01

    Background: Yohimbine is an indole alkaloid used as a promising therapy for erectile dysfunction. A number of methods were reported for the analysis of yohimbine in the bark or in pharmaceutical preparations. Materials and Method: In the present work, a simple and sensitive high performance thin layer chromatographic method is developed for determination of yohimbine (occurring as yohimbine hydrochloride) in pharmaceutical preparations and validated according to International Conference of Ha...

  2. Effective inelastic scattering cross-sections for background analysis in HAXPES of deeply buried layers

    Energy Technology Data Exchange (ETDEWEB)

    Risterucci, P., E-mail: paul.risterucci@gmail.com [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Université de Lyon, Institut des Nanotechnologies de Lyon, 36 avenue Guy de Collongue, 69134 Ecully (France); Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark); Renault, O., E-mail: olivier.renault@cea.fr [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Zborowski, C. [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Sorbonne Universités, UPMC Univ. Paris 06, CNRS, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005, Paris (France); Université de Lyon, Institut des Nanotechnologies de Lyon, 36 avenue Guy de Collongue, 69134 Ecully (France); Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark); Bertrand, D.; Torres, A. [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Rueff, J.-P. [Synchrotron SOLEIL, L' Orme des Merisiers Saint-Aubin, BP 48 91192, Gif-sur-Yvette Cedex (France); Sorbonne Universités, UPMC Univ. Paris 06, CNRS, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005, Paris (France); Ceolin, D. [Synchrotron SOLEIL, L' Orme des Merisiers Saint-Aubin, BP 48 91192, Gif-sur-Yvette Cedex (France); Grenet, G. [Université de Lyon, Institut des Nanotechnologies de Lyon, 36 avenue Guy de Collongue, 69134 Ecully (France); Tougaard, S. [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark)

    2017-04-30

    Highlights: • An effective approach for quantitative background analysis in HAXPES spectra of buried layer underneath complex overlayer structures is proposed. • The approach relies on using a weighted sum of inelastic scattering cross section of the pure layers. • The method is validated by the study of an advanced power transistor stack after successive annealing steps. • The depth distribution of crucial elements (Ti, Ga) is determined reliably at depths up to nearly 50 nm. - Abstract: Inelastic background analysis of HAXPES spectra was recently introduced as a powerful method to get access to the elemental distribution in deeply buried layers or interfaces, at depth up to 60 nm below the surface. However the accuracy of the analysis highly relies on suitable scattering cross-sections able to describe effectively the transport of photoelectrons through overlayer structures consisting of individual layers with potentially very different scattering properties. Here, we show that within Tougaard’s practical framework as implemented in the Quases-Analyze software, the photoelectron transport through thick (25–40 nm) multi-layer structures with widely different cross-sections can be reliably described with an effective cross-section in the form of a weighted sum of the individual cross-section of each layer. The high-resolution core-level analysis partly provides a guide for determining the nature of the individual cross-sections to be used. We illustrate this novel approach with the practical case of a top Al/Ti bilayer structure in an AlGaN/GaN power transistor device stack before and after sucessive annealing treatments. The analysis provides reliable insights on the Ti and Ga depth distributions up to nearly 50 nm below the surface.

  3. Structural analysis and characterization of layer perovskite oxynitrides made from Dion-Jacobson oxide precursors

    International Nuclear Information System (INIS)

    Schottenfeld, Joshua A.; Benesi, Alan J.; Stephens, Peter W.; Chen, Gugang; Eklund, Peter C.; Mallouk, Thomas E.

    2005-01-01

    A three-layer oxynitride Ruddlesden-Popper phase Rb 1+x Ca 2 Nb 3 O 10-x N x .yH 2 O (x=0.7-0.8, y=0.4-0.6) was synthesized by ammonialysis at 800 o C from the Dion-Jacobson phase RbCa 2 Nb 3 O 10 in the presence of Rb 2 CO 3 . Incorporation of nitrogen into the layer perovskite structure was confirmed by XPS, combustion analysis, and MAS NMR. The water content was determined by thermal gravimetric analysis and the rubidium content by ICP-MS. A similar layered perovskite interconversion occurred in the two-layer Dion-Jacobson oxide RbLaNb 2 O 7 to yield Rb 1+x LaNb 2 O 7-x N x .yH 2 O (x=0.7-0.8, y=0.5-1.0). Both compounds were air- and moisture-sensitive, with rapid loss of nitrogen by oxidation and hydrolysis reactions. The structure of the three-layer oxynitride Rb 1.7 Ca 2 Nb 3 O 9.3 N 0.7 .0.5H 2 O was solved in space group P4/mmm with a=3.887(3) and c=18.65(1)A, by Rietveld refinement of X-ray powder diffraction data. The two-layer oxynitride structure Rb 1.8 LaNb 2 O 6.3 N 0.7 .1.0H 2 O was also determined in space group P4/mmm with a=3.934(2) and c=14.697(2)A. GSAS refinement of synchrotron X-ray powder diffraction data showed that the water molecules were intercalated between a double layer of Rb+ ions in both the two- and three-layer Ruddlesden-Popper structures. Optical band gaps were measured by diffuse reflectance UV-vis for both materials. An indirect band gap of 2.51eV and a direct band gap of 2.99eV were found for the three-layer compound, while an indirect band gap of 2.29eV and a direct band gap of 2.84eV were measured for the two-layer compound. Photocatalytic activity tests of the three-layer compound under 380nm pass filtered light with AgNO 3 as a sacrificial electron acceptor gave a quantum yield of 0.025% for oxygen evolution

  4. Chromatographic assay of degradation products of tributyl phosphate

    International Nuclear Information System (INIS)

    Tripathi, S.C.; Ramanujam, A.; Nadkarni, M.N.; Rao, K.A.; Bandyopadhyay, C.

    1985-01-01

    Gas-liquid chromatography (GLC) and thin-layer chromatographic (TLC) procedures have been developed for the estimation of monobutyl phosphoric acid (H 2 MBP) and dibutyl phosphoric acid (HDBP) present in tributyl phosphate (TBP). Less than one microgram of H 2 MBP and HDBP is visually detected on TLC plate made of silicagel-cellulose (1:1). HDBP as separated by TLC has been quantitatively estimated in the range of 40-260 μg using an indirect spectrophotometric method. GLC method using 10 percent (W/W) XE-60 column can be effectively used for the simultaneous determination of 0.25 percent W/V H 2 MBP and HDBP present in 30 percent TBP-n-dodecane. The sensitivity may be enhanced 100 fold by careful column conditioning and judicious control of operational parameters. (author)

  5. Effects of chromatographic fractions of Euphorbia hirta on the rat ...

    African Journals Online (AJOL)

    The effects of the chromatographic fractions of Euphorbia hirta Linn on the serum biochemical parameters in rats were investigated. The ethanolic extract of this plant was subjected to chromatographic separation using the vacuum liquid chromatographic technique, a modified form of classical column chromatography.

  6. Ion beam analysis of multi-layered structure in Nb/Cu system

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Shunya; Goppelt-Langer, P; Naramoto, Hiroshi; Aoki, Yasushi; Takeshita, Hidefumi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1997-03-01

    The dependence of H concentration on the layer thickness in H charged Nb/Cu multilayer samples has been studied using {sup 15}N resonance nuclear reaction analysis({sup 15}N-NRA) and high energy elastic recoil detection analysis(HE-ERDA). Also a simulation code has been developed for accurate simulation of the {sup 1}H({sup 15}N,{alpha}{gamma}){sup 12}C4.43 MeV {gamma}-yields at 6.385 MeV and 13.365 MeV reaction energy. The simulation are in good agreement with the experimental results. The present results show smooth increase of the H concentrations in Nb layers with increasing layer thickness. (author)

  7. New approaches for the analysis of confluent cell layers with quantitative phase digital holographic microscopy

    Science.gov (United States)

    Pohl, L.; Kaiser, M.; Ketelhut, S.; Pereira, S.; Goycoolea, F.; Kemper, Björn

    2016-03-01

    Digital holographic microscopy (DHM) enables high resolution non-destructive inspection of technical surfaces and minimally-invasive label-free live cell imaging. However, the analysis of confluent cell layers represents a challenge as quantitative DHM phase images in this case do not provide sufficient information for image segmentation, determination of the cellular dry mass or calculation of the cell thickness. We present novel strategies for the analysis of confluent cell layers with quantitative DHM phase contrast utilizing a histogram based-evaluation procedure. The applicability of our approach is illustrated by quantification of drug induced cell morphology changes and it is shown that the method is capable to quantify reliable global morphology changes of confluent cell layers.

  8. Analysis of influence of buffer layers on microwave propagation through high-temperature superconducting thin films

    International Nuclear Information System (INIS)

    Ceremuga, J.; Barton, M.; Miranda, F.

    1994-01-01

    Methods of analysis of microwave propagation through superconducting thin films with buffer layers on dielectric substrates have been discussed. Expressions describing the transmission coefficient S 21 through the structure and the complex conductivity sigma of a superconductor in an analytical form have been derived. The derived equations are valid for microwave propagation in waveguides as well as in free space with relevant definition of impedances. Using the obtained solutions, the influences of buffer layers' parameters (thickness, relative permittivity and loss tangent) on the transmission coefficient has been investigated using MATLAB. Simulations have been performed for 10 GHz transmission through YBa 2 Cu 3 O 7 films on sapphire with SrTiO 3 and CeO 2 buffer layers and on silicon with CaF 2 and YSZ buffer layers. To illustrate the simulations, measurements of the transmission through YBCO film on sapphire with SrTiO 3 buffer layer have been performed. It has been shown that even lossy buffer layers have very little impact (smaller than 1% in magnitude and 0.3% in phase) on the transmission coefficient through superconducting thin films, providing their thickness is below 10 mu m. (author)

  9. Heat conduction analysis of multi-layered FGMs considering the finite heat wave speed

    International Nuclear Information System (INIS)

    Rahideh, H.; Malekzadeh, P.; Golbahar Haghighi, M.R.

    2012-01-01

    Highlights: ► Using a layerwise-incremental differential quadrature for heat transfer of FGMs. ► Superior accuracy with fewer degrees of freedom of the method with respect to FEM. ► Considering multi-layered functionally graded materials. ► Hyperbolic heat transfer analysis of thermal system with heat generation. ► Showing the effect of heat wave speed on thermal characteristic of the system. - Abstract: In this work, the heat conduction with finite wave heat speed of multi-layered domain made of functionally graded materials (FGMs) subjected to heat generation is simulated. For this purpose, the domain is divided into a set of mathematical layers, the number of which can be equal or greater than those of the physical layers. Then, in each mathematical layer, the non-Fourier heat transfer equations are employed. Since, the governing equations have variable coefficients due to FGM properties, as an efficient and accurate method the differential quadrature method (DQM) is adopted to discretize both spatial and temporal domains in each layer. This results in superior accuracy with fewer degrees of freedom than conventional finite element method (FEM). To verify this advantages through some comparison studies, a finite element solution are also obtained. After demonstrating the convergence and accuracy of the method, the effects of heat wave speed for two different set of boundary conditions on the temperature distribution and heat flux of the domain are studied.

  10. Analysis of white layers formed in hard turning of AISI 52100 steel

    International Nuclear Information System (INIS)

    Ramesh, A.; Melkote, S.N.; Allard, L.F.; Riester, L.; Watkins, T.R.

    2005-01-01

    The formation mechanisms and properties of white layers produced in machining of hardened steels are not clearly understood to date. In particular, detailed analysis of their structure and mechanical properties is lacking. This paper investigates the differences in structure and properties of white layers formed during machining of hardened AISI 52100 steel (62 HRC) at different cutting speeds. A combination of experimental techniques including transmission electron microscopy (TEM), X-ray diffraction (XRD), and nano-indentation are used to analyze the white layers formed. TEM results suggest that white layers produced at low-to-moderate cutting speeds are in large part due to grain refinement induced by severe plastic deformation, whereas white layer formation at high cutting speeds is mainly due to thermally-driven phase transformation. The white layers at all speeds are found to be comprised of very fine (nano-scale) grains compared to the bulk material. XRD-based residual stress and retained austenite measurements, and hardness data support these findings

  11. Dual quantification of dapivirine and maraviroc in cervicovaginal secretions from ophthalmic tear strips and polyester-based swabs via liquid chromatographic-tandem mass spectrometric (LC-MS/MS) analysis.

    Science.gov (United States)

    Parsons, Teresa L; Emory, Joshua F; Seserko, Lauren A; Aung, Wutyi S; Marzinke, Mark A

    2014-09-01

    Topical microbicidal agents are being actively pursued as a modality to prevent HIV viral transmission during sexual intercourse. Quantification of antiretroviral agents in specimen sources where antiviral activity is elicited is critical, and drug measurements in cervicovaginal fluid can provide key information on local drug concentrations. Two antiretroviral drugs, dapivirine and maraviroc, have gained interest as vaginal microbicidal agents, and rugged methods are required for their quantification in cervicovaginal secretions. Cervicovaginal fluid spiked with dapivirine and maraviroc were applied to ophthalmic tear strips or polyester-based swabs to mimic collection procedures used in clinical studies. Following sample extraction and the addition of isotopically labeled internal standards, samples were subjected to liquid chromatographic-tandem mass spectrometric (LC-MS/MS) analysis using a Waters BEH C8, 50mm×2.1mm, 1.7μm particle size column, on an API 4000 mass analyzer operated in selective reaction monitoring mode. The method was validated according to FDA Bioanalytical Method Validation guidelines. Due to the disparate saturation capacity of the tested collection devices, the analytical measuring ranges for dapivirine and maravirocin cervicovaginal fluid on the ophthalmic tear strip were 0.05-25ng/tear strip, and 0.025-25ng/tear strip, respectively. As for the polyester-based swab, the analytical measuring ranges were 0.25-125ng/swab for dapivirine and 0.125-125ng/swab for maraviroc. Dilutional studies were performed for both analytes to extended ranges of 25,000ng/tear strip and 11,250ng/swab. Standard curves were generated via weighted (1/x(2)) linear or quadratic regression of calibrators. Precision, accuracy, stability and matrix effects studies were all performed and deemed acceptable according to the recommendations of the FDA Bioanalytical Method Validation guidelines. A rugged LC-MS/MS method for the dual quantification of dapivirine and

  12. Crack coke in layer heat transfer analysis; Kiretsu no shinten wo tomonau kokusu sonai dennetsu kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, Hideyuki [Tohoku University, Miyagi (Japan)

    1999-03-05

    The research method heat transfer process by physical change of the coke by heat transfer from furnace wall in the retorting of coal seam filled in coke oven and flow of the gas is very complicated chamber oven style, and it does not become clear. For the purpose of the elucidation of in layer crack generation and progress mechanism, he is (1) The expansion of the softening cohesive layer. (2) Programming rate dependence of the heat. Mechanical property value on coal seam and semi- coke layer in the retorting. (3) The creep property of softening cohesive layer and semi- coke layer. (4) The setting of crack growth condition of stress intensity factor in crack tip and fracture property value of the coke by the comparison. (5) By considering the radiative heat transfer in the crack, coke in layer thermal stress analysis was carried out. The validity of these analytical result it was confirmed by the comparison with the experimental result of crack growth. Deformation behavior in the small dry distillation furnace, and crack growth mechanism in the coke layer became clear, and the prediction of the stress as micro-crack cause of generation of heating surface side coke surface and inside became possible. The numerical analysis method of the above crack growth mechanism greatly contributes to the prediction of dry distillation heating requirement and grain size of coke lump which is an index to the coke quality. Heat on material process which is accompanied by the solidification. Contraction from the softening and material migration phenomenon have been clarified by the creative research method, while this research is directly useful for energy saving of pig ironmaking process of becoming one of the ringleaders of the CO{sub 2} generation. (translated by NEDO)

  13. The use of artificial intelligence methods for visual analysis of properties of surface layers

    Directory of Open Access Journals (Sweden)

    Tomasz Wójcicki

    2014-12-01

    Full Text Available [b]Abstract[/b]. The article presents a selected area of research on the possibility of automatic prediction of material properties based on the analysis of digital images. Original, holistic model of forecasting properties of surface layers based on a multi-step process that includes the selected methods of processing and analysis of images, inference with the use of a priori knowledge bases and multi-valued fuzzy logic, and simulation with the use of finite element methods is presented. Surface layers characteristics and core technologies of their production processes such as mechanical, thermal, thermo-mechanical, thermo-chemical, electrochemical, physical are discussed. Developed methods used in the model for the classification of images of the surface layers are shown. The objectives of the use of selected methods of processing and analysis of digital images, including techniques for improving the quality of images, segmentation, morphological transformation, pattern recognition and simulation of physical phenomena in the structures of materials are described.[b]Keywords[/b]: image analysis, surface layer, artificial intelligence, fuzzy logic

  14. Analysis of Steam Heating of a Two-Layer TBP/N-Paraffin/Nitric Acid Mixtures

    International Nuclear Information System (INIS)

    Laurinat, J.E.; Hassan, N.M.; Rudisill, T.S.; Askew, N.M.

    1998-01-01

    This report presents an analysis of steam heating of a two-layer tri-n-butyl phosphate (TBP)/n-paraffin-nitric acid mixture.The purpose of this study is to determine if the degree of mixing provided by the steam jet or by bubbles generated by the TBP/nitric acid reaction is sufficient to prevent a runaway reaction

  15. Efficient CFIE-MOM Analysis of 3-D PEC Scatterers in Layered Media

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Jørgensen, E.; Meincke, Peter

    2002-01-01

    This paper presents an efficient technique for analysis of arbitrary closed perfectly conducting (PEC) scatterers in layered media. The technique is based on a method of moments (MoM) solution of the combined field integral equation (CFIE). The high efficiency is obtained by employing an accurate...

  16. Photoacoustic signal attenuation analysis for the assessment of thin layers thickness in paintings

    Science.gov (United States)

    Tserevelakis, George J.; Dal Fovo, Alice; Melessanaki, Krystalia; Fontana, Raffaella; Zacharakis, Giannis

    2018-03-01

    This study introduces a novel method for the thickness estimation of thin paint layers in works of art, based on photoacoustic signal attenuation analysis (PAcSAA). Ad hoc designed samples with acrylic paint layers (Primary Red Magenta, Cadmium Yellow, Ultramarine Blue) of various thicknesses on glass substrates were realized for the specific application. After characterization by Optical Coherence Tomography imaging, samples were irradiated at the back side using low energy nanosecond laser pulses of 532 nm wavelength. Photoacoustic waves undergo a frequency-dependent exponential attenuation through the paint layer, before being detected by a broadband ultrasonic transducer. Frequency analysis of the recorded time-domain signals allows for the estimation of the average transmitted frequency function, which shows an exponential decay with the layer thickness. Ultrasonic attenuation models were obtained for each pigment and used to fit the data acquired on an inhomogeneous painted mock-up simulating a real canvas painting. Thickness evaluation through PAcSAA resulted in excellent agreement with cross-section analysis with a conventional brightfield microscope. The results of the current study demonstrate the potential of the proposed PAcSAA method for the non-destructive stratigraphic analysis of painted artworks.

  17. Stability analysis of natural convection in superposed fluid and porous layers

    International Nuclear Information System (INIS)

    Hirata, S.C.; Goyeau, B.; Gobin, D.; Cotta, R.M.

    2005-01-01

    A linear stability analysis of the onset of thermal natural convection in superposed fluid and porous layers is called out. The resulting eigenvalue problem is solved using a integral transformation technique. The effect of the variation of the Darcy number on the stability of the system is analyzed. (authors)

  18. Stability analysis of natural convection in superposed fluid and porous layers

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, S.C.; Goyeau, B.; Gobin, D. [Paris-11 Univ. - Paris-6, FAST - UMR CNRS 7608, 91 - Orsay (France); Cotta, R.M. [Rio de Janeiro Univ. (LTTC/PEM/EE/COPPE/UFRJ), RJ (Brazil)

    2005-07-01

    A linear stability analysis of the onset of thermal natural convection in superposed fluid and porous layers is called out. The resulting eigenvalue problem is solved using a integral transformation technique. The effect of the variation of the Darcy number on the stability of the system is analyzed. (authors)

  19. A Simple Thin Layer Chromatography Method for Separation of Selected Natural Steroid Hormones

    International Nuclear Information System (INIS)

    Nowakowska, J.; Rudnicka-Litka, K.; Ciura, K.; Pikul, P.; Piotrowicz, J.

    2015-01-01

    Chromatographic properties of seven steroids: estrogens (β-estradiol and estrone), androgens (testosterone, methyltestosterone, trans-androsterone), progesterone and cholesterol have been studied by planar chromatography with usage of High Performance Thin Layer Chromatography (HPTLC) and Thin Layer Chromatography (TLC) plates. Normal, reversed and cyano-bonded silica stationary phases were tested with five binary mobile phases (acetonitrile-water, acetonitrile-DMSO, acetonitrile-methanol, acetone-petroleum ether, acetone-water) in which the concentration of organic modifier varied from 0 to 100 % (v/v). This study reports the optimization of steroid hormones separation. Principal Component Analysis (PCA) based on calculated molecular descriptors quantitatively differentiating solutes was performed in order to investigate the similarity and dissimilarity between tested compounds. The separation abilities of mobile and stationary phases were compared based on separation factor α. Chromatographic retention data and possible retention mechanisms also were discussed. (author)

  20. Quantitative Differentiation of LV Myocardium with and without Layer-Specific Fibrosis Using MRI in Hypertrophic Cardiomyopathy and Layer-Specific Strain TTE Analysis.

    Science.gov (United States)

    Funabashi, Nobusada; Takaoka, Hiroyuki; Ozawa, Koya; Kamata, Tomoko; Uehara, Masae; Komuro, Issei; Kobayashi, Yoshio

    2018-05-30

    To achieve further risk stratification in hypertrophic cardiomyopathy (HCM) patients, we localized and quantified layer-specific LVM fibrosis on MRI in HCM patients using regional layer-specific peak longitudinal strain (PLS) and peak circumferential strain (PCS) in LV myocardium (LVM) on speckle tracking transthoracic echocardiography (TTE). A total of 18 HCM patients (14 males; 58 ± 17 years) underwent 1.5T-MRI and TTE. PLS and PCS in each layer of the LVM (endocardium, epicardium, and whole-layer myocardium) were calculated for 17 AHA-defined lesions. MRI assessment showed that fibrosis was classified as endocardial, epicardial, or whole-layer (= either or both of these). Regional PLS was smaller in fibrotic endocardial lesions than in non-fibrotic endocardial lesions (P = 0.004). To detect LV endocardial lesions with fibrosis, ROC curves of regional PLS revealed an area under the curve (AUC) of 0.609 and a best cut-off point of 13.5%, with sensitivity of 65.3% and specificity of 54.3%. Regional PLS was also smaller in fibrotic epicardial lesions than in non-fibrotic epicardial lesions (P layer myocardium analysis, PLS was smaller in fibrotic lesions than in non-fibrotic lesions (P layer LV lesions with fibrosis, ROC curves of regional PLS revealed an AUC of 0.674 and a best cut-off point of 12.5%, with sensitivity of 79.0% and specificity of 50.7%. There were no significant differences in PCS of LV myocardium (endocardium, epicardium, and whole-layer) between fibrotic and non-fibrotic lesions. Quantitative regional PLS but not PCS in LV endocardium, epicardium, and whole-layer myocardium provides useful non-invasive information for layer-specific localization of fibrosis in HCM patients.

  1. Numerical analysis of mixing process of two component gases in vertical fluid layer

    International Nuclear Information System (INIS)

    Hatori, Hirofumi; Takeda, Tetsuaki; Funatani, Shumpei

    2015-01-01

    When the depressurization accident occurs in the Very-High-Temperature Reactor (VHTR), it is expected that air enter into the reactor core. Therefore, it is important to know a mixing process of different kind of gases in the stable or unstable stratified fluid layer. Especially, it is also important to examine an influence of localized natural convection and molecular diffusion on mixing process from a viewpoint of safety. In order to research the mixing process of two component gases and flow characteristics of the localized natural convection, we have carried out numerical analysis using three dimensional CFD code. The numerical model was consisted of a storage tank and a reverse U-shaped vertical slot. They were separated by a partition plate. One side of the left vertical fluid layer was heated and the other side was cooled. The right vertical fluid layer was also cooled. The procedure of numerical analysis is as follows. Firstly, the storage tank was filled with heavy gas and the reverse U-shaped vertical slot was filled with light gas. In the left vertical fluid layer, the localized natural convection was generated by the temperature difference between the vertical walls. The flow characteristics were obtained by a steady state analysis. The unsteady state analysis was started when the partition plate was opened. The gases were mixed by molecular diffusion and natural convection. After the time elapsed, natural circulation occurred. The result obtained in this numerical analysis is as follows. The temperature difference of the left vertical fluid layer was set to 100 K. The combination of the mixed gas was nitrogen and argon. After 76 minutes elapsed, natural circulation occurred. (author)

  2. Futures Business Models for an IoT Enabled Healthcare Sector: A Causal Layered Analysis Perspective

    OpenAIRE

    Julius Francis Gomes; Sara Moqaddemerad

    2016-01-01

    Purpose: To facilitate futures business research by proposing a novel way to combine business models as a conceptual tool with futures research techniques. Design: A futures perspective is adopted to foresight business models of the Internet of Things (IoT) enabled healthcare sector by using business models as a futures business research tool. In doing so, business models is coupled with one of the most prominent foresight methodologies, Causal Layered Analysis (CLA). Qualitative analysis...

  3. Numerical analysis of natural convection in a double-layer immiscible system

    International Nuclear Information System (INIS)

    Gubaidullin, A.A.; Sehgal, B.R.

    2001-01-01

    In the present paper numerical analysis has been applied to study the natural convection heat transfer in a system composed of two immiscible fluids with uniform internal heat generation in the lower layer or in both layers enclosed in a rectangular or in a semi-circular vessel. The objective of the work is to perform a parametric study to assess the effect of physical properties on the heat transfer characteristics as well as to complement results obtained from experiments by means of CFD simulations for a range of lower Rayleigh number and combine the experimental data and the computational results. (author)

  4. Analysis on Interfacial Performance of CFRPConcrete with Different Thickness of Adhesive Layer and CFRP Plate

    Directory of Open Access Journals (Sweden)

    Guo Qingyong

    2018-01-01

    Full Text Available The bond behavior of CFRP-concrete interface is the analysis foundation for concrete structures with external strengthening CFRP. In the paper, the influences of the thickness of CFRP plate and adhesive layer on interfacial adhesive properties are investigated through the finite element program. The influence rules of the thickness on the interfacial ultimate bearing capacity and the effective bond length are performed. The results show that the thickness of adhesive layer and CFRP plate has a significant effect on the interfacial performance of CFRP-concrete.

  5. Similarity analyses of chromatographic herbal fingerprints: a review.

    Science.gov (United States)

    Goodarzi, Mohammad; Russell, Paul J; Vander Heyden, Yvan

    2013-12-04

    Herbal medicines are becoming again more popular in the developed countries because being "natural" and people thus often assume that they are inherently safe. Herbs have also been used worldwide for many centuries in the traditional medicines. The concern of their safety and efficacy has grown since increasing western interest. Herbal materials and their extracts are very complex, often including hundreds of compounds. A thorough understanding of their chemical composition is essential for conducting a safety risk assessment. However, herbal material can show considerable variability. The chemical constituents and their amounts in a herb can be different, due to growing conditions, such as climate and soil, the drying process, the harvest season, etc. Among the analytical methods, chromatographic fingerprinting has been recommended as a potential and reliable methodology for the identification and quality control of herbal medicines. Identification is needed to avoid fraud and adulteration. Currently, analyzing chromatographic herbal fingerprint data sets has become one of the most applied tools in quality assessment of herbal materials. Mostly, the entire chromatographic profiles are used to identify or to evaluate the quality of the herbs investigated. Occasionally only a limited number of compounds are considered. One approach to the safety risk assessment is to determine whether the herbal material is substantially equivalent to that which is either readily consumed in the diet, has a history of application or has earlier been commercialized i.e. to what is considered as reference material. In order to help determining substantial equivalence using fingerprint approaches, a quantitative measurement of similarity is required. In this paper, different (dis)similarity approaches, such as (dis)similarity metrics or exploratory analysis approaches applied on herbal medicinal fingerprints, are discussed and illustrated with several case studies. Copyright © 2013

  6. Amalgam-chromatographic separation of magnesium isotopes

    International Nuclear Information System (INIS)

    Klinskij, G.D.; Levkin, A.V.; Ivanov, S.A.

    1990-01-01

    Separation of magnesium isotopes within Mg(Hg)-MgI 2 system (in dimethylformamide) is conducted under amalgam-chromatographic conditions. Separation maximal degree, that is (1.09), for 24 Mg and 26 Mg and separation coefficient (α = 1.0089±0.006) are determined. Light isotopes are found to concentrate in the amalgam. Technique of thermal conversion of flows within amalgam-dimethylformamide system is suggested on the basis of reversible reaction of Ca-Mg element exchange

  7. Full-Wave Analysis of Microstrip Antennas in Three-Layered Spherical Media

    Directory of Open Access Journals (Sweden)

    Tao Yu

    2013-01-01

    Full Text Available A model of three-layered spherical microstrip antenna has been analyzed based on Rao-Wilton-Glisson (RWG triangular basis functions using mixed potential integral equation (MPIE. Firstly, the model of antenna and the dyadic Green’s function in spherical microstrip antennas are given at the beginning of this paper. Then, due to the infinite series convergence problem, asymptotic extraction approach is presented to accelerate the Green’s functions convergence speed when source and field points are located in the same layer and different layers. The convergence speed can be accelerated observably by using this method. Finally, in order to simplify impedance matrix elements calculation at the junction of the probe and patch, a novel division fashion of pair of triangles is adopted in this paper. The input impedance result obtained shows the validity and effectiveness of the analysis method comparing with published data.

  8. Analysis of signals propagating in a phononic crystal PZT layer deposited on a silicon substrate.

    Science.gov (United States)

    Hladky-Hennion, Anne-Christine; Vasseur, Jérôme; Dubus, Bertrand; Morvan, Bruno; Wilkie-Chancellier, Nicolas; Martinez, Loïc

    2013-12-01

    The design of a stop-band filter constituted by a periodically patterned lead zirconate titanate (PZT) layer, polarized along its thickness, deposited on a silicon substrate and sandwiched between interdigitated electrodes for emission/reception of guided elastic waves, is investigated. The filter characteristics are theoretically evaluated by using finite element simulations: dispersion curves of a patterned PZT layer with a specific pattern geometry deposited on a silicon substrate present an absolute stop band. The whole structure is modeled with realistic conditions, including appropriate interdigitated electrodes to propagate a guided mode in the piezoelectric layer. A robust method for signal analysis based on the Gabor transform is applied to treat transmitted signals; extract attenuation, group delays, and wave number variations versus frequency; and identify stop-band filter characteristics.

  9. Trace and surface analysis of ceramic layers of solid oxide fuel cells by mass spectrometry.

    Science.gov (United States)

    Becker, J S; Breuer, U; Westheide, J; Saprykin, A I; Holzbrecher, H; Nickel, H; Dietze, H J

    1996-06-01

    For the trace analysis of impurities in thick ceramic layers of a solid oxide fuel cell (SOFC) sensitive solid-state mass spectrometric methods, such as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and radiofrequency glow discharge mass spectrometry (rf-GDMS) have been developed and used. In order to quantify the analytical results of LA-ICP-MS, the relative sensitivity coefficients of elements in a La(0.6)Sr(0.35)MnO(3) matrix have been determined using synthetic standards. Secondary ion mass spectrometry (SIMS) - as a surface analytical method - has been used to characterize the element distribution and diffusion profiles of matrix elements on the interface of a perovskite/Y-stabilized ZrO(2) layer. The application of different mass spectrometric methods for process control in the preparation of ceramic layers for the SOFC is described.

  10. Atomic-layer-resolved analysis of surface magnetism by diffraction spectroscopy

    International Nuclear Information System (INIS)

    Matsui, Fumihiko; Matsushita, Tomohiro; Daimon, Hiroshi

    2010-01-01

    X-ray absorption near edge structure (XANES) and X-ray magnetic circular dichroism (XMCD) measurements by Auger-electron-yield detection are powerful analysis tools for the electronic and magnetic structures of surfaces, but all the information from atoms within the electron mean-free-path range is summed into the obtained spectrum. In order to investigate the electronic and magnetic structures of each atomic layer at subsurface, we have proposed a new method, diffraction spectroscopy, which is the combination of X-ray absorption spectroscopy and Auger electron diffraction (AED). From a series of measured thickness dependent AED patterns, we deduced a set of atomic-layer-specific AED patterns arithmetically. Based on these AED patterns, we succeeded in disentangling obtained XANES and XMCD spectra into those from different atomic layers.

  11. Analyzing chromatographic data using multilevel modeling.

    Science.gov (United States)

    Wiczling, Paweł

    2018-06-01

    It is relatively easy to collect chromatographic measurements for a large number of analytes, especially with gradient chromatographic methods coupled with mass spectrometry detection. Such data often have a hierarchical or clustered structure. For example, analytes with similar hydrophobicity and dissociation constant tend to be more alike in their retention than a randomly chosen set of analytes. Multilevel models recognize the existence of such data structures by assigning a model for each parameter, with its parameters also estimated from data. In this work, a multilevel model is proposed to describe retention time data obtained from a series of wide linear organic modifier gradients of different gradient duration and different mobile phase pH for a large set of acids and bases. The multilevel model consists of (1) the same deterministic equation describing the relationship between retention time and analyte-specific and instrument-specific parameters, (2) covariance relationships relating various physicochemical properties of the analyte to chromatographically specific parameters through quantitative structure-retention relationship based equations, and (3) stochastic components of intra-analyte and interanalyte variability. The model was implemented in Stan, which provides full Bayesian inference for continuous-variable models through Markov chain Monte Carlo methods. Graphical abstract Relationships between log k and MeOH content for acidic, basic, and neutral compounds with different log P. CI credible interval, PSA polar surface area.

  12. Global stability analysis of axisymmetric boundary layer over a circular cylinder

    Science.gov (United States)

    Bhoraniya, Ramesh; Vinod, Narayanan

    2018-05-01

    This paper presents a linear global stability analysis of the incompressible axisymmetric boundary layer on a circular cylinder. The base flow is parallel to the axis of the cylinder at inflow boundary. The pressure gradient is zero in the streamwise direction. The base flow velocity profile is fully non-parallel and non-similar in nature. The boundary layer grows continuously in the spatial directions. Linearized Navier-Stokes (LNS) equations are derived for the disturbance flow quantities in the cylindrical polar coordinates. The LNS equations along with homogeneous boundary conditions forms a generalized eigenvalues problem. Since the base flow is axisymmetric, the disturbances are periodic in azimuthal direction. Chebyshev spectral collocation method and Arnoldi's iterative algorithm is used for the solution of the general eigenvalues problem. The global temporal modes are computed for the range of Reynolds numbers and different azimuthal wave numbers. The largest imaginary part of the computed eigenmodes is negative, and hence, the flow is temporally stable. The spatial structure of the eigenmodes shows that the disturbance amplitudes grow in size and magnitude while they are moving towards downstream. The global modes of axisymmetric boundary layer are more stable than that of 2D flat-plate boundary layer at low Reynolds number. However, at higher Reynolds number they approach 2D flat-plate boundary layer. Thus, the damping effect of transverse curvature is significant at low Reynolds number. The wave-like nature of the disturbance amplitudes is found in the streamwise direction for the least stable eigenmodes.

  13. Development of Modal Analysis for the Study of Global Modes in High Speed Boundary Layer Flows

    Science.gov (United States)

    Brock, Joseph Michael

    Boundary layer transition for compressible flows remains a challenging and unsolved problem. In the context of high-speed compressible flow, transitional and turbulent boundary-layers produce significantly higher surface heating caused by an increase in skin-friction. The higher heating associated with transitional and turbulent boundary layers drives thermal protection systems (TPS) and mission trajectory bounds. Proper understanding of the mechanisms that drive transition is crucial to the successful design and operation of the next generation spacecraft. Currently, prediction of boundary-layer transition is based on experimental efforts and computational stability analysis. Computational analysis, anchored by experimental correlations, offers an avenue to assess/predict stability at a reduced cost. Classical methods of Linearized Stability Theory (LST) and Parabolized Stability Equations (PSE) have proven to be very useful for simple geometries/base flows. Under certain conditions the assumptions that are inherent to classical methods become invalid and the use of LST/PSE is inaccurate. In these situations, a global approach must be considered. A TriGlobal stability analysis code, Global Mode Analysis in US3D (GMAUS3D), has been developed and implemented into the unstructured solver US3D. A discussion of the methodology and implementation will be presented. Two flow configurations are presented in an effort to validate/verify the approach. First, stability analysis for a subsonic cylinder wake is performed and results compared to literature. Second, a supersonic blunt cone is considered to directly compare LST/PSE analysis and results generated by GMAUS3D.

  14. An IR Sounding-Based Analysis of the Saharan Air Layer in North Africa

    Science.gov (United States)

    Nicholls, Stephen D.; Mohr, Karen I.

    2018-01-01

    Intense daytime surface heating over barren-to-sparsely vegetated surfaces results in dry convective mixing. In the absence of external forcing such as mountain waves, the dry convection can produce a deep, well-mixed, nearly isentropic boundary layer that becomes a well-mixed residual layer in the evening. These well-mixed layers (WML) retain their unique mid-tropospheric thermal and humidity structure for several days. To detect the SAL and characterize its properties, AIRS Level 2 Ver. 6 temperature and humidity products (2003-Present) are evaluated against rawinsondes and compared to model analysis at each of the 55 rawinsonde stations in northern Africa. To distinguish WML from Saharan air layers (WMLs of Saharan origin), the detection involved a two-step process: 1) algorithm-based detection of WMLs in dry environments (less than 7 g per kilogram mixing ratio) 2) identification of Sahara air layers (SAL) by applying Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) back trajectories to determine the history of each WML. WML occurrence rates from AIRS closely resemble that from rawinsondes, yet rates from model analysis were up to 30% higher than observations in the Sahara due to model errors. Despite the overly frequent occurrence of WMLs from model analysis, HYSPLIT trajectory analysis showed that SAL occurrence rates (given a WML exists) from rawinsondes, AIRS, and model analysis were nearly identical. Although the number of WMLs varied among the data sources, the proportion of WMLs which were classified as SAL was nearly the same. The analysis of SAL bulk properties showed that AIRS and model analysis exhibited a slight warm and moist bias relative to rawinsondes in non-Saharan locations, but model analysis was notably warmer than rawinsondes and AIRS within the Sahara. The latter result is likely associated with the dearth of available data assimilated by model analysis in the Sahara. The variability of SAL thicknesses was reasonably

  15. Infrared Reflectance Analysis of Epitaxial n-Type Doped GaN Layers Grown on Sapphire.

    Science.gov (United States)

    Tsykaniuk, Bogdan I; Nikolenko, Andrii S; Strelchuk, Viktor V; Naseka, Viktor M; Mazur, Yuriy I; Ware, Morgan E; DeCuir, Eric A; Sadovyi, Bogdan; Weyher, Jan L; Jakiela, Rafal; Salamo, Gregory J; Belyaev, Alexander E

    2017-12-01

    Infrared (IR) reflectance spectroscopy is applied to study Si-doped multilayer n + /n 0 /n + -GaN structure grown on GaN buffer with GaN-template/sapphire substrate. Analysis of the investigated structure by photo-etching, SEM, and SIMS methods showed the existence of the additional layer with the drastic difference in Si and O doping levels and located between the epitaxial GaN buffer and template. Simulation of the experimental reflectivity spectra was performed in a wide frequency range. It is shown that the modeling of IR reflectance spectrum using 2 × 2 transfer matrix method and including into analysis the additional layer make it possible to obtain the best fitting of the experimental spectrum, which follows in the evaluation of GaN layer thicknesses which are in good agreement with the SEM and SIMS data. Spectral dependence of plasmon-LO-phonon coupled modes for each GaN layer is obtained from the spectral dependence of dielectric of Si doping impurity, which is attributed to compensation effects by the acceptor states.

  16. Modification of ion chromatograph for analyses of radioactive samples

    International Nuclear Information System (INIS)

    Curfman, L.L.; Johnson, S.J.

    1979-01-01

    In ion chromatographic analysis, the sample is injected through a sample loop onto an analytical column where separation occurs. The sample then passes through a suppressor column to remove or neutralize background ions. A flow-through conductivity cell is used as a detector. Depending upon column and eluent selection, ion chromatography can be used for anion or cation analyses. Ion chromatography has proven to be a versatile analytical tool for the analysis of anions in Hanford waste samples. These radioactive samples range from caustic high salt solutions to hydrochloric acid dissolutions of insoluble sludges. Instrument modifications which provide safe and convenient handling of these samples without lengthening analysis time or altering instrument performance are described

  17. Resolving and quantifying overlapped chromatographic bands by transmutation

    Science.gov (United States)

    Malinowski

    2000-09-15

    A new chemometric technique called "transmutation" is developed for the purpose of sharpening overlapped chromatographic bands in order to quantify the components. The "transmutation function" is created from the chromatogram of the pure component of interest, obtained from the same instrument, operating under the same experimental conditions used to record the unresolved chromatogram of the sample mixture. The method is used to quantify mixtures containing toluene, ethylbenzene, m-xylene, naphthalene, and biphenyl from unresolved chromatograms previously reported. The results are compared to those obtained using window factor analysis, rank annihilation factor analysis, and matrix regression analysis. Unlike the latter methods, the transmutation method is not restricted to two-dimensional arrays of data, such as those obtained from HPLC/DAD, but is also applicable to chromatograms obtained from single detector experiments. Limitations of the method are discussed.

  18. A review on sample preparation and chromatographic determination of acephate and methamidophos in

    Directory of Open Access Journals (Sweden)

    Vijay Kumar

    2015-09-01

    Full Text Available Acephate and its metabolite methamidophos are common organophosphorus insecticide used for crop protection. High uses of acephate and methamidophos have induced health issues and environmental pollution. Their undesired presence in the environment is creating ecotoxicology and may harm human health. It is therefore essential to detect the presence of acephate and methamidophos even in trace level. In this review, we have tried to accommodate successful methods of detection of acephate and methamidophos in the different biological media. Their recovery and residue analysis in different media such as vegetables, human and animal tissues have also included. The most common method for their determination is based on chromatographic separation and identification. Among different chromatographic methods, LC and GC coupled with different detectors have used. But, they both need extensive pretreatment and cleanup procedure, before undergoing chromatographic separation and identification. LC coupled with mass spectrometry (LCMS is sometime able to detect acephate and methamidophos in ppm level.

  19. Optimization of the gas chromatographic separations; Optimacion de las separaciones cromatograficas en fase gaseosa

    Energy Technology Data Exchange (ETDEWEB)

    Gasco Sanchez, L

    1973-07-01

    A review and a critical study on the optimization of the gas chromatographic separations are made. After dealing with the fundamental gas chromatographic equations, some methods of expressing column performances are discussed: performance indices, performance parameters, resolution and effective plate number per unit time. This is completed with a comparative study on performances of various types of columns. Moreover, optimization methods for operating chromatographic conditions are extensively dealt with: as resolution optimization, separation time, and normalization techniques for the time of analysis in order to achieve the maximum resolution at constant time. Finally, some others non operating parameters such as: selectivity of stationary phases, column preparation and optimization methods by means of computers are studied. (Author) 68 refs.

  20. [A peak recognition algorithm designed for chromatographic peaks of transformer oil].

    Science.gov (United States)

    Ou, Linjun; Cao, Jian

    2014-09-01

    In the field of the chromatographic peak identification of the transformer oil, the traditional first-order derivative requires slope threshold to achieve peak identification. In terms of its shortcomings of low automation and easy distortion, the first-order derivative method was improved by applying the moving average iterative method and the normalized analysis techniques to identify the peaks. Accurate identification of the chromatographic peaks was realized through using multiple iterations of the moving average of signal curves and square wave curves to determine the optimal value of the normalized peak identification parameters, combined with the absolute peak retention times and peak window. The experimental results show that this algorithm can accurately identify the peaks and is not sensitive to the noise, the chromatographic peak width or the peak shape changes. It has strong adaptability to meet the on-site requirements of online monitoring devices of dissolved gases in transformer oil.

  1. Chromatographic determination of silicon and phosphorus as molybdic heteropoly acids with preconcentration

    International Nuclear Information System (INIS)

    Tikhomirova, T.I.; Krokhin, O.V.; Dubovik, D.B.; Ivanov, A.V.; Shpigun, O.A.

    2002-01-01

    Chromatographic behaviour of silicon and phosphorus as molybdic heteropoly acids with preconcentration as ion associations of heteropoly acid with tributylammonium bromide was studied. The technique of simultaneous analysis of silicon and phosphorus was developed. During investigation into the effect of acetonitril content in the probe on the form of chromatographic peak of molybdosilicic acid the negative influence of acetonitril on the form of peak was ascertained. This effect may be eliminated by the lowering of acetonitril content up to 50 %. It was found that under these conditions the chromatographic peak practically was absent, because of the heteropoly acid of the Mo(VI) abundance transformed in the MoO 2 2+ cation form without reaction with tributylammonium cation during concentration of heteropoly acid [ru

  2. Analysis of corrosion layers in ancient Roman silver coins with high resolution surface spectroscopic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Keturakis, Christopher J. [Operando Molecular Spectroscopy and Catalysis Research Laboratory, Department of Chemical Engineering, Lehigh University, Bethlehem, PA 18015 (United States); Notis, Ben [Brandeis University, Waltham, MA 02453 (United States); Blenheim, Alex [Department of Mechanical Engineering, Pennsylvania State University, College Park, PA 16802 (United States); Miller, Alfred C.; Pafchek, Rob [Zettlemoyer Center for Surface Studies, Lehigh University, Bethlehem, PA 18015 (United States); Notis, Michael R., E-mail: mrn1@lehigh.edu [Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015 (United States); Wachs, Israel E., E-mail: iew0@lehigh.edu [Operando Molecular Spectroscopy and Catalysis Research Laboratory, Department of Chemical Engineering, Lehigh University, Bethlehem, PA 18015 (United States)

    2016-07-15

    Highlights: • Five ancient silver alloy coins (225 BCE–244 CE) were analyzed using surface characterization techniques. • Both destructive and non-destructive surface characterization methods were developed. • Alloying with copper, even in small amounts, leads to the formation of an outer Cu{sub 2}O corrosion layer. - Abstract: Determination of the microchemistry of surface corrosion layers on ancient silver alloy coins is important both in terms of understanding the nature of archaeological environmental conditions to which these ancient coins were exposed and also to help in their conservation. In this present study, five ancient silver alloy coins (225 BCE–244 CE) were used as test vehicles to measure their immediate surface microchemistry and evaluate the appropriateness and limitations of High Sensitivity-Low Energy Ion Scattering Spectroscopy (HS-LEIS, 0.3 nm depth analysis), High Resolution-X-ray Photoelectron Spectroscopy (HR-XPS, 1–3 nm depth analysis) and High Resolution-Raman Spectroscopy (HR-Raman, ∼1000 nm depth analysis). Additional information about the deeper corrosion layers, up to ∼300–1000 nm, was provided by dynamic HS-LEIS and HR-Raman spectroscopy. While not archeologically significant, the use of these coins of small commercial value provides data that is more representative of the weaker signals typically obtained from ancient corroded objects, which can be in stark contrast to pristine data often obtained from carefully prepared alloys of known composition. The oldest coins, from 225 to 214 BCE, possessed an outermost surface layer containing Cu{sub 2}O, Na, Al, Pb, and adsorbed hydrocarbons, while the more recent coins, from 98 to 244 CE, contained Cu{sub 2}O, Ag, N, F, Na, Al, S, Cl, and adsorbed hydrocarbons in similar corresponding surface layers. It thus appears that alloying with copper, even in small amounts, leads to the formation of an outer Cu{sub 2}O layer. Depth profiling revealed the presence of K, Na, Cl, and

  3. Analysis of corrosion layers in ancient Roman silver coins with high resolution surface spectroscopic techniques

    International Nuclear Information System (INIS)

    Keturakis, Christopher J.; Notis, Ben; Blenheim, Alex; Miller, Alfred C.; Pafchek, Rob; Notis, Michael R.; Wachs, Israel E.

    2016-01-01

    Highlights: • Five ancient silver alloy coins (225 BCE–244 CE) were analyzed using surface characterization techniques. • Both destructive and non-destructive surface characterization methods were developed. • Alloying with copper, even in small amounts, leads to the formation of an outer Cu 2 O corrosion layer. - Abstract: Determination of the microchemistry of surface corrosion layers on ancient silver alloy coins is important both in terms of understanding the nature of archaeological environmental conditions to which these ancient coins were exposed and also to help in their conservation. In this present study, five ancient silver alloy coins (225 BCE–244 CE) were used as test vehicles to measure their immediate surface microchemistry and evaluate the appropriateness and limitations of High Sensitivity-Low Energy Ion Scattering Spectroscopy (HS-LEIS, 0.3 nm depth analysis), High Resolution-X-ray Photoelectron Spectroscopy (HR-XPS, 1–3 nm depth analysis) and High Resolution-Raman Spectroscopy (HR-Raman, ∼1000 nm depth analysis). Additional information about the deeper corrosion layers, up to ∼300–1000 nm, was provided by dynamic HS-LEIS and HR-Raman spectroscopy. While not archeologically significant, the use of these coins of small commercial value provides data that is more representative of the weaker signals typically obtained from ancient corroded objects, which can be in stark contrast to pristine data often obtained from carefully prepared alloys of known composition. The oldest coins, from 225 to 214 BCE, possessed an outermost surface layer containing Cu 2 O, Na, Al, Pb, and adsorbed hydrocarbons, while the more recent coins, from 98 to 244 CE, contained Cu 2 O, Ag, N, F, Na, Al, S, Cl, and adsorbed hydrocarbons in similar corresponding surface layers. It thus appears that alloying with copper, even in small amounts, leads to the formation of an outer Cu 2 O layer. Depth profiling revealed the presence of K, Na, Cl, and S as key

  4. Thermal analysis of a multi-layer microchannel heat sink for cooling concentrator photovoltaic (CPV) cells

    Science.gov (United States)

    Siyabi, Idris Al; Shanks, Katie; Mallick, Tapas; Sundaram, Senthilarasu

    2017-09-01

    Concentrator Photovoltaic (CPV) technology is increasingly being considered as an alternative option for solar electricity generation. However, increasing the light concentration ratio could decrease the system output power due to the increase in the temperature of the cells. The performance of a multi-layer microchannel heat sink configuration was evaluated using numerical analysis. In this analysis, three dimensional incompressible laminar steady flow model was solved numerically. An electrical and thermal solar cell model was coupled for solar cell temperature and efficiency calculations. Thermal resistance, solar cell temperature and pumping power were used for the system efficiency evaluation. An increase in the number of microchannel layers exhibited the best overall performance in terms of the thermal resistance, solar cell temperature uniformity and pressure drop. The channel height and width has no effect on the solar cell maximum temperature. However, increasing channel height leads to a reduction in the pressure drop and hence less fluid pumping power.

  5. Accumulation and distribution of elements in rice (seed, brand layer, husk) by neutron activation analysis

    International Nuclear Information System (INIS)

    Tran Van, L.; Teherani, D.K.

    1988-01-01

    Various rice samples (seed, brand layer, husk) from Vietnam were analyzed for Se, Hg, Cr, Ni, Sc, Rb, Fe, Zn and Co by neutron activation analysis. The concentration values found (seed) were as follows: Se 0.04-0.07 ppm, Hg 0.02-0.07 ppm, Cr 2.13-8.65 ppm, Ni 1.56-4.95 ppm, Sc 0.02-0.06 ppm, Rb 0.84-2.71 ppm, Fe 26.31-96.07 ppm, Zn 10.65-27.39 ppm and Co 0.02-0.15 ppm. The values were reported in ppm (dry weight). Statistical analysis showed that the content of elements varies in different parts of rice; the content of Rb, Fe, Ni, Cr of husk was significantly higher than in seed and brand layer. (author) 12 refs.; 2 figs.; 1 tab

  6. First-principles analysis of phase stability in layered-layered composite cathodes for lithium-ion batteries

    Science.gov (United States)

    Iddir, Hakim; Benedek, Roy; Voltage Fade Team

    2014-03-01

    The atomic order in layered-layered composites with composition xLi2MnO3 .(1-x)LiCoO2 is investigated with first-principles calculations at the GGA +U level. This material, and others in its class, are often regarded as solid solutions, however, only a minute solubility of Li2MnO3 in a LiCoO2 host is predicted. Calculations of Co-vacancy formation and migration energies in LiCoO2 are presented, to elucidate the rate of vacancy-mediated ordering in the transition-metal-layer, and thus determine whether low vacancy mobility could result in slow equilibration. The Co-vacancy formation energy can be predicted only to within a range, because of uncertainty in the chemical potentials. Predicted migration energies, however, are approximately 1 eV, small enough to be consistent with rapid ordering in the transition metal layer, and therefore separated Li2MnO3 and LiCoO2 phases. The relatively small (of the order of a few nm) Li2MnO3 domain sizes observed with TEM in some xLi2MnO3 .(1-x)LiMO2 composites may result from other factors, such as coherency strain, which perhaps block further domain coarsening in these materials. Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  7. Decomposition Methods For a Piv Data Analysis with Application to a Boundary Layer Separation Dynamics

    OpenAIRE

    Václav URUBA

    2010-01-01

    Separation of the turbulent boundary layer (BL) on a flat plate under adverse pressure gradient was studied experimentally using Time-Resolved PIV technique. The results of spatio-temporal analysis of flow-field in the separation zone are presented. For this purpose, the POD (Proper Orthogonal Decomposition) and its extension BOD (Bi-Orthogonal Decomposition) techniques are applied as well as dynamical approach based on POPs (Principal Oscillation Patterns) method. The study contributes...

  8. Analysis of wave-like oscillations in parameters of sporadic E layer and neutral atmosphere

    Science.gov (United States)

    Mošna, Z.; Koucká Knížová, P.

    2012-12-01

    The present study mainly concerns the wave-like activity in the ionospheric sporadic E layer (Es) and in the lower lying stratosphere. The proposed analysis involves parameters describing the state of plasma in the sporadic E layer. Critical frequencies foEs and layer heights hEs were measured at the Pruhonice station (50°N, 14.5°E) during summer campaigns 2004, 2006 and 2008. Further, we use neutral atmosphere (temperature data at 10 hPa) data from the same time interval. The analysis concentrates on vertically propagating wave-like structures within distant atmospheric regions. By means of continuous wavelet transform (CWT) we have detected significant wave-like oscillation at periods covering tidal and planetary oscillation domains both in the Es layer parameters (some of them were reported earlier, for instance in works of Abdu et al., 2003; Pancheva and Mitchel, 2004; Pancheva et al., 2003; Šauli and Bourdillon, 2008) and in stratospheric temperature variations. Further analyses using cross wavelet transform (XWT) and wavelet coherence analysis (WTC) show that despite high wave-like activity in a wide period range, there are only limited coherent wave-like bursts present in both spectra. Such common coherent wave bursts occur on periods close to eigen-periods of the terrestrial atmosphere. We suppose that vertical coupling between atmospheric regions realized by vertically propagating planetary waves occurs predominantly on periods close to those of Rossby modes. Analysis of the phase shift between data from distant atmospheric regions reveals high variability and very likely supports the non-linear scenario of the vertical coupling provided by planetary waves.

  9. Infinite elements for soil-structure interaction analysis in multi-layered halfspaces

    International Nuclear Information System (INIS)

    Yun, Chung Bang; Kim, Jae Min; Yang, Shin Chu

    1994-01-01

    This paper presents the theoretical aspects of a computer code (KIESSI) for soil-structure interaction analysis in a multi-layered halfspace using infinite elements. The shape functions of the infinite elements are derived from approximate expressions of the analytical solutions. Three different infinite elements are developed. They are the horizontal, the vertical and the comer infinite elements (HIE, VIE and CIE). Numerical example analyses are presented for demonstrating the effectiveness of the proposed infinite elements

  10. Analysis of boundary layer flow over a porous nonlinearly stretching sheet with partial slip at

    Directory of Open Access Journals (Sweden)

    Swati Mukhopadhyay

    2013-12-01

    Full Text Available The boundary layer flow of a viscous incompressible fluid toward a porous nonlinearly stretching sheet is considered in this analysis. Velocity slip is considered instead of no-slip condition at the boundary. Similarity transformations are used to convert the partial differential equation corresponding to the momentum equation into nonlinear ordinary differential equation. Numerical solution of this equation is obtained by shooting method. It is found that the horizontal velocity decreases with increasing slip parameter.

  11. Chromatographic Analysis of a Multicomponent Mixture of B1, B6, B12, Benfotiamine, and Diclofenac; Part I: HPLC and UPLC Methods for the Simultaneous Quantification of These Five Components in Tablets and Capsules.

    Science.gov (United States)

    Fayed, Ahmed Salah; Hegazy, Maha Abdel-Monem; Wahab, Nada Sayed Abdel

    2016-11-01

    New, simple, highly sensitive, precise, and accurate gradient reversed-phase chromatographic methods were developed using HPLC and ultra-HPLC (UPLC) systems for the determination of five components, namely thiamine, pyridoxine, cyanocobalamin, benfotiamine, and diclofenac in tablets and capsules. The methods were compared for their efficiency in the separation and determination of these five compounds using two different C18 columns (250 × 4.6 mm, 5 μm; and 100 × 4.6 mm, 2.6 μm) for HPLC and UPLC, respectively. Chromatographic separation was performed with a mobile phase containing acetonitrile and 0.025 M phosphate buffer (pH 3.5), with a gradient program and a flow rate of 1.5 and 1.0 mL/min for both methods, respectively. The methods were validated according to International Conference on Harmonization guidelines. Linearity was achieved in the range of 5.00 to 150.00 μg/mL for each of the five compounds. Ruggedness and intermediate precision were confirmed by different analysts on different columns on different days. Moreover, the components were subjected to an accelerated stability study under acidic, alkaline, and oxidative stress conditions and no interfering peaks were observed. The five compounds were efficiently separated in <20 min by HPLC, whereas for UPLC, separation was achieved in <8 min, which dramatically decreased the consumption of organic solvents.

  12. Quantitative analysis of retina layer elasticity based on automatic 3D segmentation (Conference Presentation)

    Science.gov (United States)

    He, Youmin; Qu, Yueqiao; Zhang, Yi; Ma, Teng; Zhu, Jiang; Miao, Yusi; Humayun, Mark; Zhou, Qifa; Chen, Zhongping

    2017-02-01

    Age-related macular degeneration (AMD) is an eye condition that is considered to be one of the leading causes of blindness among people over 50. Recent studies suggest that the mechanical properties in retina layers are affected during the early onset of disease. Therefore, it is necessary to identify such changes in the individual layers of the retina so as to provide useful information for disease diagnosis. In this study, we propose using an acoustic radiation force optical coherence elastography (ARF-OCE) system to dynamically excite the porcine retina and detect the vibrational displacement with phase resolved Doppler optical coherence tomography. Due to the vibrational mechanism of the tissue response, the image quality is compromised during elastogram acquisition. In order to properly analyze the images, all signals, including the trigger and control signals for excitation, as well as detection and scanning signals, are synchronized within the OCE software and are kept consistent between frames, making it possible for easy phase unwrapping and elasticity analysis. In addition, a combination of segmentation algorithms is used to accommodate the compromised image quality. An automatic 3D segmentation method has been developed to isolate and measure the relative elasticity of every individual retinal layer. Two different segmentation schemes based on random walker and dynamic programming are implemented. The algorithm has been validated using a 3D region of the porcine retina, where individual layers have been isolated and analyzed using statistical methods. The errors compared to manual segmentation will be calculated.

  13. Analysis of the Inhibition Layer of Galvanized Dual-Phase Steels

    International Nuclear Information System (INIS)

    Wang, K. K.; Wang, H. P.; Chang, L.; Gan, D.; Chen, T. R.; Chen, H. B.

    2012-01-01

    The formation of the Fe-Al inhibition layer in hot-dip galvanizing is a confusing issue for a long time. This study presents a characterization result on the inhibition layer formed on C-Mn-Cr and C-Mn-Si dual-phase steels after a short time galvanizing. The samples were annealed at 800 .deg. C for 60 s in N 2 -10% H 2 atmosphere with a dew point of -30 .deg. C, and were then galvanized in a bath containing 0.2%Al. X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) was employed for characterization. The TEM electron diffraction shows that only Fe 2 Al 5 intermetallic phase was formed. No orientation relationship between the Fe 2 Al 5 phase and the steel substrate could be identified. Two peaks of Al 2p photoelectrons, one from metallic aluminum and the other from Al 3+ ions, were detected in the inhibition layer, indicating that the layer is in fact a mixture of Fe 2 Al 5 and Al 2 O 3 . TEM/EDS analysis verifies the existence of Al 2 O 3 in the boundaries of Fe 2 Al 5 grains. The nucleation of Fe 2 Al 5 and the reduction of the surface oxide probably proceeded concurrently on galvanizing, and the residual oxides prohibited the heteroepitaxial growth of Fe 2 Al 5

  14. Nongray radiative heat transfer analysis in the anisotropic scattering fog layer subjected to solar irradiation

    International Nuclear Information System (INIS)

    Maruyama, Shigenao; Mori, Yusuke; Sakai, Seigo

    2004-01-01

    Radiative heat transfer in the fog layer is analyzed. Direct and diffuse solar irradiation, and infrared sky flux are considered as incident radiation. Anisotropic scattering of radiation by water droplets is taken into account. Absorption and emission of radiation by water droplets and radiative gases are also considered. Furthermore, spectral dependences of radiative properties of irradiation, reflectivity, gas absorption and scattering and absorption of mist are considered. The radiation element method by ray emission model (REM 2 ) is used for the nongray radiation analysis. Net downward radiative heat flux at the sea surface and radiative equilibrium temperature distribution in the fog layer are calculated for several conditions. Transmitted solar flux decreases as liquid water content (LWC) in the fog increases. However, the value does not become zero but has the value about 60 W/m 2 . The effect of humidity and mist on radiative cooling at night is investigated. Due to high temperature and humidity condition, the radiation cooling at night is not so large even in the clear sky. Furthermore, the radiative equilibrium temperature distribution in the fog layer in the daytime is higher as LWC increases, and the inversion layer of temperature occurs

  15. Soil Plasticity Model for Analysis of Collapse Load on Layers Soil

    Directory of Open Access Journals (Sweden)

    Md Nujid Masyitah

    2016-01-01

    Full Text Available Natural soil consist of soil deposits which is a soil layer overlying a thick stratum of another soil. The bearing capacity of layered soil studies have been conducted using different approach whether theoretical, experimental and combination of both. Numerical method in computer programme has become a powerful tool in solving complex geotechnical problems. Thus in numerical modelling, stress-strain soil behaviour is well predicted, design and interpreted using appropriate soil model. It is also important to identify parameters and soil model involve in prediction real soil problem. The sand layer overlaid clay layer soil is modelled with Mohr-Coulomb and Drucker-Prager criterion. The bearing capacity in loaddisplacement analysis from COMSOL Multiphysics is obtained and presented. In addition the stress distribution and evolution of plastic strain for each thickness ratio below centre of footing are investigated. The results indicate the linear relation on load-displacement which have similar trend for both soil models while stress and plastic strain increase as thickness ratio increase.

  16. Leveraging probabilistic peak detection to estimate baseline drift in complex chromatographic samples

    NARCIS (Netherlands)

    Lopatka, M.; Barcaru, A.; Sjerps, M.J.; Vivó-Truyols, G.

    2016-01-01

    Accurate analysis of chromatographic data often requires the removal of baseline drift. A frequently employed strategy strives to determine asymmetric weights in order to fit a baseline model by regression. Unfortunately, chromatograms characterized by a very high peak saturation pose a significant

  17. Evolved Gas Measurements Planned for the Lower Layers of the Gale Crater Mound with the Sample Analysis at Mars Instrument Suite

    Science.gov (United States)

    Mahaffy, P. R.; Franz, H.; McAdam, A.; Conrad, P. G.; Brunner, A.; Cabane, M.; Webster, C. R.

    2011-12-01

    The lower mound strata of Gale Crater provide a diverse set of chemical environments for exploration by the varied tools of the Curiosity Rover of the Mars Science Laboratory (MSL) Mission. Orbital imaging and spectroscopy clearly reveal distinct layers of hydrated minerals, sulfates, and clays with abundant evidence of a variety of fluvial processes. The three instruments of the MSL Sample Analysis at Mars (SAM) investigation, the Quadrupole Mass Spectrometer (QMS), the Tunable Laser Spectrometer (TLS), and the Gas Chromatograph (GC) are designed to analyze either atmospheric gases or volatiles thermally evolved or chemically extracted from powdered rock or soil. The presence or absence of organic compounds in these layers is of great interest since such an in situ search for this type of record has not been successfully implemented since the mid-70s Viking GCMS experiments. However, regardless of the outcome of the analysis for organics, the abundance and isotopic composition of thermally evolved inorganic compounds should also provide a rich data set to complement the mineralogical and elemental information provided by other MSL instruments. In addition, these evolved gas analysis (EGA) experiments will help test sedimentary models proposed by Malin and Edgett (2000) and then further developed by Milliken et al (2010) for Gale Crater. In the SAM EGA experiments the evolution temperatures of H2O, CO2, SO2, O2, or other simple compounds as the samples are heated in a helium stream to 1000C provides information on mineral types and their associations. The isotopic composition of O, H, C, and S can be precisely determined in several evolved compounds and compared with the present day atmosphere. Such SAM results might be able to test mineralogical evidence of changing sedimentary and alteration processes over an extended period of time. For example, Bibring et al (2006) have suggested such a major shift from early nonacidic to later acidic alteration. We will

  18. Evolved Gas Measurements Planned for the Lower Layers of the Gale Crater Mound with the Sample Analysis at Mars Instrument Suite

    Science.gov (United States)

    Mahaffy, Paul; Brunner, Anna; McAdam, Amy; Franz, Heather; Conrad, Pamela; Webster, Chris; Cabane, Michel

    2009-01-01

    The lower mound strata of Gale Crater provide a diverse set of chemical environments for exploration by the varied tools of the Curiosity Rover of the Mars Science Laboratory (MSL) Mission. Orbital imaging and spectroscopy clearly reveal distinct layers of hydrated minerals, sulfates, and clays with abundant evidence of a variety of fluvial processes. The three instruments of the MSL Sample Analysis at aMars (SAM) investigation, the Quadrupole Mass Spectrometer (QMS), the Tunable Laser Spectrometer (TLS), and the Gas Chromatograph (GC) are designed to analyze either atmospheric gases or volatiles thermally evolved or chemically extracted from powdered rock or soil. The presence or absence of organic compounds in these layers is of great interest since such an in situ search for this type of record has not been successfully implemented since the mid-60s Viking GCMS experiments. However, regardless of the outcome of the analysis for organics, the abundance and isotopic composition of thermally evolved inorganic compounds should also provide a rich data set to complement the mineralogical and elemental information provided by other MSL instruments. In addition, these evolved gas analysis (EGA) experiments will help test sedimentary models proposed by Malin and Edgett (2000) and then further developed by Milliken et al (2010) for Gale Crater. In the SAM EGA experiments the evolution temperatures of H2O, CO2, SO2, O2, or other simple compounds as the samples are heated in a helium stream to 1000 C provides information on mineral types and their associations. The isotopic composition of O, H, C, and S can be precisely determined in several evolved compounds and compared with the present day atmosphere. Such SAM results might be able to test mineralogical evidence of changing sedimentary and alteration processes over an extended period of time. For example, Bibring et al (2006) have suggested such a major shift from early nonacidic to later acidic alteration. We will

  19. Measurement uncertainty of liquid chromatographic analyses visualized by Ishikawa diagrams.

    Science.gov (United States)

    Meyer, Veronika R

    2003-09-01

    Ishikawa, or cause-and-effect diagrams, help to visualize the parameters that influence a chromatographic analysis. Therefore, they facilitate the set up of the uncertainty budget of the analysis, which can then be expressed in mathematical form. If the uncertainty is calculated as the Gaussian sum of all uncertainty parameters, it is necessary to quantitate them all, a task that is usually not practical. The other possible approach is to use the intermediate precision as a base for the uncertainty calculation. In this case, it is at least necessary to consider the uncertainty of the purity of the reference material in addition to the precision data. The Ishikawa diagram is then very simple, and so is the uncertainty calculation. This advantage is given by the loss of information about the parameters that influence the measurement uncertainty.

  20. Transfer function for a superficial layer. Parametric analysis and relationship with SM records

    International Nuclear Information System (INIS)

    Sandi, H.; Stancu, O.

    2002-01-01

    The developments presented were aimed at providing an analytical and computational support for a research project intended to examine the contribution of source mechanism and of local conditions to the features of ground motion due to Vrancea earthquakes. The project referred to is being developed jointly, by the Academy of Technical Sciences of Romania, the Institute of Geodynamics, the Technical University of Civil Engineering, Bucharest, and GEOTEC, Bucharest. The modelling of the phenomenon of seismic oscillations of ground was based on assumptions of physical and geometrical linearity. The dynamic systems considered were assumed to consist of a sequence of plane = parallel homogeneous geologic layers, accepting that the relevant physical characteristics (thickness, density, low frequency S-wave velocity, rheological characteristic) are constant for a layer, but may change from one layer to another). Alternative constitutive laws were considered (the laws referred to were of Kelvin - Voigt, Poynting and Sorokin types). The transfer function of a geological package is determined as a product of transfer functions of the successive homogeneous layers. A first step of analysis corresponded to the consideration of a single homogeneous layer, for which full analytical solutions could be derived. A parametric analysis, aimed at determining the transfer function, was undertaken considering alternative (credible) values for the parameters characterizing the constitutive laws referred to. Considering alternative possible situations, it turned out that a strong amplification occurs (for any type of constitutive law) especially for the fundamental mode of the dynamic system, while the amplification is weaker for the upper normal modes. These results correlate well with the outcome of analysis of the spectral content of ground motion as obtained from the processing of strong motion records. The most striking fact is represented by the important modifications of the

  1. Thermal Analysis On The Kinetics Of Magnesium-Aluminum Layered Double Hydroxides In Different Heating Rates

    Directory of Open Access Journals (Sweden)

    Hongbo Y.

    2015-06-01

    Full Text Available The thermal decomposition of magnesium-aluminum layered double hydroxides (LDHs was investigated by thermogravimetry analysis and differential scanning calorimetry (DSC methods in argon environment. The influence of heating rates (including 2.5, 5, 10, 15 and 20K/min on the thermal behavior of LDHs was revealed. By the methods of Kissinger and Flynn-Wall-Ozawa, the thermal kinetic parameters of activation energy and pre-exponential factor for the exothermic processes under non-isothermal conditions were calculated using the analysis of corresponding DSC curves.

  2. Toward rapid analysis, forecast and discovery of bioactive compounds from herbs by jointly using thin layer chromatography and ratiometric surface-enhanced Raman spectroscopy technique.

    Science.gov (United States)

    Gu, Xiaoling; Jin, Yang; Dong, Fang; Cai, Yueqing; You, Zhengyi; You, Junhui; Zhang, Liying; Du, Shuhu

    2018-05-10

    Conventional isolation and identification of active compounds from herbs have been extensively reported by using various chromatographic and spectroscopic techniques. However, how to quickly discover new bioactive ingredients from natural sources still remains a challenging task due to the interference of their similar structures or matrices. Here, we present a grand approach for rapid analysis, forecast and discovery of bioactive compounds from herbs based on a hyphenated strategy of thin layer chromatography and ratiometric surface-enhanced Raman spectroscopy. The performance of the hyphenated strategy is first evaluated by analyzing four protoberberine alkaloids, berberine (BER), coptisine (COP), palmatine (PAT) and jatrorrhizine (JAT), from a typical herb Coptidis Rhizoma as an example. It has been demonstrated that this coupling method can identify the four compounds by characteristic peaks at 728, 708, 736 and 732 cm -1 , and especially discriminate BER and COP (with similar migration distances) by ratiometric Raman intensity (I 708 /I 728 ). The corresponding limits of detection are 0.1, 0.05, 0.1 and 0.5 μM, respectively, which are about 1-2 orders of magnitude lower than those of direct observation method under 254 nm UV lamp. Based on these findings, the proposed method further guides forecast and discovery of unknown compounds from traditional Chinese herb Typhonii Rhizoma. Results infer that two trace alkaloids (BER and COP) from the n-butanol extract of Typhonii Rhizoma are found for the first time. Moreover, in vitro experiments manifest that BER can effectively decrease the viability of human glioma U87 cells by inducing cell cycle arrest in a concentration-dependent manner. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Forced Response Analysis of a Fan with Boundary Layer Inlet Distortion

    Science.gov (United States)

    Bakhle, Milind A.; Reddy, T. S. R.; Coroneos, Rula M.

    2014-01-01

    Boundary layer ingesting propulsion systems have the potential to significantly reduce fuel burn for future generations of commercial aircraft, but these systems must be designed to overcome the challenge of high dynamic stresses in fan blades due to forced response. High dynamic stresses can lead to high cycle fatigue failures. High-fidelity computational analysis of the fan aeromechanics is integral to an ongoing effort to design a boundary layer ingesting inlet and fan for a wind-tunnel test. An unsteady flow solution from a Reynoldsaveraged Navier Stokes analysis of a coupled inlet-fan system is used to calculate blade unsteady loading and assess forced response of the fan to distorted inflow. Conducted prior to the mechanical design of a fan, the initial forced response analyses performed in this study provide an early look at the levels of dynamic stresses that are likely to be encountered. For the boundary layer ingesting inlet, the distortion contains strong engine order excitations that act simultaneously. The combined effect of these harmonics was considered in the calculation of the forced response stresses. Together, static and dynamic stresses can provide the information necessary to evaluate whether the blades are likely to fail due to high cycle fatigue. Based on the analyses done, the overspeed condition is likely to result in the smallest stress margin in terms of the mean and alternating stresses. Additional work is ongoing to expand the analyses to off-design conditions, on-resonance conditions, and to include more detailed modeling of the blade structure.

  4. Layered structure analysis of multilayers by X-ray reflectometry using the Cu-Kβ line

    International Nuclear Information System (INIS)

    Usami, Katsuhisa; Ueda, Kazuhiro; Hirano, Tatsumi; Hoshiya, Hiroyuki; Narishige, Shinji.

    1997-01-01

    The suitability of X-ray reflectometry using the Cu-K β line for layered structure analysis of NiFe/Cu/NiFe/Ta layered films was studied. Structural parameters such as film thickness, density, and interface width can be determined more accurately than by Cu-K α1 X-ray reflectometry, owing to the abnormal dispersion effect. The standard deviations in determination of film thicknesses were within ±0.3% for NiFe and Ta films and ±0.03 nm for 2 nm Cu film. Those for the densities and interface widths were within ±2% and ±0.04 nm for all films, respectively. Analysis of some layered films regarding the change in Cu film thickness showed that in all these samples the density of the films most closely reflected the density of bulk material, and the interface width between the upper NiFe and Cu films increased with increasing Cu film thickness. (author)

  5. Stability Analysis of Hypersonic Boundary Layer over a Cone at Small Angle of Attack

    Directory of Open Access Journals (Sweden)

    Feng Ji

    2014-04-01

    Full Text Available An investigation on the stability of hypersonic boundary layer over a cone at small angle of attack has been performed. After obtaining the steady base flow, linear stability theory (LST analysis has been made with local parallel assumption. The growth rates of the first mode and second mode waves at different streamwise locations and different azimuthal angles are obtained. The results show that the boundary layer stability was greatly influenced by small angles of attack. The maximum growth rate of the most unstable wave on the leeward is larger than that on the windward. Moreover, dominating second mode wave starts earlier on the leeward than that on the windward. The LST result also shows that there is a “valley” region around 120°~150° meridian in the maximum growth rates curve.

  6. Transcriptional analysis of liver from chickens with fast (meat bird), moderate (F1 layer x meat bird cross) and low (layer bird) growth potential.

    Science.gov (United States)

    Willson, Nicky-Lee; Forder, Rebecca E A; Tearle, Rick; Williams, John L; Hughes, Robert J; Nattrass, Greg S; Hynd, Philip I

    2018-05-02

    Divergent selection for meat and egg production in poultry has resulted in strains of birds differing widely in traits related to these products. Modern strains of meat birds can reach live weights of 2 kg in 35 d, while layer strains are now capable of producing more than 300 eggs per annum but grow slowly. In this study, RNA-Seq was used to investigate hepatic gene expression between three groups of birds with large differences in growth potential; meat bird, layer strain as well as an F1 layer x meat bird. The objective was to identify differentially expressed (DE) genes between all three strains to elucidate biological factors underpinning variations in growth performance. RNA-Seq analysis was carried out on total RNA extracted from the liver of meat bird (n = 6), F1 layer x meat bird cross (n = 6) and layer strain (n = 6), males. Differential expression of genes were considered significant at P layers (19%), 2935 DE between meat birds and the cross (9.6%) and 493 DE between the cross and layers (1.6%). Comparisons between the three groups identified 155 significant DE genes. Gene ontology (GO) enrichment and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway analysis of the 155 DE genes showed the FoxO signalling pathway was most enriched (P = 0.001), including genes related to cell cycle regulation and insulin signalling. Significant GO terms included 'positive regulation of glucose import' and 'cellular response to oxidative stress', which is also consistent with FoxOs regulation of glucose metabolism. There were high correlations between FoxO pathway genes and bodyweight, as well as genes related to glycolysis and bodyweight. This study revealed large transcriptome differences between meat and layer birds. There was significant evidence implicating the FoxO signalling pathway (via cell cycle regulation and altered metabolism) as an active driver of growth variations in chicken. Functional analysis of the FoxO genes is required to

  7. High-temperature adsorption layers based on fluoridated polyimide and diatomite carrier

    Science.gov (United States)

    Yakovleva, E. Yu.; Shundrina, I. K.; Gerasimov, E. Yu.

    2017-09-01

    A way of preparing separation layers by the pyrolysis of fluorinated polyimide obtained from 2,4,6-trimethyl- m-phenylenediamine (2,4,6-TM mPDA) and 2,2-bis(3',4'-dicarboxyphenyl)hexafluoropropane (6FDA) applied onto a diatomite carrier is described. Thermogravimetry, elemental analysis, low-temperature nitrogen adsorption, high-resolution electron microscopy, and gas chromatography are used to study changes in the texture and chromatographic characteristics of these layers. It is found that changes in the structure and the effectivity of separation characteristic of the layers depend on the temperature of pyrolysis, which ranges from 250 to 1100°C. It is established that a layer of separation is formed at 250-350°C, and the order of elution of hydrocarbons is similar to their chromatographic behavior on such stationary phases as OV-101. Layers of amorphous carbon formed on the surfaces of individual particles on a diatomite surface at 500-700°C. These layers ensure highly stable and selective separation of permanent gases and hydrocarbons when they are present together.

  8. Stereospecific high-performance liquid chromatographic assay of sotalol in plasma.

    Science.gov (United States)

    Carr, R A; Foster, R T; Bhanji, N H

    1991-09-01

    A convenient high-performance liquid chromatographic (HPLC) assay was developed for determination of sotalol (STL) enantiomers in plasma. Following addition of the internal standard (IS; racemic atenolol), enantiomers of STL and IS were extracted using ethyl acetate. After evaporation of the organic layer, samples were derivatized with a solution of S-(+)-1-(1-naphthyl)ethyl isocyanate (NEIC). The resulting diastereomers were chromatographed with normal-phase HPLC with chloroform:hexane:methanol [65:33:2 (v/v)] as the mobile phase at a flow rate of 2 ml/min. The fluorescence detection wavelength was set at 220 nm for excitation with no emission filter. The suitability of the assay for pharmacokinetic studies was determined by measuring STL enantiomers in the plasma of a healthy subject after administration of a single 160-mg oral, racemic dose of STL.

  9. Applied satellite remote sensing to runoff analysis: Through the effective depth of soil layer

    International Nuclear Information System (INIS)

    Yamamoto, Y.; Kondoh, T.; Kida, T.; Nishikawa, H.

    2002-01-01

    The thickness of the soil layers in which tree roots are able to develop freely influences forest composition and growth. Trees growing in shallow soil are usually less well supplied with water and mineral nutrients than those growing in deeper soil. A soil may be deep in an absolute sense but, because of a relatively impervious layer, such as hardpan or because of a high water-table, may be shallow in a physiological sense. Penetrability measurements have been found useful in evaluating the influence of different forest types on the physical properties of soils. Commonly the penetrability of soils can be measured by using the Hasegawa-formed soil penetrometer and can be judged as the soil softness content (SSC). Previous studies report soil with more than 1.9 cm/drop of SSC to be highly permeable and therefore roots are more likely to be extensively developed. Based upon this theory the depth of soil layer with more than 1.9 cm/drop of SSC can be defined as the Effective Depth of Soil Layer (EDSL). We examined the relationship between the Ratio Vegetation Index (RVI) and the EDSL and established a 'Runoff Simulation Model (RSM)' based upon the theory of the Storage Function Model method. The conclusions are that (1) a strong positive correlation between the RVI (ground measured) and the EDSL was given, (2) applying results of conclusion (1) to satellite analysis a similar correlation between the RVI (satellite analysis of JERS 1/OPS data) and the EDSL was observed and (3) the simulated storm-runoff hydro graph coincides with the observed one well

  10. Shape Analysis of the Peripapillary RPE Layer in Papilledema and Ischemic Optic Neuropathy

    Science.gov (United States)

    Kupersmith, Mark J.; Rohlf, F. James

    2011-01-01

    Purpose. Geometric morphometrics (GM) was used to analyze the shape of the peripapillary retinal pigment epithelium–Bruch's membrane (RPE/BM) layer imaged on the SD-OCT 5-line raster in normal subjects and in patients with papilledema and ischemic optic neuropathy. Methods. Three groups of subjects were compared: 30 normals, 20 with anterior ischemic optic neuropathy (AION), and 25 with papilledema and intracranial hypertension. Twenty equidistant semilandmarks were digitized on OCT images of the RPE/BM layer spanning 2500 μm on each side of the neural canal opening (NCO). The data were analyzed using standard GM techniques, including a generalized least-squares Procrustes superimposition, principal component analysis, thin-plate spline (to visualize deformations), and permutation statistical analysis to evaluate differences in shape variables. Results. The RPE/BM layer in normals and AION have a characteristic V shape pointing away from the vitreous; the RPE/BM layer in papilledema has an inverted U shape, skewed nasally inward toward the vitreous. The differences were statistically significant. There was no significant difference in shapes between normals and AION. Pre- and posttreatment OCTs, in select cases of papilledema, showed that the inverted U-shaped RPE/BM moved posteriorly into a normal V shape as the papilledema resolved with weight loss or shunting. Conclusions. The shape difference in papilledema, absent in AION, cannot be explained by disc edema alone. The difference is a consequence of both the translaminar pressure gradient and the material properties of the peripapillary sclera. GM offers a novel way of statistically assessing shape differences of the peripapillary optic nerve head. PMID:21896851

  11. Determination of solute descriptors by chromatographic methods

    International Nuclear Information System (INIS)

    Poole, Colin F.; Atapattu, Sanka N.; Poole, Salwa K.; Bell, Andrea K.

    2009-01-01

    The solvation parameter model is now well established as a useful tool for obtaining quantitative structure-property relationships for chemical, biomedical and environmental processes. The model correlates a free-energy related property of a system to six free-energy derived descriptors describing molecular properties. These molecular descriptors are defined as L (gas-liquid partition coefficient on hexadecane at 298 K), V (McGowan's characteristic volume), E (excess molar refraction), S (dipolarity/polarizability), A (hydrogen-bond acidity), and B (hydrogen-bond basicity). McGowan's characteristic volume is trivially calculated from structure and the excess molar refraction can be calculated for liquids from their refractive index and easily estimated for solids. The remaining four descriptors are derived by experiment using (largely) two-phase partitioning, chromatography, and solubility measurements. In this article, the use of gas chromatography, reversed-phase liquid chromatography, micellar electrokinetic chromatography, and two-phase partitioning for determining solute descriptors is described. A large database of experimental retention factors and partition coefficients is constructed after first applying selection tools to remove unreliable experimental values and an optimized collection of varied compounds with descriptor values suitable for calibrating chromatographic systems is presented. These optimized descriptors are demonstrated to be robust and more suitable than other groups of descriptors characterizing the separation properties of chromatographic systems.

  12. Determination of solute descriptors by chromatographic methods.

    Science.gov (United States)

    Poole, Colin F; Atapattu, Sanka N; Poole, Salwa K; Bell, Andrea K

    2009-10-12

    The solvation parameter model is now well established as a useful tool for obtaining quantitative structure-property relationships for chemical, biomedical and environmental processes. The model correlates a free-energy related property of a system to six free-energy derived descriptors describing molecular properties. These molecular descriptors are defined as L (gas-liquid partition coefficient on hexadecane at 298K), V (McGowan's characteristic volume), E (excess molar refraction), S (dipolarity/polarizability), A (hydrogen-bond acidity), and B (hydrogen-bond basicity). McGowan's characteristic volume is trivially calculated from structure and the excess molar refraction can be calculated for liquids from their refractive index and easily estimated for solids. The remaining four descriptors are derived by experiment using (largely) two-phase partitioning, chromatography, and solubility measurements. In this article, the use of gas chromatography, reversed-phase liquid chromatography, micellar electrokinetic chromatography, and two-phase partitioning for determining solute descriptors is described. A large database of experimental retention factors and partition coefficients is constructed after first applying selection tools to remove unreliable experimental values and an optimized collection of varied compounds with descriptor values suitable for calibrating chromatographic systems is presented. These optimized descriptors are demonstrated to be robust and more suitable than other groups of descriptors characterizing the separation properties of chromatographic systems.

  13. Chromatographic profiles of extractives from leaves of Eugenia uniflora

    Directory of Open Access Journals (Sweden)

    Isabelle C.F. Bezerra

    Full Text Available ABSTRACT Eugenia uniflora L., Myrtaceae, popularly known as “pitanga”, is used in traditional medicine due the properties attributed to its chemical content, these being mainly hydrolysable tannins and flavonoids. This study provides a qualitative and quantitative evaluation of chemical profile from leaves of E. uniflora. The HPLC analysis was carried out on a C18 column (4.6 mm × 250 mm, 5 µm by gradient elution with methanol and water (acidified with trifluoracetic acid; and silica gel Plates 60-F 254 with 10–12 µm and 5–6 µm particles, respectively for TLC and High HPTLC analysis. The chromatographic data obtained from HPLC, TLC and HPTLC presented bands and peaks related to flavonoids (myricitrin and derivatives and tannins (gallic and ellagic acids, which were observed from different samples. The chromatographic similarities enabled the building of a typical fingerprint for the herbal material. The similarity analysis of the sample data by Pearson correlation showed R values >0.9 among peaks (HPLC and bands (HPTLC. In addition, the analytical methodology developed by HPLC enabled the satisfactory quantification of marker substances [ellagic acid = 0.22% and 0.20% (m/m; gallic acid = 0.20% and 0.43%; myricitrin = 0.42 and 1.74% (m/m in herbal drug and crude extract, respectively]. The procedure was also validated in accordance with the assays required by Brazilian legislation. Thus, the HPTLC and HPLC methods developed in this study provide helpful and simple tools for the quality evaluation both qualitatively and quantitatively of raw materials and extractives from leaves of E. uniflora.

  14. Pitfalls in velocity analysis for strongly contrasting, layered media - Example from the Chalk Group, North Sea

    Science.gov (United States)

    Montazeri, Mahboubeh; Uldall, Anette; Moreau, Julien; Nielsen, Lars

    2018-02-01

    Knowledge about the velocity structure of the subsurface is critical in key seismic processing sequences, for instance, migration, depth conversion, and construction of initial P- and S-wave velocity models for full-waveform inversion. Therefore, the quality of subsurface imaging is highly dependent upon the quality of the seismic velocity analysis. Based on a case study from the Danish part of the North Sea, we show how interference caused by multiples, converted waves, and thin-layer effects may lead to incorrect velocity estimation, if such effects are not accounted for. Seismic wave propagation inside finely layered reservoir rocks dominated by chalk is described by two-dimensional finite-difference wave field simulation. The rock physical properties used for the modeling are based on an exploration well from the Halfdan field in the Danish sector of the North Sea. The modeling results are compared to seismic data from the study area. The modeling shows that interference of primaries with multiples, converted waves and thin-bed effects can give rise to strong anomalies in standard velocity analysis plots. Consequently, root-mean-square (RMS) velocity profiles may be erroneously picked. In our study area, such mis-picking can introduce errors in, for example, the thickness estimation of the layers near the base of the studied sedimentary strata by 11% to 26%. Tests show that front muting and bandpass filtering cannot significantly improve the quality of velocity analysis in our study. However, we notice that spiking deconvolution applied before velocity analysis may to some extent reduce the impact of interference and, therefore, reduce the risk of erroneous picking of the velocity function.

  15. Similarity analyses of chromatographic herbal fingerprints: A review

    International Nuclear Information System (INIS)

    Goodarzi, Mohammad; Russell, Paul J.; Vander Heyden, Yvan

    2013-01-01

    Graphical abstract: -- Highlights: •Similarity analyses of herbal fingerprints are reviewed. •Different (dis)similarity approaches are discussed. •(Dis)similarity-metrics and exploratory-analysis approaches are illustrated. •Correlation and distance-based measures are overviewed. •Similarity analyses illustrated by several case studies. -- Abstract: Herbal medicines are becoming again more popular in the developed countries because being “natural” and people thus often assume that they are inherently safe. Herbs have also been used worldwide for many centuries in the traditional medicines. The concern of their safety and efficacy has grown since increasing western interest. Herbal materials and their extracts are very complex, often including hundreds of compounds. A thorough understanding of their chemical composition is essential for conducting a safety risk assessment. However, herbal material can show considerable variability. The chemical constituents and their amounts in a herb can be different, due to growing conditions, such as climate and soil, the drying process, the harvest season, etc. Among the analytical methods, chromatographic fingerprinting has been recommended as a potential and reliable methodology for the identification and quality control of herbal medicines. Identification is needed to avoid fraud and adulteration. Currently, analyzing chromatographic herbal fingerprint data sets has become one of the most applied tools in quality assessment of herbal materials. Mostly, the entire chromatographic profiles are used to identify or to evaluate the quality of the herbs investigated. Occasionally only a limited number of compounds are considered. One approach to the safety risk assessment is to determine whether the herbal material is substantially equivalent to that which is either readily consumed in the diet, has a history of application or has earlier been commercialized i.e. to what is considered as reference material. In order

  16. Similarity analyses of chromatographic herbal fingerprints: A review

    Energy Technology Data Exchange (ETDEWEB)

    Goodarzi, Mohammad [Department of Analytical Chemistry and Pharmaceutical Technology, Center for Pharmaceutical Research, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels (Belgium); Russell, Paul J. [Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ (United Kingdom); Vander Heyden, Yvan, E-mail: yvanvdh@vub.ac.be [Department of Analytical Chemistry and Pharmaceutical Technology, Center for Pharmaceutical Research, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels (Belgium)

    2013-12-04

    Graphical abstract: -- Highlights: •Similarity analyses of herbal fingerprints are reviewed. •Different (dis)similarity approaches are discussed. •(Dis)similarity-metrics and exploratory-analysis approaches are illustrated. •Correlation and distance-based measures are overviewed. •Similarity analyses illustrated by several case studies. -- Abstract: Herbal medicines are becoming again more popular in the developed countries because being “natural” and people thus often assume that they are inherently safe. Herbs have also been used worldwide for many centuries in the traditional medicines. The concern of their safety and efficacy has grown since increasing western interest. Herbal materials and their extracts are very complex, often including hundreds of compounds. A thorough understanding of their chemical composition is essential for conducting a safety risk assessment. However, herbal material can show considerable variability. The chemical constituents and their amounts in a herb can be different, due to growing conditions, such as climate and soil, the drying process, the harvest season, etc. Among the analytical methods, chromatographic fingerprinting has been recommended as a potential and reliable methodology for the identification and quality control of herbal medicines. Identification is needed to avoid fraud and adulteration. Currently, analyzing chromatographic herbal fingerprint data sets has become one of the most applied tools in quality assessment of herbal materials. Mostly, the entire chromatographic profiles are used to identify or to evaluate the quality of the herbs investigated. Occasionally only a limited number of compounds are considered. One approach to the safety risk assessment is to determine whether the herbal material is substantially equivalent to that which is either readily consumed in the diet, has a history of application or has earlier been commercialized i.e. to what is considered as reference material. In order

  17. Retinal layer segmentation in multiple sclerosis: a systematic review and meta-analysis.

    Science.gov (United States)

    Petzold, Axel; Balcer, Laura J; Calabresi, Peter A; Costello, Fiona; Frohman, Teresa C; Frohman, Elliot M; Martinez-Lapiscina, Elena H; Green, Ari J; Kardon, Randy; Outteryck, Olivier; Paul, Friedemann; Schippling, Sven; Vermersch, Patrik; Villoslada, Pablo; Balk, Lisanne J

    2017-10-01

    Structural retinal imaging biomarkers are important for early recognition and monitoring of inflammation and neurodegeneration in multiple sclerosis. With the introduction of spectral domain optical coherence tomography (SD-OCT), supervised automated segmentation of individual retinal layers is possible. We aimed to investigate which retinal layers show atrophy associated with neurodegeneration in multiple sclerosis when measured with SD-OCT. In this systematic review and meta-analysis, we searched for studies in which SD-OCT was used to look at the retina in people with multiple sclerosis with or without optic neuritis in PubMed, Web of Science, and Google Scholar between Nov 22, 1991, and April 19, 2016. Data were taken from cross-sectional cohorts and from one timepoint from longitudinal studies (at least 3 months after onset in studies of optic neuritis). We classified data on eyes into healthy controls, multiple-sclerosis-associated optic neuritis (MSON), and multiple sclerosis without optic neuritis (MSNON). We assessed thickness of the retinal layers and we rated individual layer segmentation performance by random effects meta-analysis for MSON eyes versus control eyes, MSNON eyes versus control eyes, and MSNON eyes versus MSON eyes. We excluded relevant sources of bias by funnel plots. Of 25 497 records identified, 110 articles were eligible and 40 reported data (in total 5776 eyes from patients with multiple sclerosis [1667 MSON eyes and 4109 MSNON eyes] and 1697 eyes from healthy controls) that met published OCT quality control criteria and were suitable for meta-analysis. Compared with control eyes, the peripapillary retinal nerve fibre layer (RNFL) showed thinning in MSON eyes (mean difference -20·10 μm, 95% CI -22·76 to -17·44; pmultiple sclerosis and control eyes were found in the peripapillary RNFL and macular GCIPL. Inflammatory disease activity might be captured by the INL. Because of the consistency, robustness, and large effect size, we

  18. Use of graphite layer open tubular (GLOT) in environmental analysis; Impiego di colonne GLOT (Graphite Layer Open Tubular) nell`analisi ambientale

    Energy Technology Data Exchange (ETDEWEB)

    Bruner, F.; Lattanzi, L. [Urbino Univ. (Italy). Istituto di Scienze Chimiche, Centro di Studio per la Chimica e le Tecnologie Strumentali Avanzate; Borghesi, P. [Centro Ricerca e Sviluppo, Enichem Elastomeri, Ravenna (Italy)

    1996-06-01

    Recently it has been developed a series of new capillary columns characterised by the use of graphitized carbon black modified from different amount of liquid phase. The characteristics of these columns, called graphite layer open tubular (GLOT), are described together with their application to the environmental analysis. A specific application of GLOT columns is for the direct analysis of aqueous solutions avoiding solvent extraction procedure. A comparison between a GLOT column and a traditional capillary column, estimating their behaviour after repeated direct injections of aqueous solution sample is written. Some applications regarding the analysis of the atmosphere pollutants, as aliphatic and aromatic hydrocarbons, and their compounds are written too.

  19. Wing aeroelasticity analysis based on an integral boundary-layer method coupled with Euler solver

    Directory of Open Access Journals (Sweden)

    Ma Yanfeng

    2016-10-01

    Full Text Available An interactive boundary-layer method, which solves the unsteady flow, is developed for aeroelastic computation in the time domain. The coupled method combines the Euler solver with the integral boundary-layer solver (Euler/BL in a “semi-inverse” manner to compute flows with the inviscid and viscous interaction. Unsteady boundary conditions on moving surfaces are taken into account by utilizing the approximate small-perturbation method without moving the computational grids. The steady and unsteady flow calculations for the LANN wing are presented. The wing tip displacement of high Reynolds number aero-structural dynamics (HIRENASD Project is simulated under different angles of attack. The flutter-boundary predictions for the AGARD 445.6 wing are provided. The results of the interactive boundary-layer method are compared with those of the Euler method and experimental data. The study shows that viscous effects are significant for these cases and the further data analysis confirms the validity and practicability of the coupled method.

  20. Analysis of Ground Effects on Aerodynamic Characteristics of Aerofoils Using Boundary Layer Approximation

    Science.gov (United States)

    Takahashi, Yuji; Kikuchi, Masanori; Hirano, Kimitaka

    A study of a new high-speed zero-emission transportation “Aerotrain” is being carried out in Tohoku University and the University of Miyazaki. Because the aerotrain utilizes the ground effect, research on the aerofoil section, which can harness the ground effect effectively, is important. The aerotrain moves along a U-shaped guideway, which has a ground and sidewalls, so it has many viscous interference elements. In an analysis of the ground effects on the aerodynamic characteristics of aerofoils, the boundary layers on the aerofoil surface must be considered. At first, velocity distributions on the surfaces of aerofoils in potential flows are computed using the vortex method, then the momentum integration equations of the boundary layer are solved with experimental formulas. This procedure has the following advantages: modifications of the aerofoil section are easy because it is not necessary to make complicated computational grids, boundary layer transition and separation can be predicted using empirical procedures. The aerodynamic characteristics of four types of aerofoil sections are investigated to clarify the relationship between aerofoil sections and ground effects. Computational results are compared with experimental results obtained using a towing wind tunnel to verify computational precisions. In addition, aerofoil characteristics at an actual cruise speed are analyzed.

  1. Hydraulic modelling for analysis of the hot water layer stability in research reactor

    International Nuclear Information System (INIS)

    Ribeiro, Rogerio; Yanagihara, Jurandir Itizo

    1995-01-01

    Pool reactors are research reactors, which allow easy access to the core and are simple to operate. Reactors of this kind operating at power levels higher than about one megawatt need a hot water layer at the surface of the pool, in order to keep surface activity below acceptable levels and enable free access to the upper part of the reactor. This work presents similitude criteria derived by dimensional analysis and by non dimensioning the basic equations to analyze this layer's stability in a reduced scale model. The flow in the reactor is complex. It is impossible to consider all the phenomena with a single similitude criterion. The best would be to construct several models considering all the similitude criteria and then combine the results. Economical reasons and available time in the majority of the cases are a restrain to this procedure. Then, the most important criteria to the considered phenomenon must be chosen in order to give the best results. This work identifies three similitude criteria that were considered important to analyze the pool reactor's hot water layer stability. (author)

  2. Analysis of retinal nerve fibre layer changes in anisometropic amblyopia by Heidelberg retina tomograph

    International Nuclear Information System (INIS)

    Tayyab, A.; Afzal, F.

    2013-01-01

    Objective: To identify if anisometropic amblyopia is associated with changes in optic disk morphology. Methods: The study comprised a total of 80 eyes recruited from Shifa Foundation Community Health Centre and the Pakistan Institute of Medical Sciences, Islamabad between May and October 2012. Anisometropic amblyopia was the only cause of disability (visual acuity >6/12) in amblyopic eyes whereas normal eyes had a best corrected visual acuity of 6/6 and no morbidities. Patients with other causes of amblyopia, co-morbid ocular diseases, and in whom a good-quality image could not be obtained were excluded. Mean retinal nerve fiber layer thickness was analysed using Heidelberg retina tomograph. Analysis of frequency distribution, probability and regression were run on the data collected during the study using SPSS version 15.0. Results: The mean age of the patients was 23.85+-5.85 years. The retinal nerve fibre layer thickness ranged between 0.09mm and 0.35 mm (mean: 0.23mm+-0.07) in amblyopic eyes, and between 0.18mm and 0.36mm (mean: 0.25mm+-0.05) in normal eyes. The difference was not statistically significant (p=0.087). No association was found between the retinal nerve fiber layer thickness or the age and refractive error of patients. Conclusion: The optic disk does not appear to be the site of morphological changes in amblyopia. (author)

  3. Three-dimensional instability analysis of boundary layers perturbed by streamwise vortices

    Science.gov (United States)

    Martín, Juan A.; Paredes, Pedro

    2017-12-01

    A parametric study is presented for the incompressible, zero-pressure-gradient flat-plate boundary layer perturbed by streamwise vortices. The vortices are placed near the leading edge and model the vortices induced by miniature vortex generators (MVGs), which consist in a spanwise-periodic array of small winglet pairs. The introduction of MVGs has been experimentally proved to be a successful passive flow control strategy for delaying laminar-turbulent transition caused by Tollmien-Schlichting (TS) waves. The counter-rotating vortex pairs induce non-modal, transient growth that leads to a streaky boundary layer flow. The initial intensity of the vortices and their wall-normal distances to the plate wall are varied with the aim of finding the most effective location for streak generation and the effect on the instability characteristics of the perturbed flow. The study includes the solution of the three-dimensional, stationary, streaky boundary layer flows by using the boundary region equations, and the three-dimensional instability analysis of the resulting basic flows by using the plane-marching parabolized stability equations. Depending on the initial circulation and positioning of the vortices, planar TS waves are stabilized by the presence of the streaks, resulting in a reduction in the region of instability and shrink of the neutral stability curve. For a fixed maximum streak amplitude below the threshold for secondary instability (SI), the most effective wall-normal distance for the formation of the streaks is found to also offer the most stabilization of TS waves. By setting a maximum streak amplitude above the threshold for SI, sinuous shear layer modes become unstable, as well as another instability mode that is amplified in a narrow region near the vortex inlet position.

  4. Analysis of the Inhibition Layer of Galvanized Dual-Phase Steels

    Energy Technology Data Exchange (ETDEWEB)

    Wang, K. K.; Wang, H. P.; Chang, L.; Gan, D. [National Sun Yat-Sen Univ., Kaohsiung (China); Chen, T. R.; Chen, H. B. [Steel and Aluminum R and D Development, Kaohsiung (China)

    2012-01-15

    The formation of the Fe-Al inhibition layer in hot-dip galvanizing is a confusing issue for a long time. This study presents a characterization result on the inhibition layer formed on C-Mn-Cr and C-Mn-Si dual-phase steels after a short time galvanizing. The samples were annealed at 800 .deg. C for 60 s in N{sub 2}-10% H{sub 2} atmosphere with a dew point of -30 .deg. C, and were then galvanized in a bath containing 0.2%Al. X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) was employed for characterization. The TEM electron diffraction shows that only Fe{sub 2}Al{sub 5} intermetallic phase was formed. No orientation relationship between the Fe{sub 2}Al{sub 5} phase and the steel substrate could be identified. Two peaks of Al 2p photoelectrons, one from metallic aluminum and the other from Al{sup 3+} ions, were detected in the inhibition layer, indicating that the layer is in fact a mixture of Fe{sub 2}Al{sub 5} and Al{sub 2}O{sub 3}. TEM/EDS analysis verifies the existence of Al{sub 2}O{sub 3} in the boundaries of Fe{sub 2}Al{sub 5} grains. The nucleation of Fe{sub 2}Al{sub 5} and the reduction of the surface oxide probably proceeded concurrently on galvanizing, and the residual oxides prohibited the heteroepitaxial growth of Fe{sub 2}Al{sub 5}.

  5. The investigation of a two-layer fluid soliton pair using phase plane analysis

    International Nuclear Information System (INIS)

    Momeni, M.; Moslehi-Fard, M.; Alinejad, H.; Mahmoodi, J.

    2004-01-01

    Nonlinear long waves theory in a two-layer fluid system has been studied. The dynamical equations according to the normalized heights in first order are obtained using the reductive perturbation method and the equations of shallow water in each fluid and taking boundary conditions appropriate into account. Conserve energy form by definition a independent variable is found. By definition a Lyapunov function, the condition for stability are shown. A new technique was used to prove stability as well as existence of soliton pair using phase plane analysis. (author)

  6. Experimental and computational analysis of the hot water layer for the radiological protection in swimming pool reactor

    International Nuclear Information System (INIS)

    Ribeiro, Rogerio.

    1995-01-01

    Pool reactors are research reactors, which allow easy access to the core and rare simple to operate. Reactors of this kind operating at power levels higher than about one megawatt need a hot water layer at the surface of the pool, in order to keep surface activity below acceptable levels and enable free access to the upper part of the reactor. An experimental apparatus was constructed to study the hot water layer stability. Thermocouples were used to measure the temperature field. A numerical analysis was conducted simultaneously. Regarding experimental results, representative temperature contour lines of the hot water layer were plotted. The temperature field was determined in the numerical analysis and temperature contour lines corresponding to those of the experimental results were plotted. The hot water layer kept stable for experimental and numerical results. Good agreement between the results for the hot water layer position and thickness has been obtained. (author). 21 refs., 40 figs., 15 tabs

  7. Gas-Chromatographic Determination Of Water In Freon PCA

    Science.gov (United States)

    Melton, Donald M.

    1994-01-01

    Gas-chromatographic apparatus measures small concentrations of water in specimens of Freon PCA. Testing by use of apparatus faster and provides greater protection against accidental contamination of specimens by water in testing environment. Automated for unattended operation. Also used to measure water contents of materials, other than Freon PCA. Innovation extended to development of purgeable sampling accessory for gas chromatographs.

  8. Probabilistic peak detection for first-order chromatographic data

    NARCIS (Netherlands)

    Lopatka, M.; Vivó-Truyols, G.; Sjerps, M.J.

    2014-01-01

    We present a novel algorithm for probabilistic peak detection in first-order chromatographic data. Unlike conventional methods that deliver a binary answer pertaining to the expected presence or absence of a chromatographic peak, our method calculates the probability of a point being affected by

  9. New extraction chromatographic material for rhenium separation

    International Nuclear Information System (INIS)

    Lucanikova, M.; Czech Technical University, Prague; Kucera, J.; Czech Technical University, Prague; Sebesta, F.

    2008-01-01

    Three types of the extraction chromatographic materials, composed from Aliquat R 336 deposited in the polyacrylonitrile (PAN) beads and prepared by different procedures, were compared for extraction of rhenium. The best properties were exhibited when the solid extractant was prepared by impregnation of the ready-made PAN beads. Solid extractant prepared by direct coagulation of the beads from the suspension of Aliquat R 336 in solution of PAN in nitric acid differs only by lower capacity in dynamic conditions. Material prepared from the PAN solution in dimethylsulfoxide was the worst because Aliquat R 336 was washed out from the beads during coagulation of the polymer and the extraction capacity was low. As it is shown, the first two solid extractants are fully comparable with the commercial TEVA Resin. (author)

  10. Aligning of single and multiple wavelength chromatographic

    DEFF Research Database (Denmark)

    Nielsen, Niels-Peter Vest; Carstensen, Jens Michael; Smedsgaard, Jørn

    1998-01-01

    optimised warping (COW) using two input parameters which can be estimated from the observed peak width. COW is demonstrated on constructed single trace chromatograms and on single and multiple wavelength chromatograms obtained from HPLC diode detection analyses of fungal extractsA copy of the C program......The use of chemometric data processing is becoming an important part of modern chromatography. Most chemometric analyses are performed on reduced data sets using areas of selected peaks detected in the chromatograms, which means a loss of data and introduces the problem of extracting peak data from...... to utilise the entire data matrix or rely on peak detection, thus having the same limitations as the commonly used chemometric procedures. The method presented uses the entire chromatographic data matrices and does not require any preprocessing e.g., peak detection. It relies on piecewise linear correlation...

  11. Shock timing measurements and analysis in deuterium-tritium-ice layered capsule implosions on NIF

    Energy Technology Data Exchange (ETDEWEB)

    Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Landen, O. L.; Edwards, M. J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Hohenberger, M.; Boehly, T. R. [Laboratory for Laser Energetics, Rochester, New York 14623 (United States); Nikroo, A. [General Atomics, San Diego, California 92196 (United States)

    2014-02-15

    Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three shocks, but reveals a considerable discrepancy in the timing of the 4th shock in DT ice layered implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th shock timing.

  12. Numerical combination for nonlinear analysis of structures coupled to layered soils

    Directory of Open Access Journals (Sweden)

    Wagner Queiroz Silva

    Full Text Available This paper presents an alternative coupling strategy between the Boundary Element Method (BEM and the Finite Element Method (FEM in order to create a computational code for the analysis of geometrical nonlinear 2D frames coupled to layered soils. The soil is modeled via BEM, considering multiple inclusions and internal load lines, through an alternative formulation to eliminate traction variables on subregions interfaces. A total Lagrangean formulation based on positions is adopted for the consideration of the geometric nonlinear behavior of frame structures with exact kinematics. The numerical coupling is performed by an algebraic strategy that extracts and condenses the equivalent soil's stiffness matrix and contact forces to be introduced into the frame structures hessian matrix and internal force vector, respectively. The formulation covers the analysis of shallow foundation structures and piles in any direction. Furthermore, the piles can pass through different layers. Numerical examples are shown in order to illustrate and confirm the accuracy and applicability of the proposed technique.

  13. Shock timing measurements and analysis in deuterium-tritium-ice layered capsule implosions on NIF

    Science.gov (United States)

    Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Hohenberger, M.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Boehly, T. R.; Nikroo, A.; Landen, O. L.; Edwards, M. J.

    2014-02-01

    Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three shocks, but reveals a considerable discrepancy in the timing of the 4th shock in DT ice layered implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th shock timing.

  14. Shock timing measurements and analysis in deuterium-tritium-ice layered capsule implosions on NIF

    International Nuclear Information System (INIS)

    Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Landen, O. L.; Edwards, M. J.; Hohenberger, M.; Boehly, T. R.; Nikroo, A.

    2014-01-01

    Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three shocks, but reveals a considerable discrepancy in the timing of the 4th shock in DT ice layered implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th shock timing

  15. Dynamics Evolution Investigation of Mack Mode Instability in a Hypersonic Boundary Layer by Bicoherence Spectrum Analysis

    Science.gov (United States)

    Han, Jian; Jiang, Nan

    2012-07-01

    The instability of a hypersonic boundary layer on a cone is investigated by bicoherence spectrum analysis. The experiment is conducted at Mach number 6 in a hypersonic wind tunnel. The time series signals of instantaneous fluctuating surface-thermal-flux are measured by Pt-thin-film thermocouple temperature sensors mounted at 28 stations on the cone surface along streamwise direction to investigate the development of the unstable disturbances. The bicoherence spectrum analysis based on wavelet transform is employed to investigate the nonlinear interactions of the instability of Mack modes in hypersonic laminar boundary layer transition. The results show that wavelet bicoherence is a powerful tool in studying the unstable mode nonlinear interaction of hypersonic laminar-turbulent transition. The first mode instability gives rise to frequency shifts to higher unstable modes at the early stage of hypersonic laminar-turbulent transition. The modulations subsequently lead to the second mode instability occurrence. The second mode instability governs the last stage of instability and final breakdown to turbulence with multi-scale disturbances growth.

  16. Dynamics Evolution Investigation of Mack Mode Instability in a Hypersonic Boundary Layer by Bicoherence Spectrum Analysis

    International Nuclear Information System (INIS)

    Han Jian; Jiang Nan

    2012-01-01

    The instability of a hypersonic boundary layer on a cone is investigated by bicoherence spectrum analysis. The experiment is conducted at Mach number 6 in a hypersonic wind tunnel. The time series signals of instantaneous fluctuating surface-thermal-flux are measured by Pt-thin-film thermocouple temperature sensors mounted at 28 stations on the cone surface along streamwise direction to investigate the development of the unstable disturbances. The bicoherence spectrum analysis based on wavelet transform is employed to investigate the nonlinear interactions of the instability of Mack modes in hypersonic laminar boundary layer transition. The results show that wavelet bicoherence is a powerful tool in studying the unstable mode nonlinear interaction of hypersonic laminar-turbulent transition. The first mode instability gives rise to frequency shifts to higher unstable modes at the early stage of hypersonic laminar-turbulent transition. The modulations subsequently lead to the second mode instability occurrence. The second mode instability governs the last stage of instability and final breakdown to turbulence with multi-scale disturbances growth. (fundamental areas of phenomenology(including applications))

  17. Futures Business Models for an IoT Enabled Healthcare Sector: A Causal Layered Analysis Perspective

    Directory of Open Access Journals (Sweden)

    Julius Francis Gomes

    2016-12-01

    Full Text Available Purpose: To facilitate futures business research by proposing a novel way to combine business models as a conceptual tool with futures research techniques. Design: A futures perspective is adopted to foresight business models of the Internet of Things (IoT enabled healthcare sector by using business models as a futures business research tool. In doing so, business models is coupled with one of the most prominent foresight methodologies, Causal Layered Analysis (CLA. Qualitative analysis provides deeper understanding of the phenomenon through the layers of CLA; litany, social causes, worldview and myth. Findings: It is di cult to predict the far future for a technology oriented sector like healthcare. This paper presents three scenarios for short-, medium- and long-term future. Based on these scenarios we also present a set of business model elements for different future time frames. This paper shows a way to combine business models with CLA, a foresight methodology; in order to apply business models in futures business research. Besides offering early results for futures business research, this study proposes a conceptual space to work with individual business models for managerial stakeholders. Originality / Value: Much research on business models has offered conceptualization of the phenomenon, innovation through business model and transformation of business models. However, existing literature does not o er much on using business model as a futures research tool. Enabled by futures thinking, we collected key business model elements and building blocks for the futures market and ana- lyzed them through the CLA framework.

  18. High performance thin layer chromatography fingerprint analysis of guava (Psidium guajava) leaves

    Science.gov (United States)

    Astuti, M.; Darusman, L. K.; Rafi, M.

    2017-05-01

    High-performance thin layer chromatography (HPTLC) fingerprint analysis is commonly used for quality control of medicinal plants in term of identification and authentication. In this study, we have been developed HPTLC fingerprint analysis for identification of guava (Psidium guajava) leaves raw material. A mixture of chloroform, acetone, and formic acid in the ratio 10:2:1 was used as the optimum mobile phase in HPTLC silica plate and with 13 bands were detected. As reference marker we chose gallic acid (Rf = 0.21) and catechin (Rf = 0.11). The two compound were detected as pale black bands at 366 nm after derivatization with sulfuric acid 10% v/v (in methanol) reagent. Validation of the method was met within validation criteria, so the developed method could be used for quality control of guava leaves.

  19. Chromatographic, Spectroscopic and Mass Spectrometric Approaches for Exploring the Habitability of Mars in 2012 and Beyond with the Curiosity Rover

    Science.gov (United States)

    Mahaffy, Paul

    2012-01-01

    The Sample Analysis at Mars (SAM) suite of instruments on the Curiosity Rover of Mars Science Laboratory Mission is designed to provide chemical and isotopic analysis of organic and inorganic volatiles for both atmospheric and solid samples. The goals of the science investigation enabled by the gas chromatograph mass spectrometer and tunable laser spectrometer instruments of SAM are to work together with the other MSL investigations is to quantitatively assess habitability through a series of chemical and geological measurements. We describe the multi-column gas chromatograph system employed on SAM and the approach to extraction and analysis of organic compounds that might be preserved in ancient martian rocks.

  20. Multi-scale model analysis of boundary layer ozone over East Asia

    Directory of Open Access Journals (Sweden)

    M. Lin

    2009-05-01

    Full Text Available This study employs the regional Community Multiscale Air Quality (CMAQ model to examine seasonal and diurnal variations of boundary layer ozone (O3 over East Asia. We evaluate the response of model simulations of boundary layer O3 to the choice of chemical mechanisms, meteorological fields, boundary conditions, and model resolutions. Data obtained from surface stations, aircraft measurements, and satellites are used to advance understanding of O3 chemistry and mechanisms over East Asia and evaluate how well the model represents the observed features. Satellite measurements and model simulations of summertime rainfall are used to assess the impact of the Asian monsoon on O3 production. Our results suggest that summertime O3 over Central Eastern China is highly sensitive to cloud cover and monsoonal rainfall over this region. Thus, accurate simulation of the East Asia summer monsoon is critical to model analysis of atmospheric chemistry over China. Examination of hourly summertime O3 mixing ratios from sites in Japan confirms the important role of diurnal boundary layer fluctuations in controlling ground-level O3. By comparing five different model configurations with observations at six sites, the specific mechanisms responsible for model behavior are identified and discussed. In particular, vertical mixing, urban chemistry, and dry deposition depending on boundary layer height strongly affect model ability to capture observed behavior. Central Eastern China appears to be the most sensitive region in our study to the choice of chemical mechanisms. Evaluation with TRACE-P aircraft measurements reveals that neither the CB4 nor the SAPRC99 mechanisms consistently capture observed behavior of key photochemical oxidants in springtime. However, our analysis finds that SAPRC99 performs somewhat better in simulating mixing ratios of H2O2 (hydrogen peroxide

  1. Radio Column Chromatographic Assay of H3-Labelled Substances

    International Nuclear Information System (INIS)

    Scharpenseel, H.W.; Menke, K.H.

    1962-01-01

    Combined radio-chromatographic investigations of H 3 -labelled substances are an integral part of the majority of biochemical experiments with H 3 -labelled compounds. H 3 -radio paper chromatography yields, in a scanner with a windowless flow counter, a counting efficiency of 0,5 -1,5%, depending largely on the thickness of the paper and the self-absorption of the labelled compound. The radio gas chromatography of tritiated compounds presents no major problem. Successful use is being made of a combination of a gas chromatograph with a flow ionization chamber and vibrating reed electrometer, a system originated by K. E. Wilzbach and P. Riessz, and improved by H. Dutton, L. Mason and L. Blair. Through the use of ''Teflon'' and silicone-rubber for the insulating parts of the flow ion chamber, it can be operated at close to 300 o C. Radio column chromatography with tritium holds little promise, when the column effluent is spread out as a shallow layer and slowly passes under a windowless flow counter or a scintillation counter, as was successfully tried with C 14 . Liquid scintillation spectrometry is likely to be the chosen method. Essentially, there are two different approaches feasible. These have been compared: 1. The column effluent is passed through a coil of plastic scintillator tubing, which is wound around a ''Plexiglas'' cylinder and placed in a bath of silicone oil in a light pipe with TiO 2 -reflector. Similarly, the HP-containing effluent can be directed through a test vial, filled - very much as in Steinberg's method - with plastic scintillator beads. These two approaches, that operate highly satisfactorily in the case of C 14 , offer low counting efficiencies of less than 1% for H 3 due to the unfavourable surface to volume ratio. 2. The column effluent is combined 1:30 with a mixture of 3:2 toluene/ethanol by the action of a magnet-vibrator before being assayed while passing through a K 40 -free glass - coiled between the analyser- and monitor

  2. Elimination of chromatographic and mass spectrometric problems in GC-MS analysis of Lavender essential oil by multivariate curve resolution techniques: Improving the peak purity assessment by variable size moving window-evolving factor analysis.

    Science.gov (United States)

    Jalali-Heravi, Mehdi; Moazeni-Pourasil, Roudabeh Sadat; Sereshti, Hassan

    2015-03-01

    In analysis of complex natural matrices by gas chromatography-mass spectrometry (GC-MS), many disturbing factors such as baseline drift, spectral background, homoscedastic and heteroscedastic noise, peak shape deformation (non-Gaussian peaks), low S/N ratio and co-elution (overlapped and/or embedded peaks) lead the researchers to handle them to serve time, money and experimental efforts. This study aimed to improve the GC-MS analysis of complex natural matrices utilizing multivariate curve resolution (MCR) methods. In addition, to assess the peak purity of the two-dimensional data, a method called variable size moving window-evolving factor analysis (VSMW-EFA) is introduced and examined. The proposed methodology was applied to the GC-MS analysis of Iranian Lavender essential oil, which resulted in extending the number of identified constituents from 56 to 143 components. It was found that the most abundant constituents of the Iranian Lavender essential oil are α-pinene (16.51%), camphor (10.20%), 1,8-cineole (9.50%), bornyl acetate (8.11%) and camphene (6.50%). This indicates that the Iranian type Lavender contains a relatively high percentage of α-pinene. Comparison of different types of Lavender essential oils showed the composition similarity between Iranian and Italian (Sardinia Island) Lavenders. Published by Elsevier B.V.

  3. ANÁLISIS POR CG/EM Y ACTIVIDAD ANTIMICROBIANA DE ALGUNAS FRACCIONES DEL EXTRACTO EN ACETATO DE ETILO DE Pseudopterogorgia acerosa I ANALYSIS BY GC/MS AND ANTIMICROBIAL ACTIVITY OF SOME ChROMATOGRAPhIC FRACTIONS OF ThE Pseudopterogorgia acerosa EThYL ACETATE EXTRACT

    Directory of Open Access Journals (Sweden)

    Gabriel Ordaz

    2014-02-01

    Full Text Available Psudopterogorgia acerosa, showed antimicrobial activity against Salmonella enteritidis, Bacillus subtlis, Staphylococcus aureus and Citrobacter freundii bacteria and the fungus Candida albicans, indicating the presence of bioactive constituents in these fractions. Moreover, the GC/MS analysis of some subfractions obtained through continuous chromatographic separation., allowed the identification of the constituents: pristane, bis(3,5,5-trimethylhexyl ether, 4-octadecanolide, tricloroeicosylsilane, (2-endo,7-exo-7-ethyl-2,4-dimethyl-6,8-dioxabycicle[3,2,1]oct-3-ene,1-methoxy-12-octoherbertene, butylphtalylbutylglycolate, N-methyl-N-(4-(4-methoxy-1-hexahydropyridil-2-butynylacetamide, diisobutylphtalate, 3-(4-(diphenylmethylphenyl-1-phenyl-4,4-dimethyl-1-pentanone, by comparison with WILEY databases and the study of the patterns of fragmentation of their mass spectra

  4. MultiSimplex optimization of chromatographic separation and dansyl derivatization conditions in the ultra performance liquid chromatography-tandem mass spectrometry analysis of risperidone, 9-hydroxyrisperidone, monoamine and amino acid neurotransmitters in human urine.

    Science.gov (United States)

    Cai, Hua-Lin; Zhu, Rong-Hua; Li, Huan-De; Zhang, Jun; Li, Lan-Fang

    2011-07-01

    A pre-column dansylated ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-MS/MS) method for simultaneous determination of risperidone (RIP), 9-hydroxyrisperidone (9-OH-RIP), monoamine and amino acid neurotransmitters in human urine was developed with the aim of providing data on how neurotransmitters may influence each other or change simultaneously in response to risperidone treatment. MultiSimplex based on the simplex algorithm and the fuzzy set theory was applied to the optimization of chromatographic separation and dansyl derivatization conditions during method development. This method exhibited excellent linearity for all the analytes with regression coefficients higher than 0.997. The lower limit of quantification (LLOQ) values for 9-OH-RIP and RIP were 0.11 and 0.06 ng/ml, respectively, and for neurotrasmitters ranged from 0.31 to 12.8 nM. The mean accuracy ranged from 94.7% to 108.5%. The mean recovery varied between 81.6% and 97.5%. All the RSD of precision and stability were below 9.7%. Finally, the optimized method was applied to analyze the first morning urine samples of schizophrenic patients treated with risperidone and healthy volunteers. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Chromatographic separation of rhenium in alumina-methanol/sulfuric acid system

    International Nuclear Information System (INIS)

    Oguma, Koichi

    1983-01-01

    The adsorption behavior of a number of metals on alumina was surveyed in a methanol-(0.005 -- 0.5) M H 2 SO 4 (3 : 1 v/v) developing solvent by thin-layer chromatography. Over the acid concentration range tested, Re(VII) does not favor the alumina phase to any great extent while the most other metals are strongly adsorbed on alumina. These findings allowed to establish a column chromatographic technique for selective separation of rhenium in a methanol-0.05 M H 2 SO 4 (3 : 1 v/v) eluent. The separation technique thus established was applied to molybdenite analysis for rhenium. About 100-mg powdered sample containing ca. 100 ppm rhenium was decomposed with HNO 3 and then evaporated nearly to dryness. The residue was dissolved in NH 4 OH and the excess NH 4 OH was expelled by evaporation to dryness. The residue was dissolved in 2.5-ml 0.5 M H 2 SO 4 and 10-ml water, the insoluble materials filtered off, and the filtrate diluted to exactly 25 ml with water. A 10-ml aliquot of this solution was mixed with 30-ml methanol and the mixture was passed through a column (diameter 15 mm, bed height 30 mm) containing 5 g of alumina. The column was then washed with 20 ml of a methanol-0.05 M H 2 SO 4 (3 : 1 v/v) mixture. Rhenium was recovered from the loaded solution and the subsequent washings, and was determined spectrophotometrically with Methylene Blue as a chromogenic reagent. The values obtained from four samples of molybdenite are in good agreement with those obtained by neutron activation analysis. The relative standard deviation (n = 4; calculated from the range) was between 2.0 and 5.2 %. (author)

  6. Thermal analysis of mass concrete embedded with double-layer staggered heterogeneous cooling water pipes

    International Nuclear Information System (INIS)

    Yang Jian; Hu Yu; Zuo Zheng; Jin Feng; Li Qingbin

    2012-01-01

    Removal of hydration heat from mass concrete during construction is important for the quality and safety of concrete structures. In this study, a three-dimensional finite element program for thermal analysis of mass concrete embedded with double-layer staggered heterogeneous cooling water pipes was developed based on the equivalent equation of heat conduction including the effect of cooling water pipes and hydration heat of concrete. The cooling function of the double-layer staggered heterogeneous cooling pipes in a concrete slab was derived from the principle of equivalent cooling. To improve the applicability and precision of the equivalent heat conduction equation under small flow, the cooling function was revised according to its monotonicity and empirical formulas of single-phase forced-convection heat transfer in tube flow. Considering heat hydration of concrete at later age, a double exponential function was proposed to fit the adiabatic temperature rise curve of concrete. Subsequently, the temperature variation of concrete was obtained, and the outlet temperature of cooling water was estimated through the energy conservation principle. Comparing calculated results with actual measured data from a monolith of an arch dam in China, the numerical model was proven to be effective in sufficiently simulating accurate temperature variations of mass concrete. - Highlights: ► Three-dimensional program is developed to model temperature history of mass concrete. ► Massive concrete is embedded with double-layer heterogeneous cooling pipes. ► Double exponential function is proposed to fit the adiabatic temperature rise curve. ► Outlet temperature of cooling water is estimated. ► A comparison is made between the calculated and measured data.

  7. Grain size and shape analysis of the AD 1226 tephra layer, Reykjanes volcanic system

    Science.gov (United States)

    Ösp Magnúsdóttir, Agnes; Höskuldsson, Ármann; Larsen, Guðrún; Tumi Guðmunsson, Magnús; Sigurgeirsson, Magnús Á.

    2014-05-01

    Recent explosive eruptions in Iceland have drawn attention to long range tephra transport in the atmosphere. In Iceland tephra forming explosion eruptions are frequent, due to abundance of water. However, the volcanism on the island is principally basaltic. Volcanism along the Reykjanes Peninsula is divided into five distinct volcanic systems. Volcano-tectonic activity within these systems is periodic, with recurrence intervals in the range of 1 ka. Last volcano-tectonic sequence began around AD 940, shortly after settlement of Iceland, and lasted through AD 1340. During this period activity was characterized by basaltic fissure eruptions. Furthermore, this activity period on the Reykjanes peninsula began within the eastern most volcanic system and gradually moved towards the west across the peninsula. The 1226 eruption was a basaltic fissure eruption with in the Reykjanes volcanic system. The eruption began on land and gradually progressed towards the SW until the volcanic fissure extended into the sea. Water-magma interaction changed the eruption from effusive into explosive forming the largest tephra layer on the peninsula. Due to its close proximity to the Keflavik international airport and that of the capital of Iceland it is important to get an insight into, the characteristics, generation and distribution of such tephra deposits. In this eruption the tephra produced had an approximate volume of 0.1 km3 and covered an area of some 3500 km2 within the 0.5 cm isopach. Total grain size distribution of this tephra layer will be presented along with analysis of principal grain shapes of the finer portion of the tephra layer as a function of distance from the source. The tephra grain size is dominated by particles finer than 1 millimeter with an almost complete absence of large grains independent of distance from the source. Comprehensive understanding of the characteristics of tephra generated in this eruption can help us to understand hazards posed by future

  8. Chromatographic separation and spectro-analytical characterization of a natural African mineral dye

    Directory of Open Access Journals (Sweden)

    G.B. Adebayo

    2007-08-01

    Full Text Available Chromatographic fractionation and spectroscopic characterization of a natural African mineral dye have been carried out. The chromatographic separation of the dyes made use of column and thin layer chromatographic techniques. Some physicochemical properties of the dye including solubility in polar and non-polar solvents, pH, ash and organic contents were determined. The spectro-analytical techniques used for characterization included energy dispersive X-ray fluorescence (EDXRF, X-ray diffractometry (XRD, Optical microscopy, infrared (IR and UV-VIS spectroscopy. Four different fractions having colours yellow, grey, orange and purple were obtained from the chromatographic separation. All the fractions were found to contain aromatic nucleus based on IR and UV-VIS spectroscopic data. Other functional groups detected are Ar-NH2, -CONH2, C=C, C-C and metal-carbon chelate rings. The presence of aromatic amine in the dye provides strong evidence for its use as hair dye. The dye was found to be soluble in both aqueous and non-aqueous solvents. The pH of the dye's aqueous solution was found to be 8.6, and the ash and organic content of the raw dye were 49 % and 51 % respectively. The XRF revealed that the dye contains twenty elements with concentrations ranging from major to ultra-trace levels. The XRD also showed that the sample contains about forty-six mineral phases which include both inorganic and organic components. The maximum absorption wavelength (λmax in UV-VIS of the aqueous solution was found to be 464 nm. The optical microscopic investigation gave indication that the dyes are likely to be of the marine origin.

  9. Chromatographic quality control procedures for /sup 99m/Tc-diagnostic agents

    International Nuclear Information System (INIS)

    Marinelli, M.; Pozzato, R.; Garuti, P.; Zucchini, G.L.

    1986-01-01

    The purpose of this work was to experiment simple and rapid chromatographic systems, based on paper and thin-layer techniques, to test the radiochemical purity of some common /sup 99m/Tc diagnostic agents, and select those systems able to prevent the anomalies due to oxidation and artifact production. The agents were examined under conditions which usually bring about the above mentioned anomalies, then the results were compared with those obtained under controlled conditions. Quali- and quantitative detection of the activity present on the chromatograms was carried out using the equipment available in nuclear medicine departments

  10. Identification of Painting Layers of Sennefer Tomb by Ion Beam Analysis

    International Nuclear Information System (INIS)

    Abd-El-Aal, S.

    2011-01-01

    Egypt has many pharaonic tombs for kings, queens and noblemen. The Sennefer tomb, one of the most important nobleman tombs, is located in the southern hillside of Sheikh Abd El-Qurna - west side of Luxor. It is dated back to 1439-1413 B.C. (18 th Dynasty) and is usually referred as the Tomb of Vines, due to the large part of the ceiling of the burial chamber. The vine tomb was carved inside a mountain, its walls are covered with plaster and were painted using the tempera technique (pigments mixed with organic binding medium). The analysis was performed by using particle-induced X-ray emission, microbeam particle-induced X-ray emission and optical microscope for the six samples from the Vine tomb such as white, black, red, yellow, blue and green pigments and for the ground layers of the tomb in order to identify the composition of plaster layers and pigments. The data about the nature of these materials are indispensable for conservation and cleaning. (author)

  11. Physical Layer Built-In Security Analysis and Enhancement Algorithms for CDMA Systems

    Directory of Open Access Journals (Sweden)

    Li Tongtong

    2007-01-01

    Full Text Available Historically developed for secure communication and military use, CDMA has been identified as a major modulation and multiple-access technique for 3G systems and beyond. In addition to the wide bandwidth and low power-spectrum density which make CDMA signals robust to narrowband jamming and easy to be concealed within the noise floor, the physical layer built-in information privacy of CDMA system is provided by pseudorandom scrambling. In this paper, first, security weakness of the operational and proposed CDMA airlink interfaces is analyzed. Second, based on the advanced encryption standard (AES, we propose to enhance the physical layer built-in security of CDMA systems through secure scrambling. Performance analysis demonstrates that while providing significantly improved information privacy, CDMA systems with secure scrambling have comparable computational complexity and overall system performance with that of conventionally scrambled systems. Moreover, it is shown that by scrambling the training sequence and the message sequence separately with two independent scrambling sequences, both information privacy and system performance can be further improved. The proposed scheme can readily be applied to 3G systems and beyond.

  12. Neutron activation analysis of Permian-Triassic boundary layer samples at the Selong Site in China

    International Nuclear Information System (INIS)

    Miyamoto, Y.; Sakamoto, K.; Mingqing, W.

    1997-01-01

    Thirty samples from a limestone stratum across the Permian-Triassic (P-Tr) boundary layer in China were analyzed for 30 elements by instrumental neutron activation analysis, wavelength dispersive X-ray fluorescence and ICP-MS, and also for mineral compositions with a powder X-ray diffractometer. The depth profile was found to indicate a sudden change of elemental and mineral compositions across the P-Tr boundary. Also the profile showed several peaks in elemental concentrations in the lower Permian layered samples as well as in the overlying Triassic strata, which are associated with the change of mineral compositions. Elemental profiles were found to be classified into 4 groups and to give some insights in the geochemical records. Ir is far less abundant (0.1 ppt) compared with that of the K-T boundaries (10 ppb), and the Ir/Co ratio is outside the K-T and Cl chondrite trends. This change of elementary profile is suggestive of the internal causes rather than the external ones such as an asteroid impact for the mass extinction at the P-Tr boundary. (author)

  13. Analysis of Nb3Sn surface layers for superconducting radio frequency cavity applications

    Science.gov (United States)

    Becker, Chaoyue; Posen, Sam; Groll, Nickolas; Cook, Russell; Schlepütz, Christian M.; Hall, Daniel Leslie; Liepe, Matthias; Pellin, Michael; Zasadzinski, John; Proslier, Thomas

    2015-02-01

    We present an analysis of Nb3Sn surface layers grown on a bulk Niobium (Nb) coupon prepared at the same time and by the same vapor diffusion process used to make Nb3Sn coatings on 1.3 GHz Nb cavities. Tunneling spectroscopy reveals a well-developed, homogeneous superconducting density of states at the surface with a gap value distribution centered around 2.7 ± 0.4 meV and superconducting critical temperatures (Tc) up to 16.3 K. Scanning transmission electron microscopy performed on cross sections of the sample's surface region shows an ˜2 μm thick Nb3Sn surface layer. The elemental composition map exhibits a Nb:Sn ratio of 3:1 and reveals the presence of buried sub-stoichiometric regions that have a ratio of 5:1. Synchrotron x-ray diffraction experiments indicate a polycrystalline Nb3Sn film and confirm the presence of Nb rich regions that occupy about a third of the coating volume. These low Tc regions could play an important role in the dissipation mechanisms occurring during RF tests of Nb3Sn-coated Nb cavities and open the way for further improving a very promising alternative to pure Nb cavities for particle accelerators.

  14. THz - ToF Optical Layer Analysis (OLA) to determine optical properties of dielectric materials

    Science.gov (United States)

    Spranger, Holger; Beckmann, Jörg

    2017-02-01

    Electromagnetic waves with frequencies between 0.1 and 10 THz are described as THz-radiation (T-ray). The ability to penetrate dielectric materials makes T-rays attractive to reveal discontinuities in polymer and ceramic materials. THz-Time Domain Spectroscopy Systems (THz-TDS) are available on the market today which operates with THz-pulses transmitted and received by optically pumped semiconductor antennas. In THz-TDS the travelling time (ToF) and shape of the pulse is changed if it interacts with the dielectric material and its inherent discontinuities. A tomogram of the object under the test can be reconstructed from time of flight diffraction (ToFD) scans if a synthetic focusing aperture (SAFT) algorithm is applied. The knowledge of the base materials shape and optical properties is essential for a proper reconstruction result. To obtain these properties a model is assumed which describes the device under the test as multilayer structure composed of thin layers with different dielectric characteristics. The Optical Layer Analysis (OLA) is able to fulfill these requirements. A short description why the optical properties are crucial for meaningful SAFT reconstruction results will be given first. Afterwards the OLA will be derived and applied on representative samples to discuss and evaluate its benefits and limits.

  15. Analysis of Nb{sub 3}Sn surface layers for superconducting radio frequency cavity applications

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Chaoyue [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Posen, Sam; Hall, Daniel Leslie [Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York 14853 (United States); Groll, Nickolas; Proslier, Thomas, E-mail: prolier@anl.gov [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Cook, Russell [Nanoscience and Technology Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Schlepütz, Christian M. [X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Liepe, Matthias [Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York 14853 (United States); Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Pellin, Michael [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Zasadzinski, John [Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616 (United States)

    2015-02-23

    We present an analysis of Nb{sub 3}Sn surface layers grown on a bulk Niobium (Nb) coupon prepared at the same time and by the same vapor diffusion process used to make Nb{sub 3}Sn coatings on 1.3 GHz Nb cavities. Tunneling spectroscopy reveals a well-developed, homogeneous superconducting density of states at the surface with a gap value distribution centered around 2.7 ± 0.4 meV and superconducting critical temperatures (T{sub c}) up to 16.3 K. Scanning transmission electron microscopy performed on cross sections of the sample's surface region shows an ∼2 μm thick Nb{sub 3}Sn surface layer. The elemental composition map exhibits a Nb:Sn ratio of 3:1 and reveals the presence of buried sub-stoichiometric regions that have a ratio of 5:1. Synchrotron x-ray diffraction experiments indicate a polycrystalline Nb{sub 3}Sn film and confirm the presence of Nb rich regions that occupy about a third of the coating volume. These low T{sub c} regions could play an important role in the dissipation mechanisms occurring during RF tests of Nb{sub 3}Sn-coated Nb cavities and open the way for further improving a very promising alternative to pure Nb cavities for particle accelerators.

  16. A X-ray diffraction analysis on graphene layers of Assam coal

    Energy Technology Data Exchange (ETDEWEB)

    Saikia, B.K.; Boruah, R.K.; Gogoi, P.K. [CSIR, Jorhat (India)

    2009-01-15

    The so-called turbostatic structure of carbons in coal with randomly oriented stacking of the lamellae (graphene) produces intense peaks, which are the dominant features in its X-ray diffraction profiles. The diffractogram may be conveniently divided into two regions of reciprocal space, the medium S region (1 < S < 3 {angstrom}) and a high S region (S > 3 {angstrom}) where S = 4 {pi} {lambda} {sup -1}sin{theta}. To better understand the molecular level structure of high sulphur Assam coal, two coal samples (Tirap-1 and Tirap-2) from Tirap colliery of Makum coalfield, Assam (India) has been interpreted in this study by using the X-ray diffraction profiles. Random layered (graphene) structural parameters of these coals were determined by using X-ray diffraction technique, which showed that the L{sub a} and L{sub c} are 64.99 angstrom and 22.63 angstrom for Tirap-2 and 55.54 angstrom and 23.80 angstrom for that of Tirap-1 coals respectively. The position of {gamma} band was found to be at 4.34 {angstrom} and 4.13 angstrom for Tirap-2 and Tirap-1 coals respectively. The number of layers and average number of carbon atoms (N) per aromatic graphene were found to be 21 and 8 for both the coal samples. Proximate, ultimate and ash analysis of the two coal samples were also carried out in this investigation.

  17. [Analysis of pigments from Rhodotorula glutinis by Raman spectroscopy and thin layer chromatography].

    Science.gov (United States)

    Yuan, Yu-feng; Tao, Zhan-hua; Wang, Xue; Li, Yong-qing; Liu, Jun-xian

    2012-03-01

    The pigments from Rhodotorula glutinis were separated by using thin layer chromatography, and the result showed that Rhodotorula glutinis cells could synthesize at least three kinds of pigments, which were beta-carotene, torulene, and torularhodin. The Raman spectra based on the three pigments were acquired, and original spectra were preprocessed by background elimination, baseline correction, and three-point-smoothing, then the averaged spectra from different pigments were investigated, and the result indicated that Raman shift which represents C-C bond was different, and the wave number of beta-carotene demonstrated the largest deviation, finally torulene and torularhodin in Rhodotorula glutinis had more content than beta-carotene. Quantitative analysis of Raman peak height ratio revealed that peak height ratio of pigments showed little difference, which could be used as parameters for further research on living cells, providing reference content of pigments. The above results suggest that Raman spectroscopy combined with thin layer chromatography can be applied to analyze pigments from Rhodotorula glutinis, provides abundant information about pigments, and serves as an effective method to study pigments.

  18. Analysis of Nb3Sn surface layers for superconducting radio frequency cavity applications

    International Nuclear Information System (INIS)

    Becker, Chaoyue; Posen, Sam; Hall, Daniel Leslie; Groll, Nickolas; Proslier, Thomas; Cook, Russell; Schlepütz, Christian M.; Liepe, Matthias; Pellin, Michael; Zasadzinski, John

    2015-01-01

    We present an analysis of Nb 3 Sn surface layers grown on a bulk Niobium (Nb) coupon prepared at the same time and by the same vapor diffusion process used to make Nb 3 Sn coatings on 1.3 GHz Nb cavities. Tunneling spectroscopy reveals a well-developed, homogeneous superconducting density of states at the surface with a gap value distribution centered around 2.7 ± 0.4 meV and superconducting critical temperatures (T c ) up to 16.3 K. Scanning transmission electron microscopy performed on cross sections of the sample's surface region shows an ∼2 μm thick Nb 3 Sn surface layer. The elemental composition map exhibits a Nb:Sn ratio of 3:1 and reveals the presence of buried sub-stoichiometric regions that have a ratio of 5:1. Synchrotron x-ray diffraction experiments indicate a polycrystalline Nb 3 Sn film and confirm the presence of Nb rich regions that occupy about a third of the coating volume. These low T c regions could play an important role in the dissipation mechanisms occurring during RF tests of Nb 3 Sn-coated Nb cavities and open the way for further improving a very promising alternative to pure Nb cavities for particle accelerators

  19. Controlled Dissolution of Surface Layers for Elemental Analysis by Inductively Coupled Plasma-Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lorge, Susan Elizabeth [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    Determining the composition of thin layers is increasingly important for a variety of industrial materials such as adhesives, coatings and microelectronics. Secondary ion mass spectrometry (SIMS), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), glow discharge optical emission spectroscopy (GDOES), glow discharge mass spectrometry (GDMS), and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) are some of the techniques that are currently employed for the direct analysis of the sample surface. Although these techniques do not suffer from the contamination problems that often plague sample dissolution studies, they do require matrix matched standards for quantification. Often, these standards are not readily available. Despite the costs of clean hoods, Teflon pipette tips and bottles, and pure acids, partial sample dissolution is the primary method used in the semiconductor industry to quantify surface impurities. Specifically, vapor phase decomposition (VPD) coupled to ICP-MS or total reflection x-ray fluorescence (TXRF) provides elemental information from the top most surface layers at detection sensitivities in the 107-1010atoms/cm2 range. The ability to quantify with standard solutions is a main advantage of these techniques. Li and Houk applied a VPD-like technique to steel. The signal ratio of trace element to matrix element was used for quantification. Although controlled dissolution concentrations determined for some of the dissolved elements agreed with the certified values, concentrations determined for refractory elements (Ti, Nb and Ta) were too low. LA-ICP-MS and scanning electron microscopy (SEM) measurements indicated that carbide grains distributed throughout the matrix were high in these refractory elements. These elements dissolved at a slower rate than the matrix element, Fe. If the analyte element is not removed at a rate similar to the matrix element a true

  20. Aeromechanics Analysis of a Distortion-Tolerant Fan with Boundary Layer Ingestion

    Science.gov (United States)

    Bakhle, Milind A.; Reddy, T. S. R.; Coroneos, Rula M.; Min, James B.; Provenza, Andrew J.; Duffy, Kirsten P.; Stefko, George L.; Heinlein, Gregory S.

    2018-01-01

    A propulsion system with Boundary Layer Ingestion (BLI) has the potential to significantly reduce aircraft engine fuel burn. But a critical challenge is to design a fan that can operate continuously with a persistent BLI distortion without aeromechanical failure -- flutter or high cycle fatigue due to forced response. High-fidelity computational aeromechanics analysis can be very valuable to support the design of a fan that has satisfactory aeromechanic characteristics and good aerodynamic performance and operability. Detailed aeromechanics analyses together with careful monitoring of the test article is necessary to avoid unexpected problems or failures during testing. In the present work, an aeromechanics analysis based on a three-dimensional, time-accurate, Reynolds-averaged Navier-Stokes computational fluid dynamics code is used to study the performance and aeromechanical characteristics of the fan in both circumferentially-uniform and circumferentially-varying distorted flows. Pre-test aeromechanics analyses are used to prepare for the wind tunnel test and comparisons are made with measured blade vibration data after the test. The analysis shows that the fan has low levels of aerodynamic damping at various operating conditions examined. In the test, the fan remained free of flutter except at one near-stall operating condition. Analysis could not be performed at this low mass flow rate operating condition since it fell beyond the limit of numerical stability of the analysis code. The measured resonant forced response at a specific low-response crossing indicated that the analysis under-predicted this response and work is in progress to understand possible sources of differences and to analyze other larger resonant responses. Follow-on work is also planned with a coupled inlet-fan aeromechanics analysis that will more accurately represent the interactions between the fan and BLI distortion.

  1. Improved helicopter aeromechanical stability analysis using segmented constrained layer damping and hybrid optimization

    Science.gov (United States)

    Liu, Qiang; Chattopadhyay, Aditi

    2000-06-01

    Aeromechanical stability plays a critical role in helicopter design and lead-lag damping is crucial to this design. In this paper, the use of segmented constrained damping layer (SCL) treatment and composite tailoring is investigated for improved rotor aeromechanical stability using formal optimization technique. The principal load-carrying member in the rotor blade is represented by a composite box beam, of arbitrary thickness, with surface bonded SCLs. A comprehensive theory is used to model the smart box beam. A ground resonance analysis model and an air resonance analysis model are implemented in the rotor blade built around the composite box beam with SCLs. The Pitt-Peters dynamic inflow model is used in air resonance analysis under hover condition. A hybrid optimization technique is used to investigate the optimum design of the composite box beam with surface bonded SCLs for improved damping characteristics. Parameters such as stacking sequence of the composite laminates and placement of SCLs are used as design variables. Detailed numerical studies are presented for aeromechanical stability analysis. It is shown that optimum blade design yields significant increase in rotor lead-lag regressive modal damping compared to the initial system.

  2. Analysis of Strain and Intermixing in a Single Layer Ge/Si dots using polarized Raman Spectroscopy

    OpenAIRE

    PEROVA, TANIA; MOORE, ROBERT

    2006-01-01

    PUBLISHED The built-in strain and composition of as-grown and Si-capped single layers of Ge?Si dots grown at various temperatures (460?800 ?C) are studied by a comparative analysis of the Ge-Ge and Si-Ge modes in the polarized Raman spectra of the dots. A pronounced reduction of the strain and Ge content in the dots after deposition of the cap layer at low temperatures is observed, indicating that strain-induced Si diffusion from the cap layer is occurring. For large dots grown at 700?800...

  3. Experimental analysis on stress wave in inhomogeneous multi-layered structures

    International Nuclear Information System (INIS)

    Cho, Yun Ho; Ham, Hyo Sick

    1998-01-01

    The guided wave propagation in inhomogeneous multi-layered structures is experimentally explored based on theoretical dispersion curves. It turns out that proper selection of incident angle and frequency is critical for guided wave generation in multi-layered structures. Theoretical dispersion curves greatly depend on adhesive zone thickness, layer thickness and material properties. It was possible to determine the adhesive zone thickness of an inhomogeneous multi-layered structure by monitoring experimentally the change of dispersion curves.

  4. Ultra-low energy Ar+ beam applied for SIMS depth profile analysis of layered nanostructures

    International Nuclear Information System (INIS)

    Konarski, P.; Mierzejewska, A.; Iwanejko, I.

    2001-01-01

    Secondary ion mass spectrometry (SIMS) depth profile analyses of flat layered nanostructures: 10 nm Ta 2 O 3 /Ta and 20 nm (10 x B 4 C/Mo)/Si as well as microparticles of core (illite) - shell (rutile) structure, performed with the use of ultra-low energy ion beam (180-880 eV, Ar + ), are presented. The profiles were obtained using 'mesa' scanning technique and also sample rotation. Depth profile resolution below 1 nanometer was obtained for flat nanostructures. Presented experimental results are compared with Monte Carlo sputtering simulations of analysed structures. A method of finding beam energy, optimal for the best resolution SIMS depth profile analysis, is suggested. (author)

  5. Three-phase flow analysis of dense nonaqueous phase liquid infiltration in horizontally layered porous media

    NARCIS (Netherlands)

    Wipfler, E.L.; Dijke, van M.I.J.; Zee, van der S.E.A.T.M.

    2004-01-01

    We considered dense nonaqueous phase liquid (DNAPL) infiltration into a water-unsaturated porous medium that consists of two horizontal layers, of which the top layer has a lower intrinsic permeability than the bottom layer. DNAPL is the intermediate-wetting fluid with respect to the wetting water

  6. X-ray Tomographic Analysis of Porosity Distributions in Gas Diffusion Layers of Proton Exchange Membrane Fuel Cells

    International Nuclear Information System (INIS)

    Odaya, S.; Phillips, R.K.; Sharma, Y.; Bellerive, J.; Phillion, A.B.; Hoorfar, M.

    2015-01-01

    This paper describes a method to characterize the structure of polytetrafluoroethylene (PTFE) treated gas diffusion layers (GDLs) with and without microporous layers (MPLs) using 3D X-ray micro computed tomographic (μCT) microscopy. In this work, the structure of single and dual layer GDLs is evaluated via μCT for various GDL samples (such as Toray TGP-H-060 and AvCarb EP40) loaded with different MPLs. A new method is presented for separating, or segmenting, the various phases of the GDL, i.e., void space, carbon fiber (including binder and PTFE), and MPL. Through analysis, it was found that the variation in bulk porosity and the average pore diameter of the GDLs depends highly on the GDL series manufacturing and treatment processes. Using advanced image analysis techniques, routines were developed to accurately segment the GDL fibers (including binder/PTFE) and the MPL. The percentage of the intruding MPL material into the carbon fiber paper as a function of the GDL thickness was successfully found for dual layer GDLs, with varying PTFE content and areal weight loading in the MPL. This analysis provides invaluable insight into the physical microstructure of paper-based GDLs, emphasizing the heterogeneous porosity distribution of single layer GDLs and the interaction of the MPL with the carbon fiber paper of dual layer GDLs

  7. Method for chromatographically recovering scandium and yttrium

    International Nuclear Information System (INIS)

    Snyder, T.S.; Stoltz, R.A.

    1991-01-01

    This paper describes a method for chromatographically recovering scandium and yttrium from the residue of a sand chlorinator. It comprises: providing a residue from a sand chlorinator, the residue containing scandium, yttrium, sodium, calcium and at least one radioactive metal of the group consisting of radium, thorium and uranium; digesting the residue with an acid to produce an aqueous liquid containing scandium, yttrium, sodium, calcium and at least one radioactive metal of the group consisting of radium, thorium and uranium; feeding the metal containing liquid through a cation exchanger; eluding the cation exchanger with an acid eluant to to produce: a first eluate containing at least half of the total weight of the calcium and sodium in the feed liquid; a second eluate containing at least half of the total weight of the one or more radioactive metals in the feed liquid; a third eluate containing at least half of the yttrium in the feed liquid, and a fourth eluate containing at least half of the weight of the scandium in the feed liquid

  8. Chromatographic Separation of Vitamin E Enantiomers

    Directory of Open Access Journals (Sweden)

    Ju-Yen Fu

    2017-02-01

    Full Text Available Vitamin E is recognized as an essential vitamin since its discovery in 1922. Most vegetable oils contain a mixture of tocopherols and tocotrienols in the vitamin E composition. Structurally, tocopherols and tocotrienols share a similar chromanol ring and a side chain at the C-2 position. Owing to the three chiral centers in tocopherols, they can appear as eight different stereoisomers. Plant sources of tocopherol are naturally occurring in the form of RRR while synthetic tocopherols are usually in the form of all-racemic mixture. Similarly, with only one chiral center, natural tocotrienols occur as the R-isoform. In this review, we aim to discuss a few chromatographic methods that had been used to separate the stereoisomers of tocopherols and tocotrienols. These methods include high performance liquid chromatography, gas chromatography and combination of both. The review will focus on method development including selection of chiral columns, detection method and choice of elution solvent in the context of separation efficiency, resolution and chiral purity. The applications for separation of enantiomers in vitamin E will also be discussed especially in terms of the distinctive biological potency among the stereoisoforms.

  9. Chemical Compositions, Chromatographic Fingerprints and Antioxidant Activities of Andrographis Herba

    Directory of Open Access Journals (Sweden)

    Yang Zhao

    2014-11-01

    Full Text Available This paper describes the development of an HPLC-UV-MS method for quantitative determination of andrographolide and dehydroandrographolide in Andrographis Herba and establishment of its chromatographic fingerprint. The method was validated for linearity, limit of detection and quantification, inter- and intra-day precisions, repeatability, stability and recovery. All the validation results of quantitative determination and fingerprinting methods were satisfactory. The developed method was then applied to assay the contents of andrographolide and dehydroandrographolide and to acquire the fingerprints of all the collected Andrographis Herba samples. Furthermore, similarity analysis and principal component analysis were used to reveal the similarities and differences between the samples on the basis of the characteristic peaks. More importantly, the DPPH free radical-scavenging and ferric reducing capacities of the Andrographis Herba samples were assayed. By bivariate correlation analysis, we found that six compounds are positively correlated to DPPH free radical scavenging and ferric reducing capacities, and four compounds are negatively correlated to DPPH free radical scavenging and ferric reducing capacities.

  10. Comparison of chromatographic methods for the determination of bound glycerol in biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Foglia, T.A.; Jones, K.C.; Nunez, A.; Phillips, J.G. [U.S. Dept. of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Wyndmoor, PA (United States); Mittelbach, M. [Inst. for Chemistry, Univ. of Graz, Graz (Austria)

    2004-09-01

    An important fuel criterion for biodiesel is bound glycerol, which is a function of the residual amount of triglycerides and partial glycerides in the biodiesel. Either high-temperature gas chromatography or high performance liquid chromatography can be used for determining these minor but important components in biodiesel. In this paper we have conducted a statistical study on the accuracy of the two methods for ascertaining the bound glycerol in biodiesel fuels obtained from different feedstocks. Analysis of variance showed that with one exception, namely diacylglycerols in some soy oil based biodiesel, there was no statistical difference in bound glycerol for the biodiesel samples analyzed or a difference between methods. Operationally, the high performance liquid chromatographic method is superior to the high temperature gas chromatographic method in that it requires no sample derivatization, has shorter analysis times, and is directly applicable to most biodiesel fuels. (orig.)

  11. Chromatographic measurement of hydrogen isotopic and permanent gas impurities in tritium

    International Nuclear Information System (INIS)

    Warner, D.K.; Kinard, C.; Bohl, D.C.

    1976-01-01

    This paper describes a gas chromatograph that was designed for dedicated analysis of hydrogen isotopic and permanent gas impurities in tritium and tritium-deuterium mixtures. The instrument that was developed substantially improved the accuracy and precision of hydrogen isotopic analysis in the 20 ppM to one mole percent range as compared with other analytical methods. Several unique design features of the instrument were required due to the radiation and isotopic exchange properties of the tritium in the samples; descriptions of these features are presented along with details of the complete chromatographic system. The experimental procedures used to calibrate the detector and statistically evaluate its performance are given, and the sources of analytical error are cited. The limitations of the present system are also discussed

  12. Analysis of multi-layered films. [determining dye densities by applying a regression analysis to the spectral response of the composite transparency

    Science.gov (United States)

    Scarpace, F. L.; Voss, A. W.

    1973-01-01

    Dye densities of multi-layered films are determined by applying a regression analysis to the spectral response of the composite transparency. The amount of dye in each layer is determined by fitting the sum of the individual dye layer densities to the measured dye densities. From this, dye content constants are calculated. Methods of calculating equivalent exposures are discussed. Equivalent exposures are a constant amount of energy over a limited band-width that will give the same dye content constants as the real incident energy. Methods of using these equivalent exposures for analysis of photographic data are presented.

  13. Pigments analysis and gold layer thickness evaluation of polychromy on wood objects by PXRF

    International Nuclear Information System (INIS)

    Blonski, M.S.; Appoloni, C.R.

    2014-01-01

    The X-ray fluorescence technique by energy dispersion (EDXRF), being a multi elemental and non-destructive technique, has been widely used in the analysis of artworks and archeometry. An X-ray fluorescence portable equipment from the Laboratory of Applied Nuclear Physics of the State University of Londrina (LFNA/UEL) was used for the measurement of pigments in golden parts of a Gilding Preparation Standard Plaque and also pigments measurement on the Wood Adornment of the High Altar Column of the Side Pulpit of the Immaculate Conception Church Parish Sao Paulo-SP. The portable X-ray fluorescence PXRF-LFNA-02 consists of an X-ray tube with Ag anode, a Si-PIN detector (FWHM=221 eV for Mn line at 5.9 keV), a chain of electronics nuclear standard of X-ray spectrometer, a multichannel 8 K, a notebook and a mechanical system designed for the positioning of detector and X-ray tube, which allows movements with two degrees of freedom from the system of excitation–detection. The excitation–detection time of each measurement was 100 and 500 s, respectively. The presence of elements Ti, Cr, Fe, Cu, Zn and Au was found in the golden area of the Altar Column ornament. On the other hand, analysis of the ratios for the intensities of K α /K β lines measured in the areas made it possible to explore the possibility of measuring the stratigraphies of the layers of pigments and to estimate the thickness of the same. - Highlights: • The X-ray fluorescence technique by energy dispersion (EDXRF) and an X-ray fluorescence portable equipment are used for measurement of pigments. • Analysis of the ratios for the intensities of K α /K β lines measured in the areas made it possible to explore the possibility of measuring the stratigraphies of the layers of pigments and to estimate the thickness of the same. • The result of pigment analysis performed on these objects indicates that they are of the twentieth century

  14. Chromatographic separation of low-temperature tar. Part II

    Energy Technology Data Exchange (ETDEWEB)

    Terres, E; Gebert, F; Huelsemann, H; Petereit, H; Toepsch, H; Ruppert, W

    1955-01-01

    Chromatographic methods and apparatus are discussed. The Folin-Denis reagent (Na tungstate molybdate in H/sub 3/PO/sub 4/) is used for developing paper chromatograms of phenol mixtures. Other reagents are given.

  15. Monitoring for 99Tc in borehole waters using an extraction chromatographic resin

    International Nuclear Information System (INIS)

    Davis, T.M.; Nelson, D.M.; Thompson, E.G.

    1993-01-01

    A technique using an extraction chromatographic resin for the analysis of 99 Tc in borehole waters is presented. The method involves one pass of the sample through two resins, a rinse of the resins, then counting of one of the resins by liquid scintillation counting. The technique is intended to be used as a screening method of 99 Tc. The procedure employs commercially available materials, generates little waste and requires very little operator time

  16. Ion Chromatographic Analyses of Sea Waters, Brines and Related Samples

    OpenAIRE

    Nataša Gros

    2013-01-01

    This review focuses on the ion chromatographic methods for the analyses of natural waters with high ionic strength. At the beginning a natural diversity in ionic composition of waters is highlighted and terminology clarified. In continuation a brief overview of other review articles of potential interest is given. A review of ion chromatographic methods is organized in four sections. The first section comprises articles focused on the determination of ionic composition of water samples as com...

  17. Texture and microstructure analysis of epitaxial oxide layers prepared on textured Ni-12wt%Cr tapes

    Energy Technology Data Exchange (ETDEWEB)

    Huehne, R; Kursumovic, A; Tomov, R I; Glowacki, B A [Department of Materials Science and IRC in Superconductivity, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Holzapfel, B [Institut fuer Festkoerper- und Werkstoffforschung, Helmholtzstrasse 20, 01069 Dresden (Germany); Evetts, J E [Department of Materials Science and IRC in Superconductivity, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom)

    2003-05-07

    Oxide layers for the preparation of YBa{sub 2}Cu{sub 3}O{sub 7-x} coated conductors were grown on highly textured Ni-12wt%Cr tapes in pure oxygen using surface oxidation epitaxy at temperatures between 1000 deg. C and 1300 deg. C. Microstructural investigations revealed a layered oxide structure. The upper layer consists mainly of dense cube textured NiO. This is followed by a porous layer containing NiO and NiCr{sub 2}O{sub 4} particles. A detailed texture analysis showed a cube-on-cube relationship of the NiCr{sub 2}O{sub 4} spinel to the metal substrate. Untextured Cr{sub 2}O{sub 3} particles in a nickel matrix were found in a third layer arising from internal oxidation of the alloy. A high surface roughness and mechanical instability of the oxide were observed, depending on oxidation temperature and film thickness. However, mechanically stable oxide layers have been prepared using an additional annealing step in a protective atmosphere. Additionally, mechanical polishing or a second buffer layer, which grows with a higher smoothness, may be applied to reduce the surface roughness for coated conductor applications.

  18. Capacitance-voltage analysis of electrical properties for WSe2 field effect transistors with high-k encapsulation layer

    Science.gov (United States)

    Ko, Seung-Pil; Shin, Jong Mok; Jang, Ho Kyun; You, Min Youl; Jin, Jun-Eon; Choi, Miri; Cho, Jiung; Kim, Gyu-Tae

    2018-02-01

    Doping effects in devices based on two-dimensional (2D) materials have been widely studied. However, detailed analysis and the mechanism of the doping effect caused by encapsulation layers has not been sufficiently explored. In this work, we present experimental studies on the n-doping effect in WSe2 field effect transistors (FETs) with a high-k encapsulation layer (Al2O3) grown by atomic layer deposition. In addition, we demonstrate the mechanism and origin of the doping effect. After encapsulation of the Al2O3 layer, the threshold voltage of the WSe2 FET negatively shifted with the increase of the on-current. The capacitance-voltage measurements of the metal insulator semiconductor (MIS) structure proved the presence of the positive fixed charges within the Al2O3 layer. The flat-band voltage of the MIS structure of Au/Al2O3/SiO2/Si was shifted toward the negative direction on account of the positive fixed charges in the Al2O3 layer. Our results clearly revealed that the fixed charges in the Al2O3 encapsulation layer modulated the Fermi energy level via the field effect. Moreover, these results possibly provide fundamental ideas and guidelines to design 2D materials FETs with high-performance and reliability.

  19. Few-layer graphene sheets with embedded gold nanoparticles for electrochemical analysis of adenine

    Directory of Open Access Journals (Sweden)

    Biris AR

    2013-04-01

    Full Text Available Alexandru R Biris,1 Stela Pruneanu,1 Florina Pogacean,1 Mihaela D Lazar,1 Gheorghe Borodi,1 Stefania Ardelean,1 Enkeleda Dervishi,2 Fumiya Watanabe,2 Alexandru S Biris2 1National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj-Napoca, Romania; 2Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock, Little Rock, AR, USA Abstract: This work describes the synthesis of few-layer graphene sheets embedded with various amounts of gold nanoparticles (Gr-Au-x over an Aux/MgO catalytic system (where x = 1, 2, or 3 wt%. The sheet-like morphology of the Gr-Au-x nanostructures was confirmed by transmission electron microscopy and high resolution transmission electron microscopy, which also demonstrated that the number of layers within the sheets varied from two to seven. The sample with the highest percentage of gold nanoparticles embedded within the graphitic layers (Gr-Au-3 showed the highest degree of crystallinity. This distinct feature, along with the large number of edge-planes seen in high resolution transmission electron microscopic images, has a crucial effect on the electrocatalytic properties of this material. The reaction yields (40%–50% and the final purity (96%–98% of the Gr-Au-x composites were obtained by thermogravimetric analysis. The Gr-Au-x composites were used to modify platinum substrates and subsequently to detect adenine, one of the DNA bases. For the bare electrode, no oxidation signal was recorded. In contrast, all of the modified electrodes showed a strong electrocatalytic effect, and a clear peak for adenine oxidation was recorded at approximately +1.05 V. The highest increase in the electrochemical signal was obtained using a platinum/Gr-Au-3-modified electrode. In addition, this modified electrode had an exchange current density (I0, obtained from the Tafel plot one order of magnitude higher than that of the bare platinum electrode, which also confirmed that

  20. Liquid chromatographic separation of zalcitabine and its stereoisomers.

    Science.gov (United States)

    Scypinski, S; Ross, A J

    1994-10-01

    A liquid chromatographic method capable of separating and quantitating the stereoisomers of zalcitabine has been developed and validated. The separation was achieved with an Astec Cyclobond I--RSP column and a mobile phase of 0.25% triethylamine in water adjusted to a pH of 6.5 with glacial acetic acid. All enantiomers were found to exhibit a linear response in the range of 0.1-10% in the presence of 100% zalcitabine. Precision of analysis was found to be less than 1.5% at a level of 1% relative to zalcitabine. The limit of detection for two of the three enantiomeric impurities was determined to be 0.05% relative to zalcitabine. The detection limit for the third was found to be 0.1%. This method was successfully applied to the analysis of reference standards and several production scale batches. All of these materials were found to be stereochemically pure to a level of 99.8% or better.