Gains or Losses of Ultratrace Elements in Polyethylene Containers

DEFF Research Database (Denmark)

Heydorn, Kaj; Damsgaard, Else

1982-01-01

The extent of elimination of losses and reduction of blank values in ultratrace elemental analysis can only be ascertained by comprehensive investigations for each element separately. Different, and partially conflicting precautions are found to be needed in the determination of manganese, copper......, selenium, and mercury by neutron-activation analysis when polyethylene irradiation containers are used....

Temperature Programmed Desorption of Quench-condensed Krypton and Acetone in Air; Selective Concentration of Ultra-trace Gas Components.

Science.gov (United States)

Suzuki, Taku T; Sakaguchi, Isao

2016-01-01

Selective concentration of ultra-trace components in air-like gases has an important application in analyzing volatile organic compounds in the gas. In the present study, we examined quench-condensation of the sample gas on a ZnO substrate below 50 K followed by temperature programmed desorption (TPD) (low temperature TPD) as a selective gas concentration technique. We studied two specific gases in the normal air; krypton as an inert gas and acetone as a reactive gas. We evaluated the relationship between the operating condition of low temperature TPD and the lowest detection limit. In the case of krypton, we observed the selective concentration by exposing at 6 K followed by thermal desorption at about 60 K. On the other hand, no selectivity appeared for acetone although trace acetone was successfully concentrated. This is likely due to the solvent effect by a major component in the air, which is suggested to be water. We suggest that pre-condensation to remove the water component may improve the selectivity in the trace acetone analysis by low temperature TPD.

Solar UV-assisted sample preparation of river water for ultra-trace determination of uranium by adsorptive stripping voltammetry

International Nuclear Information System (INIS)

Woldemichael, G.; Tulu, T.; Flechsig, G.-U.

2012-01-01

The article describes how solar ultraviolet-A radiation can be used to digest samples as needed for voltammetric ultratrace determination of uranium(VI) in river water. We applied adsorptive stripping voltammetry (AdSV) using chloranilic acid as the complexing agent. Samples from the river Warnow in Rostock (Germany) were pretreated with either soft solar UV or wit artificial hard UV from a 30-W source emitting 254-nm light. Samples were irradiated for 12 h, and both methods yielded the same results. We were able to detect around 1 μg.L -1 of uranium(VI) in a sample of river water that also contained dissolved organic carbon at a higher mg.L -1 levels. No AdSV signal was obtained for U(VI) without any UV pre-treatment. Pseudo-polarographic experiments confirmed the dramatic effect of both digestion techniques the the AdSV response. The new method is recommended for use in mobile ultratrace voltammetry of heavy metals for most kinds of natural water samples including tap, spring, ground, sea, and river waters. The direct use of solar radiation for sample pre-treatment represents a sustainable technique for sample preparation that does not consume large quantities of chemicals or energy. (author)

Novel ion-imprinted polymer coated on nanoporous silica as a highly selective sorbent for the extraction of ultratrace quantities of gold ions from mine stone samples

International Nuclear Information System (INIS)

Ebrahimzadeh, H.; Moazzen, E.; Amini, M.; Sadeghi, O.

2013-01-01

We have developed a gold ion-imprinted polymer (GIP) by incorporating a dipyridyl ligand into an ethylene glycol dimethacrylate matrix which then was coated onto porous silica particles. The material was used for the selective extraction of ultratrace quantities of gold ion from mine stones, this followed by its quantitation by FAAS. The effects of concentration and volume of eluent, pH of the solution, flow rates of sample and eluent, and effect of potentially interfering ions, especially palladium and platinum, was investigated. The limit of detection is -1 , the precision (RSD%) is 1.03 %, and recoveries are >99 %. In order to show the high selectivity and efficiency of the new sorbent, the results were compared to those obtained with more simple sorbents possessing the same functional groups. The accuracy of the method was demonstrated by the accurate determination of gold ions in a certified reference material. To the best of our knowledge, there is no report so far on an imprint for gold ions that has such a selectivity over Pd(II) and Pt(II) ions. (author)

A molecularly imprinted electrochemiluminescence sensor based on the mimetic enzyme catalytic effect for ultra-trace Ni2+ determination.

Science.gov (United States)

Yang, Bin; Li, Jianping; Zhang, Lianming; Xu, Guobao

2016-10-21

A novel molecularly imprinted polymer (MIP) electrochemiluminescence (MIP-ECL) sensor was developed for the highly sensitive and selective determination of ultra-trace levels of Ni 2+ . The complex Ni 2+ -dimethylglyoxime (Ni-DMG) was chosen as the template molecule to construct the MIP and then acted as a mimetic enzyme to catalyse the oxidisation of luminol to enhance the ECL signal. When the imprinted cavities were occupied by Ni-DMG in the rebinding process, the ECL intensities produced by the luminol-H 2 O 2 ECL system on the MIP-modified electrode surface increased with increased concentration of the Ni-DMG complex. The highly sensitive determination of Ni 2+ was achieved through a catalytic reaction. This technique could be used for the quantitative analysis of Ni 2+ with concentrations from 3.0 × 10 -12 mol L -1 to 6.0 × 10 -9 mol L -1 . The detection limit was 1.01 × 10 -12 mol L -1 , which is much lower than that reported previously. In addition, the allowable amounts of interference ions in the MIP-ECL sensor were higher than that in other common molecularly imprinted sensors because of its excellent recognition of 3D cavity-to-complex molecules and ligand-to-metal ions. This method was successfully used to determine Ni 2+ in real samples, such as apples, carrots and grapes, and has been proven feasible for practical applications.

Considerations on ultra-trace analysis of phthalates in drinking water.

Science.gov (United States)

Serôdio, P; Nogueira, J M F

2006-07-01

Stir bar sorptive extraction with liquid desorption followed by large volume injection and capillary gas chromatography coupled to mass spectrometry (SBSE-LD/LVI-GC-MS), had been applied for the determination of ultra-traces of seven-phthalates (dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, butyl benzyl phthalate, bis(2-ethylhexyl) adipate, bis(2-ethylhexyl) phthalate and bis(1-octyl) phthalate) in drinking water samples, which are included in the priority lists set by several international regulatory organizations. Instrumental calibration under the selected-ion monitoring mode acquisition (LVI-GC-MS(SIM)), experimental parameters that could affect the SBSE-LD efficiency, as well as, the control of the contamination profile are fully discussed. Throughout systematic assays on 30 mL water samples spiked at the 0.40 microg/L level, it had been established that stir bars coated with 47 microL of polydimethylsiloxane, an equilibrium time of 60 min (1,000 rpm) and methanol as back extraction solvent, allowed the best analytical performance to monitor phthalates in water matrices. From the data obtained, good accuracy and a remarkable reproducibility (water partition coefficients (K(PDMS/W) approximately K(O/W)), with the exception of bis(2-ethylhexyl) adipate, bis(2-ethylhexyl) phthalate and bis(1-octyl) phthalate, for which lower yields were measured. Additionally, a remarkable linear dynamic range between 25 and 2,000 ng/L (r(2)>0.99) and low detection limits (3-40 ng/L) were also achieved for the seven-phthalates studied. The application of the present method to monitor phthalates in tap and bottled mineral water samples, allowed convenient selectivity and high sensitivity up to 1.0 microg/L level, using the standard addition methodology. The proposed method showed to be feasible and sensitive with a low sample volume requirement to monitor phthalates in drinking water matrices at the ultra-trace level, in compliance with international regulatory

Intercomparison and certification of some Chinese and international food and biological matrix CRMs for several uncertified ultratrace elements by NAA

International Nuclear Information System (INIS)

Weizhi, T.; Bangfa, N.; Pingsheng, W.; Huiling, N.; Lei, C.; Yangmei, Z.

2001-01-01

Radiochemical neutron activation analysis was used for determinations of 8 rare elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in two Chinese CRMs, GBW 08503 (wheat) and GBW 09101 (hair), and Cs, Sr, Th and U in five NIST SRMs, 1548 (Total Diet), 1486 (Bone Meal), 8414 (Bovine Muscle), 1566a (Oyster Powder ) and 1575 (Pine Needles). These determinations are for eventual certification of above ultratrace elements so far not certified. The radiochemical separation scheme used in RNAA of NIST SRMs is an anion exchange followed by the coprecipitation by (REE)F 3 for U and Th, and SrSo 4 precipitation for Sr and Cs. For RNAA of the two Chinese CRMs, a one step (REE)F 3 precipitation was used. Chemical yields were determined for all relevant elements by tracer experiments. All these materials were also analyzed by ICPMS, that offered an opportunity to compare the two major trace analytical techniques on their merits and drawbacks for these particular cases. RNAA is proven to be one of the important techniques in ultratrace analysis, especially in certification of some ultratrace elements. Determination of elements in sub-ng/g level is still an area to be further investigated because: (1) some such elements are important in food and health related environmental studies, (2) many of these elements have no (or very few) certified values in existing biological CRMs, (3) reliable techniques qualified for ultratrace analysis are needed to be established, and (4) sampling behavior of elements at these levels is still not very well known (recommended minimum sample size may not be adequate). (author)

Determination of trace and ultra-trace elements in Dergaon meteorite by inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Balaram, V.; Gnaneswara Rao, T.; Anjaiah, K.V.; Phukon, N.; Majumdar, A.C.

2003-01-01

In this paper, a detailed methodology for high precision measurement of several trace and ultra-trace elements including REE and PGE have been presented using effective sample preparation techniques and inductively coupled plasma mass spectrometry. Discussion is focussed on aspects, such as total dissolution and recovery of all elements, minimization of oxide and doubly-charged and other polyatomic ion interferences, calibration by matrix matching standards, accuracy and precision

Present and Future Challenges in Trace and Ultra-Trace Analysis

International Nuclear Information System (INIS)

Toulhoat, P.

2005-01-01

The analysis of trace and ultra-trace elements is continuously stimulating the progress in analytical chemistry. Environmental chemistry, radiochemistry, biology, health, agri-food are prescribers of trace analyses, with continuously increasing exigencies: lowering detection limits, lowering costs and analysis time, improving the quality of analytical information. Precise data about the chemical identity and chemical environment of analytes are now requested. Such pieces of information, beyond simple numerical data and confidence intervals, are necessary to understand studied systems, and to predict their evolution. From environmental contamination cases, one can envisage the various aspects of a problem, with for each of them its own exigencies and specificities in terms of analytical methods and approaches. The detection of traces and ultra-traces of actinides and fission products has been recently revisited and stimulates new technological developments (non proliferation issues, waste management). Data on their speciation in geological and biological media are essential for evaluating the safety of nuclear waste repositories. Various techniques are now used to determine speciation in liquid samples or on surfaces, with tremendous spatial resolutions or sensitivities. A new revolution in analytical chemistry is expected with the development of micro- or nano-analytical technologies. (author)

Ultra-trace determination of neptunium-237 and plutonium isotopes in urine samples by compact accelerator mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Dai, X.; Christl, M.; Kramer-Tremblay, S., E-mail: sheila.kramer-tremblay@cnl.ca [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada); Synal, H-A. [ETH Zurich, Lab. of Ion Beam Physics, Zurich (Switzerland)

2015-12-15

Ultra-trace analysis of actinides, such as Pu isotopes and {sup 237}Np, in bioassay samples is often needed for radiation protection programs at nuclear facilities. Accelerator mass spectrometry (AMS), particularly the compact ETH Zurich system “Tandy”, has evolved over the years as one of the most sensitive, selective, and robust techniques for actinide analysis. Employment of the AMS technique can reduce the demands on sample preparation chemistry and increase sample analysis throughput, due to very low instrumental detection limit, high rejection of interferences, and low susceptibility to adverse sample matrices. Initial research and development tests were performed to explore and demonstrate the analytical capability of AMS for Pu and Np urine bioassay. In this study, urine samples spiked with femtogram levels of Np and Pu isotopes were prepared and measured using compact ETH AMS system and the results showed excellent analytical capability for measuring Np and Pu isotopes at femtogram/litre levels in urine. (author)

Bio-inspired photonic-crystal microchip for fluorescent ultratrace detection.

Science.gov (United States)

Hou, Jue; Zhang, Huacheng; Yang, Qiang; Li, Mingzhu; Song, Yanlin; Jiang, Lei

2014-06-02

Ultratrace detection attracts great interest because it is still a challenge to the early diagnosis and drug testing. Enriching the targets from highly diluted solutions to the sensitive area is a promising method. Inspired by the fog-collecting structure on Stenocara beetle's back, a photonic-crystal (PC) microchip with hydrophilic-hydrophobic micropattern was fabricated by inkjet printing. This device was used to realize high-sensitive ultratrace detection of fluorescence analytes and fluorophore-based assays. Coupled with the fluorescence enhancement effect of a PC, detection down to 10(-16) mol L(-1) was achieved. This design can be combined with biophotonic devices for the detection of drugs, diseases, and pollutions of the ecosystem. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Atomic absorption determination of ultratrace tellurium in rocks utilizing high sensitivity sampling systems

International Nuclear Information System (INIS)

Beaty, R.D.

1973-01-01

The sampling boat and the graphite furnace were shown to possess the required sensitivity to detect tellurium at ultratrace levels, in a variety of sample types, by atomic absorption. In the sampling boat approach, tellurium in sample solutions is chemically separated and concentrated by extraction into methyl isobutyl ketone before measurement. For samples exhibiting extraction interferences or excessively high background absorption, a preliminary separation of tellurium by coprecipitation with selenium is described. Using this technique, tellurium can be quantitatively detected down to 5 nanograms and linear response is observed to 100 nanograms. Relative standard deviations of better than 7 percent are achieved for 50 nanograms of tellurium. For samples that have a tellurium content below the detection limits of the sampling boat, the graphite furnace is used for atomization. By this method, as little as 0.07 nanograms of tellurium can be detected, and a precision of 1 percent relative standard deviation is achievable at the 5 nanogram level. A routinely applicable procedure was developed for determining tellurium in rocks, using the graphite furnace, after a hydrofluoric acid decomposition of the sample. Using this procedure, tellurium data were obtained on 20 different rocks, and the significance of this new information is discussed. (Diss. Abstr. Int., B)

Multi-actinide analysis with AMS for ultra-trace determination and small sample sizes: advantages and drawbacks

Energy Technology Data Exchange (ETDEWEB)

Quinto, Francesca; Lagos, Markus; Plaschke, Markus; Schaefer, Thorsten; Geckeis, Horst [Institute for Nuclear Waste Disposal, Karlsruhe Institute of Technology (Germany); Steier, Peter; Golser, Robin [VERA Laboratory, Faculty of Physics, University of Vienna (Austria)

2016-07-01

With the abundance sensitivities of AMS for U-236, Np-237 and Pu-239 relative to U-238 at levels lower than 1E-15, a simultaneous determination of several actinides without previous chemical separation from each other is possible. The actinides are extracted from the matrix elements via an iron hydroxide co-precipitation and the nuclides sequentially measured from the same sputter target. This simplified method allows for the use of non-isotopic tracers and consequently the determination of Np-237 and Am-243 for which isotopic tracers with the degree of purity required by ultra-trace mass-spectrometric analysis are not available. With detection limits of circa 1E+4 atoms in a sample, 1E+8 atoms are determined with circa 1 % relative uncertainty due to counting statistics. This allows for an unprecedented reduction of the sample size down to 100 ml of natural water. However, the use of non-isotopic tracers introduces a dominating uncertainty of up to 30 % related to the reproducibility of the results. The advantages and drawbacks of the novel method will be presented with the aid of recent results from the CFM Project at the Grimsel Test Site and from the investigation of global fallout in environmental samples.

Solvent microextraction-flame atomic absorption spectrometry (SME-FAAS) for determination of ultratrace amounts of cadmium in meat and fish samples.

Science.gov (United States)

Goudarzi, Nasser

2009-02-11

A simple, low cost and highly sensitive method based on solvent microextraction (SME) for separation/preconcentration and flame atomic absorption spectrometry (FAAS) was proposed for the determination of ultratrace amounts of cadmium in meat and fish samples. The analytical procedure involved the formation of a hydrophobic complex by mixing the analyte solution with an ammonium pyrrolidinedithiocarbamate (APDC) solution. In suitable conditions, the complex of cadmium-APDC entered the micro organic phase, and thus, separation of the analyte from the matrix was achieved. Under optimal chemical and instrumental conditions, a detection limit (3 sigma) of 0.8 ng L(-1) and an enrichment factor of 93 were achieved. The relative standard deviation for the method was found to be 2.2% for Cd. The interference effects of some anions and cations were also investigated. The developed method has been applied to the determination of trace Cd in meat and fish samples.

Determination of ultratrace levels of tributyltin in waters by isotope dilution and gas chromatography coupled to tandem mass spectrometry.

Science.gov (United States)

Rodríguez-Cea, Andrés; Rodríguez-González, Pablo; Font Cardona, Nuria; Aranda Mares, José Luís; Ballester Nebot, Salomé; García Alonso, J Ignacio

2015-12-18

The current EU legislation lays down the Environmental Quality Standards (EQS) of 45 priority substances in surface water bodies. In particular, the concentration of tributyltin (TBT) must not exceed 0.2ngL(-1) and analytical methodologies with a Limit of Quantification (LOQ) equal or below 0.06ngL(-1) are urged to be developed. This work presents a procedure for the determination of ultratrace levels of TBT in water samples by Isotope Dilution and GC-MS/MS operating in Selected Reaction Monitoring (SRM) mode which meets current EU requirements. The method requires the monitorization of five consecutive transitions (287>175 to 291>179) for the sensitive and selective detection of TBT. The measured isotopic distribution of TBT fragment ions was in agreement with the theoretical values computed by a polynomial expansion algorithm. The combined use of Tandem Mass Spectrometry, a sample volume of 250mL, the preconcentration of 1mL of organic phase to 30μL and an injection volume of 25μL by Programmed Temperature Vaporization provided a LOQ of 0.0426ngL(-1) for TBT (calculated as ten times the standard deviation of nine independent blanks). The recovery for TBT calculated in Milli-Q water at the EQS level was 106.3±4%. A similar procedure was also developed for the quantification of dibutyltin (DBT) and monobutyltin (MBT) in water samples showing satisfactory results. The method was finally implemented in a routine testing laboratory to demonstrate its applicability to real samples obtaining quantitative recoveries for TBT at the EQS level in mineral water, river water and seawater. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrochemical detection of ultratrace nitroaromatic explosives using ordered mesoporous carbon

Energy Technology Data Exchange (ETDEWEB)

Zang Jianfeng; Guo Chunxian; Hu Fengping [School of Chemical and Biomedical Engineering and Center for Advanced Bionanosystems, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457 (Singapore); Yu Lei [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, Storrs, CT 06269 (United States); Li Changming, E-mail: ecmli@ntu.edu.sg [School of Chemical and Biomedical Engineering and Center for Advanced Bionanosystems, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457 (Singapore)

2011-01-10

A sensitive electrochemical sensor has been fabricated to detect ultratrace nitroaromatic explosives using ordered mesoporus carbon (OMC). OMC was synthesized and characterized by scanning electron microscopy, transmission electron microscopy and nitrogen adsorption/desorption measurements. Glassy carbon electrodes functionalized with OMC show high sensitivity of 62.7 {mu}A cm{sup -2} per ppb towards 2,4,6-trinitrotoluene (TNT). By comparison with other materials such as carbon nanotubes and ordered mesoporous silica, it is found that the high performance of OMC toward sensing TNT is attributed to its large specific surface area and fast electron transfer capability. As low as 0.2 ppb TNT, 1 ppb 2,4-dinitrotoluene and 1 ppb 1,3-dinitrobenzene can be detected on OMC based electrodes. This work renders new opportunities to detect ultratrace explosives for applications of environment protections and home securities against chemical warfare agents.

Ultratrace determination of lead by hydride generation in-atomizer trapping atomic absorption spectrometry: Optimization of plumbane generation and analyte preconcentration in a quartz trap-and-atomizer device

Energy Technology Data Exchange (ETDEWEB)

Kratzer, Jan, E-mail: jkratzer@biomed.cas.cz

2012-05-15

A compact trap-and-atomizer device and a preconcentration procedure based on hydride trapping in excess of oxygen over hydrogen in the collection step, both constructed and developed previously in our laboratory, were employed to optimize plumbane trapping in this device and to develop a routine method for ultratrace lead determination subsequently. The inherent advantage of this preconcentration approach is that 100% preconcentration efficiency for lead is reached in this device which has never been reported before using quartz or metal traps. Plumbane is completely retained in the trap-and-atomizer device at 290 Degree-Sign C in oxygen-rich atmosphere and trapped species are subsequently volatilized at 830 Degree-Sign C in hydrogen-rich atmosphere. Effect of relevant experimental parameters on plumbane trapping and lead volatilization are discussed, and possible trapping mechanisms are hypothesized. Plumbane trapping in the trap-and-atomizer device can be routinely used for lead determination at ultratrace levels reaching a detection limit of 0.21 ng ml{sup -1} Pb (30 s preconcentration, sample volume 2 ml). Further improvement of the detection limit is feasible by reducing the blank signal and increasing the trapping time. - Highlights: Black-Right-Pointing-Pointer In-atomizer trapping HG-AAS was optimized for Pb. Black-Right-Pointing-Pointer A compact quartz trap-and-atomizer device was employed. Black-Right-Pointing-Pointer Generation, preconcentration and atomization steps were investigated in detail. Black-Right-Pointing-Pointer 100% preconcentration efficiency for lead was reached. Black-Right-Pointing-Pointer Routine analytical method was developed for Pb determination (LOD of 0.2 ng ml{sup -1} Pb).

Highly selective micro-sequential injection lab-on-valve (muSI-LOV) method for the determination of ultra-trace concentrations of nickel in saline matrices using detection by electrothermal atomic absorption spectrometry.

Science.gov (United States)

Long, Xiangbao; Miró, Manuel; Jensen, Rikard; Hansen, Elo Harald

2006-10-01

A highly selective procedure is proposed for the determination of ultra-trace level concentrations of nickel in saline aqueous matrices exploiting a micro-sequential injection Lab-On-Valve (muSI-LOV) sample pretreatment protocol comprising bead injection separation/pre-concentration and detection by electrothermal atomic absorption spectrometry (ETAAS). Based on the dimethylglyoxime (DMG) reaction used for nickel analysis, the sample, as contained in a pH 9.0 buffer, is, after on-line merging with the chelating reagent, transported to a reaction coil attached to one of the external ports of the LOV to assure sufficient reaction time for the formation of Ni(DMG)(2) chelate. The non-ionic coordination compound is then collected in a renewable micro-column packed with a reversed-phase copolymeric sorbent [namely, poly(divinylbenzene-co-N-vinylpyrrolidone)] containing a balanced ratio of hydrophilic and lipophilic monomers. Following elution by a 50-muL methanol plug in an air-segmented modality, the nickel is finally quantified by ETAAS. Under the optimized conditions and for a sample volume of 1.8 mL, a retention efficiency of 70 % and an enrichment factor of 25 were obtained. The proposed methodology showed a high tolerance to the commonly encountered alkaline earth matrix elements in environmental waters, that is, calcium and magnesium, and was successfully applied for the determination of nickel in an NIST standard reference material (NIST 1640-Trace elements in natural water), household tap water of high hardness and local seawater. Satisfying recoveries were achieved for all spiked environmental water samples with maximum deviations of 6 %. The experimental results for the standard reference material were not statistically different to the certified value at a significance level of 0.05.

Accurate determination of ultra-trace levels of Ti in blood serum using ICP-MS/MS

International Nuclear Information System (INIS)

Balcaen, Lieve; Bolea-Fernandez, Eduardo; Resano, Martín; Vanhaecke, Frank

2014-01-01

Graphical abstract: -- Highlights: •Novel method for determination of Ti at ultra-trace levels in clinical samples (serum). •Novel method based on Ti(NH 3 ) 6 + reaction product ion formation and double mass selection using recently introduced ICP-QQQ instrumentation. •Lowest limits of detection ever obtained using quadrupole-based instrumentation for Ti. •Accurate determination of basal levels of Ti in blood serum. -- Abstract: Ti is frequently used in implants and prostheses and it has been shown before that the presence of these in the human body can lead to elevated Ti concentrations in body fluids such as serum and urine. As identification of the exact mechanisms responsible for this increase in Ti concentrations, and the risks associated with it, are not fully understood, it is important to have sound analytical methods that enable straightforward quantification of Ti levels in body fluids (for both implanted and non-implanted individuals). Until now, only double-focusing sector field ICP-mass spectrometry (SF-ICP-MS) offered limits of detection that are good enough to deal with the very low basal levels of Ti in human serum. This work reports on the development of a novel method for the accurate and precise determination of trace levels of Ti in human serum samples, based on the use of ICP-MS/MS. O 2 and NH 3 /He have been compared as reaction gases. While the use of O 2 did not enable to overcome all spectral interferences, it has been shown that conversion of Ti + ions into Ti(NH 3 ) 6 + cluster ions by using NH 3 /He as a reaction gas in an ICP-QQQ-MS system, operated in MS/MS mode, provided interference-free conditions and sufficiently low limits of detection, down to 3 ng L −1 (instrumental detection limit obtained for the most abundant Ti isotope). The accuracy of the method proposed was evaluated by analysis of a Seronorm Trace Elements Serum L-1 reference material and by comparing the results obtained with those achieved by means of SF

Development and optimization of a nuclear method to determine the lead concentration as an ultra-trace element in ultra-pure water

International Nuclear Information System (INIS)

Amara, A.; Giovagnoli, A.; Barrandon, J.N.

1994-01-01

Here we intend to perfect a nuclear analytical technique for the determination of lead concentration as an ultra-trace element in ultra-pure water Inmost cases the analysis of an aqueous solution is made by non-nuclear methods, therefore methods which are sensitive to the chemical form of the element to be determined. To ovoid this problem we developed a nuclear technique using a cyclotron,which allows the determination of the lead concentration in any of its chemical forms. We studied the possibilities of several incident beams, like neutral particles and charged particles. Proton activation showed to be the most sensitive of all the irradiation procedures. Several points have though be studied and developed: - an irradiation cell for liquids irradiation under a strong proton current; - the bismuth chemical separation. This element has two radio-isotopes allowing the determination of lead;-optimize the experimental irradiation and measurements parameters in order to reach the lower detection limit. At last an intercomparison of several techniques has been made for different standards. It clearly showed that, contrary to atomic,potentiometric or mass spectrometry methods,only activation technique give accurate and reproducible results. (author).1 fig., 2 tabs., 4 refs

Ultra-trace determination of Persistent Organic Pollutants in Artic ice using stir bar sorptive extraction and gas chromatography coupled to mass spectrometry

OpenAIRE

Lacorte Bruguera, Silvia; Quintana, Jordi; Tauler, Romà; Ventura, Francesc; Tovar-Sánchez, Antonio; Duarte, Carlos M.

2010-01-01

This study presents the optimization and application of an analytical method based on the use of stirbarsorptiveextraction (SBSE) gaschromatographycoupled to massspectrometry (GC–MS) for the ultra-trace analysis of POPs (PersistentOrganicPollutants) in Arctic ice. In a first step, the mass-spectrometry conditions were optimized to quantify 48 compounds (polycyclic aromatic hydrocarbons, brominated diphenyl ethers, chlorinated biphenyls, and organochlorinated pesticides) at the low pg/L level....

Ultratrace analysis of transuranic actinides by laser-induced fluorescence

Science.gov (United States)

Miller, S.M.

1983-10-31

Ultratrace quantities of transuranic actinides are detected indirectly by their effect on the fluorescent emissions of a preselected fluorescent species. Transuranic actinides in a sample are coprecipitated with a host lattice material containing at least one preselected fluorescent species. The actinide either quenches or enhances the laser-induced fluorescence of the preselected fluorescent species. The degree of enhancement or quenching is quantitatively related to the concentration of actinide in the sample.

Ultratrace analysis of plutonium in environmental samples by resonance ionization mass spectrometry (RIMS)

International Nuclear Information System (INIS)

Trautmann, N.; Erdmann, N.; Gruening, C.; Kratz, J. V.; Waldek, A.; Huber, G.; Nunnemann, M.; Passler, G.

2000-01-01

Plutonium is present in the environment mainly as a result of global fallout from nuclear weapons tests, satellite and reactor accidents as well as releases from nuclear facilities. Sensitive and fast detection methods are required for risk assessment, low-level surveillance of the environment, personnel dose monitoring, studies of biological effects and investigations of the migration behavior of plutonium. Furthermore, the isotopic composition is of interest to get information from what source the plutonium contamination originated. Alpha-spectroscopy is most frequently used for the determination of trace amounts of plutonium in the environment with the disadvantage that the detection sensitivity depends on the half-life of the isotope to be measured and that there are limitations in the isotopic resolution. Conventional mass spectrometry may suffer from isobaric interferences. Therefore, in the last years resonant laser ionization mass spectrometry (RIMS) has been explored as an alternative for ultratrace analysis of plutonium. This method provides a high element and isotope selectivity and a good overall efficiency, resulting in a detection limit of ∼10 6 atoms (∼0.4 fg). RIMS meets also the requirements of a low background and a short measuring time (1-2 h)

Technetium-99 and strontium-90: Abundance determination at ultratrace sensitivity by AMS as signatures of undeclared nuclear reprocessing activity

International Nuclear Information System (INIS)

McAninch, J.E.; Proctor, I.D.

1995-03-01

The purpose of this White Paper is to examine the use of the ultratrace technique Accelerator Mass Spectrometry (AMS) to lower detection limits for 99 Tc and 90 Sr, and to examine the utility of these isotopes as signatures of a convert reprocessing facility. The International Atomic Energy Agency (IAEA) has committed to improving the effectiveness of the IAEA Safeguards System. This is in some degree a result of the discovery in 1991 of an undeclared Iraqi EMIS program. Recommendations from the March 1993 Consultants Group Meeting have resulted in several studies and follow on field trials to identify environmental signatures from covert nuclear fuel reprocessing activity. In particular, the April, 1993 reports of the Standing Advisory Group on Safeguards Implementation (SAGSI) identified the long-lived radioisotopes Technetium-99 and strontium-90 as two reliable signatures of fuel reprocessing activity. This report also suggested pathways in the chemical processing of irradiated fuel where these elements would be volatilized and potentially released in amounts detectable with ultratrace sensitivity techniques. Based on measured 99 Tc background levels compiled from a variety of sources, it is estimated that AMS can provide 10% measurements of environmental levels of 99 Tc in a few minutes using modestly sized samples: a few grams for soils, plants, or animal tissues; one to several liters for rain or seawater samples; and tens to hundreds of cubic meters for air sampling. Small sample sizes and high sample throughput result in significant increases in feasibility, cost effectiveness, and quality of data for a regional monitoring program. Similar results are expected for 90 Sr

Determination of ultratrace elements in natural waters by solid-phase extraction and atomic spectrometry methods.

Science.gov (United States)

Grotti, Marco; Abelmoschi, Maria Luisa; Soggia, Francesco; Frache, Roberto

2003-01-01

A study was carried out on the preconcentration of ultratrace amounts of cadmium, lead, manganese, copper and iron from high-salinity aqueous samples and determination by atomic spectrometry methods. Sample volume, amount of resin, loading flow rate, and elution volume were optimized in order to obtain the simultaneous preconcentration of all the analytes. Quantitative recoveries were obtained by using 200 mg of iminodiacetic resin with a loading flow rate of 2 mL min(-1), elution volume of 3 mL and sample volume of 50-450 mL. Only copper in seawater samples was not completely retained by the resin (60-70% recovery), due to unfavorable competition of iminodiacetic-active groups with organically bound metal.To quantify the metals in the eluates, two atomic spectrometry techniques were compared: electrothermal atomization atomic absorption spectrometry (ETAAS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) with simultaneous CCD detection system. Both techniques are suitable for sample analysis with detection limits of 1.0, 4.7, 3.3, 6.8, and 53 ng L(-1) using ETAAS and 12, 122, 3.4, 17, and 21 ng L(-1) using ICP-OES for Cd, Pb, Mn, Cu, and Fe, respectively. Relative standard deviations of the procedures ranged from 1.7 to 14% at the sub-microg L(-1) concentration level. The accuracy of both methods was verified by analyzing various certified reference materials (river water, estuarine water, coastal and off-shore seawater).

Determination of ultratrace elements in natural waters by solid-phase extraction and atomic spectrometry methods

Energy Technology Data Exchange (ETDEWEB)

Grotti, Marco; Abelmoschi, Maria Luisa; Soggia, Francesco; Frache, Roberto [Department of Chemistry and Industrial Chemistry, University of Genoa, Via Dodecaneso, 31-16146, Genoa (Italy)

2003-01-01

A study was carried out on the preconcentration of ultratrace amounts of cadmium, lead, manganese, copper and iron from high-salinity aqueous samples and determination by atomic spectrometry methods. Sample volume, amount of resin, loading flow rate, and elution volume were optimized in order to obtain the simultaneous preconcentration of all the analytes. Quantitative recoveries were obtained by using 200 mg of iminodiacetic resin with a loading flow rate of 2 mL min{sup -1}, elution volume of 3 mL and sample volume of 50-450 mL. Only copper in seawater samples was not completely retained by the resin (60-70% recovery), due to unfavorable competition of iminodiacetic-active groups with organically bound metal.To quantify the metals in the eluates, two atomic spectrometry techniques were compared: electrothermal atomization atomic absorption spectrometry (ETAAS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) with simultaneous CCD detection system. Both techniques are suitable for sample analysis with detection limits of 1.0, 4.7, 3.3, 6.8, and 53 ng L{sup -1} using ETAAS and 12, 122, 3.4, 17, and 21 ng L{sup -1} using ICP-OES for Cd, Pb, Mn, Cu, and Fe, respectively. Relative standard deviations of the procedures ranged from 1.7 to 14% at the sub-{mu}g L{sup -1} concentration level. The accuracy of both methods was verified by analyzing various certified reference materials (river water, estuarine water, coastal and off-shore seawater). (orig.)

Simultaneous determination of major to ultratrace elements in geological samples by fusion-dissolution and inductively coupled plasma mass spectrometry techniques

International Nuclear Information System (INIS)

Madinabeitia, S. Garcia de; Lorda, M.E. Sanchez; Ibarguchi, J.I. Gil

2008-01-01

A method has been developed for the simultaneous quantification of major to ultratrace elements in geological samples using quadrupole ICP-MS techniques. The sample preparation involves fusion with LiBO 2 and dilution in HNO 3 -HF which allows complete decomposition of refractory minerals and quantification of the elements of interest. The effects of high Total Dissolved Solids (TDS) and Li in the solution are minimized using a matrix-tolerant interface and conditioning the instrument with LiBO 2 solution. The signal drift is moreover controlled using conventional internal standards and specific Drift Correction Standards (DCS). A key issue of the technique is the external calibration using selected Certified Reference Materials (CRM). Depending on the sample type and analytes of interest three optimized programmable modes are used sequentially: Standard, Collision Cell (CCT) and Kinetic Energy Discrimination (KED) mode. The method allows to quantify more than 40 elements in concentrations from tens-of-percent to <0.1 ppm levels during a single experiment. The method has been validated through the analysis of different CRMs with recovery factors of ca. 100% and typical 2σ errors of <10%

Simultaneous determination of major to ultratrace elements in geological samples by fusion-dissolution and inductively coupled plasma mass spectrometry techniques

Energy Technology Data Exchange (ETDEWEB)

Madinabeitia, S. Garcia de [Servicio de Geocronologia y Geoquimica Isotopica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/EHU, Sarriena s/n, 48940 Leioa (Spain); Lorda, M.E. Sanchez [Servicio de Geocronologia y Geoquimica Isotopica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/EHU, Sarriena s/n, 48940 Leioa (Spain); Departamento de Mineralogia-Petrologia, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/EHU, Sarriena s/n, 48940 Leioa (Spain); Ibarguchi, J.I. Gil [Servicio de Geocronologia y Geoquimica Isotopica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/EHU, Sarriena s/n, 48940 Leioa (Spain)], E-mail: josei.gil@ehu.es

2008-09-12

A method has been developed for the simultaneous quantification of major to ultratrace elements in geological samples using quadrupole ICP-MS techniques. The sample preparation involves fusion with LiBO{sub 2} and dilution in HNO{sub 3}-HF which allows complete decomposition of refractory minerals and quantification of the elements of interest. The effects of high Total Dissolved Solids (TDS) and Li in the solution are minimized using a matrix-tolerant interface and conditioning the instrument with LiBO{sub 2} solution. The signal drift is moreover controlled using conventional internal standards and specific Drift Correction Standards (DCS). A key issue of the technique is the external calibration using selected Certified Reference Materials (CRM). Depending on the sample type and analytes of interest three optimized programmable modes are used sequentially: Standard, Collision Cell (CCT) and Kinetic Energy Discrimination (KED) mode. The method allows to quantify more than 40 elements in concentrations from tens-of-percent to <0.1 ppm levels during a single experiment. The method has been validated through the analysis of different CRMs with recovery factors of ca. 100% and typical 2{sigma} errors of <10%.

Ultratrace element contents in rat tissues: Comparative analysis of serum and hair as indicative matrices of the total body burden

Directory of Open Access Journals (Sweden)

Skalny Anatoly V.

2016-01-01

Full Text Available The aim of this study was to investigate the distribution of ultratrace elements in rat tissues and to perform a comparative analysis of hair and serum as potential bioindicators of the total ultratrace element content. Thirty-six male Wistar rats were fed a standard chow containing 0.006±0.000, 0.001±0.000, 0.017±0.002, 0.382±0.031, 0.168±0.014, 3.211±0.134, 0.095±0.006, 0.000±0.000, 6.675±0.336, 15.327±0.564, 0.002±0.000, and 1.185±0.202 μg/g of silver (Ag, gold (Au, cesium (Cs, gallium (Ga, germanium (Ge, lanthanum (La, niobium (Nb, platinum (Pt, rubidium (Rb, titanium (Ti, thallium (Tland zirconium (Zr, respectively, from weaning to 3 months old. The ultratrace element content in the liver, kidney, muscle, heart, serum and hair was assessed using inductively coupled plasma mass spectrometry. The obtained data indicate that the highest concentrations of most of the studied elements (Ti, Zr, Ge, Nb, tungsten (W, La, uranium (U, Ag, Au, Pt are in hair, whereas the lowest were observed in the serum. Statistical analysis revealed a significant association between concentrations in the hair and other tissues for Cs, Ti, Nb, Tl, La, U and Au. At the same time, serum Cs, Rb, Ti, Ge, Nb, W, Ga, Tl and La concentrations significantly correlated with the tissue content of the respective ultratrace elements. It can be concluded that hair may be used as a potential bioindicator for certain ultratrace element content in the mammalian organism.

Application of l-cystine modified zeolite for preconcentration and determination of ultra-trace levels of cadmium by flame atomic absorption spectrometry.

Science.gov (United States)

Rezvani, Seyyed Ahmad; Soleymanpour, Ahmad

2016-03-04

A very convenient, sensitive and precise solid phase extraction (SPE) system was developed for enrichment and determination of ultra-trace of cadmium ion in water and plant samples. This method was based on the retention of cadmium(II) ions by l-cystine adsorbed in Y-zeolite and carry out in a packed mini-column. The retained cadmium ions then were eluted and determined by flame atomic absorption spectrometry. The scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) spectroscopy techniques were applied for the characterization of cystine modified zeolite (CMZ). Some experimental conditions affecting the analytical performance such as pH, eluent type, concentration of sample, eluent flow rate and also the presence of interfering ions were investigated. The calibration graph was linear within the range of 0.1-7.5ngmL(-1) and limit of detection was obtained 0.04ngmL(-1) with the preconcentration factor of 400. The relative standard deviation (RSD) was obtained 1.4%, indicating the excellent reproducibility of this method. The proposed method was successfully applied for the extraction and determination of cadmium(II) ion in black tea, cigarette's tobacco and also various water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultratrace analysis of uranium and plutonium by mass spectrometry

International Nuclear Information System (INIS)

Wogman, N.A.; Wacker, J.F.; Olsen, K.B.; Petersen, S.L.; Farmer, O.T.; Kelley, J.M.; Eiden, G.C.; Maiti, T.C.

2002-01-01

Full text: Uranium and plutonium have traditionally been analyzed using alpha energy spectrometry. Both isotopic compositions and elemental abundances can be characterized on samples containing microgram to milligram quantities of uranium and nanogram to microgram quantities of plutonium. In the past ten years or so, considerable interest has developed in measuring nanograms quantities of uranium and sub-picogram quantities of plutonium in environmental samples. Such measurements require high sensitivity and as a consequence, sensitive mass spectrometric-based methods have been developed. Thus, the analysis of uranium and plutonium have gone from counting decays to counting atoms, with considerable increases in both sensitivity and precision for isotopic measurements. At the Pacific Northwest National Laboratory (PNNL), we have developed highly sensitive methods to analyze uranium and plutonium in environmental samples. The development of an ultratrace analysis capability for measuring uranium and plutonium has arisen from a need to detect and characterize environmental samples for signatures associated with nuclear industry processes. Our most sensitive well-developed methodologies employ thermal ionization mass spectrometry (TIMS), however, recent advances in inductively coupled plasma mass spectrometry (ICP-MS) have shown considerable promise for use in detecting uranium and plutonium at ultratrace levels. The work at PNNL has included the development of both chemical separation and purification techniques, as well as the development of mass spectrometric instrumentation and techniques. At the heart of our methodology for TIMS analysis is a procedure that utilizes 100-microliter-volumes of analyte for chemical processing to purify, separate, and load actinide elements into resin beads for subsequent mass spectrometric analysis. The resin bead technique has been combined with a thorough knowledge of the physicochemistry of thermal ion emission to achieve

Molecularly imprinted sensor based on Russian Matryoshka structured molecules for enhanced specific identification and double amplification in ultra-trace Tb3+ determination.

Science.gov (United States)

Li, Jianping; Yang, Bin; Pan, Hongcheng; Xu, Guobao

2018-06-30

The selective and sensitive detection of rare earth elements is thought to be difficult because the concentration of those elements in the sample is commonly at a low level and they normally have severe mutual interference which is caused by homologous chemical properties. In this study, a novel molecularly imprinted polymer (MIP) sensor was fabricated for highly sensitive and selective determination of ultra-trace Tb 3+ . The Tb 3+ -ethylenediaminetetraacetic acid complex (Tb-EDTA) as the template molecule was incorporated into mono-6-mercapto-β-cyclodextrin (mono-6-SH-β-CD) to form a Russian Matryoshka (RM)-structured molecule (CD/Tb-EDTA). Titanium isopropoxide was utilized in vapor sol-gel polymerization to construct MIP membrane. Moreover, the selectivity of the RM MIP sensor was remarkably enhanced by the "triple-selectivity" recognition of EDTA-to-Tb 3+ , β-CD-to-(Tb-EDTA), and 3D cavity-to-(CD/Tb-EDTA), while the sensitivity of the MIP sensor was significantly improved by ECL signal enhancement based on double amplification, in other words, the electrochemiluminescence resonance energy transfer (ECL-RET) between the ECL donor of CD/Tb-EDTA and the ECL acceptor of Ru(bpy) 3 2+ , and the ECL enhancement by the co-reactant of CD/Tb-EDTA on Ru(bpy) 3 Cl 2 . When the imprinted cavities were occupied by Tb-EDTA during rebinding, the host-guest inclusion structured complex was formed and the ECL intensities produced by the Ru(bpy) 3 Cl 2 ECL system increased with increasing concentration of Tb-EDTA. The proposed sensor was used for quantitative analysis of Tb 3+ with concentrations ranging from 8.00 × 10 -13 mol/L to 4.00 × 10 -9 mol/L and successfully applied to detect Tb 3+ in seawater samples. The detection limit of the sensor was found to be 3.90 × 10 -13 mol/L (DL = 3δ b /K), which is lower than previously reported values. Thus, the fabricated sensor is feasible for practical applications. Copyright © 2018 Elsevier B.V. All rights

Ultratrace determination of Pb, Se and As in wine samples by electrothermal vaporization inductively coupled plasma mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Grindlay, Guillermo, E-mail: guillermo.grindlay@ua.es [Department of Analytical Chemistry, Nutrition and Food Sciences, University of Alicante, PO Box 99, 03080 - Alicante (Spain); Mora, Juan; Gras, Luis [Department of Analytical Chemistry, Nutrition and Food Sciences, University of Alicante, PO Box 99, 03080 - Alicante (Spain); de Loos-Vollebregt, M.T.C. [Delft University of Technology, Fac. Applied Sciences, Julianalaan 67, 2628 BC - Delft (Netherlands)

2009-10-12

The determination of Pb, Se and As in wine has a great interest due to health risks and legal requirements. To perform the analysis of wine, two considerations must be taken into account: (i) the low concentration level of the analytes; and (ii) the risk of interferences due to wine matrix components. The goal of this work is to evaluate electrothermal vaporization (ETV) sample introduction for ultratrace determination of Pb, Se and As in wine samples by inductively coupled plasma mass spectrometry (ICP-MS). The results obtained with ETV-ICP-MS were compared to those obtained with conventional liquid sample introduction in ICP-MS and electrothermal atomic absorption spectrometry (ETAAS). Analytical figures of merit of ETV sample introduction strongly depend on the amount of wine sample, on the modifier nature (i.e. Pd, ascorbic acid or citric acid) and concentration and on the temperature program. Wine matrix components exert a great influence on analyte transport efficiency. Due to this fact, the analysis of wine cannot be performed by means of external calibration but the standard addition methodology should be used. The determination of Pb and Se in wine by ETV-ICP-MS provides similar results as conventional liquid sample introduction ICP-MS. For As, the concentration values obtained with ETV sample introduction were between two and four times lower than with the conventional system. These differences are related to the lower intensity of polyatomic interferences (i.e. {sup 40}Ar{sup 35}Cl{sup +} vs. {sup 75}As{sup +}) obtained for ETV sample introduction when compared to the conventional system. Finally, no differences for Pb determination were observed between ETV sample introduction and ETAAS. Unfortunately, the limits of detection for As and Se in ETAAS were not low enough to quantify these elements in the wine samples tested.

Ultratrace determination of Pb, Se and As in wine samples by electrothermal vaporization inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Grindlay, Guillermo; Mora, Juan; Gras, Luis; de Loos-Vollebregt, M.T.C.

2009-01-01

The determination of Pb, Se and As in wine has a great interest due to health risks and legal requirements. To perform the analysis of wine, two considerations must be taken into account: (i) the low concentration level of the analytes; and (ii) the risk of interferences due to wine matrix components. The goal of this work is to evaluate electrothermal vaporization (ETV) sample introduction for ultratrace determination of Pb, Se and As in wine samples by inductively coupled plasma mass spectrometry (ICP-MS). The results obtained with ETV-ICP-MS were compared to those obtained with conventional liquid sample introduction in ICP-MS and electrothermal atomic absorption spectrometry (ETAAS). Analytical figures of merit of ETV sample introduction strongly depend on the amount of wine sample, on the modifier nature (i.e. Pd, ascorbic acid or citric acid) and concentration and on the temperature program. Wine matrix components exert a great influence on analyte transport efficiency. Due to this fact, the analysis of wine cannot be performed by means of external calibration but the standard addition methodology should be used. The determination of Pb and Se in wine by ETV-ICP-MS provides similar results as conventional liquid sample introduction ICP-MS. For As, the concentration values obtained with ETV sample introduction were between two and four times lower than with the conventional system. These differences are related to the lower intensity of polyatomic interferences (i.e. 40 Ar 35 Cl + vs. 75 As + ) obtained for ETV sample introduction when compared to the conventional system. Finally, no differences for Pb determination were observed between ETV sample introduction and ETAAS. Unfortunately, the limits of detection for As and Se in ETAAS were not low enough to quantify these elements in the wine samples tested.

Sequential injection/bead injection lab-on-valve schemes for on-line solid phase extraction and preconcentration of ultra-trace levels of heavy metals with determination by ETAAS and ICPMS

DEFF Research Database (Denmark)

Wang, Jianhua; Hansen, Elo Harald; Miró, Manuel

2003-01-01

are focused on the applications of SI-BI-LOV protocols for on-line microcolumn based solid phase extraction of ultra-trace levels of heavy metals, employing the so-called renewable surface separation and preconcentration manipulatory scheme. Two types of sorbents have been employed as packing material...

Flow-injection chemiluminescence assay for ultra-trace determination of DNA using rhodamine B-Ce(IV)-DNA ternary system in sulfuric acid media

International Nuclear Information System (INIS)

Ma Yongjun; Zhou Min; Jin Xiaoyong; Zhang Ziyu; Teng Xiulan; Chen Hui

2004-01-01

A novel flow-injection chemiluminescence method for the determination of DNA at ultra-trace level has been established. In 0.8 M sulfuric acid media, the chemiluminescence of the rhodamine B-cerium (IV) or Ce(IV) system is enhanced by DNA, activated previously by imidazole-HCl buffer solution (pH 7.0). The enhanced intensity of chemiluminescence is in proportion to log DNA concentration 1.0x10 -8 to 0.1 μg ml -1 for herring sperm DNA and 2.0x10 -6 to 0.2 μg ml -1 for calf thymus DNA with 3σ detection limits of 8.3x10 -9 μg ml -1 for herring sperm DNA and 3.5x10 -7 μg ml -1 for calf thymus DNA, respectively. The relative standard deviation for 1.0x10 -4 μg ml -1 herring sperm DNA was 0.99% and 2.0x10 -3 μg ml -1 for calf thymus DNA was 1.1% (n=11). Using the optimized system, DNA contents in six synthetic samples has been determined with recoveries of 99.5-109.0%. The possible mechanism has also been studied in this paper

Flow-injection chemiluminescence assay for ultra-trace determination of DNA using rhodamine B-Ce(IV)-DNA ternary system in sulfuric acid media

Energy Technology Data Exchange (ETDEWEB)

Ma Yongjun; Zhou Min; Jin Xiaoyong; Zhang Ziyu; Teng Xiulan; Chen Hui

2004-01-09

A novel flow-injection chemiluminescence method for the determination of DNA at ultra-trace level has been established. In 0.8 M sulfuric acid media, the chemiluminescence of the rhodamine B-cerium (IV) or Ce(IV) system is enhanced by DNA, activated previously by imidazole-HCl buffer solution (pH 7.0). The enhanced intensity of chemiluminescence is in proportion to log DNA concentration 1.0x10{sup -8} to 0.1 {mu}g ml{sup -1} for herring sperm DNA and 2.0x10{sup -6} to 0.2 {mu}g ml{sup -1} for calf thymus DNA with 3{sigma} detection limits of 8.3x10{sup -9} {mu}g ml{sup -1} for herring sperm DNA and 3.5x10{sup -7} {mu}g ml{sup -1} for calf thymus DNA, respectively. The relative standard deviation for 1.0x10{sup -4} {mu}g ml{sup -1} herring sperm DNA was 0.99% and 2.0x10{sup -3} {mu}g ml{sup -1} for calf thymus DNA was 1.1% (n=11). Using the optimized system, DNA contents in six synthetic samples has been determined with recoveries of 99.5-109.0%. The possible mechanism has also been studied in this paper.

Ultratrace Determination of Cr(VI and Pb(II by Microsample Injection System Flame Atomic Spectroscopy in Drinking Water and Treated and Untreated Industrial Effluents

Directory of Open Access Journals (Sweden)

Jameel Ahmed Baig

2013-01-01

Full Text Available Simple and robust analytical procedures were developed for hexavalent chromium (Cr(VI and lead (Pb(II by dispersive liquid-liquid microextraction (DLLME using microsample injection system coupled with flame atomic absorption spectrophotometry (MIS-FAAS. For the current study, ammonium pyrrolidine dithiocarbamate (APDC, carbon tetrachloride, and ethanol were used as chelating agent, extraction solvent, and disperser solvent, respectively. The effective variables of developed method have been optimized and studied in detail. The limit of detection of Cr(VI and Pb(II were 0.037 and 0.054 µg/L, respectively. The enrichment factors in both cases were 400 with 40 mL of initial volumes. The relative standard deviations (RSDs, were 96%. The proposed method was successfully applied to the determination of Cr(VI and Pb(II at ultratrace levels in natural drinking water and industrial effluents wastewater of Denizli. Moreover, the proposed method was compared with the literature reported method.

Spacer for enhancing selectivity of functionalized polymer towards Pu(IV)

International Nuclear Information System (INIS)

Chavan, Vivek; Pandey, A.K.; Goswami, A.

2012-01-01

To address problems in selective and fast preconcentration of Pu(IV) at ultratrace concentration from the multicomponents aqueous media and low level nuclear waste, a new functionalized polymer sorbent was developed

Ultra-trace determination of Persistent Organic Pollutants in Arctic ice using stir bar sorptive extraction and gas chromatography coupled to mass spectrometry.

Science.gov (United States)

Lacorte, S; Quintana, J; Tauler, R; Ventura, F; Tovar-Sánchez, A; Duarte, C M

2009-12-04

This study presents the optimization and application of an analytical method based on the use of stir bar sorptive extraction (SBSE) gas chromatography coupled to mass spectrometry (GC-MS) for the ultra-trace analysis of POPs (Persistent Organic Pollutants) in Arctic ice. In a first step, the mass-spectrometry conditions were optimized to quantify 48 compounds (polycyclic aromatic hydrocarbons, brominated diphenyl ethers, chlorinated biphenyls, and organochlorinated pesticides) at the low pg/L level. In a second step, the performance of this analytical method was evaluated to determine POPs in Arctic cores collected during an oceanographic campaign. Using a calibration range from 1 to 1800 pg/L and by adjusting acquisition parameters, limits of detection at the 0.1-99 and 102-891 pg/L for organohalogenated compounds and polycyclic aromatic hydrocarbons, respectively, were obtained by extracting 200 mL of unfiltered ice water. alpha-hexachlorocyclohexane, DDTs, chlorinated biphenyl congeners 28, 101 and 118 and brominated diphenyl ethers congeners 47 and 99 were detected in ice cores at levels between 0.5 to 258 pg/L. We emphasise the advantages and disadvantages of in situ SBSE in comparison with traditional extraction techniques used to analyze POPs in ice.

Multielement determination of major-to-ultratrace elements in plant reference materials by ICP-AES/ICP-MS and evaluation of their enrichment factors

International Nuclear Information System (INIS)

Hokura, Akiko; Matsuura, Hirotaka; Katsuki, Fumie; Haraguchi, Hiroki

2000-01-01

The multielement determination of major-to-ultratrace elements in plant reference materials (SRM Pine Needles, SRM Tomato Leaves, and NIES Tea Leaves) was carried out by ICP-AES (inductively coupled plasma atomic emission spectrometry) and ICP-MS (inductively coupled plasma mass spectrometry). The plant sample was decomposed with nitric acid and hydrofluoric acid in a Teflon beaker on a hot plate. The digest was dissolved in 1 M HNO 3 solution, and then subjected to elemental analyses. As a consequence, the analytical data for about 40 elements including rare earth elements (REEs) were obtained over a wide concentration range, for example, from 49600 μg g -1 of Ca to 6.2 ng g -1 of Lu in Tomato Leaves. The enrichment factors, which were estimated by normalizing the observed concentrations of analyte elements in plant reference materials to their soil abundances, were evaluated in order to discuss the relative abundances of various elements between plants and soil. It was found that most of the elements, except for REEs in Pine Needles and Tea Leaves, were significantly accumulated in the plant reference materials. In particular, the essential elements (K, Mg, Ca, Mn, Cu, Zn, B and P) for plant growth provided large enrichment factors. (author)

Determination of Ultra-trace Rhodium in Water Samples by Graphite Furnace Atomic Absorption Spectrometry after Cloud Point Extraction Using 2-(5-Iodo-2-Pyridylazo)-5-Dimethylaminoaniline as a Chelating Agent.

Science.gov (United States)

Han, Quan; Huo, Yanyan; Wu, Jiangyan; He, Yaping; Yang, Xiaohui; Yang, Longhu

2017-03-24

A highly sensitive method based on cloud point extraction (CPE) separation/preconcentration and graphite furnace atomic absorption spectrometry (GFAAS) detection has been developed for the determination of ultra-trace amounts of rhodium in water samples. A new reagent, 2-(5-iodo-2-pyridylazo)-5-dimethylaminoaniline (5-I-PADMA), was used as the chelating agent and the nonionic surfactant TritonX-114 was chosen as extractant. In a HAc-NaAc buffer solution at pH 5.5, Rh(III) reacts with 5-I-PADMA to form a stable chelate by heating in a boiling water bath for 10 min. Subsequently, the chelate is extracted into the surfactant phase and separated from bulk water. The factors affecting CPE were investigated. Under the optimized conditions, the calibration graph was linear in the range of 0.1-6.0 ng/mL, the detection limit was 0.023 ng/mL for rhodium and relative standard deviation was 3.67% ( c = 1.0 ng/mL, n = 11)．The method has been applied to the determination of trace rhodium in water samples with satisfactory results.

Enantioselective column coupled electrophoresis employing large bore capillaries hyphenated with tandem mass spectrometry for ultra-trace determination of chiral compounds in complex real samples.

Science.gov (United States)

Piešťanský, Juraj; Maráková, Katarína; Kovaľ, Marián; Havránek, Emil; Mikuš, Peter

2015-12-01

A new multidimensional analytical approach for the ultra-trace determination of target chiral compounds in unpretreated complex real samples was developed in this work. The proposed analytical system provided high orthogonality due to on-line combination of three different methods (separation mechanisms), i.e. (1) isotachophoresis (ITP), (2) chiral capillary zone electrophoresis (chiral CZE), and (3) triple quadrupole mass spectrometry (QqQ MS). The ITP step, performed in a large bore capillary (800 μm), was utilized for the effective sample pretreatment (preconcentration and matrix clean-up) in a large injection volume (1-10 μL) enabling to obtain as low as ca. 80 pg/mL limits of detection for the target enantiomers in urine matrices. In the chiral CZE step, the different chiral selectors (neutral, ionizable, and permanently charged cyclodextrins) and buffer systems were tested in terms of enantioselectivity and influence on the MS detection response. The performance parameters of the optimized ITP - chiral CZE-QqQ MS method were evaluated according to the FDA guidance for bioanalytical method validation. Successful validation and application (enantioselective monitoring of renally eliminated pheniramine and its metabolite in human urine) highlighted great potential of this chiral approach in advanced enantioselective biomedical applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inductively coupled plasma – Tandem mass spectrometry (ICP-MS/MS): A powerful and universal tool for the interference-free determination of (ultra)trace elements – A tutorial review

Energy Technology Data Exchange (ETDEWEB)

Balcaen, Lieve; Bolea-Fernandez, Eduardo [Ghent University, Department of Analytical Chemistry, Krijgslaan 281-S12, B-9000 Ghent (Belgium); Resano, Martín [University of Zaragoza, Department of Analytical Chemistry, Pedro Cerbuna 12, E-50009 Zaragoza (Spain); Vanhaecke, Frank, E-mail: Frank.Vanhaecke@UGent.be [Ghent University, Department of Analytical Chemistry, Krijgslaan 281-S12, B-9000 Ghent (Belgium)

2015-09-24

This paper is intended as a tutorial review on the use of inductively coupled plasma – tandem mass spectrometry (ICP-MS/MS) for the interference-free quantitative determination and isotope ratio analysis of metals and metalloids in different sample types. Attention is devoted both to the instrumentation and to some specific tools and procedures available for advanced method development. Next to the more typical reaction gases, e.g., H{sub 2}, O{sub 2} and NH{sub 3}, also the use of promising alternative gases, such as CH{sub 3}F, is covered, and the possible reaction pathways with those reactive gases are discussed. A variety of published applications relying on the use of ICP-MS/MS are described, to illustrate the added value of tandem mass spectrometry in (ultra)trace analysis. - Highlights: • First review on tandem ICP-mass spectrometry (ICP-MS/MS). • Clear description of operating principles of ICP-MS/MS. • Description on how to make use of product ion scans, precursor ion scans and neutral gain scans in method development. • Overview of applications published so far.

Inductively coupled plasma – Tandem mass spectrometry (ICP-MS/MS): A powerful and universal tool for the interference-free determination of (ultra)trace elements – A tutorial review

International Nuclear Information System (INIS)

Balcaen, Lieve; Bolea-Fernandez, Eduardo; Resano, Martín; Vanhaecke, Frank

2015-01-01

This paper is intended as a tutorial review on the use of inductively coupled plasma – tandem mass spectrometry (ICP-MS/MS) for the interference-free quantitative determination and isotope ratio analysis of metals and metalloids in different sample types. Attention is devoted both to the instrumentation and to some specific tools and procedures available for advanced method development. Next to the more typical reaction gases, e.g., H_2, O_2 and NH_3, also the use of promising alternative gases, such as CH_3F, is covered, and the possible reaction pathways with those reactive gases are discussed. A variety of published applications relying on the use of ICP-MS/MS are described, to illustrate the added value of tandem mass spectrometry in (ultra)trace analysis. - Highlights: • First review on tandem ICP-mass spectrometry (ICP-MS/MS). • Clear description of operating principles of ICP-MS/MS. • Description on how to make use of product ion scans, precursor ion scans and neutral gain scans in method development. • Overview of applications published so far.

A sensitive flow-batch system for on board determination of ultra-trace ammonium in seawater: Method development and shipboard application.

Science.gov (United States)

Zhu, Yong; Yuan, Dongxing; Huang, Yongming; Ma, Jian; Feng, Sichao

2013-09-10

Combining fluorescence detection with flow analysis and solid phase extraction (SPE), a highly sensitive and automatic flow system for measurement of ultra-trace ammonium in open ocean water was established. Determination was based on fluorescence detection of a typical product of o-phthaldialdehyde and ammonium. In this study, the fluorescence reaction product could be efficiently extracted onto an SPE cartridge (HLB, hydrophilic-lipophilic balance). The extracted fluorescence compounds were rapidly eluted with ethanol and directed into a flow cell for fluorescence detection. Compared with the common used fluorescence method, the proposed one offered the benefits of improved sensitivity, reduced reagent consumption, negligible salinity effect and lower cost. Experimental parameters were optimized using a univariate experimental design. Calibration curves, ranging from 1.67 to 300nM, were obtained with different reaction times. The recoveries were between 89.5 and 96.5%, and the detection limits in land-based and shipboard laboratories were 0.7 and 1.2nM, respectively. The relative standard deviation was 3.5% (n=5) for an aged seawater sample spiked with 20nM ammonium. Compared with the analytical results obtained using the indophenol blue method coupled to a long-path liquid waveguide capillary cell, the proposed method showed good agreement. The method had been applied on board during a South China Sea cruise in August 2012. A vertical profile of ammonium in the South East Asia Time-Series (SEATS, 18° N, 116° E) station was produced. The distribution of ammonium in the surface seawater of the Qiongdong upwelling in South China Sea is also presented. Copyright © 2013 Elsevier B.V. All rights reserved.

Visual and sensitive fluorescent sensing for ultratrace mercury ions by perovskite quantum dots.

Science.gov (United States)

Lu, Li-Qiang; Tan, Tian; Tian, Xi-Ke; Li, Yong; Deng, Pan

2017-09-15

Mercury ions sensing is an important issue for human health and environmental safety. A novel fluorescence nanosensor was designed for rapid visual detection of ultratrace mercury ions (Hg 2+ ) by using CH 3 NH 3 PbBr 3 perovskite quantum dots (QDs) based on the surface ion-exchange mechanism. The synthesized CH 3 NH 3 PbBr 3 QDs can emitt intense green fluorescence with high quantum yield of 50.28%, and can be applied for Hg 2+ sensing with the detection limit of 0.124 nM (24.87 ppt) in the range of 0 nM-100 nM. Furthermore, the interfering metal ions have no any influence on the fluorescence intensity of QDs, showing the perovskite QDs possess the high selectivity and sensitivity for Hg 2+ detection. The sensing mechanism of perovskite QDs for Hg 2+ is has also been investigated by XPS, EDX studies, showing Pb 2+ on the surface of perovskite QDs has been partially replaced by Hg 2+ . Spot plate test shows that the perovskite QDs can also be used for visual detection of Hg 2+ . Our research indicated the perovskite QDs are promising candidates for the visual fluorescence detection of environmental micropollutants. Copyright © 2017 Elsevier B.V. All rights reserved.

In-situ pre-concentration through repeated sampling and pyrolysis for ultrasensitive determination of thallium in drinking water by electrothermal atomic absorption spectrometry.

Science.gov (United States)

Liu, Liwei; Zheng, Huaili; Xu, Bincheng; Xiao, Lang; Chigan, Yong; Zhangluo, Yilan

2018-03-01

In this paper, a procedure for in-situ pre-concentration in graphite furnace by repeated sampling and pyrolysis is proposed for the determination of ultra-trace thallium in drinking water by graphite furnace atomic absorption spectrometry (GF-AAS). Without any other laborious enrichment processes that routinely result in analyte loss and contamination, thallium was directly concentrated in the graphite furnace automatically and subsequently subject to analysis. The effects of several key factors, such as the temperature for pyrolysis and atomization, the chemical modifier, and the repeated sampling times were investigated. Under the optimized conditions, a limit of detection of 0.01µgL -1 was obtained, which fulfilled thallium determination in drinking water by GB 5749-2006 regulated by China. Successful analysis of thallium in certified water samples and drinking water samples was demonstrated, with analytical results in good agreement with the certified values and those by inductively coupled plasma mass spectrometry (ICP-MS), respectively. Routine spike-recovery tests with randomly selected drinking water samples showed satisfactory results of 80-96%. The proposed method is simple and sensitive for screening of ultra-trace thallium in drinking water samples. Copyright © 2017. Published by Elsevier B.V.

Development of a new microelectrolysis system for in-situ electrodeposition of ultra-traces of gold prior to measurement by ETAAS.

Science.gov (United States)

Najafi, Nahid Mashkouri; Manouchehri, Nastaran

2003-06-01

Electrodeposition is known to be suitable for separation and preconcentration of extremely low concentrations of analyte from bulk samples and is instrumentally is very simple. In this approach a new combined system was designed for in-situ electrodeposition of ultratrace levels of gold from micro samples on to a graphite furnace prior to determination by electrothermal atomic absorption spectrometry (ETAAS). Sediment samples were digested and traces of the gold content were extracted with boiling aqua regia. To prevent the highly corrosive effect of aqua regia media, the graphite tube surface was pre-coated by electrodeposition of ppm amounts of Pd prior to sample introduction. Separation of the analyte from the matrix was achieved by electrodeposition of the analyte in situ on the Pd/C surface of the furnace tube. Vanadium was also used as a modifier to stabilize the analyte from decomposition at charring temperatures. By using the proposed microelectrolysis preconcentration technique a considerable improvement in sensitivity and detection limit was achieved compared with conventional ETAAS. Characteristic masses for ED-ETAAS techniques in both nitric acid and aqua regia were reported to be m(o)=4.1 pg, with %RSD=2.9; the calculated LOD was 0.105 ppb, and typical calibration graphs for this element in nitric acid and aqua regia for both techniques were linear up to 70 microg L(-1) with about 99% recovery. Six reference sediments samples were tested by the proposed technique and by the Conv-ETAAS method. The results were in agreement with recommended values (reported by a reference laboratory using UV-visible spectrometry), demonstrating the efficiency of extraction and preconcentration of ultratrace levels of gold.

Recent developments in and applications of resonance ionization mass spectrometry

International Nuclear Information System (INIS)

Wendt, K.; Blaum, K.; Horn, R.; Huber, G.; Kunz, P.; Mueller, P.; Noertershaeuser, W.; Nunnemann, M.; Passler, G.; Schmitt, A.; Gruening, C.; Kratz, J.V.; Trautmann, N.; Waldek, A.

1999-01-01

Resonance Ionization Mass Spectrometry (RIMS) has nowadays reached the status of a routine method for sensitive and selective ultratrace determination of long-lived radioactive isotopes in environmental, biomedical and technical samples. It provides high isobaric suppression, high to ultra-high isotopic selectivity and good overall efficiency. Experimental detection limits are as low as 10 6 atoms per sample and permit the fast and sensitive determination of ultratrace amounts of radiotoxic contaminations. Experimental arrangements for the detection of different radiotoxic isotopes, e.g. 236-244 Pu, 89,90 Sr and 99 Tc in environmental samples are described, and the application of RIMS to the ultrarare long-lived radioisotope 41 Ca for cosmochemical, radiodating and medical purposes are presented. (orig.)

Trace determination of uranium and thorium in biological samples by radiochemical neutron activation analysis

International Nuclear Information System (INIS)

Benedik, Ljudmila; Repinc, Urska; Byrne, Anthony R.; Stegnar, Peter

2002-01-01

Radiochemical neutron activation analysis (RNAA) is an excellent method for determining uranium and thorium; it offers unique possibilities for their ultratrace analysis using selective radiochemical separations. Regarding the favourably sensitive nuclear characteristics of uranium and of thorium with respect to RNAA, but the different half-lives of their induced nuclides, two different approaches were used. In the first approach uranium and thorium were determined separately via 239 U, 239 Np and 233 Pa. In the second approach these elements were 239 239 233 determined simultaneously in a single sample using U and/or Np and Pa. Isolation of induced nuclides was based on separation by extraction and/or anion exchange chromatography. Chemical yields were measured in each sample aliquot using added 235 U, 238 Np and 231 Pa radioisotopic tracers. (author)

Trends and applications of integrated automated ultra-trace sample handling and analysis (T9)

International Nuclear Information System (INIS)

Kingston, H.M.S.; Ye Han; Stewart, L.; Link, D.

2002-01-01

Full text: Automated analysis, sub-ppt detection limits, and the trend toward speciated analysis (rather than just elemental analysis) force the innovation of sophisticated and integrated sample preparation and analysis techniques. Traditionally, the ability to handle samples at ppt and sub-ppt levels has been limited to clean laboratories and special sample handling techniques and equipment. The world of sample handling has passed a threshold where older or 'old fashioned' traditional techniques no longer provide the ability to see the sample due to the influence of the analytical blank and the fragile nature of the analyte. When samples require decomposition, extraction, separation and manipulation, application of newer more sophisticated sample handling systems are emerging that enable ultra-trace analysis and species manipulation. In addition, new instrumentation has emerged which integrate sample preparation and analysis to enable on-line near real-time analysis. Examples of those newer sample-handling methods will be discussed and current examples provided as alternatives to traditional sample handling. Two new techniques applying ultra-trace microwave energy enhanced sample handling have been developed that permit sample separation and refinement while performing species manipulation during decomposition. A demonstration, that applies to semiconductor materials, will be presented. Next, a new approach to the old problem of sample evaporation without losses will be demonstrated that is capable of retaining all elements and species tested. Both of those methods require microwave energy manipulation in specialized systems and are not accessible through convection, conduction, or other traditional energy applications. A new automated integrated method for handling samples for ultra-trace analysis has been developed. An on-line near real-time measurement system will be described that enables many new automated sample handling and measurement capabilities. This

Ligandless, ion pair-based and ultrasound assisted emulsification solidified floating organic drop microextraction for simultaneous preconcentration of ultra-trace amounts of gold and thallium and determination by GFAAS.

Science.gov (United States)

Fazelirad, Hamid; Taher, Mohammad Ali

2013-01-15

In the present work, a new, simple and efficient method for simultaneous preconcentration of ultra-trace amounts of gold and thallium is developed using an ion pair based-ultrasound assisted emulsification-solidified floating organic drop microextraction procedure before graphite furnace atomic absorption spectrometry determination. This methodology was used to preconcentrate the ion pairs formed between AuCl(4)(-) and TlCl(4)(-) and [C(23)H(42)]N(+) in a microliter-range volume of 1-undecanol. Several factors affecting the microextraction efficiency, such as HCl volume, type and volume of extraction solvent, sonication time, sample volume, temperature, ionic strength and [C(23)H(42)]NCl volume were investigated and optimized. Under the optimized conditions, the enrichment factor of 441 and 443 and calibration graphs of 2.2-89 and 22.2-667 ng L(-1) for gold and thallium were obtained, respectively. The intra- and inter-day precision of ± 4.4 and ± 4.9% for Au and ± 4.8 and ± 5.4% for Tl were obtained. The detection limit was 0.66 ng L(-1) for Au and 4.67 ng L(-1) for Tl. The results show that the liquid-liquid pretreatment using ion pair forming, is sensitive, rapid, simple and safe method for the simultaneous preconcentration of gold and thallium. The method was successfully applied for determination of gold and thallium in natural water and hair samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Ultra-trace analysis of hormones, pharmaceutical substances, alkylphenols and phthalates in two French natural mineral waters

Energy Technology Data Exchange (ETDEWEB)

Dévier, Marie-Hélène; Le Menach, Karyn [Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC, UMR 5805 CNRS), Laboratoire de Physico- et Toxico-Chimie de l' Environnement (LPTC), Université de Bordeaux, 351 cours de la Libération, 33405 Talence cedex (France); Viglino, Liza [Danone Waters Analytical Center, Aqualab, Place de la Gare, 74500 Evian-Les-Bains (France); Di Gioia, Lodovico [Danone Research, R and D Waters Division, RD 128, 91767 Palaiseau Cedex (France); Lachassagne, Patrick [Danone Waters France, Environment and Water Resources Division, BP 87, 11 av. Général Dupas, 74500 Evian-Les-Bains cedex (France); Budzinski, Hélène, E-mail: h.budzinski@epoc.u-bordeaux1.fr [Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC, UMR 5805 CNRS), Laboratoire de Physico- et Toxico-Chimie de l' Environnement (LPTC), Université de Bordeaux, 351 cours de la Libération, 33405 Talence cedex (France)

2013-01-15

The aim of this work was to investigate the potential presence of a broad range of organic compounds, such as hormones, alkylphenols, bisphenol A and phthalates, as well as pharmaceutical substances in two brands of bottled natural mineral waters (Evian and Volvic, Danone). The phthalates were determined by solid-phase microextraction coupled to gas chromatography–mass spectrometry (SPME-GC–MS) and the other compounds by liquid chromatography–tandem mass spectrometry (LC–MS/MS) or gas chromatography–mass spectrometry (GC–MS) after solid-phase extraction. The potential migration of alkylphenols, bisphenol A and phthalates from polyethylene terephthalate (PET) bottles was also investigated under standardized test conditions. Evian and Volvic natural mineral waters contain none of the around 120 targeted organic compounds. Traces of 3 pharmaceuticals (ketoprofen, salicylic acid, and caffeine), 3 alkylphenols (4-nonylphenol, 4-t-octylphenol, and 4-nonylphenol diethoxylate), and some phthalates including di(2-ethylhexyl)phthalate (DEHP) were detected in the samples, but they were also present in the procedural blanks at similar levels. The additional test procedures demonstrated that the few detected compounds originated from the background laboratory contamination. Analytical procedures have been designed both in the bottling factory and in the laboratory in order to investigate the sources of DEHP and to minimize to the maximum this unavoidable laboratory contamination. It was evidenced that no migration of the targeted compounds from bottles occurred under the test conditions. The results obtained in this study underline the complexity of reaching a reliable measure to qualify the contamination of a sample at ultra-trace level, in the field of very pure matrices. The analytical procedures involving glassware, equipment, hoods, and rooms specifically dedicated to trace analysis allowed us to reach reliable procedural limits of quantification at the ng

Ultra-trace analysis of hormones, pharmaceutical substances, alkylphenols and phthalates in two French natural mineral waters

International Nuclear Information System (INIS)

Dévier, Marie-Hélène; Le Menach, Karyn; Viglino, Liza; Di Gioia, Lodovico; Lachassagne, Patrick; Budzinski, Hélène

2013-01-01

The aim of this work was to investigate the potential presence of a broad range of organic compounds, such as hormones, alkylphenols, bisphenol A and phthalates, as well as pharmaceutical substances in two brands of bottled natural mineral waters (Evian and Volvic, Danone). The phthalates were determined by solid-phase microextraction coupled to gas chromatography–mass spectrometry (SPME-GC–MS) and the other compounds by liquid chromatography–tandem mass spectrometry (LC–MS/MS) or gas chromatography–mass spectrometry (GC–MS) after solid-phase extraction. The potential migration of alkylphenols, bisphenol A and phthalates from polyethylene terephthalate (PET) bottles was also investigated under standardized test conditions. Evian and Volvic natural mineral waters contain none of the around 120 targeted organic compounds. Traces of 3 pharmaceuticals (ketoprofen, salicylic acid, and caffeine), 3 alkylphenols (4-nonylphenol, 4-t-octylphenol, and 4-nonylphenol diethoxylate), and some phthalates including di(2-ethylhexyl)phthalate (DEHP) were detected in the samples, but they were also present in the procedural blanks at similar levels. The additional test procedures demonstrated that the few detected compounds originated from the background laboratory contamination. Analytical procedures have been designed both in the bottling factory and in the laboratory in order to investigate the sources of DEHP and to minimize to the maximum this unavoidable laboratory contamination. It was evidenced that no migration of the targeted compounds from bottles occurred under the test conditions. The results obtained in this study underline the complexity of reaching a reliable measure to qualify the contamination of a sample at ultra-trace level, in the field of very pure matrices. The analytical procedures involving glassware, equipment, hoods, and rooms specifically dedicated to trace analysis allowed us to reach reliable procedural limits of quantification at the ng

Miniaturized preconcentration methods based on liquid-liquid extraction and their application in inorganic ultratrace analysis and speciation: A review

International Nuclear Information System (INIS)

Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

2009-01-01

Liquid-liquid extraction (LLE) is widely used as a pre-treatment technique for separation and preconcentration of both organic and inorganic analytes from aqueous samples. Nevertheless, it has several drawbacks, such as emulsion formation or the use of large volumes of solvents, which makes LLE expensive and labour intensive. Therefore, miniaturization of conventional liquid-liquid extraction is needed. The search for alternatives to the conventional LLE using negligible volumes of extractant and the minimum number of steps has driven the development of three new miniaturized methodologies, i.e. single-drop microextraction (SDME), hollow fibre liquid-phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME). The aim of this paper is to provide an overview of these novel preconcentration approaches and their potential use in analytical labs involved in inorganic (ultra)trace analysis and speciation. Relevant applications to the determination of metal ions, metalloids, organometals and non-metals are included

A large-scale superhydrophobic surface-enhanced Raman scattering (SERS) platform fabricated via capillary force lithography and assembly of Ag nanocubes for ultratrace molecular sensing.

Science.gov (United States)

Tan, Joel Ming Rui; Ruan, Justina Jiexin; Lee, Hiang Kwee; Phang, In Yee; Ling, Xing Yi

2014-12-28

An analytical platform with an ultratrace detection limit in the atto-molar (aM) concentration range is vital for forensic, industrial and environmental sectors that handle scarce/highly toxic samples. Superhydrophobic surface-enhanced Raman scattering (SERS) platforms serve as ideal platforms to enhance detection sensitivity by reducing the random spreading of aqueous solution. However, the fabrication of superhydrophobic SERS platforms is generally limited due to the use of sophisticated and expensive protocols and/or suffers structural and signal inconsistency. Herein, we demonstrate a high-throughput fabrication of a stable and uniform superhydrophobic SERS platform for ultratrace molecular sensing. Large-area box-like micropatterns of the polymeric surface are first fabricated using capillary force lithography (CFL). Subsequently, plasmonic properties are incorporated into the patterned surfaces by decorating with Ag nanocubes using the Langmuir-Schaefer technique. To create a stable superhydrophobic SERS platform, an additional 25 nm Ag film is coated over the Ag nanocube-decorated patterned template followed by chemical functionalization with perfluorodecanethiol. Our resulting superhydrophobic SERS platform demonstrates excellent water-repellency with a static contact angle of 165° ± 9° and a consequent analyte concentration factor of 59-fold, as compared to its hydrophilic counterpart. By combining the analyte concentration effect of superhydrophobic surfaces with the intense electromagnetic "hot spots" of Ag nanocubes, our superhydrophobic SERS platform achieves an ultra-low detection limit of 10(-17) M (10 aM) for rhodamine 6G using just 4 μL of analyte solutions, corresponding to an analytical SERS enhancement factor of 10(13). Our fabrication protocol demonstrates a simple, cost- and time-effective approach for the large-scale fabrication of a superhydrophobic SERS platform for ultratrace molecular detection.

Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers: A novel technique for ultratrace gas analysis and high-resolution spectroscopy.

Science.gov (United States)

Hippler, Michael; Mohr, Christian; Keen, Katherine A; McNaghten, Edward D

2010-07-28

Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers (OF-CERPAS) is introduced as a novel technique for ultratrace gas analysis and high-resolution spectroscopy. In the scheme, a single-mode cw diode laser (3 mW, 635 nm) is coupled into a high-finesse linear cavity and stabilized to the cavity by optical feedback. Inside the cavity, a build-up of laser power to at least 2.5 W occurs. Absorbing gas phase species inside the cavity are detected with high sensitivity by the photoacoustic effect using a microphone embedded in the cavity. To increase sensitivity further, coupling into the cavity is modulated at a frequency corresponding to a longitudinal resonance of an organ pipe acoustic resonator (f=1.35 kHz and Q approximately 10). The technique has been characterized by measuring very weak water overtone transitions near 635 nm. Normalized noise-equivalent absorption coefficients are determined as alpha approximately 4.4x10(-9) cm(-1) s(1/2) (1 s integration time) and 2.6x10(-11) cm(-1) s(1/2) W (1 s integration time and 1 W laser power). These sensitivities compare favorably with existing state-of-the-art techniques. As an advantage, OF-CERPAS is a "zero-background" method which increases selectivity and sensitivity, and its sensitivity scales with laser power.

Recent Developments in Trace, Ultratrace and Isotope Ratio Measurements in Inductively Coupled Plasma Mass Spectrometry

International Nuclear Information System (INIS)

Zahran, N. F.

2004-01-01

Inductively coupled plasma mass spectrometry (ICP-MS) and Laser Ablation (LA-ICP-MS) are recent techniques for trace, ultratrace and isotope ratio measurements. Main features of these techniques and their figure of merit and capabilities are discussed. An overview of ICP-MS instrument is presented in addition to its precision, accuracy and detection limits. Uses of ICP-MS in environmental monitoring in some cases for detection of some radio nuclides are presented. Two geological applications namely, zircon grains analysis and age dating of Rb-Sr method are presented. Zn elemental and isotopic analyses in blood and serum as a biological application is shown. (Author)

Ultra-trace determination of Strontium-90 in environmental soil samples from Qatar by collision/reaction cell-inductively coupled plasma mass spectrometry (CRC-ICP-MS/MS)

Energy Technology Data Exchange (ETDEWEB)

Al-Meer, S. H.; Amr, M. A. [Central Laboratories Unit, Qatar University, Doha (Qatar); Helal, A.I. [Atomic Energy Authority, Cairo (Egypt); Al-Kinani, A.T. [Minstery of Environment, Doha (Qatar)

2013-07-01

Because of the very low level of {sup 90}Sr in the environmental soil samples and its determination by beta counting may take several weeks, we developed a procedure for ultra-trace determination of {sup 90}Sr using collision reaction cell-inductively coupled plasma tandem mass spectrometry (CRC-ICP-MS/MS, Agilent 8800). Soil samples were dried at 105 deg. C and then heated in a furnace at 550 deg. C to remove any organics present. 500 g of each soil samples were aliquoted into 2000 ml glass beakers. Each Soils samples were soaked in 2 ppm Sr solution carrier to allow determination of chemical yield. The solid to liquid ratio was 1:1. Finally the soil samples were dried at 105 deg. C. Five hundred milliliters concentrated nitric acid and 250 ml hydrochloric acid volumes were added on 500 g soil samples. The samples were digested on hot plate at 80 deg. C to prevent spraying with continuous manual mixing. The leachate solution was separated. The solids were rinsed with 500 ml deionized water, warmed on a hot plate and the leachate plus previous leachate were filtered and the total volume was reduced to 500 ml by evaporation. Final leachate volume was transferred to a centrifuge tubes. The centrifuge tubes were centrifuged at 3,500 rpm for 10 min. The leachate was transferred to a 1 L beaker and heated on a hot plate to evaporate the leachate to dryness. The reside was re-dissolved in 100 ml of 2% HNO{sub 3} and reduced by evaporation to 10 mL. The solution was measured directly by CRC-ICP-MS/MS by setting the first quadruple analyzer to m/z 90 and introducing oxygen gas into the reaction cell for elimination isobar interference from zirconium-90. The method was validated by measurements of standard reference materials and applied on environmental soil samples. The overall time requirement for the measurement of strontium-90 by CRC-ICP-MS/MS is 2 days, significantly shorter than any radioanalytical protocol currently available. (authors)

Direct analysis of ultra-trace semiconductor gas by inductively coupled plasma mass spectrometry coupled with gas to particle conversion-gas exchange technique.

Science.gov (United States)

Ohata, Masaki; Sakurai, Hiromu; Nishiguchi, Kohei; Utani, Keisuke; Günther, Detlef

2015-09-03

An inductively coupled plasma mass spectrometry (ICPMS) coupled with gas to particle conversion-gas exchange technique was applied to the direct analysis of ultra-trace semiconductor gas in ambient air. The ultra-trace semiconductor gases such as arsine (AsH3) and phosphine (PH3) were converted to particles by reaction with ozone (O3) and ammonia (NH3) gases within a gas to particle conversion device (GPD). The converted particles were directly introduced and measured by ICPMS through a gas exchange device (GED), which could penetrate the particles as well as exchange to Ar from either non-reacted gases such as an air or remaining gases of O3 and NH3. The particle size distribution of converted particles was measured by scanning mobility particle sizer (SMPS) and the results supported the elucidation of particle agglomeration between the particle converted from semiconductor gas and the particle of ammonium nitrate (NH4NO3) which was produced as major particle in GPD. Stable time-resolved signals from AsH3 and PH3 in air were obtained by GPD-GED-ICPMS with continuous gas introduction; however, the slightly larger fluctuation, which could be due to the ionization fluctuation of particles in ICP, was observed compared to that of metal carbonyl gas in Ar introduced directly into ICPMS. The linear regression lines were obtained and the limits of detection (LODs) of 1.5 pL L(-1) and 2.4 nL L(-1) for AsH3 and PH3, respectively, were estimated. Since these LODs revealed sufficiently lower values than the measurement concentrations required from semiconductor industry such as 0.5 nL L(-1) and 30 nL L(-1) for AsH3 and PH3, respectively, the GPD-GED-ICPMS could be useful for direct and high sensitive analysis of ultra-trace semiconductor gas in air. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrochemical selective detection of dopamine on microbial carbohydrate-doped multiwall carbon nanotube-modified electrodes.

Science.gov (United States)

Jin, Joon-Hyung; Cho, Eunae; Jung, Seunho

2010-03-01

Microbial carbohydrate-doped multiwall carbon nanotube (MWNT)-modified electrodes were prepared for the purpose of determining if 4-(2-aminoethyl)benzene-1,2-diol (3,4-dihydroxyphenylalanine; dopamine) exists in the presence of 0.5 mM ascorbic acid, a representative interfering agent in neurotransmitter detection. The microbial carbohydrate dopants were alpha-cyclosophorohexadecaose (alpha-C16) from Xanthomonas oryzae and cyclic-(1 --> 2)-beta-d-glucan (Cys) from Rhizobium meliloti. The cyclic voltammetric responses showed that the highest sensitivity (5.8 x 10(-3) mA cm(-2) microM(-1)) is attained with the Cys-doped MWNT-modified ultra-trace carbon electrode, and that the alpha-C16-doped MWNT-modified glassy carbon electrode displays the best selectivity to dopamine (the approximate peak potential separation is 310 mV).

Optimizing detectability

International Nuclear Information System (INIS)

Anon.

1992-01-01

HPLC is useful for trace and ultratrace analyses of a variety of compounds. For most applications, HPLC is useful for determinations in the nanogram-to-microgram range; however, detection limits of a picogram or less have been demonstrated in certain cases. These determinations require state-of-the-art capability; several examples of such determinations are provided in this chapter. As mentioned before, to detect and/or analyze low quantities of a given analyte at submicrogram or ultratrace levels, it is necessary to optimize the whole separation system, including the quantity and type of sample, sample preparation, HPLC equipment, chromatographic conditions (including column), choice of detector, and quantitation techniques. A limited discussion is provided here for optimization based on theoretical considerations, chromatographic conditions, detector selection, and miscellaneous approaches to detectability optimization. 59 refs

Geochemical and isotopic determination of deep groundwater contributions and salinity to the shallow groundwater and surface water systems, Mesilla Basin, New Mexico, Texas, and Mexico

Science.gov (United States)

Robertson, A.; Carroll, K. C.; Kubicki, C.; Purtshert, R.

2017-12-01

The Mesilla Basin/Conejos-Médanos aquifer system, extending from southern New Mexico to Chihuahua, Mexico, is a priority transboundary aquifer under the 2006 United States­-Mexico Transboundary Aquifer Assessment Act. Declining water levels, deteriorating water quality, and increasing groundwater use by municipal, industrial, and agricultural users on both sides of the international border raise concerns about long-term aquifer sustainability. Relative contributions of present-day and "paleo" recharge to sustainable fresh groundwater yields has not been determined and evidence suggests that a large source of salinity at the distal end of the Mesilla Basin is saline discharge from deep groundwater flow. The magnitude and distribution of those deep saline flow paths are not determined. The contribution of deep groundwater to discharge and salinity in the shallow groundwater and surface water of the Mesilla Basin will be determined by collecting discrete groundwater samples and analyzing for aqueous geochemical and isotopic tracers, as well as the radioisotopes of argon and krypton. Analytes include major ions, trace elements, the stable isotopes of water, strontium and boron isotopes, uranium isotopes, the carbon isotopes of dissolved inorganic carbon, noble gas concentrations and helium isotope ratios. Dissolved gases are extracted and captured from groundwater wells using membrane contactors in a process known as ultra-trace sampling. Gas samples are analyzed for radioisotope ratios of krypton by the ATTA method and argon by low-level counting. Effectiveness of the ultra-trace sampling device and method was evaluated by comparing results of tritium concentrations to the krypton-85 content. Good agreement between the analyses, especially in samples with undetectable tritium, indicates that the ultra-trace procedure is effective and confirms that introduction of atmospheric air has not occurred. The geochemistry data indicate a complex system of geochemical

Determination of total mercury in nuts at ultratrace level

Energy Technology Data Exchange (ETDEWEB)

Silva, Maria José da, E-mail: maryquimica@yahoo.com.br [Departamento de Química – Universidade Federal Rural de Pernambuco, Rue Dom Manoel de Medeiros s/n. Dois irmãos, 52171-900 Recife, PE (Brazil); Paim, Ana Paula S. [Departamento de Química Fundamental – Universidade Federal de Pernambuco, Cidade Universitária, 50740-550 Recife, PE (Brazil); Pimentel, Maria Fernanda [Departamento de Engenharia Química – Universidade Federal de Pernambuco, Recife, PE (Brazil); Cervera, M. Luisa; Guardia, Miguel de la [Department of Analytical Chemistry, Research Building, University of Valencia, 50th Dr. Moliner Street, E-46100 Burjassot, Valencia (Spain)

2014-08-01

Highlights: • Direct analysis of Hg in nuts has been improved by a previous fat removal. • Comparison of cold vapour atomic fluorescence and direct analysis of Hg in nuts. • Mercury content in tree nuts was determined. - Abstract: Total mercury, at μg kg{sup −1} level, was determined in different types of nuts (cashew nut, Brazil nuts, almond, pistachio, peanut, walnut) using a direct mercury analyser after previous sample defatting and by cold vapour atomic fluorescence spectrometry. There is not enough sensitivity in the second approach to determine Hg in previously digested samples due to the strong matrix effect. Mercury levels in 25 edible nut samples from Brazil and Spain were found in the range from 0.6 to 2.7 μg kg{sup −1} by using the pyrolysis of sample after the extraction of the nut fat. The accuracy of the proposed method was confirmed by analysing certified reference materials of Coal Fly Ash-NIST SRM 1633b, Fucus-IAEA 140 and three unpolished Rice Flour NIES-10. The observed results were in good agreement with the certified values. The recoveries of different amounts of mercury added to nut samples ranged from 94 to 101%. RSD values corresponding to three measurements varied between 2.0 and 14% and the limit of detection and quantification of the method were 0.08 and 0.3 μg kg{sup −1}, respectively.

Determination of total mercury in nuts at ultratrace level

International Nuclear Information System (INIS)

Silva, Maria José da; Paim, Ana Paula S.; Pimentel, Maria Fernanda; Cervera, M. Luisa; Guardia, Miguel de la

2014-01-01

Highlights: • Direct analysis of Hg in nuts has been improved by a previous fat removal. • Comparison of cold vapour atomic fluorescence and direct analysis of Hg in nuts. • Mercury content in tree nuts was determined. - Abstract: Total mercury, at μg kg −1 level, was determined in different types of nuts (cashew nut, Brazil nuts, almond, pistachio, peanut, walnut) using a direct mercury analyser after previous sample defatting and by cold vapour atomic fluorescence spectrometry. There is not enough sensitivity in the second approach to determine Hg in previously digested samples due to the strong matrix effect. Mercury levels in 25 edible nut samples from Brazil and Spain were found in the range from 0.6 to 2.7 μg kg −1 by using the pyrolysis of sample after the extraction of the nut fat. The accuracy of the proposed method was confirmed by analysing certified reference materials of Coal Fly Ash-NIST SRM 1633b, Fucus-IAEA 140 and three unpolished Rice Flour NIES-10. The observed results were in good agreement with the certified values. The recoveries of different amounts of mercury added to nut samples ranged from 94 to 101%. RSD values corresponding to three measurements varied between 2.0 and 14% and the limit of detection and quantification of the method were 0.08 and 0.3 μg kg −1 , respectively

Solid sampling graphite furnace atomic absorption spectrometry for the direct analysis of microextraction solvent bars used for metal ultra-trace pre-concentration

Science.gov (United States)

González-Álvarez, Rafael Jesús; Pinto, Juan J.; Bellido-Milla, Dolores; Moreno, Carlos

2017-09-01

The potential applicability of the continuum source solid sampling graphite furnace atomic absorption spectroscopy (CS SS-GF AAS) technique has been studied to carry out the direct analysis of microextraction solvent bars used for metal ultra-trace pre-concentration in natural waters. An optimisation of the temperature program was developed for this purpose. Preliminary chamber furnace studies were performed in order to understand the behaviour of the bars with the increasing temperature. Solvent bars were filled with an acceptor solution, impregnated with an organic extractant and placed into the chamber furnace to carry out several temperature programs. Results led to perform a correct optimisation of the drying and pyrolysis steps of the furnace temperature program, which was tested with silver once completed. Blank solvent bars as well as standards containing silver were measured, obtaining a calibration curve with a correlation coefficient of 0.991. The results exhibited good repeatability and reproducibility, with relative standard deviations below 10% in both cases, indicating a promising applicability of the CS SS-GF AAS technique to directly determine metallic species in microextraction solvent bars.

Cloud Point Extraction and Determination of Silver Ion in Real Sample using Bis((1H-benzo[d ]imidazol-2ylmethylsulfane

Directory of Open Access Journals (Sweden)

Farshid Ahmadi

2011-01-01

Full Text Available Bis((1H-benzo[d]imidazol-2ylmethylsulfane (BHIS was used as a complexing agent in cloud point extraction for the first time and applied for selective pre-concentration of trace amounts of silver. The method is based on the extraction of silver at pH 8.0 by using non-ionic surfactant T-X114 and bis((1H-benzo[d]imidazol-2ylmethylsulfane as a chelating agent. The adopted concentrations for BHIS, Triton X-114 and HNO3, bath temperature, centrifuge rate and time were optimized. Detection limits (3SDb/m of 1.7 along with enrichment factor of 39 for silver ion was achieved. The high efficiency of cloud point extraction to carry out the determination of analytes in complex matrices was demonstrated. The proposed method was successfully applied to the ultra-trace determination of silver in real samples.

Determination of trace amounts of impurities in molybdenum by spark source and glow discharge mass spectrometry

International Nuclear Information System (INIS)

Saito, Morimasa

1994-01-01

For the determination of trace and ultra-trace amounts of impurities in high-purity molybdenum, spark source mass spectrometry and glow discharge mass spectrometry were studied. In spark source mass spectrometry using the metal probe method, the liquid-helium cryogenic pump was used in order to protect the surface of the samples from oxidation. The theoretical relative sensitivity factors (Mo=1) calculated from physical properties were used. The analytical results obtained for molybdenum tablet and high-purity molybdenum were in good agreement with those obtained by other methods (atomic absorption spectrometry and others). In glow discharge mass spectrometry, the relative sensitivity factors were calculated by using the results obtained by spark source mass spectrometry and atomic absorption spectrometry, and this method was applied to the determination of ultra-trace amounts of impurities in ultra high-purity molybdenum and gave the satisfactory results. The detection limits (2σ, n=10) in the integration time of 600 s for U and Th were 0.6 ppb and 0.3 ppb, and the values for Al, Si, Cr, Mn and Cu were in the range of 10 ppb to 0.5 ppb. (author)

Plutonium determination in seawater by inductively coupled plasma mass spectrometry: A review.

Science.gov (United States)

Cao, Liguo; Bu, Wenting; Zheng, Jian; Pan, Shaoming; Wang, Zhongtang; Uchida, Shigeo

2016-05-01

Knowing the concentration and isotopic ratio of Pu in seawater is of critical importance for assessing Pu contamination and investigating oceanic processes. In recent decades, the concentration of (239+240)Pu in seawater, particularly for surface seawater, has presented an exponential decreasing trend with time; thus determination of Pu in seawater has become a challenge nowadays. Here, we have summarized and critically discussed a variety of reported analytical methods for Pu determination in seawater sample based on inductively coupled plasma mass spectrometry (ICP-MS) analytical technique for rapid ultra-trace detection of Pu. Generally, pretreatments for seawater sample include co-precipitation, valence adjustment and chemical separation and purification procedures, all of which are comprehensively reviewed. Overall, the selected anion-exchange, extraction resins and operation condition are important for decontamination of interference from matrix elements and achieving satisfactory chemical yields. In addition, other mass spectrometric and radiometric detections are briefly addressed and compared with the focus on assessing ICP-MS. Finally, we discuss some issues and prospects in determination and application of Pu isotopes in seawater samples for future research. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of thallium at ultra-trace levels in water and biological samples using solid phase spectrophotometry.

Science.gov (United States)

Amin, Alaa S; El-Sharjawy, Abdel-Azeem M; Kassem, Mohammed A

2013-06-01

A new simple, very sensitive, selective and accurate procedure for the determination of trace amounts of thallium(III) by solid-phase spectrophotometry (SPS) has been developed. The procedure is based on fixation of Tl(III) as quinalizarin ion associate on a styrene-divinylbenzene anion-exchange resin. The absorbance of resin sorbed Tl(III) ion associate is measured directly at 636 and 830 nm. Thallium(I) was determined by difference measurements after oxidation of Tl(I) to Tl(III) with bromine. Calibration is linear over the range 0.5-12.0 μg L(-1) of Tl(III) with relative standard deviation (RSD) of 1.40% (n=10). The detection and quantification limits are 150 and 495 ng L(-1) using 0.6 g of the exchanger. The molar absorptivity and Sandell sensitivity are also calculated and found to be 1.31×10(7) L mol(-1)cm(-1) and 0.00156 ng cm(-2), respectively. The proposed procedure has been successfully applied to determine thallium in water, urine and serum samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of thallium at ultra-trace levels in water and biological samples using solid phase spectrophotometry

Science.gov (United States)

Amin, Alaa S.; El-Sharjawy, Abdel-Azeem M.; Kassem, Mohammed A.

2013-06-01

A new simple, very sensitive, selective and accurate procedure for the determination of trace amounts of thallium(III) by solid-phase spectrophotometry (SPS) has been developed. The procedure is based on fixation of Tl(III) as quinalizarin ion associate on a styrene-divinylbenzene anion-exchange resin. The absorbance of resin sorbed Tl(III) ion associate is measured directly at 636 and 830 nm. Thallium(I) was determined by difference measurements after oxidation of Tl(I) to Tl(III) with bromine. Calibration is linear over the range 0.5-12.0 μg L-1 of Tl(III) with relative standard deviation (RSD) of 1.40% (n = 10). The detection and quantification limits are 150 and 495 ng L-1 using 0.6 g of the exchanger. The molar absorptivity and Sandell sensitivity are also calculated and found to be 1.31 × 107 L mol-1 cm-1 and 0.00156 ng cm-2, respectively. The proposed procedure has been successfully applied to determine thallium in water, urine and serum samples.

Selection gradients, the opportunity for selection, and the coefficient of determination.

Science.gov (United States)

Moorad, Jacob A; Wade, Michael J

2013-03-01

Abstract We derive the relationship between R(2) (the coefficient of determination), selection gradients, and the opportunity for selection for univariate and multivariate cases. Our main result is to show that the portion of the opportunity for selection that is caused by variation for any trait is equal to the product of its selection gradient and its selection differential. This relationship is a corollary of the first and second fundamental theorems of natural selection, and it permits one to investigate the portions of the total opportunity for selection that are involved in directional selection, stabilizing (and diversifying) selection, and correlational selection, which is important to morphological integration. It also allows one to determine the fraction of fitness variation not explained by variation in measured phenotypes and therefore attributable to random (or, at least, unknown) influences. We apply our methods to a human data set to show how sex-specific mating success as a component of fitness variance can be decoupled from that owing to prereproductive mortality. By quantifying linear sources of sexual selection and quadratic sources of sexual selection, we illustrate that the former is stronger in males, while the latter is stronger in females.

The mechanisms of determiner selection and its relation to lexical selection : An ERP study

NARCIS (Netherlands)

D'Hooge, Elisah; De Baene, W.; Hartsuiker, Robert J

2016-01-01

The language production literature has given only little attention to the dynamics of closed class word selection, such as determiner selection, and its temporal relation to the selection of open class words. The goal of this paper was to investigate whether determiner selection follows serially

Hyphenating multisyringe flow injection lab-on-valve analysis with atomic fluorescence spectrometry for on-line bead-injection preconcentration and determination of trace levels of hydride-forming elements in environmental samples

DEFF Research Database (Denmark)

Long, Xiangbao; Miró, Manuel; Hansen, Elo Harald

2006-01-01

the determination of ultratrace level concentrations of total inorganic arsenic in freshwater. Employing quantitative preoxidation of As(III) to As(V) in the samples by means of permanganate, the method involves the preconcentration of arsenate at pH 10 on a renewable anion exchanger, namely Q-Sepharose, packed...

Sex selection and restricting abortion and sex determination.

Science.gov (United States)

Zilberberg, Julie

2007-11-01

Sex selection in India and China is fostered by a limiting social structure that disallows women from performing the roles that men perform, and relegates women to a lower status level. Individual parents and individual families benefit concretely from having a son born into the family, while society, and girls and women as a group, are harmed by the widespread practice of sex selection. Sex selection reinforces oppression of women and girls. Sex selection is best addressed by ameliorating the situations of women and girls, increasing their autonomy, and elevating their status in society. One might argue that restricting or prohibiting abortion, prohibiting sex selection, and prohibiting sex determination would eliminate sex selective abortion. But this decreases women's autonomy rather than increases it. Such practices will turn underground. Sex selective infanticide, and slower death by long term neglect, could increase. If abortion is restricted, the burden is placed on women seeking abortions to show that they have a legally acceptable or legitimate reason for a desired abortion, and this seriously limits women's autonomy. Instead of restricting abortion, banning sex selection, and sex determination, it is better to address the practice of sex selection by elevating the status of women and empowering women so that giving birth to a girl is a real and positive option, instead of a detriment to the parents and family as it is currently. But, if a ban on sex selective abortion or a ban on sex determination is indeed instituted, then wider social change promoting women's status in society should be instituted simultaneously.

Electrochemical Detection of Ultratrace (Picomolar) Levels of Hg2+ Using a Silver Nanoparticle-Modified Glassy Carbon Electrode.

Science.gov (United States)

Suherman, Alex L; Ngamchuea, Kamonwad; Tanner, Eden E L; Sokolov, Stanislav V; Holter, Jennifer; Young, Neil P; Compton, Richard G

2017-07-05

Ultratrace levels of Hg 2+ have been quantified by undertaking linear sweep voltammetry with a silver nanoparticle-modified glassy carbon electrode (AgNP-GCE) in aqueous solutions containing Hg 2+ . This is achieved by monitoring the change in the silver stripping peak with Hg 2+ concentration resulting from the galvanic displacement of silver by mercury: Ag(np) + 1/2Hg 2+ (aq) → Ag + (aq) + 1/2Hg(l). This facile and reproducible detection method exhibits an excellent linear dynamic range of 100.0 pM to 10.0 nM Hg 2+ concentration with R 2 = 0.982. The limit of detection (LoD) based on 3σ is 28 pM Hg 2+ , while the lowest detectable level for quantification purposes is 100.0 pM. This method is appropriate for routine environmental monitoring and drinking water quality assessment since the guideline value set by the US Environmental Protection Agency (EPA) for inorganic mercury in drinking water is 0.002 mg L -1 (10 nM).

Determination of zirconium by fluoride ion selective electrode

International Nuclear Information System (INIS)

Mahanty, B.N.; Sonar, V.R.; Gaikwad, R.; Raul, S.; Das, D.K.; Prakash, A.; Afzal, Md.; Panakkal, J.P.

2010-01-01

Full text: Zirconium is used in a wide range of applications including nuclear clad, catalytic converters, surgical appliances, metallurgical furnaces, superconductors, ceramics, lamp filaments, anti corrosive alloys and photographical purposes. Irradiation testing of U-Zr and U-Pu-Zr fuel pins has also demonstrated their feasibility as fuel in liquid metal reactors. Different methods that are employed for the determination of zirconium are spectrophotometry, potentiometry, neutron activation analysis and mass spectrometry. Ion-selective electrode (ISE), selective to zirconium ion has been studied for the direct potentiometric measurements of zirconium ions in various samples. In the present work, an indirect method has been employed for the determination of zirconium in zirconium nitrate sample using fluoride ion selective electrode. This method is based on the addition of known excess amount of fluoride ion to react with the zirconium ion to produce zirconium tetra fluoride at about pH 2-3, followed by determination of residual fluoride ion selective electrode. The residual fluoride ion concentrations were determined from the electrode potential data using calibration plot. Subsequently, zirconium ion concentrations were determined from the concentration of consumed fluoride ions. A precision of about 2% (RSD) with the mean recovery of more than 94% has been achieved for the determination of zirconium at the concentration of 4.40 X 10 -3 moles lit -1

Ambient-Temperature Trap/Release of Arsenic by Dielectric Barrier Discharge and Its Application to Ultratrace Arsenic Determination in Surface Water Followed by Atomic Fluorescence Spectrometry.

Science.gov (United States)

Mao, Xuefei; Qi, Yuehan; Huang, Junwei; Liu, Jixin; Chen, Guoying; Na, Xing; Wang, Min; Qian, Yongzhong

2016-04-05

A novel dielectric barrier discharge reactor (DBDR) was utilized to trap/release arsenic coupled to hydride generation atomic fluorescence spectrometry (HG-AFS). On the DBD principle, the precise and accurate control of trap/release procedures was fulfilled at ambient temperature, and an analytical method was established for ultratrace arsenic in real samples. Moreover, the effects of voltage, oxygen, hydrogen, and water vapor on trapping and releasing arsenic by DBDR were investigated. For trapping, arsenic could be completely trapped in DBDR at 40 mL/min of O2 input mixed with 600 mL/min Ar carrier gas and 9.2 kV discharge potential; prior to release, the Ar carrier gas input should be changed from the upstream gas liquid separator (GLS) to the downstream GLS and kept for 180 s to eliminate possible water vapor interference; for arsenic release, O2 was replaced by 200 mL/min H2 and discharge potential was adjusted to 9.5 kV. Under optimized conditions, arsenic could be detected as low as 1.0 ng/L with an 8-fold enrichment factor; the linearity of calibration reached R(2) > 0.995 in the 0.05 μg/L-5 μg/L range. The mean spiked recoveries for tap, river, lake, and seawater samples were 98% to 103%; and the measured values of the CRMs including GSB-Z50004-200431, GBW08605, and GBW(E)080390 were in good agreement with the certified values. These findings proved the feasibility of DBDR as an arsenic preconcentration tool for atomic spectrometric instrumentation and arsenic recycling in industrial waste gas discharge.

Estimation of ultratrace level of uranium in sea water by laser fluorimeter

International Nuclear Information System (INIS)

Sahoo, S.K.; Tripathi, R.M.; Mohapatra, S.; Patra, A.C.; Lenka, P.; Puranik, V.D.

2010-01-01

Full text: Uranium, a naturally occurring primordial radionuclide, is imperative in the present Indian Nuclear Power Programme. Seawater may be an alternate source of uranium to meet the future demand. The total estimated quantity of uranium in seawater is around four and a half billion tonnes. Estimation of uranium in sea water is cumbersome and tedious because of ultra-trace concentration of uranium with high salt content and other interfering elements of sea water. Mainly chloride interferes in sea water analysis for estimation of nanogram level uranium because the ion at high concentration in sea water depresses uranyl complex fluorescence. At 500 ppm of chloride, the fluorescence response from a given uranium level is reduced by nearly 50%. Dilution method may be used in order to minimize the interference effect but it can't be implemented in this case as sea water contains 19000 ppm chloride but only 2-3 ppb of uranium. Thus, the separation of the interfering elements is necessary to analyze nanogram level of uranium in sea water. In the present study, an attempt has been made to analyze uranium in sea water by laser fluorimeter. Sample was treated with potassium persulphate to remove chloride ion and subsequent measurement was carried out after pH adjustment. The method was used for analysis of uranium content in 23 seawater samples ranged from 0.2 ± 0.1 μg/l to 2.2 ± 0.4 μg/l with a mean value of 1.01 ± 0.11 μg/l

Trace analysis of actinides in the environment using resonance ionization mass spectrometry

International Nuclear Information System (INIS)

Raeder, Sebastian

2011-01-01

In this work the resonant ionization of neutral atoms using laser radiation was applied and optimized for ultra-trace analysis of the actinides thorium, uranium, neptunium and plutonium. The sensitive detection of these actinides is a challange for the monitoring and quantification of radioactive releases from nuclear facilities. Using resonance ionization spectroscopy combined with a newly developed quadrupole-mass-spectrometer, numerous energy levels in the atomic structure of these actinides could be identified. With this knowledge efficient excitation schemes for the mentioned actinides could be identified and characterised. The applied in-source-ionization ensures for a high detection efficiency due to the good overlap of laser radiation with the atomic beam and allows therefore for a low sample consumption which is required for the analysis of radio nuclides. The selective excitation processes in the resonant ionization method supresses unwanted contaminations and was optimized for analytical detection of ultra-trace amounts in environmental samples as well as for determination of isotopic compositions. The efficient in-source-ionization combined with high power pulsed laser radiation allows for detections efficiency up to 1%. For plutonium detection limits in the range of 10 4 -10 5 atoms could be demonstrated for synthetic samples as well as for first environmental samples. The usage of narrow bandwidth continuous wave lasers in combination with a transversal overlap of the laser radiation and the free propagating atomic beam enable for resolving individual isotopic shifts of the resonant transitions. This results in a high selectivity against dominant neighboring isotopes but with a significant loss in detection efficiency. For the ultra-trace isotope 236 U a detection limit down to 10 -9 for the isotope ratio N ( 236 U)/N ( 238 U) could be determined.

Trace analysis of actinides in the environment using resonance ionization mass spectrometry; Spurenanalyse von Aktiniden in der Umwelt mittels Resonanzionisations-Massenspektrometrie

Energy Technology Data Exchange (ETDEWEB)

Raeder, Sebastian

2011-04-12

In this work the resonant ionization of neutral atoms using laser radiation was applied and optimized for ultra-trace analysis of the actinides thorium, uranium, neptunium and plutonium. The sensitive detection of these actinides is a challange for the monitoring and quantification of radioactive releases from nuclear facilities. Using resonance ionization spectroscopy combined with a newly developed quadrupole-mass-spectrometer, numerous energy levels in the atomic structure of these actinides could be identified. With this knowledge efficient excitation schemes for the mentioned actinides could be identified and characterised. The applied in-source-ionization ensures for a high detection efficiency due to the good overlap of laser radiation with the atomic beam and allows therefore for a low sample consumption which is required for the analysis of radio nuclides. The selective excitation processes in the resonant ionization method supresses unwanted contaminations and was optimized for analytical detection of ultra-trace amounts in environmental samples as well as for determination of isotopic compositions. The efficient in-source-ionization combined with high power pulsed laser radiation allows for detections efficiency up to 1%. For plutonium detection limits in the range of 10{sup 4}-10{sup 5} atoms could be demonstrated for synthetic samples as well as for first environmental samples. The usage of narrow bandwidth continuous wave lasers in combination with a transversal overlap of the laser radiation and the free propagating atomic beam enable for resolving individual isotopic shifts of the resonant transitions. This results in a high selectivity against dominant neighboring isotopes but with a significant loss in detection efficiency. For the ultra-trace isotope {sup 236}U a detection limit down to 10{sup -9} for the isotope ratio N ({sup 236}U)/N ({sup 238}U) could be determined.

The Customers’ Determinant Factors of the Bank Selection

Directory of Open Access Journals (Sweden)

Umbas Krisnanto

2011-04-01

Full Text Available Some previous researchers are still arguing about the factors that determine the selection of a bank. These factors depend on the intensity of marketing activities undertaken by the bank, reputation of the bank, credit availability, friendly staffs, appropriate interest rates, and location. Jakarta was selected for the research location since Jakarta is the biggest city in Indonesia that represents the advancement of the banking industry. Different statistics tools are applied to find the accurate opinion why respondent choose a bank. Based on the results, the research concludes factors that determine in selecting a bank tend to be based on the secondary factors such as recommendation from friends, and advice from family members.

The Customers’ Determinant Factors of the Bank Selection

Directory of Open Access Journals (Sweden)

Umbas Krisnanto

2011-04-01

Full Text Available Some previous researchers are still arguing about the factors that determine the selection of a bank. These factors depend on the intensity of marketing activities undertaken by the bank, reputation of the bank, credit availability, friendly staffs, appropriate interest rates, and location. Jakarta was selected for the research location since Jakarta is the biggest city in Indonesia that represents the advancement of the banking industry. Different statistics tools are applied to find the accurate opinion why respondent choose a bank. Based on the results, the research concludes factors that determine in selecting a bank tend to be based on the secondary factors such as recommendation from friends, and advice from family members..

Selective determination of dopamine using quantum-sized gold nanoparticles protected with charge selective ligands

Science.gov (United States)

Kwak, Kyuju; Kumar, S. Senthil; Lee, Dongil

2012-06-01

We report here the selective determination of dopamine (DA) using quantum-sized gold nanoparticles coated with charge selective ligands. Glutathione protected gold nanoparticles (GS-Au25) were synthesized and immobilized into a sol-gel matrix via thiol linkers. The GS-Au25 modified sol-gel electrode was found to show excellent electrocatalytic activity towards the oxidation of DA but no activity towards the oxidation of ascorbic acid. The role of electrostatic charge in the selective electrocatalytic activity of GS-Au25 was verified by voltammetry of redox markers carrying opposite charges. The pH dependent sensitivity for the determination of DA further confirmed the charge screening effect of GS-Au25. Mechanistic investigation revealed that the selectivity is attained by the selective formation of an electrostatic complex between the negatively charged GS-Au25 and DA cation. The GS-Au25 modified sol-gel electrode also showed excellent selectivity for DA in the presence of an interferent, ascorbic acid.We report here the selective determination of dopamine (DA) using quantum-sized gold nanoparticles coated with charge selective ligands. Glutathione protected gold nanoparticles (GS-Au25) were synthesized and immobilized into a sol-gel matrix via thiol linkers. The GS-Au25 modified sol-gel electrode was found to show excellent electrocatalytic activity towards the oxidation of DA but no activity towards the oxidation of ascorbic acid. The role of electrostatic charge in the selective electrocatalytic activity of GS-Au25 was verified by voltammetry of redox markers carrying opposite charges. The pH dependent sensitivity for the determination of DA further confirmed the charge screening effect of GS-Au25. Mechanistic investigation revealed that the selectivity is attained by the selective formation of an electrostatic complex between the negatively charged GS-Au25 and DA cation. The GS-Au25 modified sol-gel electrode also showed excellent selectivity for DA in the

Longevity enhances selection of environmental sex determination.

Science.gov (United States)

Bull, J J; Bulmer, M G

1989-12-01

Environmental sex determination (ESD) is a mechanism in which an individual develops as male or female largely in response to some environmental effect experienced early in life. Its forms range from sex determination by egg incubation temperature in reptiles to sex determination of photoperiod in amphipods. Previous theoretical work as suggested that ESD is favored by natural selection if the fitness consequences of the early environmental experience differ for males and females, so that an individual benefits by being male under some conditions and female under others. A drawback of ESD is that it enables climatic changes to influence the population sex ratio, and such fluctuations select against ESD. This study employed numerical analyses to investigate the balance between these two opposing forces. The negative impact of climatic fluctuations appears to depend greatly on species longevity: substantial between-year fluctuations are of little consequence in selecting against ESD in long-lived species because annual sex ratio fluctuations tend to cancel and thus alter the total population sex ratio only slightly. Thus, if a species is sufficiently long-lived, extreme ESD can be maintained despite only a weak advantage. This result offers one explanation for the failure to demonstrate an advantage for the extreme forms of ESD observed in reptiles.

Determination of 129I/127I isotope ratios in liquid solutions and environmental soil samples by ICP-MS with hexapole collision cell

OpenAIRE

Izmer, A. V.; Boulyga, S. F.; Becker, J. S.

2003-01-01

The determination of I-129 in environmental samples at ultratrace levels is very difficult by ICP-MS due to a high noise caused by Xe impurities in argon plasma gas (interference of Xe-129(+)), possible (IH2+)-I-127 interference and an insufficient abundance ratio sensitivity of the ICP mass spectrometer for I-129/I-127 isotope ratio measurement. A sensitive, powerful and fast analytical technique for iodine isotope ratio measurements in aqueous solutions and contaminated soil samples directl...

Determination of detection limits for a VPD ICPMS method of analysis; Determination des limites de detection d'une methode d'analyse VPD ICPMS

Energy Technology Data Exchange (ETDEWEB)

Badard, M.; Veillerot, M

2007-07-01

This training course report presents the different methods of detection and quantifying of metallic impurities in semiconductors. One of the most precise technique is the collection of metal impurities by vapor phase decomposition (VPD) followed by their analysis by ICPMS (inductively coupled plasma mass spectrometry). The study shows the importance of detection limits in the domain of chemical analysis and the way to determine them for the ICPMS analysis. The results found on detection limits are excellent. Even if the detection limits reached with ICPMS performed after manual or automatic VPD are much higher than detection limits of ICPMS alone, this method remains one of the most sensible for ultra-traces analysis. (J.S.)

Determination of ultra trace arsenic species in water samples by hydride generation atomic absorption spectrometry after cloud point extraction

Energy Technology Data Exchange (ETDEWEB)

Ulusoy, Halil Ibrahim, E-mail: hiulusoy@yahoo.com [University of Cumhuriyet, Faculty of Science, Department of Chemistry, TR-58140, Sivas (Turkey); Akcay, Mehmet; Ulusoy, Songuel; Guerkan, Ramazan [University of Cumhuriyet, Faculty of Science, Department of Chemistry, TR-58140, Sivas (Turkey)

2011-10-10

Graphical abstract: The possible complex formation mechanism for ultra-trace As determination. Highlights: {yields} CPE/HGAAS system for arsenic determination and speciation in real samples has been applied first time until now. {yields} The proposed method has the lowest detection limit when compared with those of similar CPE studies present in literature. {yields} The linear range of the method is highly wide and suitable for its application to real samples. - Abstract: Cloud point extraction (CPE) methodology has successfully been employed for the preconcentration of ultra-trace arsenic species in aqueous samples prior to hydride generation atomic absorption spectrometry (HGAAS). As(III) has formed an ion-pairing complex with Pyronine B in presence of sodium dodecyl sulfate (SDS) at pH 10.0 and extracted into the non-ionic surfactant, polyethylene glycol tert-octylphenyl ether (Triton X-114). After phase separation, the surfactant-rich phase was diluted with 2 mL of 1 M HCl and 0.5 mL of 3.0% (w/v) Antifoam A. Under the optimized conditions, a preconcentration factor of 60 and a detection limit of 0.008 {mu}g L{sup -1} with a correlation coefficient of 0.9918 was obtained with a calibration curve in the range of 0.03-4.00 {mu}g L{sup -1}. The proposed preconcentration procedure was successfully applied to the determination of As(III) ions in certified standard water samples (TMDA-53.3 and NIST 1643e, a low level fortified standard for trace elements) and some real samples including natural drinking water and tap water samples.

Alumina physically loaded by thiosemicarbazide for selective preconcentration of mercury(II) ion from natural water samples

International Nuclear Information System (INIS)

Ahmed, Salwa A.

2008-01-01

The multifunctional ligand, thiosemicarbazide, was physically loaded on neutral alumina. The produced alumina-modified solid phase (SP) extractor named, alumina-modified thiosemicarbazide (AM-TSC), experienced high thermal and medium stability. This new phase was identified based on surface coverage determination by thermal desorption method to be 0.437 ± 0.1 mmol g -1 . The selectivity of AM-TSC phase towards the uptake of different nine metal ions was checked using simple, fast and direct batch equilibration technique. AM-TSC was found to have the highest capacity in selective extraction of Hg(II) from aqueous solutions all over the range of pH used (1.0-7.0), compared to the other eight tested metal ions. So, Hg(II) uptake was 1.82 mmol g -1 (distribution coefficient log K d = 5.658) at pH 1.0 or 2.0 and 1.78, 1.73, 1.48, 1.28 and 1.28 mmol g -1 (log K d = 4.607, 4.265, 3.634, 3.372 and 3.372), at pH 3.0, 4.0, 5.0, 6.0 and 7.0, respectively. On the other hand, the metal ions Ca(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) showed low uptake values in range 0.009-0.720 mmol g -1 (log K d < 3.0) at their optimum pH values. A mechanism was suggested to explain the unique uptake of Hg(II) ions based on their binding as neutral and chloroanionic species predominate at pH values ≤3.0 of a medium rich in chloride ions. Application of the new phase for the preconcentration of ultratrace amounts of Hg(II) ions spiked natural water samples: doubly distilled water (DDW), drinking tap water (DTW) and Nile river water (NRW) using cold vapor atomic absorption spectroscopy (CV-AAS) was studied. The high recovery values obtained using AM-TSC (98.5 ± 0.5, 98.0 ± 0.5 and 103.0 ± 1.0) for DDW, DTW and NRW samples, respectively based on excellent enrichment factor 1000, along with a good precision (R.S.D.% 0.51-0.97%, n 3) demonstrate the accuracy and validity of the new modified alumina sorbent for preconcentrating ultratrace amounts of Hg(II) with no

Determination of detection limits for a VPD ICPMS method of analysis

International Nuclear Information System (INIS)

Badard, M.; Veillerot, M.

2007-01-01

This training course report presents the different methods of detection and quantifying of metallic impurities in semiconductors. One of the most precise technique is the collection of metal impurities by vapor phase decomposition (VPD) followed by their analysis by ICPMS (inductively coupled plasma mass spectrometry). The study shows the importance of detection limits in the domain of chemical analysis and the way to determine them for the ICPMS analysis. The results found on detection limits are excellent. Even if the detection limits reached with ICPMS performed after manual or automatic VPD are much higher than detection limits of ICPMS alone, this method remains one of the most sensible for ultra-traces analysis. (J.S.)

Determination of 236U and transuranium elements in depleted uranium ammunition by α-spectrometry and ICP-MS

International Nuclear Information System (INIS)

Desideri, D.; Meli, M.A.; Roselli, C.; Testa, C.; Boulyga, S.F.; Becker, J.S.

2002-01-01

It is well known that ammunition containing depleted uranium (DU) was used by NATO during the Balkan conflict. To evaluate the origin of DU (the enrichment of natural uranium or the reprocessing of spent nuclear fuel) it is necessary to directly detect the presence of activation products ( 236 U, 239 Pu, 240 Pu, 241 Am, and 237 Np) in the ammunition. In this work the analysis of actinides by α-spectrometry was compared with that by inductively coupled plasma mass spectrometry (ICP-MS) after selective separation of ultratraces of transuranium elements from the uranium matrix. 242 Pu and 243 Am were added to calculate the chemical yield. Plutonium was separated from uranium by extraction chromatography, using tri-n-octylamine (TNOA), with a decontamination factor higher than 10 6 ; after elution plutonium was determined by ICP-MS ( 239 Pu and 240 Pu) and α-spectrometry ( 239+240 Pu) after electroplating. The concentration of Pu in two DU penetrator samples was 7 x 10 -12 g g -1 and 2 x 10 -11 g g -1 . The 240 Pu/ 239 Pu isotope ratio in one penetrator sample (0.12±0.04) was significantly lower than the 240 Pu/ 239 Pu ratios found in two soil samples from Kosovo (0.35±0.10 and 0.27±0.07). 241 Am was separated by extraction chromatography, using di(2-ethylhexyl)phosphoric acid (HDEHP), with a decontamination factor as high as 10 7 . The concentration of 241 Am in the penetrator samples was 2.7 x 10 -14 g g -1 and -15 g g -1 . In addition 237 Np was detected at ultratrace levels. In general, ICP-MS and α-spectrometry results were in good agreement.The presence of anthropogenic radionuclides ( 236 U, 239 Pu, 240 Pu, 241 Am, and 237 Np) in the penetrators indicates that at least part of the uranium originated from the reprocessing of nuclear fuel. Because the concentrations of radionuclides are very low, their radiotoxicological effect is negligible. (orig.)

Determination of (236)U and transuranium elements in depleted uranium ammunition by alpha-spectrometry and ICP-MS.

Science.gov (United States)

Desideri, D; Meli, M A; Roselli, C; Testa, C; Boulyga, S F; Becker, J S

2002-11-01

It is well known that ammunition containing depleted uranium (DU) was used by NATO during the Balkan conflict. To evaluate the origin of DU (the enrichment of natural uranium or the reprocessing of spent nuclear fuel) it is necessary to directly detect the presence of activation products ((236)U, (239)Pu, (240)Pu, (241)Am, and (237)Np) in the ammunition. In this work the analysis of actinides by alpha-spectrometry was compared with that by inductively coupled plasma mass spectrometry (ICP-MS) after selective separation of ultratraces of transuranium elements from the uranium matrix. (242)Pu and (243)Am were added to calculate the chemical yield. Plutonium was separated from uranium by extraction chromatography, using tri- n-octylamine (TNOA), with a decontamination factor higher than 10(6); after elution plutonium was determined by ICP-MS ((239)Pu and (240)Pu) and alpha-spectrometry ((239+240)Pu) after electroplating. The concentration of Pu in two DU penetrator samples was 7 x 10(-12) g g(-1) and 2 x 10(-11) g g(-1). The (240)Pu/(239)Pu isotope ratio in one penetrator sample (0.12+/-0.04) was significantly lower than the (240)Pu/(239)Pu ratios found in two soil samples from Kosovo (0.35+/-0.10 and 0.27+/-0.07). (241)Am was separated by extraction chromatography, using di(2-ethylhexyl)phosphoric acid (HDEHP), with a decontamination factor as high as 10(7). The concentration of (241)Am in the penetrator samples was 2.7 x 10(-14) g g(-1) and <9.4 x 10(-15) g g(-1). In addition (237)Np was detected at ultratrace levels. In general, ICP-MS and alpha-spectrometry results were in good agreement. The presence of anthropogenic radionuclides ((236)U, (239)Pu,(240)Pu, (241)Am, and (237)Np) in the penetrators indicates that at least part of the uranium originated from the reprocessing of nuclear fuel. Because the concentrations of radionuclides are very low, their radiotoxicological effect is negligible.

Selectivity determinants of GPCR-G-protein binding

DEFF Research Database (Denmark)

Flock, Tilman; Hauser, Alexander S; Lund, Nadia

2017-01-01

of the G-protein barcode through distinct residues, like multiple keys (receptors) opening the same lock (G protein) using non-identical cuts. Considering the evolutionary history of GPCRs allows the identification of these selectivity-determining residues. These findings lay the foundation...

Spectrophotometric determination of trace and ultratrace levels of boron in silicon and chlorosilane samples

International Nuclear Information System (INIS)

Chen, J.S.; Lin, H.M.; Yang, M.H.

1991-01-01

Spectrophotometric methods for the determination of boron in the low μg/g and ng/g range in high-purity silicon and dichloro- and trichlorosilanes were investigated in detail. The procedures established involve dissolution of silicon samples and the hydrolyzed products of chlorosilane samples in hydrofluoric acid-containing reagents followed by evaporation of the silicon matrix as H 2 SiF 6 . The boron retained in the treated sample solution was then determined by a spectrophotometric method using carminic acid as a chromatic reagent. Special effort has been paid to the control of the analytical blank and reproducible determination of boron. The results indicate that addition of mannitol and proper control of the evaporation process are effective in preventing volatilization of boron during the evaporation of silicon matrix and can thus attain high recovery of boron and reproducible analysis. Through meticulous control of the analytical blank and experimental conditions, the limit of detection for boron determination with the established method can be as low as ng/g levels. Application of the methods to the determination of boron in various stages of purification of silicon and trichlorosilane as well as in borophosphosilicate film was conducted. (orig.)

Ultratrace determination of tin by hydride generation in-atomizer trapping atomic absorption spectrometry

Energy Technology Data Exchange (ETDEWEB)

Průša, Libor [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Charles University in Prague, Faculty of Science, Department of Analytical Chemistry, Hlavova 8, Prague 2, CZ 128 43 Czech Republic (Czech Republic); Dědina, Jiří [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Kratzer, Jan, E-mail: jkratzer@biomed.cas.cz [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic)

2013-12-04

Graphical abstract: -- Highlights: •In-atomizer trapping HG-AAS was optimized for Sn. •A compact quartz trap-and-atomizer device was employed. •Generation, preconcentration and atomization steps were investigated in detail. •Hundred percent preconcentration efficiency for tin was reached. •Routine analytical method was developed for Sn determination (LOD of 0.03 ng mL{sup −1} Sn). -- Abstract: A quartz multiatomizer with its inlet arm modified to serve as a trap (trap-and-atomizer device) was employed to trap tin hydride and subsequently to volatilize collected analyte species with atomic absorption spectrometric detection. Generation, atomization and preconcentration conditions were optimized and analytical figures of merit of both on-line atomization as well as preconcentration modes were quantified. Preconcentration efficiency of 95 ± 5% was found. The detection limits reached were 0.029 and 0.14 ng mL{sup −1} Sn, respectively, for 120 s preconcentration period and on-line atomization mode without any preconcentration. The interference extent of other hydride forming elements (As, Se, Sb and Bi) on tin determination was found negligible in both modes of operation. The applicability of the developed preconcentration method was verified by Sn determination in a certified reference material as well as by analysis of real samples.

ICP MS selection of radiopure materials for the GERDA experiment

Science.gov (United States)

di Vacri, M. L.; Nisi, S.; Cattadori, C.; Janicsko, J.; Lubashevskiy, A.; Smolnikov, A.; Walter, M.

2015-08-01

The GERDA (GERmanium Detector Array) experiment, located in the Gran Sasso Underground Laboratory (LNGS, Italy) aims to search for neutrinoless double beta (0νββ) decay of the 76Ge isotope. Both an ultra-low radioactivity background environment and active techniques to abate the residual background are required to reach the background index (of 10-3 counts/keV kg y) at the Qββ. In order to veto and suppress those events that partially deposit energy in Ge detectors, the readout of liquid argon (LAr) scintillation light (SL) has been implemented for the second GERDA experimental Phase. A double veto system has been designed and constructed using highly radiopure materials (scintillating fibers, wavelength shifters, polymeric foils, reflective foils). This work describes the study of lead, thorium and uranium ultra-trace content, performed at the LNGS Chemistry Laboratory by High Resolution Mass Spectrometry (HR ICP MS), for the selection of all materials involved in the construction of the veto system

ICP MS selection of radiopure materials for the GERDA experiment

Energy Technology Data Exchange (ETDEWEB)

Di Vacri, M. L., E-mail: divacrim@lngs.infn.it [INFN, Laboratori Nazionali del Gran Sasso, via G.Acitelli 22, 67100 Assergi (Italy); Dipartimento di Scienze Fisiche e Chimiche, University of L’Aquila, via Vetoio, 67100 L’Aquila (Italy); Nisi, S., E-mail: nisi@lngs.infn.it [INFN, Laboratori Nazionali del Gran Sasso, via G.Acitelli 22, 67100 Assergi (AQ) (Italy); Cattadori, C., E-mail: cattadori@lngs.infn.it [INFN Sezione di Milano Bicocca, Milano (Italy); Janicsko, J. [TUM Munich (Germany); Lubashevskiy, A. [MPIK, Heidelberg (Germany); JINR, Dubna (Russian Federation); Smolnikov, A. [MPIK, Heidelberg (Germany); Walter, M. [Physik-Institut, Universitat Zurich, 8057 Zurich (Switzerland)

2015-08-17

The GERDA (GERmanium Detector Array) experiment, located in the Gran Sasso Underground Laboratory (LNGS, Italy) aims to search for neutrinoless double beta (0νββ) decay of the {sup 76}Ge isotope. Both an ultra-low radioactivity background environment and active techniques to abate the residual background are required to reach the background index (of 10{sup −3} counts/keV kg y) at the Q{sub ββ}. In order to veto and suppress those events that partially deposit energy in Ge detectors, the readout of liquid argon (LAr) scintillation light (SL) has been implemented for the second GERDA experimental Phase. A double veto system has been designed and constructed using highly radiopure materials (scintillating fibers, wavelength shifters, polymeric foils, reflective foils). This work describes the study of lead, thorium and uranium ultra-trace content, performed at the LNGS Chemistry Laboratory by High Resolution Mass Spectrometry (HR ICP MS), for the selection of all materials involved in the construction of the veto system.

Determination of cadmium in seawater by chelate vapor generation atomic fluorescence spectrometry

Science.gov (United States)

Sun, Rui; Ma, Guopeng; Duan, Xuchuan; Sun, Jinsheng

2018-03-01

A method for the determination of cadmium in seawater by chelate vapor generation (Che-VG) atomic fluorescence spectrometry is described. Several commercially available chelating agents, including ammonium pyrrolidine dithiocarbamate (APDC), sodium dimethyl dithiocarbamate (DMDTC), ammonium dibutyl dithiophosphate (DBDTP) and sodium O,O-diethyl dithiophosphate (DEDTP), are compared with sodium diethyldithiocarbamate (DDTC) for the Che-VG of cadmium, and results showed that DDTC and DEDTP had very good cadmium signal intensity. The effect of the conditions of Che-VG with DDTC on the intensity of cadmium signal was investigated. Under the optimal conditions, 85 ± 3% Che-VG efficiency is obtained for cadmium. The detection limit (3σ) obtained in the optimal conditions was 0.19 ng ml- 1. The relative standard deviation (RSD, %) for ten replicate determinations at 2 ng ml- 1 Cd was 3.42%. The proposed method was successfully applied to the ultratrace determination of cadmium in seawater samples by the standard addition method.

Determination of ultratrace levels of mercury in three SRMs by combustion RNAA

International Nuclear Information System (INIS)

Norman, B.R.; Becker, D.A.

2000-01-01

A radiochemical neutron activation analysis (RNAA) combustion method coupled with a neutron exposure normalization technique was used to determine low μg/kg mercury levels in three National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs). Two coals (sub-bituminous and bituminous) and a diet material were analyzed. The results obtained provided recommended values of approximately 5 μg/kg for SRM 1548a Typical Diet, 24 μg/kg for SRM 1635 Trace Elements in Coal (sub-bituminous), and 100 μg/kg for SRM 1632b Trace Elements in Coal (bituminous). (author)

Ultra-trace monitoring of copper in environmental and biological samples by inductively coupled plasma atomic emission spectrometry after separation and preconcentration by using octadecyl silica membrane disks modified by a new schiff's base

Directory of Open Access Journals (Sweden)

Mohammad Reza Ganjali

2004-04-01

Full Text Available Ultra-trace amounts of Cu(II were separated and preconcentrated by solid phase extraction on octadecyl-bonded silica membrane disks modified with a new Schiff,s base (Bis- (2-Hydroxyacetophenone -2,2-dimethyl-1,3-propanediimine (SBTD followed by elution and inductively coupled plasma atomic emission spectrometric detection. The method was applied as a separation and detection method for copper(II in environmental and biological samples. Extraction efficiency and the influence of sample matrix, flow rate, pH, and type and minimum amount of stripping acid were investigated. The concentration factor and detection limit of the proposed method are 500 and 12.5 pg mL-1, respectively.

Determination of 210Pb at ultra-trace levels in water by ICP-MS

International Nuclear Information System (INIS)

Lariviere, D.; Reiber, K.M.; Evans, R.D.; Cornett, R.J.

2005-01-01

210 Pb (t 1/2 = 22.26 years) is one of the most difficult naturally occurring radionuclides to analyze directly via radiometric measurement due to its low-energy radioactive decay. In this work, inductively coupled plasma mass spectrometry (ICP-MS) was investigated as a possible alternative to radiometric counting for the determination of 210 Pb. The formation of isobaric and polyatomic (molecular) interferences was studied and various strategies (i.e. co-precipitation, extraction chromatography, and derivatization) were tested to assess their usefulness in reducing these interferences. In addition, the potential of these strategies as pre-concentration methods was demonstrated. A 210 Pb pre-concentration of >300-fold and recoveries of 63-73% were obtained using a combined co-precipitation and extraction chromatography protocol followed by derivatization using an ethylating reagent. The abundance sensitivity at m/z = 210 in the presence of stable Pb was also investigated for three types of mass spectrometers (sector-field (ICP-SFMS), quadrupole-based (ICP-QMS), and quadrupole-based with a dynamic reaction cell (ICP-QMS (DRC))). Finally, the method was applied to determine 210 Pb in water samples and a detection limit of 90 mBq L -1 (10 pg L -1 ) was obtained

Laser-induced fluorescence with an OPO system. Part II: direct determination of lead content in seawater by electrothermal atomization-laser-excited atomic fluorescence (ETA-LEAF).

Science.gov (United States)

Le Bihan, A; Lijour, Y; Giamarchi, P; Burel-Deschamps, L; Stephan, L

2003-03-01

Fluorescence was induced by coupling a laser with an optical parametric oscillator (OPO) to develop an analytical method for the direct determination of lead content, at ultra-trace level, in seawater by electrothermal atomization-laser-excited atomic fluorescence (ETA-LEAF). The optimization of atomization conditions, laser pulse energy, and mainly temporal parameters allowed us to reach a 3 fg detection limit (0.3 ng L(-1)) despite the low repetition rate of the device. The expected error on predicted concentrations of lead, at trace levels, in seawater was below 15%.

Comparison of the samples injection systems with ultrasonic nebulizer and with pneumatic nebulizer for the metal determination in water by inductively coupled plasma optical emission spectrometry

International Nuclear Information System (INIS)

Marin, Sergio R; Pismante, Paola A

2005-01-01

The natural waters, depending on their use, must fulfill the exigencies and requirements that fix national and international norms. These establish conditions with respect to the concentration levels that must be some metals. In this work the development of inductively coupled plasma emission optical spectrometry with ultrasonic injection system is presented. The determination of aluminum, arsenic, barium, cadmium, zinc, cobalt, chromium, copper, iron, manganese, molybdenum, nickel, lead, strontium and vanadium, at levels of ultra-trace in water samples is studied by this technique. The wavelengths that represented better sensitivity and minors spectral interferences, were selected from the Literature specialized in the analysis of this type of material. Also the conditions of work for the ultrasonic nebulization: temperature, pressure, flow speed of argon, and flow speed of sample was determined. The greater sensitivity of the injection system by ultrasonic nebulization forehead to the injection system by pneumatic nebulization, is verified when comparing the spectral intensity of the selected wavelengths. Also the limits of detection and quantification was obtained by both systems. The validity of the results obtained in this method is verified applying the test of Fisher, who determines the degree of homogeneity of the variances, and the test of Student, to determine the trazability obtained with these values. For these studies, the certified material of reference TM-24.2 of National Water Research Institute Environment Canada (NWRI), was used. The positive answer to the criteria of evaluation E and Z-Score, obtained by this technique, allows to verify that it fulfills the exigencies to be used in the determination of metals at the required levels (au)

Determination of lead in red wine for CCQM-K30 international comparison by using ID-ICPMS

International Nuclear Information System (INIS)

Zhou Tao; Wang Jun; Lu Hai; Zhao Motian

2007-01-01

The content of lead in red wine for CCQM-K30 international key comparison is determined by using isotope dilution mass spectrometry (IDMS). This test almost reach detect limit of the method because the content of lead in red wine was only 3 ng/g and the procedure blank was about 0.3 ng. The comparison results indicate that it is easy to achieve agreements using IDMS. In uncertainty analysis, all of the factors about IDMS method were considered. But, procedure blank took great inference to experiment precision and enlarged the total uncertainty. Therefore the controls of procedure blank were very important for the analysis of ultra-trace concentration of samples. (authors)

Lead ultra-trace on-line preconcentration and determination using selective solid phase extraction and electrothermal atomic absorption spectrometry: applications in seawaters and biological samples

Energy Technology Data Exchange (ETDEWEB)

Vereda Alonso, E.; Siles Cordero, M.T.; Garcia de Torres, A.; Cano Pavon, J.M. [University of Malaga, Department of Analytical Chemistry Faculty of Sciences, Malaga (Spain)

2006-08-15

In this work, a new chelating resin [1,5-bis (2-pyridyl)-3-sulphophenyl methylene] thiocarbonohydrazide immobilised on aminopropyl-controlled pore glass (550 Aa; PSTH-cpg) was synthesised and packed in a microcolumn which replaced the sample tip of the autosampler arm. The system was applied to the preconcentration of lead. When microliters of 10% HNO{sub 3}, which acts as elution agent, pass through the microcolumn, the preconcentrated Pb(II) is eluted and directly deposited in a tungsten-rhodium coated graphite tube. With the use of the separation and preconcentration step and the permanent modifiers, the analytical characteristics of the technique were improved. The proposed method has a linear calibration range from 0.012 to 10 ng ml{sup -1} of lead. At a sample frequency of 36 h{sup -1} with a 90 s preconcentration time, the enrichment factor was 20.5, the detection and determination limits were 0.012 and 0.14 ng ml{sup -1}, respectively and the precision, expressed as relative standard deviation, was 3.2% (at 1 ng ml{sup -1}). Results from the determination of Pb in biological certified reference materials were in agreement with the certified values. Seawaters and other biological samples were analysed too. (orig.)

Pu and Am determination in the environment method development

International Nuclear Information System (INIS)

Afonin, M.; Simonoff, M.; Donard, O.; Michel, H.; Ardisson, G.

2002-01-01

A few articles were published in the recent years regarding the application of ICP MS HR to the determination of ultratrace Pu in the environment. Si removal was not applied in recent publications. It is well known from marine biology that some microorganisms use Si derivatives in their metabolism. This implies that important amounts of Pu will not be dissolved and instead will rest in the solid residue. In our work we chose a combination of methods from EML-300 Handbook: Pu-02-RC Plutonium in Soil Samples, Pu-03-RC Plutonium in Soil Residue - Total Dissolution Method, Pu-11-RC Plutonium Purification - Ion Exchange Technique, Pu-12-RC Plutonium and/or Americium in Soil or Sediments. A high resolution inductively coupled plasma mass spectrometric method was developed for the determination of Am and the 240 Pu/ 239 Pu isotope ratio. The total plutonium concentrations ( 239+240 Pu) measured in environmental samples by this method were in good agreement with recommended data obtained from alpha-spectrometry. A reduction in the time of analysis over 33% was achieved

Determination of {sup 236}U and transuranium elements in depleted uranium ammunition by {alpha}-spectrometry and ICP-MS

Energy Technology Data Exchange (ETDEWEB)

Desideri, D.; Meli, M.A.; Roselli, C.; Testa, C. [General Chemistry Institute, Urbino University, Urbino (Italy); Boulyga, S.F.; Becker, J.S. [Central Department of Analytical Chemistry, Research Centre Juelich, Juelich (Germany)

2002-11-01

It is well known that ammunition containing depleted uranium (DU) was used by NATO during the Balkan conflict. To evaluate the origin of DU (the enrichment of natural uranium or the reprocessing of spent nuclear fuel) it is necessary to directly detect the presence of activation products ({sup 236}U, {sup 239}Pu, {sup 240}Pu, {sup 241}Am, and {sup 237}Np) in the ammunition. In this work the analysis of actinides by {alpha}-spectrometry was compared with that by inductively coupled plasma mass spectrometry (ICP-MS) after selective separation of ultratraces of transuranium elements from the uranium matrix. {sup 242}Pu and {sup 243}Am were added to calculate the chemical yield. Plutonium was separated from uranium by extraction chromatography, using tri-n-octylamine (TNOA), with a decontamination factor higher than 10{sup 6}; after elution plutonium was determined by ICP-MS ({sup 239}Pu and {sup 240}Pu) and {alpha}-spectrometry ({sup 239+240}Pu) after electroplating. The concentration of Pu in two DU penetrator samples was 7 x 10{sup -12} g g{sup -1} and 2 x 10{sup -11} g g{sup -1}. The {sup 240}Pu/{sup 239}Pu isotope ratio in one penetrator sample (0.12{+-}0.04) was significantly lower than the {sup 240}Pu/{sup 239}Pu ratios found in two soil samples from Kosovo (0.35{+-}0.10 and 0.27{+-}0.07). {sup 241}Am was separated by extraction chromatography, using di(2-ethylhexyl)phosphoric acid (HDEHP), with a decontamination factor as high as 10{sup 7}. The concentration of {sup 241}Am in the penetrator samples was 2.7 x 10{sup -14} g g{sup -1} and <9.4 x 10{sup -15} g g{sup -1}. In addition {sup 237}Np was detected at ultratrace levels. In general, ICP-MS and {alpha}-spectrometry results were in good agreement.The presence of anthropogenic radionuclides ({sup 236}U, {sup 239}Pu,{sup 240}Pu, {sup 241}Am, and {sup 237}Np) in the penetrators indicates that at least part of the uranium originated from the reprocessing of nuclear fuel. Because the concentrations of

Determination of trace inorganic mercury species in water samples by cloud point extraction and UV-vis spectrophotometry.

Science.gov (United States)

Ulusoy, Halil Ibrahim

2014-01-01

A new micelle-mediated extraction method was developed for preconcentration of ultratrace Hg(II) ions prior to spectrophotometric determination. 2-(2'-Thiazolylazo)-p-cresol (TAC) and Ponpe 7.5 were used as the chelating agent and nonionic surfactant, respectively. Hg(II) ions form a hydrophobic complex with TAC in a micelle medium. The main factors affecting cloud point extraction efficiency, such as pH of the medium, concentrations of TAC and Ponpe 7.5, and equilibration temperature and time, were investigated in detail. An overall preconcentration factor of 33.3 was obtained upon preconcentration of a 50 mL sample. The LOD obtained under the optimal conditions was 0.86 microg/L, and the RSD for five replicate measurements of 100 microg/L Hg(II) was 3.12%. The method was successfully applied to the determination of Hg in environmental water samples.

Separation and selective determination of molybdenum with sodiumthiosulfate and ethylacetate

International Nuclear Information System (INIS)

Hainberger, L.; de Oliveira Andrade, W.

1982-01-01

A sensitive and selective method of spectrophotometric determination of molybdenum is described. Molybdenum is extracted to more than 97%. Lambert-Beer's law is obeyed between 0.35 and 30μg/10ml of the used aqueous solution. 43 ions concerning their interference are studied. The method was used to determine the content of molybdenum in black beans. (Author)

Selective extraction-photometric determination of cadmium by basic dyes

Energy Technology Data Exchange (ETDEWEB)

Kish, P P; Balog, J S [Uzhgorodskij Gosudarstvennyj Univ. (Ukrainian SSR)

1979-12-01

Two variants of selective extraction-photometric determination of cadmium with basic dyes have been developed. In the first one, cadmium is extracted as the iodide by a tributyl phosphate solution in benzene from aqueous solutions containing 0.1 M KI (pH 6-10). Then the cadmium is transformed into a coloured ion associate by treatment of the extracts with Malachite Green in the presence of iodide ions. In the second case, the extract is equilibrated with an equeous solutions of Rhodamine B in the presence of KBr. In this variant, the cadmium is transformed into an anionic iodide-bromide complex which reacts with Rhodamine B cations to form an ion associate. Procedures have been developed of selective extraction-photometric determination of cadmium in sulphur, indium-gallium and zinc concentrates, Zn-As-Cd-Se and Zn-As-Cd-Te films, Cd-S-In and Ga-Sb-Cd-Te alloys.

High-resolution, three-step resonance ionization mass spectrometry of gadolinium

International Nuclear Information System (INIS)

Blaum, K.; Wendt, K.; Bushaw, B.A.; Noertershaeuser, W.

2001-01-01

High-resolution resonance ionization mass spectrometry has been used to measure triple-resonance autoionization (AI) spectra of gadolinium. Al resonances as narrow as 10 MHz have been observed and isotope shifts and hyperfine structure have been measured in selected AI states. The strongest AI state observed at 49663.576 cm-1 with a photoionization cross section of >3.6x10 -15 cm 2 was found to have an overall detection efficiency of >3x10 -5 , allowing application to a number of ultratrace determination problems. Analytical measurements with a diode-laser-based system have been successfully performed on bio-medical tissue samples

Optical wavelength selection for portable hemoglobin determination by near-infrared spectroscopy method

Science.gov (United States)

Tian, Han; Li, Ming; Wang, Yue; Sheng, Dinggao; Liu, Jun; Zhang, Linna

2017-11-01

Hemoglobin concentration is commonly used in clinical medicine to diagnose anemia, identify bleeding, and manage red blood cell transfusions. The golden standard method for determining hemoglobin concentration in blood requires reagent. Spectral methods were advantageous at fast and non-reagent measurement. However, model calibration with full spectrum is time-consuming. Moreover, it is necessary to use a few variables considering size and cost of instrumentation, especially for a portable biomedical instrument. This study presents different wavelength selection methods for optical wavelengths for total hemoglobin concentration determination in whole blood. The results showed that modelling using only two wavelengths combination (1143 nm, 1298 nm) can keep on the fine predictability with full spectrum. It appears that the proper selection of optical wavelengths can be more effective than using the whole spectra for determination hemoglobin in whole blood. We also discussed the influence of water absorptivity on the wavelength selection. This research provides valuable references for designing portable NIR instruments determining hemoglobin concentration, and may provide some experience for noninvasive hemoglobin measurement by NIR methods.

An Analysis of Determinants of Recruitment and Selection Outsourcing Implementation

Directory of Open Access Journals (Sweden)

Jana Cocuľová

2015-01-01

Full Text Available In order for the companies to maintain their positions in the current market, they are forced to find new opportunities and ways to streamline their operations. One of such options for the company is outsourcing, which is the subject of this paper. Given the increasing trend of outsourcing in human resource management, the article deals specifically with the issue of outsourcing of selected human resource (HR activity – the recruitment and selection process (R & S. The main goal of the research study is to establish a set of determinants of the success of implementation of R & S outsourcing. The research was carried out by using a questionnaire survey from February 2013 as the primary data source. Questionnaires were distributed to a sample of organizations operating in Slovakia. In order to achieve the research objective, six hypotheses have been contested by correlation analysis and Mann Whitney U test, while in five cases statistically significant correlation between selected determinants and the perceived success of the outsourcing implementation have been confirmed.

Multiwall carbon nanotube- zirconium oxide nanocomposite hollow fiber solid phase microextraction for determination of polyaromatic hydrocarbons in water, coffee and tea samples.

Science.gov (United States)

Yazdi, Mahnaz Nozohour; Yamini, Yadollah; Asiabi, Hamid

2018-06-15

The purpose of this study was to evaluate the application of hollow fiber solid-phase microextraction (HF-SPME) followed by HPLC-UV to determine the ultra-trace amounts of polycyclic aromatic hydrocarbons (PAHs) as model analytes in complex coffee and tea samples. HF-SPME can be effectively used as an alternative to the direct immersion SPME (DI-SPME) method in complex matrices. The DI-SPME method suffers from serious limitation in dirty and complicated matrices with low sample clean-up, while the HF-SPME method has high clean-up and selectivity due to the high porosity of hollow fiber that can pick out analyte from complicated matrices. As a hollow fiber sorbent, a novel multiwall carbon nanotube/zirconium oxide nanocomposite (MWCNT/ZrO 2 ) was fabricated. The excellent adsorption of PAHs on the sorbent was attributed to the dominant roles of π-π stacking interaction and hydrophobic interaction. Under the optimized extraction conditions, the wide linear range of 0.1-200 μg L -1 with coefficients of determination better than 0.998 and low detection limits of 0.033-0.16 μg L -1 with satisfactory precision (RSD tea samples were in the range of 92.0-106.0%. Compared to other methods, MWCNT/ZrO 2 hollow fiber solid phase microextraction demonstrated a good capability for determination of PAHs in complex coffee and tea samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Determining the productivity of frontal-selective excavation equipment

Energy Technology Data Exchange (ETDEWEB)

Baikenzhin, A E; Ermekov, T E

1979-01-01

The engineering parameters of the VMF-2 frontal-selective excavation machine are given. Calculation formulae are given for determining the feed speed of the working tool relative to the difference in the motion of the arm of the working tool and the feed speed of the hydraulic jack lifter. A methodology is developed for calculating the productivity of the excavator depending on various engineering conditions, accounting for modifications in its design.

A Note on the Determination of "Acceptable" Performance in Thorndike's Standard of Fair Selection.

Science.gov (United States)

Brown, Charles

1980-01-01

The determination of acceptable performance in Thorndike's constant ratio standard of fair selection is considered. It is shown that suitable choice of acceptable performance can make any minority-majority selection disparity consistent with Thorndike's standard. A rule for determining acceptable performance which avoids the Petersen-Novick…

Determinants of Smartphone Selection: An Application of the University Students

Directory of Open Access Journals (Sweden)

Halim TATLI

2015-12-01

Full Text Available In this study, we aimed to identify the factors that impact on smartphone selection of university students. In this context, the data is obtained from a survey which is conducted to students that are studying in Bingöl University. This questionnaire was administered to 400 students in the November-October 2014. Student’s smartphone selection response variable, the logarithm of age, the logarithm of income and logarithm of the scores of the students' perspective on smart phone is taken as an explanatory variable. In the analysis were used logistic regression. The estimated results of logistic regression analysis; logarithm of the scores of the students' perspective on smart phone and the the logarithm of income was be found to increase the likelihood of smartphone selection in a meaningful way. Between the logarithm of age and smartphone selection was not found to be significant relationship. The results of the study, showed that the major determinants of smartphone selection monthly income and students' perspective on smartphones.

Nonmathematical models for evolution of altruism, and for group selection (peck order-territoriality-ant colony-dual-determinant model-tri-determinant model).

Science.gov (United States)

Darlington, P J

1972-02-01

Mathematical biologists have failed to produce a satisfactory general model for evolution of altruism, i.e., of behaviors by which "altruists" benefit other individuals but not themselves; kin selection does not seem to be a sufficient explanation of nonreciprocal altruism. Nonmathematical (but mathematically acceptable) models are now proposed for evolution of negative altruism in dual-determinant and of positive altruism in tri-determinant systems. Peck orders, territorial systems, and an ant society are analyzed as examples. In all models, evolution is primarily by individual selection, probably supplemented by group selection. Group selection is differential extinction of populations. It can act only on populations preformed by selection at the individual level, but can either cancel individual selective trends (effecting evolutionary homeostasis) or supplement them; its supplementary effect is probably increasingly important in the evolution of increasingly organized populations.

Determination of long-lived radionuclides at ultratrace level using advanced mass spectrometric techniques

International Nuclear Information System (INIS)

Zoriy, M.

2005-11-01

Determination of long-lived radionuclides at sub-fg concentration level is a challenging task in analytical chemistry. Inductively coupled plasma mass spectrometry (ICP-MS) with its ability to provide the sensitive and fast multielemental analysis is one of the most suitable method for the measurements of long lived radionuclides in the trace and ultra trace concentration range. In present the Ph.D. study a variety of procedures have been developed permitting the sub fg ml-1 determination of long-lived radionuclides (e.g. U, Th, Pu) as well as 226 Ra (T 1/2 = 1600 y) and 90 Sr (T 1/2 = 28.1 y) in different samples. In order to avoid isobaric interferences, to increase the sensitivity, precision and accuracy of the methods the application of different techniques: pre-concentration of the sample, off-line separation on the crown resin, measurements under cold plasma conditions, using microconcentric nebulizers (e.g DIHEN, DS-5) or the application of LA-ICP-MS for sample introduction have been studied. The limits of detection for different radionuclides was significantly improved in comparison to the ones reported in the literature, and, depending on the method applied, was varied from 10 -15 to 10 -18 g ml -1 concentration range. In addition to the analysis of long lived radionuclides, some other elements, that can present potential interest to the analyzed sample, were measured within the framework of the present study. Laser ablation inductively coupled plasma mass spectrometry (LAICP- MS) was used to produce images of element distribution in 20μm m thin sections of human brain tissue. The sample surface was scanned (raster area ∝80 mm 2 ) with a focused laser beam (wavelength 213 nm, diameter of laser crater 50μm, and laser power density 3x10 9 W cm -2 ) in a cooled laser ablation chamber developed for these measurements. Cross sections of human brain samples - hippocampus as well as brain tissues infected and non-infected with Glioblastoma Multiforme (tumor

Analysis of molybdenum, tungsten, and vanadium in surface water of the Atlantic Ocean using solid phase extraction with 8-hydroxyquinoline and ICP MS determination

Science.gov (United States)

Rimskaya-Korsakova, M. N.; Berezhnaya, E. D.; Dubinin, A. V.

2017-07-01

An analytical technique is proposed to determine ultratrace concentrations of Mo, V, and W found in seawater using mass spectrometry with inductively coupled plasma (ICP MS) after preliminary concentration by solid-phase extraction of metal complexes with 8-hydroxyquinoline (8-HQ) on C18 octadecyl silica. The technique utilizes 150 mL of a water sample. A preconcentration factor 50 is obtained. The detection limits are 0.25 nmol/kg, 0.041 nmol/kg, and 5 pmol/kg for Mo, V, and W, respectively. Dissolved Mo, V, and Wconcentrations in surface seawater from Atlantic Ocean transect were determined. The concentrations ranges along the transect were: 91-108 nmol/kg for Mo, 28-35 nmol/kg for V, and 55-75 pmol/kg for W. The Mo/W ratio varied from 1300 to 1800.

On-line sample-pre-treatment schemes for trace-level determinations of metals by coupling flow injection or sequential injection with ICP-MS

DEFF Research Database (Denmark)

Wang, Jianhua; Hansen, Elo Harald

2003-01-01

a polytetrafluoroethylene (PTFE) knotted reactor (KR), solvent extraction-back extraction and hydride/vapor generation. It also addresses a novel, robust approach, whereby the protocol of SI-LOV-bead injection (BI) on-line separation and pre-concentration of ultra-trace levels of metals by a renewable microcolumn...

Sequential injection-bead injection-lab-on-valve schemes for on-line solid phase extraction and preconcentration of ultra-trace levels of heavy metals with determination by electrothermal atomic absorption spectrometry and inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Wang Jianhua; Hansen, Elo Harald; Miro, Manuel

2003-01-01

This communication presents an overview of the state-of-the-art of the exploitation of sequential injection (SI)-bead injection (BI)-lab-on-valve (LOV) schemes for automatic on-line sample pre-treatments interfaced with ETAAS and ICPMS detection as conducted in the authors' group. The discussions are focused on the applications of SI-BI-LOV protocols for on-line microcolumn based solid phase extraction of ultra-trace levels of heavy metals, employing the so-called renewable surface separation and preconcentration manipulatory scheme. Two types of sorbents have been employed as packing material, that is, the hydrophilic SP Sephadex C-25 cation exchange and iminodiacetate based Muromac A-1 chelating resins, and the hydrophobic poly(tetrafluoroethylene) (PTFE) and poly(styrene-divinylbenzene) copolymer alkylated with octadecyl groups (C 18 -PS/DVB). Using ETAAS as detection device, the easy-to-handle hydrophilic renewable reactors hold the features of improved R.S.D.s and LODs as compared to those operated in the conventional, permanent mode, in addition to the elimination of flow resistance. The hydrophobic columns fall into two categories, that is, the renewable one packed with C 18 -PS/DVB beads entails analogous R.S.D.s and LODs with respect to the conventional approach, while those with PTFE beads result in slightly inferior R.S.D.s and LODs by similar comparison, yet offering a wider dynamic range than when using an external permanent column. Moreover, the hydrophilic materials result in much higher enrichment of the analyte than the hydrophobic ones, although PTFE is the packing material that exhibits the best retention efficiency

Selectivity coefficients of ion-selective magnesium electrodes used for simultaneous determination of magnesium and calcium ions.

Science.gov (United States)

Maj-Zurawska, Magdalena; Lewenstam, Andrzej

2011-12-15

Membrane ion-selective magnesium electrodes are commonly used to determine ionized magnesium concentration in blood serum and intracellular fluid by potentiometric clinical analyzers. The selectivity of these electrodes against calcium ion is typically insufficient to avoid calcium interference in blood serum analysis. For this reason the selectivity coefficient for calcium ion has to be studied to make possible any mathematical corrections for calcium ion influence. Existing methods relate to the thermodynamic concept of ISE response which suggest a single constant value of the selectivity coefficient and slope that are stable over the concentration ranges of calcium and magnesium ions in the samples. Unfortunately, this rarely happens, and we rather observe dependences on solution and membrane composition, readout time, matrices (anticoagulant, vial coats) that justify usage of apparent selectivities and slopes. To get the practical insight into the response of magnesium ion-selective electrodes a novel method for estimating the selectivity coefficients and the slope of the electrode characteristics is proposed. This method is an effective starting point for selecting electrodes and designing transient signal software in a potentiometric clinical analyzer. The method allows obtaining the ionized magnesium concentration in blood serum with minimal possible error by addressing the assessed targets, i.e. apparent selectivity and slope. The method is based on computer simulation and on the Nicolsky-Eisenman equation. Usually only a few iterations are needed to obtain stable congruent results. The method presented is particularly useful in conditions where is not possible to obtain calibration curve, which is typical for clinical analyzer where at most three point calibration is performed. Copyright © 2011 Elsevier B.V. All rights reserved.

Voltammetric determination of copper in selected pharmaceutical preparations--validation of the method.

Science.gov (United States)

Lutka, Anna; Maruszewska, Małgorzata

2011-01-01

It were established and validated the conditions of voltammetric determination of copper in pharmaceutical preparations. The three selected preparations: Zincuprim (A), Wapń, cynk, miedź z wit. C (B), Vigor complete (V) contained different salts and different quantity of copper (II) and increasing number of accompanied ingredients. For the purpose to transfer copper into solution, the samples of powdered tablets of the first and second preparation were undergone extraction and of the third the mineralization procedures. The concentration of copper in solution was determined by differential pulse voltammetry (DP) using comparison with standard technique. In the validation process, the selectivity, accuracy, precision and linearity of DP determination of copper in three preparations were estimated. Copper was determined within the concentration range of 1-9 ppm (1-9 microg/mL): the mean recoveries approached 102% (A), 100% (B), 102% (V); the relative standard deviations of determinations (RSD) were 0.79-1.59% (A), 0.62-0.85% (B) and 1.68-2.28% (V), respectively. The mean recoveries and the RSDs of determination satisfied the requirements for the analyte concentration at the level 1-10 ppm. The statistical verification confirmed that the tested voltammetric method is suitable for determination of copper in pharmaceutical preparation.

Using Confidence Interval-Based Estimation of Relevance to Select Social-Cognitive Determinants for Behavior Change Interventions

Directory of Open Access Journals (Sweden)

Rik Crutzen

2017-07-01

Full Text Available When developing an intervention aimed at behavior change, one of the crucial steps in the development process is to select the most relevant social-cognitive determinants. These determinants can be seen as the buttons one needs to push to establish behavior change. Insight into these determinants is needed to select behavior change methods (i.e., general behavior change techniques that are applied in an intervention in the development process. Therefore, a study on determinants is often conducted as formative research in the intervention development process. Ideally, all relevant determinants identified in such a study are addressed by an intervention. However, when developing a behavior change intervention, there are limits in terms of, for example, resources available for intervention development and the amount of content that participants of an intervention can be exposed to. Hence, it is important to select those determinants that are most relevant to the target behavior as these determinants should be addressed in an intervention. The aim of the current paper is to introduce a novel approach to select the most relevant social-cognitive determinants and use them in intervention development. This approach is based on visualization of confidence intervals for the means and correlation coefficients for all determinants simultaneously. This visualization facilitates comparison, which is necessary when making selections. By means of a case study on the determinants of using a high dose of 3,4-methylenedioxymethamphetamine (commonly known as ecstasy, we illustrate this approach. We provide a freely available tool to facilitate the analyses needed in this approach.

Using Confidence Interval-Based Estimation of Relevance to Select Social-Cognitive Determinants for Behavior Change Interventions.

Science.gov (United States)

Crutzen, Rik; Peters, Gjalt-Jorn Ygram; Noijen, Judith

2017-01-01

When developing an intervention aimed at behavior change, one of the crucial steps in the development process is to select the most relevant social-cognitive determinants. These determinants can be seen as the buttons one needs to push to establish behavior change. Insight into these determinants is needed to select behavior change methods (i.e., general behavior change techniques that are applied in an intervention) in the development process. Therefore, a study on determinants is often conducted as formative research in the intervention development process. Ideally, all relevant determinants identified in such a study are addressed by an intervention. However, when developing a behavior change intervention, there are limits in terms of, for example, resources available for intervention development and the amount of content that participants of an intervention can be exposed to. Hence, it is important to select those determinants that are most relevant to the target behavior as these determinants should be addressed in an intervention. The aim of the current paper is to introduce a novel approach to select the most relevant social-cognitive determinants and use them in intervention development. This approach is based on visualization of confidence intervals for the means and correlation coefficients for all determinants simultaneously. This visualization facilitates comparison, which is necessary when making selections. By means of a case study on the determinants of using a high dose of 3,4-methylenedioxymethamphetamine (commonly known as ecstasy), we illustrate this approach. We provide a freely available tool to facilitate the analyses needed in this approach.

Solar UV-treatment of water samples for stripping-voltammetric determination of trace heavy metals in Awash river, Ethiopia

Directory of Open Access Journals (Sweden)

Gelaneh Woldemichael

2016-03-01

Full Text Available We report about testing a new mobile and sustainable water sample digestion method in a preliminary field trial in Ethiopia. In order to determine heavy metals at the ultra-trace level by stripping voltammetric techniques in water samples from Awash River, we applied our new method of solar UV-assisted sample pretreatment to destroy the relevant interfering dissolved organic matter. The field tests revealed that 24 h of solar UV irradiation were sufficient to achieve the same sample pretreatment results as with classic digestion method based on intense and hard UV. Analytical results of this study suggest that both a hydroelectric power station and agrichemical applications at Koka Lake have increased the levels of the investigated metals zinc, cadmium, lead, copper, cobalt, nickel, and uranium.

Differential pulse anodic stripping voltametry for ultratrace determination of cadmium and lead in Antarctic snow

International Nuclear Information System (INIS)

Scarponi, G.; Barbante, C.; Cescon, P.

1994-01-01

Differential pulse anodic stripping voltametry has sufficient sensitivity to be used for direct determination of heavy metals in Antarctic snow, thus avoiding long and contamination-prone enrichment procedures. A result of particular concern to global change studies can be drawn from these preliminary data: lead concentration in Antarctic snow decreased rapidly during the 1980s from about 10-15 pg/g to 2-4 pg/g in 1991. (authors). 16 refs., 3 figs., 1 tab

Highly selective determination of methylmercury with methylmercury-imprinted polymers

Energy Technology Data Exchange (ETDEWEB)

Liu Yongwen [Department of Chemistry, Shanxi Datong University, Datong 037009 (China)]. E-mail: dtlyw@263.net; Zai Yunhui [School of Chemistry and Chemical Engineering of Lanzhou University, Lanzhou 730000 (China); Chang Xijun [School of Chemistry and Chemical Engineering of Lanzhou University, Lanzhou 730000 (China); Guo Yong [Department of Chemistry, Shanxi Datong University, Datong 037009 (China); Meng Shuangming [Department of Chemistry, Shanxi Datong University, Datong 037009 (China); Feng Feng [Department of Chemistry, Shanxi Datong University, Datong 037009 (China)

2006-08-11

Methylmercury-imprinted and non-imprinted polymers were prepared by formation monomer complex of methylmercury with (4-ethenylphenyl)-4-formate-6-phenyl-2,2'-bipyridine and thermally polymerizing with divinylbenzene (crosslinker) in the presence of 2,2'-azobisisobutyronitrile as initiator and subsequently leached with the acidic thiourea solution (1.0 mol L{sup -1} of thiourea and 4.0 mol L{sup -1} of HCl). In the same way, non-imprinted copolymers were prepared without methylmercury chloride added. The separation and preconcentration characteristics of the polymers for methylmercury were investigated by batch and column procedures. The results demonstrated that the methylmercury-imprinted polymers had higher adsorption capacity (170 {mu}mol g{sup -1} of dry microbeads) and good selectivity for methylmercury compared to non-imprinted polymers. The distribution ratio (D) values of the methylmercury-imprinted polymers increased for methylmercury with respect to both D values of Hg(II), Cu(II), Zn(II), Cd(II) and non-imprinted polymers. The relatively selective factor ({alpha} {sub r}) values of CH{sub 3}Hg{sup +}/Hg(II), CH{sub 3}Hg{sup +}/Cu(II), CH{sub 3}Hg{sup +}/Zn(II), and CH{sub 3}Hg{sup +}/Cd(II) are 24.0, 46.7, 50.7, and 40.2, which are greater than 1. The methylmercury-imprinted polymers can be used at least twenty times with recoveries no less than 95%. Based on the packed columns with methylmercury-imprinted polymers, a highly selective solid-phase extraction (SPE) and preconcentration method for methylmercury was developed. The metal ion imprinted polymer solid-phase extraction (MIIP-SPE) preconcentration procedure showed a linear calibration curve within concentration range from 0.093 to 22 {mu}g L{sup -1}. The detection limit and quantification limit were 0.041 and 0.093 {mu}g L{sup -1} (3{sigma}) for cold vapor atomic absorption spectrometry (CVAAS). The relative standard deviation of the 10 replicate determinations was 3.5% for the

Equipment considerations

International Nuclear Information System (INIS)

Anon.

1992-01-01

Trace or ultratrace analyses require that the HPLC equipment used, including the detector, be optimal for such determinations. HPLC detectors are discussed at length in Chapter 4; discussion here is limited to the rest of the equipment. In general, commercial equipment is adequate for trace analysis; however, as the authors approach ultratrace analysis, it becomes very important to examine the equipment thoroughly and optimize it, where possible. For this reason they will review the equipment commonly used in HPLC and discuss the optimization steps. Detectability in HPLC is influenced by two factors (1): (a) baseline noise or other interferences that lead to errors in assigning the baseline absorbance; (b) peak width. 87 refs

High adsorptive γ-AlOOH(boehmite)@SiO2/Fe3O4 porous magnetic microspheres for detection of toxic metal ions in drinking water.

Science.gov (United States)

Wei, Yan; Yang, Ran; Zhang, Yong-Xing; Wang, Lun; Liu, Jin-Huai; Huang, Xing-Jiu

2011-10-21

γ-AlOOH(boehmite)@SiO(2)/Fe(3)O(4) porous magnetic microspheres with high adsorption capacity toward heavy metal ions were found to be useful for the simultaneous and selective electrochemical detection of five metal ions, such as ultratrace zinc(II), cadmium(II), lead(II), copper(II), and mercury(II), in drinking water.

A new ultrasonic-assisted cloud-point-extraction procedure for pre-concentration and determination of ultra-trace levels of copper in selected beverages and foods by flame atomic absorption spectrometry.

Science.gov (United States)

Altunay, Nail; Gürkan, Ramazan; Orhan, Ulaş

2015-01-01

A new ultrasonic-assisted cloud-point-extraction (UA-CPE) method was developed for the pre-concentration of Cu(II) in selected beverage and food samples prior to flame atomic absorption spectrometric (FAAS) analysis. For this purpose, Safranin T was used as an ion-pairing reagent based on charge transfer in the presence of oxalate as the primary chelating agent at pH 10. Non-ionic surfactant, poly(ethyleneglycol-mono-p-nonylphenylether) (PONPE 7.5) was used as an extracting agent in the presence of NH4Cl as the salting out agent. The variables affecting UA-CPE efficiency were optimised in detail. The linear range for Cu(II) at pH 10 was 0.02-70 µg l(-)(1) with a very low detection limit of 6.10 ng l(-)(1), while the linear range for Cu(I) at pH 8.5 was 0.08-125 µg l(-)(1) with a detection limit of 24.4 ng l(-)(1). The relative standard deviation (RSD %) was in the range of 2.15-4.80% (n = 5). The method was successfully applied to the quantification of Cu(II), Cu(I) and total Cu in selected beverage and food samples. The accuracy of the developed method was demonstrated by the analysis of two standard reference materials (SRMs) as well as recoveries of spiked samples.

Potentiometric determination of sulfate with EDTA and the cupric-selective electrode

International Nuclear Information System (INIS)

Baumann, E.W.

1976-11-01

Sulfate was indirectly determined by precipitating sulfate as BaSO 4 and then dissolving BaSO 4 in excess ammoniacal EDTA. The excess EDTA was titrated potentiometrically with La 3+ . A cupric-selective electrode was used to detect the end point. About 10 -3 M SO 4 2- was determined in 3M HCl solutions of metal oxides with a relative standard deviation of 3.5 percent and a bias of +4 percent

Determinants of Individual Academic Achievement - Group Selectivity Effects Have Many Dimensions

NARCIS (Netherlands)

Zwick, Th.

2013-01-01

This paper measures determinants of individual academic achievements. In addition to an extensive list of individual characteristics, skills obtained during study and socio-economic background factors, many dimensions of selectivity into academic study subjects are shown to drive individual academic

Ultra-sensitive speciation analysis of mercury by CE-ICP-MS together with field-amplified sample stacking injection and dispersive solid-phase extraction.

Science.gov (United States)

Chen, YiQuan; Cheng, Xian; Mo, Fan; Huang, LiMei; Wu, Zujian; Wu, Yongning; Xu, LiangJun; Fu, FengFu

2016-04-01

A simple dispersive solid-phase extraction (DSPE) used to extract and preconcentrate ultra-trace MeHg, EtHg and Hg(2+) from water sample, and a sensitive method for the simultaneous analysis of MeHg, EtHg and Hg(2+) by using capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) with field-amplified sample stacking injection (FASI) were first reported in this study. The DSPE used thiol cotton particles as adsorbent, and is simple and effective. It can be used to extract and preconcentrate ultra-trace mercury compounds in water samples within 30 min with a satisfied recovery and no mercury species alteration during the process. The FASI enhanced the sensitivity of CE-ICP-MS with 25-fold, 29-fold and 27-fold for MeHg, EtHg and Hg(2+) , respectively. Using FASI-CE-ICP-MS together with DSPE, we have successfully determined ultra-trace MeHg, EtHg and Hg(2+) in tap water with a limits of quantification (LOQs) of 0.26-0.45 pg/mL, an RSD (n = 3) mercury. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of Selected Amino Acids in Serum of Patients with Liver Disease.

Science.gov (United States)

Kanďár, Roman; Drábková, Petra; Toiflová, Tereza; Čegan, Alexander

2016-01-01

The determination of amino acids can be a reliable approach for extended diagnosis of liver diseases. This is because liver disease can be a cause of impaired amino acid metabolism. Therefore, a method for the determination of serum amino acids, applicable for clinical purposes, is necessary. The aim of this study was to find differences in the levels of selected amino acids between patients with liver disease and a control group. Samples of peripheral venous blood were obtained from a group of patients with liver disease (n = 131, 59 women at an average age of 60 years and 72 men at an average age of 52 years) and a control group (n = 105, 47 women at an average age of 62 years and 58 men at an average age of 58 years). Before the separation, the amino acids were derivatized with naphthalene-2,3-dicarboxaldehyde. For the separation, reverse phase column was used. The effluent was monitored with a fluorescence detector. There were significant differences in the concentrations of some amino acids between the patients and the control group, but also between women and men. Correlations between some amino acids and markers of liver blood tests and lipid metabolism were observed. A simple, relatively rapid and selective HPLC method with fluorescence detection for the determination of selected amino acids in serum has been developed.

Determination of extractable fluoride in contaminated soils with ion-selective electrode

OpenAIRE

Mirlean, Nicolai; Baraj, Besnik; Garcia, Marina Reback Domingues; Niencheski, Luis Felipe Hax; Baisch, Paulo Roberto Martins; Casartelli, Maria Regina de Oliveira; Robinson, Daniel

2003-01-01

In a factorial design study involving the determination of F- by ion-selective electrodes, a significant interference was demonstrated for Fe, with an even more pronounced interference for Al. The fluoride leaching procedure from polluted soil showed more reliable results using 0.5 M citric acid

Column preconcentration and electrothermal atomic absorption spectrometric determination of rhodium in some food and standard samples.

Science.gov (United States)

Taher, Mohammad Ali; Pourmohammad, Fatemeh; Fazelirad, Hamid

2015-12-01

In the present work, an electrothermal atomic absorption spectrometric method has been developed for the determination of ultra-trace amounts of rhodium after adsorption of its 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol/tetraphenylborate ion associated complex at the surface of alumina. Several factors affecting the extraction efficiency such as the pH, type of eluent, sample and eluent flow rates, sorption capacity of alumina and sample volume were investigated and optimized. The relative standard deviation for eight measurements of 0.1 ng/mL of rhodium was ±6.3%. In this method, the detection limit was 0.003 ng/mL in the original solution. The sorption capacity of alumina and the linear range for Rh(III) were evaluated as 0.8 mg/g and 0.015-0.45 ng/mL in the original solution, respectively. The proposed method was successfully applied for the extraction and determination of rhodium content in some food and standard samples with high recovery values. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Killer whale prey - Determining prey selection by southern resident killer whales (SRKW)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Prey selectivity by southern resident killer whales is being determined by analyses of fish scales and tissue from predation events and feces. Information on killer...

Sex ratio selection and multi-factorial sex determination in the housefly : A dynamic model

NARCIS (Netherlands)

Kozielska, M.A.; Pen, I.R.; Beukeboom, L.W.; Weissing, F.J.

Sex determining (SD) mechanisms are highly variable between different taxonomic groups and appear to change relatively quickly during evolution. Sex ratio selection could be a dominant force causing such changes. We investigate theoretically the effect of sex ratio selection on the dynamics of a

Method for routine determination of fluoride in urine by selective ion- electrode

International Nuclear Information System (INIS)

Pires, M.A.F.; Bellintani, S.A.

1985-01-01

A simple, fast and sensitive method is outlined for determining fluoride in urine of workers who handle fluoride compounds. The determination is based on the measurement of fluoride by ion selective electrode. Cationic interferents like Ca ++ , Mg ++ , Fe +++ and Al +++ are complexed by EDTA and citric acid. Common anions present in urine, such as Cl - , PO --- 4 and SO -- 4 do not interfere in the method. (Author) [pt

Determination of selenium in roasted beans coffee samples consumed in Algeria by radiochemical neutron activation analysis method

International Nuclear Information System (INIS)

Messaoudi, Mohammed; Begaa, Samir; Hamidatou, Lylia; Salhi, M'hamed

2018-01-01

The essential trace element selenium is a focus of attention due to its effects on human health, there being consequences of both its deficiency and excess. Due to the ultra-trace content of selenium, the neutron activation analysis method (NAA) is difficult to apply. We therefore made use of the radiochemical neutron activation analysis (RNAA) to determine Se at low level concentrations in several consumed food items in Algeria. A radiochemical procedure based on liquid-liquid separation was established in our laboratory. In this research we focused on the determination of selenium in two species of coffee: Arabica and Robusta. The accuracy of the method was assessed by analyzing the certified reference material NIST-SRM 1573a (tomato leaves). The results obtained show a selenium variation from 0.025 to 0.052 μg/g in coffee beans and an average yield of the separation of about 85%. The results of this study were compared with those obtained with samples from Brazilian, Caribbean, Indian and Kenyan coffee beans.

Trace and ultratrace analysis methods for the determination of phosphorus by flow-injection techniques.

Science.gov (United States)

Motomizu, Shoji; Li, Zhen-Hai

2005-04-15

Trace (phosphorus determination by flow-injection analysis are reviewed. Most of the methods cited in this review are fundamentally based on the reaction of orthophosphate with molybdate to form heteropoly acids, such as molybdenum yellow and molybdenum blue, and some of the methods are based on the formation of such secondary reactions as ion associates and their aggregates with bulky cations, such as cationic dyes and quaternary ammonium ions. The heteropoly acids themselves can be measured by spectrophotometry, and the ion associate formed with a cationic dye, Malachite Green (MG), can be measured based on the coloration of MG. Light scattering detection methods can be used for measuring the aggregates of ion associates formed with bulky cations. Highly sensitive detection of phosphorus can be accomplished by fluorophotometry; Rhodamine B (RB) and its analogues react with molybdophosphate to form ion associates, which shows fluorescence quenching of RB: LOD is about 5 nM. The detection method based on the chemiluminescence of luminal oxidized with molybdophosphoric acids is probably the most sensitive of all the detection methods reported so far: LOD of the method is as low as 1nM. The LOD of the molybdenum blue method can be improved by using a liquid core waveguide: LOD is 0.5 nM.

Highly selective coulometric method and equipment for the automated determination of plutonium

International Nuclear Information System (INIS)

Jackson, D.D.; Hollen, R.M.; Roensch, F.R.; Rein, J.E.

1977-01-01

A highly selective, controlled-potential coulometric method has been developed for the determination of plutonium. An automated instrument, consisting of commercial electronic components under control of a programmable calculator, is being constructed. Half-cell potentials and interfering anions are listed

Evolution of the complementary sex-determination gene of honey bees: balancing selection and trans-species polymorphisms.

Science.gov (United States)

Cho, Soochin; Huang, Zachary Y; Green, Daniel R; Smith, Deborah R; Zhang, Jianzhi

2006-11-01

The mechanism of sex determination varies substantively among evolutionary lineages. One important mode of genetic sex determination is haplodiploidy, which is used by approximately 20% of all animal species, including >200,000 species of the entire insect order Hymenoptera. In the honey bee Apis mellifera, a hymenopteran model organism, females are heterozygous at the csd (complementary sex determination) locus, whereas males are hemizygous (from unfertilized eggs). Fertilized homozygotes develop into sterile males that are eaten before maturity. Because homozygotes have zero fitness and because common alleles are more likely than rare ones to form homozygotes, csd should be subject to strong overdominant selection and negative frequency-dependent selection. Under these selective forces, together known as balancing selection, csd is expected to exhibit a high degree of intraspecific polymorphism, with long-lived alleles that may be even older than the species. Here we sequence the csd genes as well as randomly selected neutral genomic regions from individuals of three closely related species, A. mellifera, Apis cerana, and Apis dorsata. The polymorphic level is approximately seven times higher in csd than in the neutral regions. Gene genealogies reveal trans-species polymorphisms at csd but not at any neutral regions. Consistent with the prediction of rare-allele advantage, nonsynonymous mutations are found to be positively selected in csd only in early stages after their appearances. Surprisingly, three different hypervariable repetitive regions in csd are present in the three species, suggesting variable mechanisms underlying allelic specificities. Our results provide a definitive demonstration of balancing selection acting at the honey bee csd gene, offer insights into the molecular determinants of csd allelic specificities, and help avoid homozygosity in bee breeding.

Determination of Selected Perfluorinated Alkyl Acids in ...

Science.gov (United States)

The 1996 amendments to the Safe Drinking Water Act (SDWA) required EPA to establish a Contaminant Candidate List (CCL), that contains a list of drinking water contaminants that the Agency will consider for future regulation. EPA must make a regulatory determination on a minimum of five contaminants every five years. The first CCL was published in 1998, and updates were anticipated every five years thereafter. One of the key pieces of information that must be available in order to make a regulatory determination is nationwide occurrence data for the chemical contaminants under consideration. Historically, EPA has collected the necessary occurrence data under its Unregulated Contaminant Monitoring Regulations (UCMR). Under the UCMR, monitoring is conducted at selected drinking water utilities for specific contaminants of interest. The chemical analyses are usually performed by the utilities or by commercial laboratories. To meet the requirements of monitoring under the UCMR program, the analytical methods developed should be specific, sensitive, and practical enough for application in commercial laboratories. This task will focus on the development of analytical methods for chemicals identified on future CCLs or emerging contaminants not yet listed on the CCL. These methods will be used for the collection of occurrence data under future UCMRs. The objective of this research effort is to develop analytical methods to be used to measure the occurrence of

Selective electrochemical determination of homocysteine in the presence of cysteine and glutathione

International Nuclear Information System (INIS)

Salehzadeh, Hamid; Mokhtari, Banafsheh; Nematollahi, Davood

2014-01-01

Graphical abstract: 3,5-Di-tert-buthylcatechol was used for the selective electrochemical determination of homocysteine in the presence of cysteine and glutathione at the glassy carbon and carbon nanotube modified glassy carbon electrode. - Highlights: • Selective electrochemical determination of homocysteine. • Catalytic electron transfer of 3,5-di-tert-buthylcatechol in the presence of homocysteine. • Michael type addition reaction of electrochemically generated 3,5-di-tert-buthyl-o-benzoquinone with glutathione. - Abstract: The electrochemical oxidation of 3,5-di-tert-buthylcatechol in the presence of homocysteine was used for the selective electrochemical determination of homocysteine in the presence of cysteine and glutathione at a glassy carbon and a glassy carbon electrode modified with carbon nanotube. The results revealed that the electrochemically generated 3,5-di-tert-butylcyclohexa-3,5-diene-1,2-dione exhibits high catalytic activity toward homocysteine oxidation at reduced over-potential and low catalytic activity for oxidation of cysteine. The catalytic activity 3,5-di-tert-butylcyclohexa-3,5-diene-1,2-dione toward cysteine was suppressed in the presence of 4-N,N-dimethylaminocinnamaldehyde. Contrary to homocysteine and cysteine, the reaction of glutathione with 3,5-di-tert-butylcyclohexa-3,5-diene-1,2-dione is a substituation reaction. This method exhibits three dynamic linear ranges of 2.5 to 10 μmol L −1 , 10 to 100 μmol L −1 and 100 to 1000 μmol L −1 , and a lower detection limit (3σ) of 0.89 ± 3.53% μmol L −1 for homocysteine

A purple giraffe is faster than a purple elephant: Inconsistent phonology affects determiner selection in English

NARCIS (Netherlands)

Spalek, K.; Bock, K.; Schriefers, H.J.

2010-01-01

The form of a determiner is dependent on different contextual factors: in some languages grammatical number and grammatical gender determine the choice of a determiner variant. In other languages, the phonological onset of the element immediately following the determiner affects selection, too.

Experimental design of membrane sensor for selective determination of phenazopyridine hydrochloride based on computational calculations

International Nuclear Information System (INIS)

Attia, Khalid A.M.; El-Abasawi, Nasr M.; Abdel-Azim, Ahmed H.

2016-01-01

Computational study has been done electronically and geometrically to select the most suitable ionophore to design a novel sensitive and selective electrochemical sensor for phenazopyridine hydrochloride (PAP). This study has revealed that sodium tetraphenylbarate (NaTPB) fits better with PAP than potassium tetrakis (KTClPB). The sensor design is based on the ion pair of PAP with NaTPB using dioctyl phthalate as a plasticizer. Under optimum conditions, the proposed sensor shows the slope of 59.5 mV per concentration decade in the concentration range of 1.0 × 10 −2 –1.0 × 10 −5 M with detection limit 8.5 × 10 −6 M. The sensor exhibits a very good selectivity for PAP with respect to a large number of interfering species as inorganic cations and sugars. The sensor enables track of determining PAP in the presence of its oxidative degradation product 2, 3, 6-Triaminopyridine, which is also its toxic metabolite. The proposed sensor has been successfully applied for the selective determination of PAP in pharmaceutical formulation. Also, the obtained results have been statistically compared to a reported electrochemical method indicating no significant difference between the investigated method and the reported one with respect to accuracy and precision. - Highlights: • Novel use of ISE for selective determination of phenazopyridine hydrochloride. • Investigating the degradation pathway of phenazopyridine with enough confirmation scan. • To avoid time-consuming and experimental trials, computational studies have been applied. • The proposed sensor shows high selectivity, reasonable detection limit and fast response.

Experimental design of membrane sensor for selective determination of phenazopyridine hydrochloride based on computational calculations

Energy Technology Data Exchange (ETDEWEB)

Attia, Khalid A.M.; El-Abasawi, Nasr M.; Abdel-Azim, Ahmed H., E-mail: Ahmed.hussienabdelazim@hotmil.com

2016-04-01

Computational study has been done electronically and geometrically to select the most suitable ionophore to design a novel sensitive and selective electrochemical sensor for phenazopyridine hydrochloride (PAP). This study has revealed that sodium tetraphenylbarate (NaTPB) fits better with PAP than potassium tetrakis (KTClPB). The sensor design is based on the ion pair of PAP with NaTPB using dioctyl phthalate as a plasticizer. Under optimum conditions, the proposed sensor shows the slope of 59.5 mV per concentration decade in the concentration range of 1.0 × 10{sup −2}–1.0 × 10{sup −5} M with detection limit 8.5 × 10{sup −6} M. The sensor exhibits a very good selectivity for PAP with respect to a large number of interfering species as inorganic cations and sugars. The sensor enables track of determining PAP in the presence of its oxidative degradation product 2, 3, 6-Triaminopyridine, which is also its toxic metabolite. The proposed sensor has been successfully applied for the selective determination of PAP in pharmaceutical formulation. Also, the obtained results have been statistically compared to a reported electrochemical method indicating no significant difference between the investigated method and the reported one with respect to accuracy and precision. - Highlights: • Novel use of ISE for selective determination of phenazopyridine hydrochloride. • Investigating the degradation pathway of phenazopyridine with enough confirmation scan. • To avoid time-consuming and experimental trials, computational studies have been applied. • The proposed sensor shows high selectivity, reasonable detection limit and fast response.

Studies on the matched potential method for determining the selectivity coefficients of ion-selective electrodes based on neutral ionophores: experimental and theoretical verification.

Science.gov (United States)

Tohda, K; Dragoe, D; Shibata, M; Umezawa, Y

2001-06-01

A theory is presented that describes the matched potential method (MPM) for the determination of the potentiometric selectivity coefficients (KA,Bpot) of ion-selective electrodes for two ions with any charge. This MPM theory is based on electrical diffuse layers on both the membrane and the aqueous side of the interface, and is therefore independent of the Nicolsky-Eisenman equation. Instead, the Poisson equation is used and a Boltzmann distribution is assumed with respect to all charged species, including primary, interfering and background electrolyte ions located at the diffuse double layers. In this model, the MPM-selectivity coefficients of ions with equal charge (ZA = ZB) are expressed as the ratio of the concentrations of the primary and interfering ions in aqueous solutions at which the same amounts of the primary and interfering ions permselectively extracted into the membrane surface. For ions with unequal charge (ZA not equal to ZB), the selectivity coefficients are expressed as a function not only of the amounts of the primary and interfering ions permeated into the membrane surface, but also of the primary ion concentration in the initial reference solution and the delta EMF value. Using the measured complexation stability constants and single ion distribution coefficients for the relevant systems, the corresponding MPM selectivity coefficients can be calculated from the developed MPM theory. It was found that this MPM theory is capable of accurately and precisely predicting the MPM selectivity coefficients for a series of ion-selective electrodes (ISEs) with representative ionophore systems, which are generally in complete agreement with independently determined MPM selectivity values from the potentiometric measurements. These results also conclude that the assumption for the Boltzmann distribution was in fact valid in the theory. The recent critical papers on MPM have pointed out that because the MPM selectivity coefficients are highly concentration

Layer-by-Layer-Assembled AuNPs-Decorated First-Generation Poly(amidoamine) Dendrimer with Reduced Graphene Oxide Core as Highly Sensitive Biosensing Platform with Controllable 3D Nanoarchitecture for Rapid Voltammetric Analysis of Ultratrace DNA Hybridization.

Science.gov (United States)

Jayakumar, Kumarasamy; Camarada, María Belén; Dharuman, Venkataraman; Rajesh, Rajendiran; Venkatesan, Rengarajan; Ju, Huangxian; Maniraj, Mahalingam; Rai, Abhishek; Barman, Sudipta Roy; Wen, Yangping

2018-06-12

The structure and electrochemical properties of layer-by-layer-assembled gold nanoparticles (AuNPs)-decorated first-generation (G1) poly(amidoamine) dendrimer (PD) with reduced graphene oxide (rGO) core as a highly sensitive and label-free biosensing platform with a controllable three-dimensional (3D) nanoarchitecture for the rapid voltammetric analysis of DNA hybridization at ultratrace levels were characterized. Mercaptopropinoic acid (MPA) was self-assembled onto Au substrate, then GG1PD formed by the covalent functionalization between the amino terminals of G1PD and carboxyl terminals of rGO was covalently linked onto MPA, and finally AuNPs were decorated onto GG1PD by strong physicochemical interaction between AuNPs and -OH of rGO in GG1PD, which was characterized through different techniques and confirmed by computational calculation. This 3D controllable thin-film electrode was optimized and evaluated using [Fe(CN) 6 ] 3-/4- as the redox probe and employed to covalently immobilize thiol-functionalized single-stranded DNA as biorecognition element to form the DNA nanobiosensor, which achieved fast, ultrasensitive, and high-selective differential pulse voltammetric analysis of DNA hybridization in a linear range from 1 × 10 -6 to 1 × 10 -13 g m -1 with a low detection limit of 9.07 × 10 -14 g m -1 . This work will open a new pathway for the controllable 3D nanoarchitecture of the layer-by-layer-assembled metal nanoparticles-functionalized lower-generation PD with two-dimensional layered nanomaterials as cores that can be employed as ultrasensitive and label-free nanobiodevices for the fast diagnosis of specific genome diseases in the field of biomedicine.

Gas chromatographic determination of polycyclic aromatic hydrocarbons in water and smoked rice samples after solid-phase microextraction using multiwalled carbon nanotube loaded hollow fiber.

Science.gov (United States)

Matin, Amir Abbas; Biparva, Pourya; Gheshlaghi, Mohammad

2014-12-29

A novel solid-phase microextraction fiber was prepared based on multiwalled carbon nanotubes (MWCNTs) loaded on hollow fiber membrane pores. Stainless steel wire was used as unbreakable support. The major advantages of the proposed fiber are its (a) high reproducibility due to the uniform structure of the hollow fiber membranes, (b) high extraction capacity related to the porous structure of the hollow fiber and outstanding adsorptive characteristics of MWCNTs. The proposed fiber was applied for the microextraction of five representative polycyclic aromatic hydrocarbons (PAHs) from aqueous media (river and hubble-bubble water) and smoked rice samples followed by gas chromatographic determination. Analytical merits of the method, including high correlation coefficients [(0.9963-0.9992) and (0.9982-0.9999)] and low detection limits [(9.0-13.0ngL(-1)) and (40.0-150.0ngkg(-1))] for water and rice samples, respectively, made the proposed method suitable for the ultra-trace determination of PAHs. Copyright © 2014 Elsevier B.V. All rights reserved.

Method for fluoride routine determination in urine of personnel exposed, by ion selective electrode

International Nuclear Information System (INIS)

Pires, M.A.F.; Bellintani, S.A.

1986-01-01

A simple, fast and sensible method is outlined for the determination of fluoride in urine of workers that handle fluorine compounds. The determination is based on the measurement of fluoride by ion selective electrode. Cationic interference like Ca ++ , Mg ++ , Fe +++ and Al +++ are complexed by EDTA and citric acid. (Author) [pt

Separation Techniques for Uranium and Plutonium at Trace Levels for the Thermal Ionization Mass Spectrometric Determination

International Nuclear Information System (INIS)

Suh, M. Y.; Han, S. H.; Kim, J. G.; Park, Y. J.; Kim, W. H.

2005-12-01

This report describes the state of the art and the progress of the chemical separation and purification techniques required for the thermal ionization mass spectrometric determination of uranium and plutonium in environmental samples at trace or ultratrace levels. Various techniques, such as precipitation, solvent extraction, extraction chromatography, and ion exchange chromatography, for separation of uranium and plutonium were evaluated. Sample preparation methods and dissolution techniques for environmental samples were also discussed. Especially, both extraction chromatographic and anion exchange chromatographic procedures for uranium and plutonium in environmental samples, such as soil, sediment, plant, seawater, urine, and bone ash were reviewed in detail in order to propose some suitable methods for the separation and purification of uranium and plutonium from the safeguards environmental or swipe samples. A survey of the IAEA strengthened safeguards system, the clean room facility of IAEA's NWAL(Network of Analytical Laboratories), and the analytical techniques for safeguards environmental samples was also discussed here

Separation Techniques for Uranium and Plutonium at Trace Levels for the Thermal Ionization Mass Spectrometric Determination

Energy Technology Data Exchange (ETDEWEB)

Suh, M. Y.; Han, S. H.; Kim, J. G.; Park, Y. J.; Kim, W. H

2005-12-15

This report describes the state of the art and the progress of the chemical separation and purification techniques required for the thermal ionization mass spectrometric determination of uranium and plutonium in environmental samples at trace or ultratrace levels. Various techniques, such as precipitation, solvent extraction, extraction chromatography, and ion exchange chromatography, for separation of uranium and plutonium were evaluated. Sample preparation methods and dissolution techniques for environmental samples were also discussed. Especially, both extraction chromatographic and anion exchange chromatographic procedures for uranium and plutonium in environmental samples, such as soil, sediment, plant, seawater, urine, and bone ash were reviewed in detail in order to propose some suitable methods for the separation and purification of uranium and plutonium from the safeguards environmental or swipe samples. A survey of the IAEA strengthened safeguards system, the clean room facility of IAEA's NWAL(Network of Analytical Laboratories), and the analytical techniques for safeguards environmental samples was also discussed here.

A general definition of the heritable variation that determines the potential of a population to respond to selection.

Science.gov (United States)

Bijma, Piter

2011-12-01

Genetic selection is a major force shaping life on earth. In classical genetic theory, response to selection is the product of the strength of selection and the additive genetic variance in a trait. The additive genetic variance reflects a population's intrinsic potential to respond to selection. The ordinary additive genetic variance, however, ignores the social organization of life. With social interactions among individuals, individual trait values may depend on genes in others, a phenomenon known as indirect genetic effects. Models accounting for indirect genetic effects, however, lack a general definition of heritable variation. Here I propose a general definition of the heritable variation that determines the potential of a population to respond to selection. This generalizes the concept of heritable variance to any inheritance model and level of organization. The result shows that heritable variance determining potential response to selection is the variance among individuals in the heritable quantity that determines the population mean trait value, rather than the usual additive genetic component of phenotypic variance. It follows, therefore, that heritable variance may exceed phenotypic variance among individuals, which is impossible in classical theory. This work also provides a measure of the utilization of heritable variation for response to selection and integrates two well-known models of maternal genetic effects. The result shows that relatedness between the focal individual and the individuals affecting its fitness is a key determinant of the utilization of heritable variance for response to selection.

A Purple Giraffe Is Faster than a Purple Elephant: Inconsistent Phonology Affects Determiner Selection in English

Science.gov (United States)

Spalek, Katharina; Bock, Kathryn; Schriefers, Herbert

2010-01-01

The form of a determiner is dependent on different contextual factors: in some languages grammatical number and grammatical gender determine the choice of a determiner variant. In other languages, the phonological onset of the element immediately following the determiner affects selection, too. Previous work has shown that the activation of…

Flame atomic absorption spectrometric determination of trace quantities of cadmium in water samples after cloud point extraction in Triton X-114 without added chelating agents

International Nuclear Information System (INIS)

Afkhami, Abbas; Madrakian, Tayyebeh; Siampour, Hajar

2006-01-01

A new micell-mediated phase separation method for preconcentration of ultra-trace quantities of cadmium as a prior step to its determination by flame atomic absorption spectrometry has been developed. The method is based on the cloud point extraction (CPE) of cadmium in iodide media with Triton X-114 in the absence of any chelating agent. The optimal extraction and reaction conditions (e.g., acid concentration, iodide concentration, effect of time) were studied, and the analytical characteristics of the method (e.g., limit of detection, linear range, preconcentration, and improvement factors) were obtained. Linearity was obeyed in the range of 3-300 ng mL -1 of cadmium. The detection limit of the method is 1.0 ng mL -1 of cadmium. The interference effect of some anions and cations was also tested. The method was applied to the determination of cadmium in tap water, waste water, and sea water samples

Sodium dithionite as a selective demasking agent for the complexometric determination of thallium

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PRAKASH SHETTY

2005-11-01

Full Text Available Sodium dithionite is proposed as a new demasking agent for the rapid and selective complexometric determination of thallium(III. In the presence of diverse metal ions, thallium (III was first complexed with excess EDTA and the surplus EDTAwas then titrated with a standard zinc sulphate solution at pH 5–6 (hexamine buffer using Xylenol Orange as the indicator. The EDTAequivalent to thallium was then released selectively with sodium dithionite and back titrated with a standard zinc sulphate solution as before. Reproducible and accurate results were obtained in the range 4–100 mg of thallium with a relative error of ±27 % and a coefficient of variation (n = 6 of not more than 0.30 %. The effects of various diverse ions were studied. The method was applied to the determination of thallium in its complexes and in alloys.

Rapid determination of 99Tc in environmental samples by high resolution ICP-MS coupled with on-line flow injection system

International Nuclear Information System (INIS)

Kim, C.K.; Kim, C.S.; Rho, B.H.; Lee, J.I.

2002-01-01

High resolution inductively coupled plasma mass spectrometry coupled with an on-line flow injection system (FI-HR-ICP-MS) was applied to determine the ultra-trace level 99 Tc in soil. The flow injection system (PrepLab TM ) was composed of two TEVA-Spec R resins, reduced remarkably the sample amounts and the analysis time, compared to the conventional analytical methods. In the flow injection system, Mo and Ru were sufficiently eliminated by using the flow injection system, with the decontamination factors of 1.6 x 10 4 and 9.9 x 10 5 , respectively. With the present method, it was possible to determine ultra-low level of 99 Tc in 3∼6 soil at 3-5 hours of analysis time per sample. The relative standard deviation for each sample was less than 4%. The detection limits for 99 Tc was 85 fg x ml -1 (0.05 mBq x ml -1 ), which was calculated from the three times standard deviation of the count rate of the blank. (author)

Sensitive and selective magnetoimmunosensing platform for determination of the food allergen Ara h 1

International Nuclear Information System (INIS)

Montiel, V. Ruiz-Valdepeñas; Campuzano, S.; Pellicanò, A.; Torrente-Rodríguez, R.M.; Reviejo, A.J.; Cosio, M.S.; Pingarrón, J.M.

2015-01-01

Highlights: • First amperometric magnetoimmunosensor for Ara h 1 determination. • Sensitive and selective detection of Ara h 1 in 2 h. • LOD of 6.3 ng mL −1 . • Determinations in food extracts and saliva. • Potential applicability in food safety and consumer protection. - Abstract: A highly sensitive disposable amperometric immunosensor based on the use of magnetic beads (MBs) is described for determination of Ara h 1, the major peanut allergen, in only 2 h. The approach uses a sandwich configuration involving selective capture and biotinylated detector antibodies and carboxylic acid-modified MBs (HOOC-MBs). The MBs bearing the immunoconjugates are captured by a magnet placed under the surface of a disposable screen-printed carbon electrode (SPCE) and the affinity reactions are monitored amperometrically at −0.20 V (vs a Ag pseudo-reference electrode) in the presence of hydroquinone (HQ) as electron transfer mediator and upon addition of H 2 O 2 as the enzyme substrate. The developed immunosensor exhibits a wide range of linearity between 20.8 and 1000.0 ng mL −1 Ara h 1, a detection limit of 6.3 ng mL −1 , a great selectivity, a good reproducibility with a RSD of 6.3% for six different immunosensors and a useful lifetime of 25 days. The usefulness of the immunosensor was demonstrated by determining Ara h 1 in different matrices (food extracts and saliva). The results correlated properly with those provided by a commercial ELISA method offering a reliable and promising analytical screening tool in the development of user-friendly devices for on-site determination of Ara h 1

Sensitive and selective magnetoimmunosensing platform for determination of the food allergen Ara h 1

Energy Technology Data Exchange (ETDEWEB)

Montiel, V. Ruiz-Valdepeñas, E-mail: victor_lega90@hotmail.com [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Campuzano, S., E-mail: susanacr@quim.ucm.es [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Pellicanò, A., E-mail: alessandro.pellicano@unimi.it [Department of Food, Environmental and Nutritional Sciences (DEFENS), University of Milan, Via Celoria 2, 20133 Milan (Italy); Torrente-Rodríguez, R.M., E-mail: rebeca.magnolia@gmail.com [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Reviejo, A.J., E-mail: reviejo@quim.ucm.es [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Cosio, M.S., E-mail: stella.cosio@unimi.it [Department of Food, Environmental and Nutritional Sciences (DEFENS), University of Milan, Via Celoria 2, 20133 Milan (Italy); Pingarrón, J.M., E-mail: pingarro@quim.ucm.es [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

2015-06-23

Highlights: • First amperometric magnetoimmunosensor for Ara h 1 determination. • Sensitive and selective detection of Ara h 1 in 2 h. • LOD of 6.3 ng mL{sup −1}. • Determinations in food extracts and saliva. • Potential applicability in food safety and consumer protection. - Abstract: A highly sensitive disposable amperometric immunosensor based on the use of magnetic beads (MBs) is described for determination of Ara h 1, the major peanut allergen, in only 2 h. The approach uses a sandwich configuration involving selective capture and biotinylated detector antibodies and carboxylic acid-modified MBs (HOOC-MBs). The MBs bearing the immunoconjugates are captured by a magnet placed under the surface of a disposable screen-printed carbon electrode (SPCE) and the affinity reactions are monitored amperometrically at −0.20 V (vs a Ag pseudo-reference electrode) in the presence of hydroquinone (HQ) as electron transfer mediator and upon addition of H{sub 2}O{sub 2} as the enzyme substrate. The developed immunosensor exhibits a wide range of linearity between 20.8 and 1000.0 ng mL{sup −1} Ara h 1, a detection limit of 6.3 ng mL{sup −1}, a great selectivity, a good reproducibility with a RSD of 6.3% for six different immunosensors and a useful lifetime of 25 days. The usefulness of the immunosensor was demonstrated by determining Ara h 1 in different matrices (food extracts and saliva). The results correlated properly with those provided by a commercial ELISA method offering a reliable and promising analytical screening tool in the development of user-friendly devices for on-site determination of Ara h 1.

Selective methods for polyphenols and sulphur dioxide determination in wines.

Science.gov (United States)

García-Guzmán, Juan J; Hernández-Artiga, María P; Palacios-Ponce de León, Lourdes; Bellido-Milla, Dolores

2015-09-01

A critical review to the methods recommended by international bodies and widely used in the winery industry and research studies was performed. A Laccase biosensor was applied to the selective determination of polyphenols in wines. The biosensor response was characterised and it responds mainly to o-diphenols which are the principal polyphenols responsible for the stability and sensory qualities of wines. The spectrophotometric method to determine free and total sulphur dioxide recommended for beers was applied directly to wines. A sampling of 14 red and white wines was performed and they were analysed for biosensor polyphenol index (IBP) and sulphur dioxide concentration (SO2). The antioxidant capacity by the ABTS(+) spectrophotometric method was also determined. A correlation study was performed to elucidate the influence of the polyphenols and SO2 on the wines stability. High correlations were found between IBP and antioxidant capacity and low correlation between SO2 and antioxidant capacity. To evaluate the benefits of wine drinking a new parameter (IBP/SO2) is proposed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Liquid chromatography-tandem mass spectrometry and passive sampling: powerful tools for the determination of emerging pollutants in water for human consumption.

Science.gov (United States)

Mirasole, Cristiana; Di Carro, Marina; Tanwar, Shivani; Magi, Emanuele

2016-09-01

Among the wide range of emerging pollutants, perfluorinated compounds and various pharmaceuticals, such as nonsteroidal anti-inflammatory drugs, are showing growing concern. These contaminants can be found in freshwater ecosystems because of their incomplete removal during wastewater treatments so, their water solubility and poor degradability result in their continuous discharge and pseudo-persistent contamination. Usually, expected levels of these analytes are particularly low; therefore, sensitive and selective analytical techniques are required for their determination. Moreover, sampling and preconcentration are fundamental steps to reach the low detection limits required. The polar organic chemical integrative sampler (POCIS) represents a modern sampling approach that allows the in-situ preconcentration of ultra-trace pollutants. In this work, a fast liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method was developed for the determination of diclofenac, ketoprofen, mefenamic acid, naproxen, ibuprofen, perfluorooctanoic acid, perfluorooctanesulfonate and caffeine in water for human consumption. The chromatographic separation of analytes was achieved in less than 6 min. Quantitative analysis was performed in multiple reaction monitoring mode using ketoprofen-d3 as internal standard. Two different sites of Northern Italy were studied deploying POCIS for four weeks in both inlet and outlet of two drinking water treatment plants. The evaluation of time-weighted average concentration of contaminants was accomplished after the calibration of POCIS; to this aim, the sampling rate values for each compound were obtained by means of a simple calibration system developed in our laboratory. Ketoprofen, perfluorooctane sulfonate, perfluorooctanoate and caffeine were measured in both sites at the ng l(-1) level. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Algorithm for selection of optimized EPR distance restraints for de novo protein structure determination

Science.gov (United States)

Kazmier, Kelli; Alexander, Nathan S.; Meiler, Jens; Mchaourab, Hassane S.

2010-01-01

A hybrid protein structure determination approach combining sparse Electron Paramagnetic Resonance (EPR) distance restraints and Rosetta de novo protein folding has been previously demonstrated to yield high quality models (Alexander et al., 2008). However, widespread application of this methodology to proteins of unknown structures is hindered by the lack of a general strategy to place spin label pairs in the primary sequence. In this work, we report the development of an algorithm that optimally selects spin labeling positions for the purpose of distance measurements by EPR. For the α-helical subdomain of T4 lysozyme (T4L), simulated restraints that maximize sequence separation between the two spin labels while simultaneously ensuring pairwise connectivity of secondary structure elements yielded vastly improved models by Rosetta folding. 50% of all these models have the correct fold compared to only 21% and 8% correctly folded models when randomly placed restraints or no restraints are used, respectively. Moreover, the improvements in model quality require a limited number of optimized restraints, the number of which is determined by the pairwise connectivities of T4L α-helices. The predicted improvement in Rosetta model quality was verified by experimental determination of distances between spin labels pairs selected by the algorithm. Overall, our results reinforce the rationale for the combined use of sparse EPR distance restraints and de novo folding. By alleviating the experimental bottleneck associated with restraint selection, this algorithm sets the stage for extending computational structure determination to larger, traditionally elusive protein topologies of critical structural and biochemical importance. PMID:21074624

Determination of 90Sr and Pu isotopes in contaminated groundwater samples by inductively coupled plasma mass spectrometry

Science.gov (United States)

Zoriy, Miroslav V.; Ostapczuk, Peter; Halicz, Ludwik; Hille, Ralf; Becker, J. Sabine

2005-04-01

A sensitive analytical method for determining the artificial radionuclides 90Sr, 239Pu and 240Pu at the ultratrace level in groundwater samples from the Semipalatinsk Test Site area in Kazakhstan by double-focusing sector field inductively coupled plasma mass spectrometry (ICP-SFMS) was developed. In order to avoid possible isobaric interferences at m/z 90 for 90Sr determination (e.g. 90Zr+, 40Ar50Cr+, 36Ar54Fe+, 58Ni16O2+, 180Hf2+, etc.), the measurements were performed at medium mass resolution under cold plasma conditions. Pu was separated from uranium by means of extraction chromatography using Eichrom TEVA resin with a recovery of 83%. The limits of detection for 90Sr, 239Pu and 240Pu in water samples were determined as 11, 0.12 and 0.1 fg ml-1, respectively. Concentrations of 90Sr and 239Pu in contaminated groundwater samples ranged from 18 to 32 and from 28 to 856 fg ml-1, respectively. The 240Pu/239Pu isotopic ratio in groundwater samples was measured as 0.17. This isotope ratio indicates that the most probable source of contamination of the investigated groundwater samples was the nuclear weapons tests at the Semipalatinsk Test Site conducted by the USSR in the 1960s.

Rapid determination method of radiocesium in sea water by cesium-selective resin

International Nuclear Information System (INIS)

Nakaoka, A.; Yokoyama, H.; Fukushima, M.; Takagi, S.

1980-01-01

A rapid and precise method of determining radiocesium corresponding to 5 mrem/y (the Japan AEC's guideline) was proposed. The development and practical performance of cesium-selective resin and the determination method are described in this paper. The resin was prepared by the formation of ammonium molybdophosphate in the structure of Amberlite XAD-7 resin. It took only 3 hours to carry out all the procedures the authors proposed. This value represents 1/10 to 1/2 of the time of the conventional method. The concentration of 137 Cs and 134 Cs in sea water was determined to be 0.13 to 0.16 pCi/l and less than 7.1x10 -2 pCi/l, respectively. (author)

Determination of ultratrace concentrations of uranium and thorium in natural waters by x-ray fluorescence

International Nuclear Information System (INIS)

Stewart, J.H. Jr.; Brooksbank, R.D.

1981-01-01

An x-ray fluorescence method for the simultaneous determination of uranium and thorium at the less than 1 ppM level in natural waters is described. Uranium and thorium are coprecipitated with an internal standard, yttrium, and incorporated into an iron-aluminum hydroxide carrier. The hydroxide precipitate is filtered, and the filter disk is analyzed by the energy-dispersive x-ray fluorescence technique. Matrix interferences caused by the presence of unpredictable anions and cations are compensated for by the internal standard. The U/Y and Th/Y ratios are linear over the 5- to 100-μg range of interest, and the detection limit of each element on the filter disk is 2 μg (3 sigma). Relative standard deviation was 17% at the 15-μg and 4% at the 100-μg level for thorium and 11% at the 11-μg and 2% at the 100-μg level for uranium. Analysis of spiked solutions showed a recovery of 19.6 +- 0.3 μg for uranium and 19.8 +- 0.3 μg for thorium at the 20-μg level, and the normal lower reporting limit is 5 μg. Fifty disks can be routinely measured during a normal working day

Uranium Age Determination by Measuring the 230Th / 234U Ratio

International Nuclear Information System (INIS)

LAMONT, STEPHEN P.

2004-01-01

A radiochemical isotope dilution mass spectrometry method has been developed to determine the age of uranium materials. The amount of 230Th activity, the first progeny of 234U, that had grown into a small uranium metal sample was used to determine the elapsed time since the material was last radiochemically purified. To preserve the sample, only a small amount of oxidized uranium was removed from the surface of the sample and dissolved. Aliquots of the dissolved sample were spiked with 233U tracer and radiochemically purified by anion-exchange chromatography. The 234U isotopic concentration was then determined by thermal ionization mass spectrometry. Additional aliquots of the sample were spiked with 229Th tracer, and the thorium was purified using two sequential anion-exchange chromatography separations. The isotopic concentrations of 230Th and 232Th were determined by TIMS. The lack of any 232Th confirmed the assumption that all thorium was removed from the uranium sample at the time of purification. The 230Th and 234U mass concentrations were converted to activities and the 230Th/234U ratio for the sample was calculated. The experimental 230Th/234U ratio showed the uranium in this sample was radiochemically purified in about 1945. Isotope dilution thermal ionization mass spectrometry has sufficient sensitivity to determine the age of 100 samples of uranium. This method could certainly be employed as a nuclear forensic method to determine the age of small quantities of uranium metal or salts. Accurate determination of the ultra-trace 230Th radiochemically separated from the uranium is possible due to the use of 229Th as an isotope dilution tracer. The precision in the experimental age of the uranium could be improved by making additional replicate measurements of the 230Th/234U isotopic ratio or using a larger initial sample

Hemi-ordered nanoporous carbon electrode material for highly selective determination of nitrite in physiological and environmental systems

Energy Technology Data Exchange (ETDEWEB)

Zhou, Shenghai; Wu, Hongmin; Wu, Ying; Shi, Hongyan; Feng, Xun; Jiang, Shang; Chen, Jian; Song, Wenbo, E-mail: wbsong@jlu.edu.cn

2014-08-01

Hemi-ordered nanoporous carbon (HONC) was obtained from a mesoporous silica template through a nano-replication method using furfuryl alcohol as the carbon source. The structure and morphology of HONC were characterized and analyzed in detail by X-ray diffraction, N{sub 2}-sorption, Raman spectroscopy and transmission electron microscopy. HONC was then demonstrated as active electrode material for selective determination of nitrite in either physiological or environmental system. Well separated oxidation peaks of ascorbic acid, dopamine, uric acid and nitrite were observed in physiological system, and simultaneous discrimination of catechol, hydroquinone, resorcinol and nitrite in environmental system was also accomplished. Distinctly improved performances for selective determination of nitrite (such as significantly fast and sensitive current response with especially high selectivity) coexisted with ascorbic acid, dopamine and uric acid in the physiological system, as well as with catechol, hydroquinone and resorcinol in the environmental system were achieved at HONC electrode material. The excellent discriminating ability and high selectivity for NO{sub 2}{sup −} determination were ascribed to the good electronic conductivity, unique hemi-ordered porous structure, large surface area and large number of edge plane defect sites contained on the surface of nanopore walls of HONC. Results in this work demonstrated that HONC is one of the promising catalytic electrode materials for nitrite sensor fabrication. - Highlights: • Hemi-ordered nanoporous carbon as an active electrode material • Good discriminating ability towards NO{sub 2}{sup −} from physiological or environmental system • Highly selective determination of nitrite with fast and sensitive current response.

Retroviral DNA integration: viral and cellular determinants of target-site selection.

Directory of Open Access Journals (Sweden)

Mary K Lewinski

2006-06-01

Full Text Available Retroviruses differ in their preferences for sites for viral DNA integration in the chromosomes of infected cells. Human immunodeficiency virus (HIV integrates preferentially within active transcription units, whereas murine leukemia virus (MLV integrates preferentially near transcription start sites and CpG islands. We investigated the viral determinants of integration-site selection using HIV chimeras with MLV genes substituted for their HIV counterparts. We found that transferring the MLV integrase (IN coding region into HIV (to make HIVmIN caused the hybrid to integrate with a specificity close to that of MLV. Addition of MLV gag (to make HIVmGagmIN further increased the similarity of target-site selection to that of MLV. A chimeric virus with MLV Gag only (HIVmGag displayed targeting preferences different from that of both HIV and MLV, further implicating Gag proteins in targeting as well as IN. We also report a genome-wide analysis indicating that MLV, but not HIV, favors integration near DNase I-hypersensitive sites (i.e., +/- 1 kb, and that HIVmIN and HIVmGagmIN also favored integration near these features. These findings reveal that IN is the principal viral determinant of integration specificity; they also reveal a new role for Gag-derived proteins, and strengthen models for integration targeting based on tethering of viral IN proteins to host proteins.

Element availability of bivalve with symbiotic zooxanthellae in coral sea area as studied by multielement profiling analysis

Science.gov (United States)

Itoh, A.; Kabe, N.

2008-12-01

In coral sea, a characteristic ecosystem is formed by many kinds of marine animals and plants, although seawater is uneutrophic. This may be explained by the fact that various chemical species with bioessentiality are effectively taken and used by lower animals and plants in coral sea area. A symbiotic relationship often found among different animals and plants in this area is considered to be working as one of such processes. However, the specific bioavailability of the elements for the marine animals and plants in coral reef area has not been studied from the viewpoints of trace and ultratrace elements. It is found by the present authors that bivalve with symbiotic zooxanthellae (Tridacna crocea) living on coral reef had relatively higher bio- accumulation factors for many bio-essential elements than other kinds of bivalves, although they live in the uneutrophic sea area. The present authors focused on Tridacna crocea as one of the symbiotic animals. Thus, in the present study, at first, multielement determination of major-to-ultratrace elements (about 20 elements) in each organ of Tridacna crocea with symbiotic zooxanthellae, were carried out by ICP-AES, ICP- MS, and CHN coder. At Second, the specific bioavailability of trace and ultratrace elements in Tridacna crocea was discussed on the multielement data for seawater, seaweeds, and other bivalves in coral sea area.

Determination of uranyl ion by potentiometric titration using an uranyl-selective electrode

International Nuclear Information System (INIS)

Nassory, N.S.

1990-01-01

A potentiometric titration of uranyl ion is described using an uranyl selective electrode based on a membrane containing a complex of UO 2 -bis[di-4-(1,1,3,3-tetramethylbutyl)phenyl phosphate] as an ion-exchanger and tritolyl phosphate as a solvent mediator. The titrations were carried out with various titrants: Sodium hydroxide, potassium fluoride and sodium salts of acetate, oxalate and citrate. The equivalence points were determined by Gran's method. Good results were obtained by using sodium oxalate as a titrant for the determination of uranium in several samples of ammonium diuranate. The results were quite comparable with those obtained by X-ray fluorescence spectrometry. (orig.)

P ersonal Attributes as Determinants of Sport Participation among Undergraduates in Selected Nigerian Universities

Directory of Open Access Journals (Sweden)

Yomi AWOSIKA

2014-03-01

Full Text Available This study focuses on personal attributes of undergraduates as determinants of sport participation in selected Nigerian universities which include age, gender and marital status. The instrument for the study is a self - developed, validated questionnaire. The subjects of the study are undergraduates in selected Nigerian universities. Analysis is the use of percentages and inferential statistics of chi square X 2 at 0.05 level of significance. The results derived from the study reveal that students’ personal attributes significantly determine their sport participation. Among other recommendations made is that it is highly imperative for university authorities to make frantic efforts to develop modalities capable of enco uraging students’ sport participation since most of them have sport potentials as evident in their post - primary school sport records. This will enable our universities groom healthy and academically sound graduates.

Determination of lithium in organic matrix by potentiometric titration using fluoride ion selective electrode

International Nuclear Information System (INIS)

Govindan, R.; Alamelu, D.; Shah, Raju; Aggarwal, S.K.

2008-01-01

A method has been developed for the determination of lithium (Li) present in organic matrix containing hexa methylene tetramine (HMTA) and urea used in the sol-gel process for preparing lithium titanate microspheres, using fluoride ion selective electrode and potentiometric end point. Lithium is present in the wash solutions of the Sol-Gel process employed for the preparation of lithium titanate microspheres, proposed to be used in TBM (Test Blanket Module) of International Thermonuclear Experimental Reactor (ITER) project. Methods such as ICP-AES, AAS etc. used in aqueous solutions cannot be employed directly for lithium determination in organic matrix containing hexa methylene tetramine (HMTA), urea, NH 4 NO 3 , NH 4 Cl etc. A potentiometric method using a combination fluoride ion selective electrode for end point detection was developed and has been employed for lithium determination in the process streams from sol-gel process. The method is simple and rapid and an accuracy of about 0.5 % was achieved for the determination of Li in the range of 1 to 20 mg. The method is based on the complexation of Li by adding a known excess of NH 4 F solution, followed by potentiometric end point detection using fluoride ISE

Heavy atom enhanced room-temperature phosphorimetry for ultratrace determination of harmane

OpenAIRE

Flávia F. de Carvalho Marques; Flávia da Silva Figueiredo; Ricardo Queiroz Aucelio

2008-01-01

Harmane has been proposed for the treatment of epilepsy, AIDS and leshmaniosis. Its room-temperature phosphorescence was induced using either AgNO3 or TlNO3, enabling absolute limits of detection of 0.12 and 2.4 ng respectively, with linear dynamic ranges extending up to 456 ng (AgNO3) and 911 ng (TlNO3). Relative standard deviations around 3% were observed for substrates containing 46 ng of harmane. Such sensitivity and precision are needed because harmane intake must be strictly controlled ...

Heavy atom enhanced room-temperature phosphorimetry for ultratrace determination of harmane

Directory of Open Access Journals (Sweden)

Flávia F. de Carvalho Marques

2008-01-01

Full Text Available Harmane has been proposed for the treatment of epilepsy, AIDS and leshmaniosis. Its room-temperature phosphorescence was induced using either AgNO3 or TlNO3, enabling absolute limits of detection of 0.12 and 2.4 ng respectively, with linear dynamic ranges extending up to 456 ng (AgNO3 and 911 ng (TlNO3. Relative standard deviations around 3% were observed for substrates containing 46 ng of harmane. Such sensitivity and precision are needed because harmane intake must be strictly controlled to achieve proper therapeutic response. Interference studies were performed using thalidomide, reserpine and yohimbine. Recovery of 104±6% was achieved using solid surface room-temperature phosphorimetry. The result was comparable to the one obtained by micellar electrokinetic chromatography.

Selective modes determine evolutionary rates, gene compactness and expression patterns in Brassica.

Science.gov (United States)

Guo, Yue; Liu, Jing; Zhang, Jiefu; Liu, Shengyi; Du, Jianchang

2017-07-01

It has been well documented that most nuclear protein-coding genes in organisms can be classified into two categories: positively selected genes (PSGs) and negatively selected genes (NSGs). The characteristics and evolutionary fates of different types of genes, however, have been poorly understood. In this study, the rates of nonsynonymous substitution (K a ) and the rates of synonymous substitution (K s ) were investigated by comparing the orthologs between the two sequenced Brassica species, Brassica rapa and Brassica oleracea, and the evolutionary rates, gene structures, expression patterns, and codon bias were compared between PSGs and NSGs. The resulting data show that PSGs have higher protein evolutionary rates, lower synonymous substitution rates, shorter gene length, fewer exons, higher functional specificity, lower expression level, higher tissue-specific expression and stronger codon bias than NSGs. Although the quantities and values are different, the relative features of PSGs and NSGs have been largely verified in the model species Arabidopsis. These data suggest that PSGs and NSGs differ not only under selective pressure (K a /K s ), but also in their evolutionary, structural and functional properties, indicating that selective modes may serve as a determinant factor for measuring evolutionary rates, gene compactness and expression patterns in Brassica. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Ultrasensitive determination of mercury in human saliva by atomic fluorescence spectrometry based on solidified floating organic drop microextraction

International Nuclear Information System (INIS)

Yuan, C.-G.; Wang, J.; Jin, Y.

2012-01-01

We report on a new, rapid and simple method for the determination of ultra-trace quantities of mercury ion in human saliva. It is based on solidified floating organic drop microextraction and detection by cold vapor atomic fluorescence spectrometry (CV-AFS). Mercury ion was complexed with diethyldithiocarbamate, and the hydrophobic complex was then extracted into fine droplets of 1-undecanol. By cooling in an ice bath after extraction, the droplets in solution solidify to form a single ball floating on the surface of solution. The solidified micro drop containing the mercury complex was then transferred for determination by CV-AFS. The effects of pH value, concentration of chelating reagent, quantity of 1-undecanol, sample volume, equilibration temperature and time were investigated. Under the optimum conditions, the preconcentration of a 25-mL sample is accomplished with an enrichment factor of 182. The limit of detection is 2.5 ng L -1 . The relative standard deviation for seven replicate determinations at 0.1 ng mL -1 level is 4.1%. The method was applied to the determination of mercury in saliva samples collected from four volunteers. Two volunteers having dental amalgam fillings had 0.4 ng mL -1 mercury in their saliva, whereas mercury was not detectable in the saliva of two volunteers who had no dental fillings. (author)

Fluorimetric determination of copper(II) in aqueous solution using lucifer yellow CH as selective metal reagent

Energy Technology Data Exchange (ETDEWEB)

Mayr, T.; Wencel, D.; Werner, T. [Univ. of Regensburg (Germany) Inst. of Analytical Chemistry, Chemo- and Biosensors

2001-09-01

Lucifer yellow CH is shown to be a highly selective fluorescent reagent for the determination of Cu(II) in the {mu}g L{sup -1} concentration range. The fluorophore is statically quenched by Cu(II); the carbohydrazide group was assigned as the complexing part of the dye molecule. A total range of Cu(II) determination from 0.06 mg L{sup -1} (1 {mu}mol L{sup -1}) to 6.3 mg L{sup -1} (100 {mu}mol L{sup -1}) with a limit of detection of 0.019 mg L{sup -1} (0.3 {mu}mol L{sup -1}) was obtained, along with surprisingly high selectivity. There was no interference from alkaline and earth alkaline metal ions. The cross sensitivity to heavy metal ions was evaluated by the separate solution method and by competitive binding experiments. Calibration plots are shown for Cu(II) determination at different pH and the dissociation constant was determined. The application of the reagent was demonstrated by the determination of the Cu(II) content of tap water samples. (orig.)

Study on adsorption of activated carbon fiber to background-level xenon in air by the method of 133Xe tracer

International Nuclear Information System (INIS)

Zhang Haitao; Wang Yalong; Zhang Lixing; Wang Xuhui; Zhang Xiaolin

2001-01-01

The adsorption behaviors of the different activated carbon fibers to ultra-trace xenon in air are studied using the method of 133 Xe as tracer. The efficiency equation of adsorption columns are determined. The comparison of adsorptive capacity between activated carbon fibers and activated carbon indicates that activated carbon fibers are better than activated carbon under low temperature

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.

Development of Ultra-sensitive Laser Spectroscopic Analysis Technology

Energy Technology Data Exchange (ETDEWEB)

Cha, H. K.; Kim, D. H.; Song, K. S. (and others)

2007-04-15

Laser spectroscopic analysis technology has three distinct merits in detecting various nuclides found in nuclear fields. High selectivity originated from small bandwidth of tunable lasers makes it possible to distinguish various kinds of isotopes and isomers. High intensity of focused laser beam makes it possible to analyze ultratrace amount. Remote delivery of laser beam improves safety of workers who are exposed in dangerous environment. Also it can be applied to remote sensing of environment pollution.

Development of Ultra-sensitive Laser Spectroscopic Analysis Technology

International Nuclear Information System (INIS)

Cha, H. K.; Kim, D. H.; Song, K. S.

2007-04-01

Laser spectroscopic analysis technology has three distinct merits in detecting various nuclides found in nuclear fields. High selectivity originated from small bandwidth of tunable lasers makes it possible to distinguish various kinds of isotopes and isomers. High intensity of focused laser beam makes it possible to analyze ultratrace amount. Remote delivery of laser beam improves safety of workers who are exposed in dangerous environment. Also it can be applied to remote sensing of environment pollution

Selective masking and demasking for the stepwise complexometric determination of aluminium, lead and zinc from the same solution

Directory of Open Access Journals (Sweden)

Singh Nahar

2008-03-01

Full Text Available Abstract Background A complexometric method based on selective masking and de-masking has been developed for the rapid determination of aluminium, lead and zinc from the same solution in glass and glass frit samples. The determination is carried out using potassium cyanide to mask zinc, and excess disodium salt of EDTA to mask lead and aluminium. The excess EDTA was titrated with standard Mn(IISO4 solution using Erichrome Black-T as the indicator. Subsequently selective de-masking agents – triethanolamine, 2,3-dimercaptopropanol and a formaldehyde/acetone mixture – were used to determine quantities of aluminium, lead and zinc in a stepwise and selective manner. Results The accuracy of the method was established by analysing glass certified reference material NBS 1412. The standard deviation of the measurements, calculated by analysing five replicates of each sample, was found to be less than 1.5% for the method proposed. Conclusion The novelty of the method lies in its simplicity and accuracy afforded by there not being a need for a prior separation or instrumentation. The proposed method was found to be highly selective for the precise determination of aluminum, zinc and lead in the routine analysis of glass batch and allied materials.

Selective changes in expression of HLA class I polymorphic determinants in human solid tumors

International Nuclear Information System (INIS)

Natali, P.G.; Nicotra, M.R.; Bigotti, A.; Venturo, I.; Giacomini, P.; Marcenaro, L.; Russo, C.

1989-01-01

Analysis of surgical biopsies with monoclonal antibodies (mAbs) to framework determinants of major histocompatibility complex class I antigens has shown that malignant transformation is frequently associated with a marked loss of these cell surface molecules. The present study sought to determine whether more selective losses of major histocompatibility complex class I expression occur. Multiple specimens from 13 different types of primary and metastatic tumors were tested utilizing mAb BB7.2, which recognizes a polymorphic HLA-A2 epitope. In each case, expression of HLA-A,B,C molecules was determined by testing with mAb W6/32 directed to a framework HLA class I determinant. The authors have found that in HLA-A2-positive patients, HLA-A2 products are not detectable or are reduced in their expression in 70-80% of endometrial, colorectal, mammary, and renal tumors; in 40-60% of soft-tissue, skin, ovary, urinary bladder, prostate, and stomach tumors; and in 25-30% of melanomas and lung carcinomas tested. All tumors expressed the framework HLA-A,B.C determinant. The HLA-A2 epitope recognized by mAb BB7.2 is located in a portion of the HLA-A2 molecule postulated to react with the T-cell receptor. The selective loss of an HLA class I polymorphic epitope shown in this study may explain the mechanism by which tumor cells escape both T-cell recognition and natural killer cell surveillance

Using ion-selective electrode for determining iodine-131 preparation specific activity

International Nuclear Information System (INIS)

Melnik, M.I.; Nazirova, T.E.

2002-01-01

A pilot facility was developed in 2000 for the production of iodine-131. The parameters of the preparation are as follows: chemical form: sodium iodide solution (NaI-131) in a carbonate-bicarbonate buffer (or in 0.001M NaOH); specific activity: carrier free (> 5 Ci/mg); solution pH: 7-10; radionuclide purity: > 99.9%; radiochemical purity: > 97%; bulk activity: 0.15 Ci/ml. The experimental results of investigation aimed at the determination of the specific activity of the I-131 preparation using a iodine-selective electrode are described. The method enables the analytical concentration of iodide ions in the carbonate-bicarbonate buffer (pH = 8-11) and NaOH solution (0.01 mol/l, pH = 8-11) to be determined. A micro-cell has been developed for the analysis of the I-131 solution allowing the sample volume to be reduced to below 0.3 ml. The relative error of determination of the analytical concentration of iodide (10 -6 to 10 -1 mol/l) does not exceed 1%

Determination of trace amounts of plutonium in environmental samples by RIMS using a high repetition rate solid state laser system

International Nuclear Information System (INIS)

Gruening, C.; Kratz, J.V.; Trautmann, N.; Waldek, A.; Huber, G.; Passler, G.; Wendt, K.

2001-01-01

A reliable and easy to handle high repetition rate solid state laser system has been set up for routine applications of Resonance Ionization Mass Spectrometry (RIMS). It consists of three Titanium-Sapphire (Ti:Sa) lasers pumped by one Nd:YAG laser, providing up to 3 W of tunable laser light each in a wavelength range from 725 nm to 895 nm. The isotope shifts for 238 Pu to 244 Pu have been measured in an efficient ionization scheme with λ 1 =420.76 nm, λ 2 =847.28 nm and λ 3 =767.53 nm. An overall detection efficiency of the RIMS apparatus of ε=1x10 -5 is routinely reached, resulting in a detection limit of 2x10 6 atoms (0.8 fg) of plutonium. The isotopic compositions of synthetic samples and the NIST standard reference material SRM996 were measured. The content of 238 Pu to 242 Pu has been determined in dust samples from the surroundings of a nuclear power plant and 244 Pu was determined in urine samples for the National Radiation Protection Board (NRPB), U.K. Routine operation of plutonium ultratrace detection could thus be established

Selection of Models for Ingestion Pathway and Relocation Radii Determination

International Nuclear Information System (INIS)

Blanchard, A.

1998-01-01

The distance at which intermediate phase protective actions (such as food interdiction and relocation) may be needed following postulated accidents at three Savannah River Site nonreactor nuclear facilities will be determined by modeling. The criteria used to select dispersion/deposition models are presented. Several models were considered, including ARAC, MACCS, HOTSPOT, WINDS (coupled with PUFF-PLUME), and UFOTRI. Although ARAC and WINDS are expected to provide more accurate modeling of atmospheric transport following an actual release, analyses consistent with regulatory guidance for planning purposes may be accomplished with comparatively simple dispersion models such as HOTSPOT and UFOTRI. A recommendation is made to use HOTSPOT for non-tritium facilities and UFOTRI for tritium facilities

Development of a radiochemical neutron activation analysis procedure for determination of rhenium in biological and environmental samples at ultratrace level

International Nuclear Information System (INIS)

Kucera, J.; Lucanikova, M.; Czech Technical Univ., Prague

2006-01-01

Radiochemical neutron activation procedures using liquid-liquid extraction with tetraphenylarsonium chloride in chloroform from 1M HCl and solid extraction with ALIQUAT 336 incorporated in a polyacrylonitrile binding matrix from 0.1M HCl were developed for accurate determination of rhenium in biological and environmental samples at the sub-ng x g -1 level. Concentrations of Re in the range of 0.1 to 2.4 ng x g -1 were determined in several botanical reference materials (RM), while in a RM of road dust a value of ∼ 10 ng x g -1 was found. Significantly elevated values of Re, up to 90 ng x g -1 were found in seaweed (brown algae). Results for Re in the brown algae Fucus vesiculosus in which elevated 99 Tc values had previously been determined suggested possible competition between Re and Tc in the accumulation process. (author)

Structural determinants for selective recognition of peptide ligands for endothelin receptor subtypes ETA and ETB.

Science.gov (United States)

Lättig, Jens; Oksche, Alexander; Beyermann, Michael; Rosenthal, Walter; Krause, Gerd

2009-07-01

The molecular basis for recognition of peptide ligands endothelin-1, -2 and -3 in endothelin receptors is poorly understood. Especially the origin of ligand selectivity for ET(A) or ET(B) is not clearly resolved. We derived sequence-structure-function relationships of peptides and receptors from mutational data and homology modeling. Our major findings are the dissection of peptide ligands into four epitopes and the delineation of four complementary structural portions on receptor side explaining ligand recognition in both endothelin receptor subtypes. In addition, structural determinants for ligand selectivity could be described. As a result, we could improve the selectivity of BQ3020 about 10-fold by a single amino acid substitution, validating our hypothesis for ligand selectivity caused by different entrances to the receptors' transmembrane binding sites. A narrow tunnel shape in ET(A) is restrictive for a selected group of peptide ligands' N-termini, whereas a broad funnel-shaped entrance in ET(B) accepts a variety of different shapes and properties of ligands.

Decision Support System for Determining Scholarship Selection using an Analytical Hierarchy Process

Science.gov (United States)

Puspitasari, T. D.; Sari, E. O.; Destarianto, P.; Riskiawan, H. Y.

2018-01-01

Decision Support System is a computer program application that analyzes data and presents it so that users can make decision more easily. Determining Scholarship Selection study case in Senior High School in east Java wasn’t easy. It needed application to solve the problem, to improve the accuracy of targets for prospective beneficiaries of poor students and to speed up the screening process. This research will build system uses the method of Analytical Hierarchy Process (AHP) is a method that solves a complex and unstructured problem into its group, organizes the groups into a hierarchical order, inputs numerical values instead of human perception in comparing relative and ultimately with a synthesis determined elements that have the highest priority. The accuracy system for this research is 90%.

Sol-gel based sensor for selective formaldehyde determination

Energy Technology Data Exchange (ETDEWEB)

Bunkoed, Opas [Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Department of Chemistry and Center for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Davis, Frank [Cranfield Health, Cranfield University, Bedford MK43 0AL (United Kingdom); Kanatharana, Proespichaya, E-mail: proespichaya.K@psu.ac.th [Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Department of Chemistry and Center for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Thavarungkul, Panote [Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Department of Physics, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Higson, Seamus P.J., E-mail: s.p.j.higson@cranfield.ac.uk [Cranfield Health, Cranfield University, Bedford MK43 0AL (United Kingdom)

2010-02-05

We report the development of transparent sol-gels with entrapped sensitive and selective reagents for the detection of formaldehyde. The sampling method is based on the adsorption of formaldehyde from the air and reaction with {beta}-diketones (for example acetylacetone) in a sol-gel matrix to produce a yellow product, lutidine, which was detected directly. The proposed method does not require preparation of samples prior to analysis and allows both screening by visual detection and quantitative measurement by simple spectrophotometry. The detection limit of 0.03 ppmv formaldehyde is reported which is lower than the maximum exposure concentrations recommended by both the World Health Organisation (WHO) and the Occupational Safety and Health Administration (OSHA). This sampling method was found to give good reproducibility, the relative standard deviation at 0.2 and 1 ppmv being 6.3% and 4.6%, respectively. Other carbonyl compounds i.e. acetaldehyde, benzaldehyde, acetone and butanone do not interfere with this analytical approach. Results are provided for the determination of formaldehyde in indoor air.

Sol-gel based sensor for selective formaldehyde determination

International Nuclear Information System (INIS)

Bunkoed, Opas; Davis, Frank; Kanatharana, Proespichaya; Thavarungkul, Panote; Higson, Seamus P.J.

2010-01-01

We report the development of transparent sol-gels with entrapped sensitive and selective reagents for the detection of formaldehyde. The sampling method is based on the adsorption of formaldehyde from the air and reaction with β-diketones (for example acetylacetone) in a sol-gel matrix to produce a yellow product, lutidine, which was detected directly. The proposed method does not require preparation of samples prior to analysis and allows both screening by visual detection and quantitative measurement by simple spectrophotometry. The detection limit of 0.03 ppmv formaldehyde is reported which is lower than the maximum exposure concentrations recommended by both the World Health Organisation (WHO) and the Occupational Safety and Health Administration (OSHA). This sampling method was found to give good reproducibility, the relative standard deviation at 0.2 and 1 ppmv being 6.3% and 4.6%, respectively. Other carbonyl compounds i.e. acetaldehyde, benzaldehyde, acetone and butanone do not interfere with this analytical approach. Results are provided for the determination of formaldehyde in indoor air.

Selective masking and demasking for the stepwise complexometric determination of aluminium, lead and zinc from the same solution

OpenAIRE

Kayal, Nijhuma; Singh, Nahar

2008-01-01

Abstract Background A complexometric method based on selective masking and de-masking has been developed for the rapid determination of aluminium, lead and zinc from the same solution in glass and glass frit samples. The determination is carried out using potassium cyanide to mask zinc, and excess disodium salt of EDTA to mask lead and aluminium. The excess EDTA was titrated with standard Mn(II)SO4 solution using Erichrome Black-T as the indicator. Subsequently selective de-masking agents – t...

Determination of the Influence of Substrate Concentration on Enzyme Selectivity Using Whey Protein Isolate and Bacillus licheniformis Protease

NARCIS (Netherlands)

Butré, C.I.; Sforza, S.; Gruppen, H.; Wierenga, P.A.

2014-01-01

Increasing substrate concentration during enzymatic protein hydrolysis results in a decrease in hydrolysis rate. To test if changes in the mechanism of hydrolysis also occur, the enzyme selectivity was determined. The selectivity is defined quantitatively as the relative rate of hydrolysis of each

Detection of land mines by amplified fluorescence quenching of polymer films: a man-portable chemical sniffer for detection of ultratrace concentrations of explosives emanating from land mines

Science.gov (United States)

la Grone, Marcus J.; Cumming, Colin J.; Fisher, Mark E.; Fox, Michael J.; Jacob, Sheena; Reust, Dennis; Rockley, Mark G.; Towers, Eric

2000-08-01

The explosive charge within a landmine is the source for a mixture of chemical vapors that form a distinctive 'chemical signature' indicative of a landmine. The concentration of these compounds in the air over landmines is extremely low, well below the minimum detection limits of most field- portable chemical sensors. Described in this paper is a man- portable landmine detection system that has for the first time demonstrated the ability to detect landmines by direct sensing of the vapors of signature compounds in the air over landmines. The system utilizes fluorescent polymers developed by collaborators at the MIT. The sensor can detect ultra-trace concentrations of TNT vapor and other nitroaromatic compounds found in many landmine explosives. Thin films of the polymers exhibit intense fluorescence, but when exposed to vapors of nitroaromatic explosives the intensity of the light emitted from the films decreases. A single molecule of TNT binding to a receptor site quenches the fluorescence from many polymer repeat units, increasing the sensitivity by orders of magnitude. A sensor prototype has been develop that response in near real-time to low femtogram quantities of nitroaromatic explosives. The prototype is portable, lightweight, has low power consumption, is simple to operate, and is relatively inexpensive. Simultaneous field testing of the sensor and experienced canine landmine detection teams was recently completed. Although the testing was limited in scope, the performance of the senor met or exceeded that of the canines against buried landmines.

Determination of ultratrace amounts of uranium and thorium in aluminium and aluminium alloys by electrothermal vaporization/ICP-MS

International Nuclear Information System (INIS)

Nakamura, Yasushi; Kobayashi, Yoshio; Kakurai, Yousuke

1993-01-01

A method has been developed for determining the 0.01 ng g -1 level of uranium and thorium in aluminium and aluminium alloys by electrothermal vaporization (ETV)/ICP-MS. This method was found to be significantly interfered with any matrices or other elements contained. An ion-exchange technique was therefore applied to separate uranium and thorium from aluminium and other elements. It was known that uranium are adsorbed on an anion-exchange resin and thorium are adsorbed on cation-exchange resin. However, aluminium and copper were eluted with 6 M hydrochloric acid. Dissolve the sample with hydrochloric acid containing copper which was added for analysis of pure aluminium, and oxidize with hydrogen peroxide. Concentration of hydrochloric acid in the solution was adjusted to 6 M, and then passed the solution through the mixed ion-exchange resin column. After the uranium and thorium were eluted with 1 M hydrofluoric acid-0.1 M hydrochloric acid, the solution was evaporated to dryness. It was then dissolved with 1 M hydrochloric acid. Uranium and thorium were analyzed by ETV/ICP-MS using tungsten and molybdenum boats, respectively, since the tungsten boat contained high-level thorium and the molybdenum boat contained uranium. The determination limit of uranium and thorium were 0.003 and 0.005 ng g -1 , respectively. (author)

Sensitive method for the determination of nitrated polycyclic aromatic hydrocarbons in the human diet

Energy Technology Data Exchange (ETDEWEB)

Siegmund, B.; Weiss, R.; Pfannhauser, W. [Graz Univ. of Technology (Austria). Inst. of Food Chemistry

2003-01-01

The presence of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) as contaminants in foods is nowadays a legitimate cause of concern, as they are reported to be strong direct-acting mutagens and carcinogens that may pose a risk to human health. Nevertheless, their concentrations in foods are in the ultra-trace region. In this study, we present a very sensitive analytical method for the determination of this compound class in complex food matrices. Special emphasis was put on sample extraction and clean up. Recoveries of 75% could be obtained for 1- and 2-nitronaphthalene; for all other compounds investigated the recoveries were {>=}94%. The determination of the compounds was performed by gas chromatography-mass spectrometry. The results show that the use of negative chemical ionization (NCI) increases the sensitivity by one order of magnitude in comparison to electron impact ionization (EI) (limits of detection 0.07-0.25 {mu}g kg{sup -1} for EI and 0.01-0.02 {mu}g kg{sup -1} for NCI). The influence of the sample matrix on the sensitivity of the method is demonstrated with extracts of a sample from a duplicate diet study. Due to the lack of a certified reference material the suitability of the method is demonstrated with pumpkin seed oil that was spiked with nitro-PAHs at two different concentration levels. (orig.)

Ionic Liquid Crystals Modifier for Selective Determination of Terazosin Antihypertensive Drug in Presence of Common Interference Compounds

Directory of Open Access Journals (Sweden)

Nada F. Atta

2017-01-01

Full Text Available Electrochemical sensor was fabricated based on carbon paste electrode modified with an ionic liquid crystal ILC (2-chloro-1,3-dimethyl-imidazolidinium hexafluorophosphate in presence of sodium dodecyl sulfate for the selective electrochemical determination of Terazosin (TZ in presence of common interference compounds. The electrode performance was compared in presence of other ionic liquids ILs (1-Butyl-4-methyl pyridinium tetrafluoroborate and (1-n-Hexyl-3-methyl imidazolium tetrafluoroborate. Ultrasensitive determination of Terazosin HCl at the ILC modified electrode in the linear dynamic ranges of 0.002 to 0.09 μmol·L−1 and 0.2 to 30 μmol·L−1 with correlation coefficients 0.996 and 0.995 and LODs 1.69 × 10−11 mol·L−1 and 6.43 × 10−9 mol·L−1, respectively, were obtained. Selective determination of TZ in presence of uric acid and ascorbic acid and simultaneous determination of binary mixtures of TZ/dopamine, TZ/paracetamol and TZ/Morphine were also determined successfully using the modified sensor.

CdTe amplification nanoplatforms capped with thioglycolic acid for electrochemical aptasensing of ultra-traces of ATP

Energy Technology Data Exchange (ETDEWEB)

Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com [Department of Chemistry, Razi University, P.O. Box 67149-67346, Kermanshah (Iran, Islamic Republic of); Farzin, Leila [Department of Analytical Chemistry, School of Chemistry, College of Science, University of Tehran, P.O. Box 14174-66191, Tehran (Iran, Islamic Republic of); Tabrizi, Mahmoud Amouzadeh [Research Center for Science and Technology in Medicine,Tehran University of Medical Sciences, P.O. Box 14197-33131, Tehran (Iran, Islamic Republic of); Shanehsaz, Maryam [Analytical Chemistry Research Laboratory, Mobin Shimi Azma Company, P.O. Box 14768-44949, Tehran (Iran, Islamic Republic of)

2016-12-01

A “signal off” voltammetric aptasensor was developed for the sensitive and selective detection of ultra-low levels of adenosine triphosphate (ATP). For this purpose, a new strategy based on the principle of recognition-induced switching of aptamers from DNA/DNA duplex to DNA/target complex was designed using thioglycolic acid (TGA)-capped CdTe quantum dots (QDs) as the signal amplifying nano-platforms. Owing to the small size, high surface-to-volume ratio and good conductivity, quantum dots were immobilized on the electrode surface for signal amplification. In this work, methylene blue (MB) adsorbed to DNA was used as a sensitive redox reporter. The intensity of voltammetric signal of MB was found to decrease linearly upon ATP addition over a concentration range of 0.1 nM to 1.6 μM with a correlation coefficient of 0.9924. Under optimized conditions, the aptasensor was able to selectively detect ATP with a limit of detection of 45 pM at 3σ. The results also demonstrated that the QDs-based amplification strategy could be feasible for ATP assay and presented a potential universal method for other small biomolecular aptasensors. - Highlights: • A “signal off” voltammetric aptasensor has been reported. • The DPV technique was used for the determination of ATP. • The determination of ATP up to 1.6 μM with a detection limit 45 pM, respectively.

Bismuth Modified Carbon-Based Electrodes for the Determination of Selected Neonicotinoid Insecticides

Directory of Open Access Journals (Sweden)

Marko Rodić

2011-05-01

Full Text Available Two types of bismuth modified electrodes, a bismuth-film modified glassy carbon (BiF-GCE and a bismuth bulk modified carbon paste, were applied for the determination of selected nitroguanidine neonicotinoid insecticides. The method based on an ex situ prepared BiF-GCE operated in the differential pulse voltammetric (DPV mode was applied to determine clothianidin in the concentration range from 2.5 to 23 μg cm−3 with a relative standard deviation (RSD not exceeding 1.5%. The tricresyl phosphate-based carbon paste electrodes (TCP-CPEs, bulk modified with 5 and 20 w/w% of bismuth, showed a different analytical performance in the determination of imidacloprid, regarding the peak shape, potential window, and noise level. The TCP-CPE with 5% Bi was advantageous, and the developed DPV method based on it allowed the determination in the concentration range from 1.7 to 60 μg cm−3 with an RSD of 2.4%. To get a deeper insight into the morphology of the bismuth-based sensor surfaces, scanning electron microscopic measurements were performed of both the surface film and the bulk modified electrodes.

Determination of chlorine in nuclear-grade uranium compounds by ion-selective electrode

International Nuclear Information System (INIS)

Yang Chunqing; Liu Fuyun; Huang Dianfan.

1989-01-01

The determination of microamount chlorine in nuclear-grade uranium compounds is described. Chlorine is separated from uranium oxide pyrohydrolytically with stream of wet oxygen in a furnace at 800-900 deg C. Chlorine is volatilized as hydrochloric acid, which then is absorbed in a dilute alkaline solution and measured with chlorine selective electrode. This method covers the concentration range of 10-500 ppm chlorine in uranium oxide. The relative standard diviation is better than 10% and recovery of 85-108% has been reported

Ultra-trace determination of iodine in sediments and biological material using UV photochemical generation-inductively coupled plasma mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Grinberg, Patricia [Institute for National Measurements Standards, National Research Council Canada, Ottawa, Ontario, K1A 0R6 (Canada)], E-mail: patricia.grinberg@nrc.ca; Sturgeon, Ralph E. [Institute for National Measurements Standards, National Research Council Canada, Ottawa, Ontario, K1A 0R6 (Canada)

2009-03-15

Several sample preparation techniques have been evaluated for the determination of iodine using UV-photochemical generation-quadrupole inductively coupled plasma mass spectrometry. Thermal decomposition of samples at 1000 {sup o}C followed by capture of the liberated iodine in dilute acetic acid permitted subsequent UV-photochemical generation of a volatile iodine species that serves to enhance sensitivity 25-fold over conventional solution nebulization, delivering reagent blank detection limits of 8.75 pg g{sup -1127}I and 0.075 pg g{sup -1129}I for solid samples (400 mg test mass). The methodology was validated through determination of total iodine in several Standard Reference Materials, including NIST 1572 Citrus leaves, NIST 1549 Non-fat milk powder, NIST 1566a Oyster tissue and NIST 2709 San Joaquin Soil. Liberation of iodine from samples and its collection as well as photochemical generation were quantitative, permitting calibration to be achieved using standards prepared in dilute acetic acid.

Pure zinc sulfide quantum dot as highly selective luminescent probe for determination of hazardous cyanide ion

International Nuclear Information System (INIS)

Shamsipur, Mojtaba; Rajabi, Hamid Reza

2014-01-01

A rapid and simple fluorescence method is presented for selective and sensitive determination of hazardous cyanide ion in aqueous solution based on functionalized zinc sulfide (ZnS) quantum dot (QD) as luminescent prob. The ultra-small ZnS QDs were synthesized using a chemical co-precipitation method in the presence of 2-mercaptoethanol (ME) as an efficient capping agent. The prepared pure ZnS QDs was applied as an optical sensor for determination of cyanide ions in aqueous solutions. ZnS nanoparticles have exhibited a strong fluorescent emission at about 424 nm. The fluorescence intensity of QDs is linearly proportional to the cyanide ion concentration in the range 2.44 × 10 −6 to 2.59 × 10 −5 M with a detection limit of 1.70 × 10 −7 M at pH 11. The designed fluorescent sensor possesses remarkable selectivity for cyanide ion over other anions such as Cl − , Br − , F − , I − , IO 3 − , ClO 4 − , BrO 3 − , CO 3 2− , NO 2 − , NO 3 − , SO 4 2− , S 2 O 4 2− , C 2 O 4 2− , SCN − , N 3 − , citrate and tartarate with negligible influences on the cyanide detection by fluorescence spectroscopy. - Highlights: • Preparation of functionalized ZnS quantum dots in aqueous media • Highly selective quantum dot based luminescent probe for determination of cyanide • Fast and sensitive determination of hazardous CN − by fluorescence quenching

Immersed single-drop microextraction interfaced with sequential injection analysis for determination of Cr(VI) in natural waters by electrothermal-atomic absorption spectrometry

International Nuclear Information System (INIS)

Pena, Francisco; Lavilla, Isela; Bendicho, Carlos

2008-01-01

Single-drop microextraction (SDME) and sequential injection analysis have been hyphenated for ultratrace metal determination by Electrothermal-Atomic Absorption Spectrometry (ETAAS). The novel method was targeted on extraction of the Cr(VI)-APDC chelate and encompasses the potential of SDME as a miniaturized and virtually solvent-free preconcentration technique, the ability of sequential injection analysis to handle samples and the versatility of furnace autosamplers for introducing microliter samples in ETAAS. The variables influencing the microextraction of Cr(VI) onto an organic solvent drop, i.e., type of organic solvent, microextraction time, stirring rate of the sample solution, drop volume, immersion depth of the drop, salting-out effect, temperature of the sample, concentration of the complexing agent and pH of the sample solution were fully investigated. For a 5 and 20 min microextraction time, the preconcentration factors were 20 and 70, respectively. The detection limit was 0.02 μg/L of Cr(VI) and the repeatability expressed as relative standard deviation was 7%. The SDME-SIA-ETAAS technique was validated against BCR CRM 544 (lyophilized solution) and applied to ultrasensitive determination of Cr(VI) in natural waters

Immersed single-drop microextraction interfaced with sequential injection analysis for determination of Cr(VI) in natural waters by electrothermal-atomic absorption spectrometry

Energy Technology Data Exchange (ETDEWEB)

Pena, Francisco; Lavilla, Isela [Departamento de Quimica Analitica y Alimentaria, Area de Quimica Analitica, Facultad de Quimica, Universidad de Vigo, Campus As Lagoas-Marcosende, s/n, 36310 Vigo (Spain); Bendicho, Carlos [Departamento de Quimica Analitica y Alimentaria, Area de Quimica Analitica, Facultad de Quimica, Universidad de Vigo, Campus As Lagoas-Marcosende, s/n, 36310 Vigo (Spain)], E-mail: bendicho@uvigo.es

2008-04-15

Single-drop microextraction (SDME) and sequential injection analysis have been hyphenated for ultratrace metal determination by Electrothermal-Atomic Absorption Spectrometry (ETAAS). The novel method was targeted on extraction of the Cr(VI)-APDC chelate and encompasses the potential of SDME as a miniaturized and virtually solvent-free preconcentration technique, the ability of sequential injection analysis to handle samples and the versatility of furnace autosamplers for introducing microliter samples in ETAAS. The variables influencing the microextraction of Cr(VI) onto an organic solvent drop, i.e., type of organic solvent, microextraction time, stirring rate of the sample solution, drop volume, immersion depth of the drop, salting-out effect, temperature of the sample, concentration of the complexing agent and pH of the sample solution were fully investigated. For a 5 and 20 min microextraction time, the preconcentration factors were 20 and 70, respectively. The detection limit was 0.02 {mu}g/L of Cr(VI) and the repeatability expressed as relative standard deviation was 7%. The SDME-SIA-ETAAS technique was validated against BCR CRM 544 (lyophilized solution) and applied to ultrasensitive determination of Cr(VI) in natural waters.

Application of a Lithium-ion Selective Metallacrown to Extraction-Spectrophotometric Determination of Lithium in Saline Water.

Science.gov (United States)

Katsuta, Shoichi; Saito, Yuki; Takahashi, Suguru

2018-01-01

The solvent-extraction behavior of Li + and Na + with a Li + selective metallacrown, [{Ru(η 6 -3,5-dimethylanisole)(2,3-pyridinediolate)} 3 ], was investigated in the presence of organic dye anions, 3',3″,5',5″-tetrabromophenolphthalein ethyl ester ([TBPE] - ), 2,6-dichloroindophenolate, and picrate ([pic] - ). Each alkali metal ion was extracted as a 1:1:1 ternary complex of the metal ion, metallacrown, and anion. The Li + /Na + extraction selectivity is anion dependent and highest with [pic] - . Therefore, we devised an extraction-spectrophotometric determination method for Li + in saline water based on the extraction of Li + using the metallacrown and [pic] - for high selectivity and subsequent replacement of [pic] - in the extracted species with [TBPE] - for high sensitivity. When applying this to artificial seawater samples containing known concentrations of Li + , a linear relationship was observed between the absorbance at 571 nm of the organic phase and the Li + concentration in the samples. By this method, the determination of Li + at the sub-ppm level in natural seawater is possible.

Cloud point extraction and spectrophotometric determination of mercury species at trace levels in environmental samples.

Science.gov (United States)

Ulusoy, Halil İbrahim; Gürkan, Ramazan; Ulusoy, Songül

2012-01-15

A new micelle-mediated separation and preconcentration method was developed for ultra-trace quantities of mercury ions prior to spectrophotometric determination. The method is based on cloud point extraction (CPE) of Hg(II) ions with polyethylene glycol tert-octylphenyl ether (Triton X-114) in the presence of chelating agents such as 1-(2-pyridylazo)-2-naphthol (PAN) and 4-(2-thiazolylazo) resorcinol (TAR). Hg(II) ions react with both PAN and TAR in a surfactant solution yielding a hydrophobic complex at pH 9.0 and 8.0, respectively. The phase separation was accomplished by centrifugation for 5 min at 3500 rpm. The calibration graphs obtained from Hg(II)-PAN and Hg(II)-TAR complexes were linear in the concentration ranges of 10-1000 μg L(-1) and 50-2500 μg L(-1) with detection limits of 1.65 and 14.5 μg L(-1), respectively. The relative standard deviations (RSDs) were 1.85% and 2.35% in determinations of 25 and 250 μg L(-1) Hg(II), respectively. The interference effect of several ions were studied and seen commonly present ions in water samples had no significantly effect on determination of Hg(II). The developed methods were successfully applied to determine mercury concentrations in environmental water samples. The accuracy and validity of the proposed methods were tested by means of five replicate analyses of the certified standard materials such as QC Metal LL3 (VWR, drinking water) and IAEA W-4 (NIST, simulated fresh water). Copyright © 2011 Elsevier B.V. All rights reserved.

Selective determination of cyanide complexes of copper, zinc and cadmium in electrolytes by spectrophotometric titration

International Nuclear Information System (INIS)

Kuznetsov, V.V.; Korchagina, O.A.; Samorukova, O.L.

1986-01-01

Selective, sensitive and rapid method for determining Cd, Zn, Cu and their mixtures in cyanide electrolytes of galvanic bathes has been developed. Analysis is performed by means of indicator spectrophotometric titration with barium and strontium salts of cadmium cyanide complexes in organic-aqueous solvents

Complexometric determination of thallium(III using ethanethiol as a selective masking agent

Directory of Open Access Journals (Sweden)

Karthikeyan J.

2006-01-01

Full Text Available A simple and selective complexometric method for the determination of thallium in presence of other metal ions is proposed based on the selective masking ability of ethanethiol towards thallium(III. Thallium present in a given sample solution is first complexed with a known excess of EDTA and the surplus EDTA is titrated with standard zinc sulphate solution at pH 5-6(hexamine using xylenol orange as the indicator. A 0.3% aqueous solution of ethanethiol is then added to displace EDTA from the Tl(III-EDTA complex. The released EDTA is titrated with standard zinc sulphate solution as before. Reproducible and accurate results are obtained for 3.70 mg to 74.07 mg of Tl (III with relative error less than ? 0.44% and coefficient of variation not more than 0.27%. The interference of various ions was studied and the method was used for the analysis of thallium in its synthetic alloy mixtures and also in complexes.

Application of graphene oxide/lanthanum-modified carbon paste electrode for the selective determination of dopamine

Energy Technology Data Exchange (ETDEWEB)

Ye, Fengying; Feng, Chenqi; Fu, Ning; Wu, Huihui; Jiang, Jibo, E-mail: jibojiang0506@163.com; Han, Sheng, E-mail: hansheng654321@sina.com

2015-12-01

Highlights: • The effective surface area of the modified CPE has been expanded after self-assembly. • The GO–La composite exhibited excellent electrocatalytic activity toward DA. • The GO–La/CPE presented high selectivity, sensitivity, excellent stability and repeatability. - Abstract: A home-made carbon paste electrode (CPE) was reformed by graphene oxide (GO)/lanthanum (La) complexes, and a modified electrode, called GO–La/CPE, was fabricated for the selective determination of dopamine (DA) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Several factors affecting the electrocatalytic performance of the modified sensor were investigated. Owning to the combination of GO and La ions, the GO–La/CPE sensor exhibited large surface area, well selectivity, good repeatability and stability in the oxidation reaction of DA. At optimal conditions, the response of the GO–La/CPE electrode for determining DA was linear in the region of 0.01–0.1 μM and 0.1–400.0 μM. The limit of detection was down to 0.32 nM (S/N = 3). In addition, this modified electrode was successfully applied to the detection of DA in real urine and serum samples by using standard adding method, showing its promising application in the electroanalysis of real samples.

Determination of water quality of ground water in selected Payatas residential areas using ion-selective electrodes (ISE) and atomic absorption spectroscopy (AAS) (determination of NO3, Cl, Pb, Cd, Zn)

International Nuclear Information System (INIS)

Tahir, Samsudin A.; Roque, Willie P.; Arididon, Bonifacio D. Jr.; Gardon, Ruel W.

2003-01-01

This study aims to determine the water-soluble ions using ion-selective electrodes (ISE) and trace metals using atomic absorption spectroscopy (AAS). Seven water samples were chosen from the thirteen sites, which were gathered from the selected Payatas residential areas in Quezon City. For the trace metals the lowest detection of AAS in lead was obtained in La Brea site and was found to be -0.5 ppm. Lead content has a value of -0.04 ppm and was found to be below the detection limit of 0.1 ppm. The remaining sites obtained high value of lead concentrations in AAS reading. The range of concentration for lead was from 0.5 ppm for La Brea site to 1.4 ppm for Velasco site. The cadmium as trace metal in groundwater samples from Payatas residential area was found to be below the lowest limit of detection ( 3 which is 15.6 ppm and it was obtained by the used of ion selective electrodes (ISE) Horiba model type. Second to it was the La Brea site, which is 10.04 ppm All the other samples do not exceeds to the maximum allowable concentration of nitrate (50.0 ppm), and it ranged from 4.10 ppm for open-well site to 15.6 ppm for Lopez site. In chloride determination, Lagro High School obtained a reading of 57.6 ppm using ISE and it was the highest concentration amount present in seven samples. Next to it was the Ungrin site (36.8 ppm), samples ranged from 6.7 ppm for La Brea site to 57.6 ppm for Lagro high school site. All the samples do not exceeds to the maximum allowable concentration for chloride, which is 250 ppm. (Authors)

Derivative flame atomic absorption spectrometry and its application in trace analysis

International Nuclear Information System (INIS)

Sun, H. W.; Li, L. Q.

2005-01-01

Flame atomic absorption spectrometry is an accepted and widely used method for the determination of trace elements in a great variety of samples. But its sensitivity doesn't meet the demands of trace and ultra-trace analysis for some samples. The derivative signal processing technique, with a very high capability for enhancing sensitivity, was developed for flame atomic absorption spectrometry. The signal models of conventional flame atomic absorption spectrometry are described. The equations of derivative signals are established for flame atomic absorption spectrometry, flow injection atomic absorption spectrometry (FI-FAAS) and atom trapping flame atomic absorption spectrometry (AT-FAAS). The principle and performance of the derivative atomic absorption spectrometry are evaluated. The derivative technique based on determination of variation rate of signal intensity with time (dl/dt) is different from the derivative spectrophotometry based on determination of variation rate of signal intensity with wavelength (dl/dhλ). Derivative flame atomic absorption spectrometry has higher sensitivity, lower detection limits and better accuracy. It has been applied to the direct determination of trace elements without preconcentration. If the derivative technique was combined with several preconcentration techniques, the sensitivity would be enhanced further for ultra-trace analysis with good linearity. The applications of derivative flame atomic absorption spectroscopy are reviewed for trace element analysis in biological, pharmaceutical, environmental and food samples

Selective determination of plutonium and transplutonic elements (Am, Cm) in feces ashes

International Nuclear Information System (INIS)

Ballada, J.; Verry, M.; Daburon, M.L.; Jeanmaire, L.

1983-02-01

A technique has been developed for the selective determination of the main transplutonic elements of the fuel cycle in feces ashes. The natural elements (U, Ra, Th and their isotopes) usually present in the human diet, are eliminated. Plutonium separation is carried out in a classical way by ion exchange resin. After elimination of U and Th, Am-Cm are collected on a millipore filter for α spectrometry or global counting. Yields are 95% (σ = 4) for Pu and 81.7% (σ = 6,2) for Am-Cm [fr

Determination of fluoride content in UO2F2 and ADUF solution by ion selective electrode

International Nuclear Information System (INIS)

Samanta, Papu; Kumar, Pradeep; Bagchi, A.C.

2017-01-01

During production of uranium metal powder, liquid solution UO 2 F 2 and ADUF containing high content of fluoride gets generated. Fluoride being corrosive in nature, fluorides concentration needs to determined. Ion selective electrode, LaF 3 (Eu) crystal, has been used. Uranium was found to interfere with fluoride analysis. Study was carried out to selectively remove uranium by solvent extraction employing D2EHPA+Cyanex 923 and TBP in dodecane. The TBP was found effective to remove uranium. (author)

New Isotope Analysis Method: Atom Trap Mass Spectrometry

International Nuclear Information System (INIS)

Ko, Kwang Hoon; Park, Hyun Min; Han, Jae Min; Kim, Taek Soo; Cha, Yong Ho; Lim, Gwon; Jeong, Do Young

2011-01-01

Trace isotope analysis has been an important role in science, archaeological dating, geology, biology and nuclear industry. Some fission products such as Sr-90, Cs-135 and Kr-85 can be released to the environment when nuclear accident occurs and the reprocessing factory operates. Thus, the analysis of artificially produced radioactive isotopes has been of interest in nuclear industry. But it is difficult to detect them due to low natural abundance less then 10 -10 . In general, radio-chemical method has been applied to detect ultra-trace radio isotopes. But this method has disadvantages of long measurement time for long lived radioisotopes and toxic chemical process for the purification. The Accelerator Mass Spectrometer has high isotope selectivity, but the system is huge and its selectivity is affected by isobars. The laser based method, such as RIMS (Resonance Ionization Mass Spectrometry) has the advantage of isobar-effect free characteristics. But the system size is still huge for high isotope selective system. Recently, ATTA (Atom Trap Trace Analysis) has been successfully applied to detect ultra-trace isotope, Kr-81 and Kr-85. ATTA is the isobar-effect free detection with high isotope selectivity and the system size is small. However, it requires steady atomic beam source during detection, and is not allowed simultaneous detection of several isotopes. In this presentation, we introduce new isotope detection method which is a coupled method of Atom Trap Mass Spectrometry (ATMS). We expect that it can overcome the disadvantage of ATTA while it has both advantages of ATTA and mass spectrometer. The basic concept and the system design will be presented. In addition, the experimental status of ATMS will also be presented

Electrochemical sensor based on a carbon nanotube-modified imprinted sol–gel for selective and sensitive determination of β2-agonists

International Nuclear Information System (INIS)

Xu, Wei; Liu, Ping; Guo, Chunhui; Dong, Chao; Zhang, Xiuhua; Wang, Shengfu

2013-01-01

We describe a molecularly imprinted electrochemical sensor for selective and sensitive determination of β2-agonists. It is making use of a combination of single-wall carbon nanotubes (SWNTs) with a molecularly imprinted sol–gel. The SWNTs were introduced in order to enhance electron transport and sensitivity. The imprinted sol–gel film with its specific binding sites acts as a selective recognition element and as a preconcentrator for β 2 -agonists. The morphology of the imprinted film was characterized by scanning electron microscopy. The optimized sensor displays high sensitivity and excellent selectivity for the β 2 -agonists as shown for their determination in human serum samples. (author)

Multielement Determination of Major-to Ultratrace Elements in a Cabbage, Spinach, and the Japanese Radish by ICP-AES After Acid Digestion

OpenAIRE

畑山, 友紀; 奴田原, 杏奈; 藤井, 和美; 西島, 基弘; ハタヤマ, ユキ; ヌタハラ, アンナ; フジイ, カズミ; ニシジマ, モトヒロ; Yuki, Hatayama; anna, Nutahara; Kazumi, Fujii; Motohiro, Nishijima

2011-01-01

A multi-element determination in a cabbage, spinach, and the Japanese radish was carried out by inductively coupled plasma atomic emission spectrometry (ICP). We investigated whether there was a difference in content according to the part of the vegetables. The dried vegetables (0.5g) were digested with nitric acid and with hydrogen peroxide acid in a resolution device As a result, about 9 elements were successfully determined. The values of the coefficient of variance for part interval by ea...

Isolating E.Coli Bacteriophage from Raw Sewage and Determining its Selectivity to the Host Cell

Directory of Open Access Journals (Sweden)

SM Imeni

2016-05-01

Full Text Available Introduction: Bacteriophages are viruses that infect and destroy prokaryote cells, specifically the bacteria. They act too selective, so as each bacteriophage affects only on specific type of bacteria. Due to their specific features, bacteriophages can be used as an appropriate substitute for antibiotics in infectious diseases treatment. Therefore, this study aimed to isolate E. coli-specific bacteriophage from raw sewage. Methods: Eight samples of raw sewage, each containing approximately 50 ml of raw sewage with 10 minute gap, were prepared from Zargandeh wastewater treatment plant, Tehran, Iran. The sewages were mixed with Brain-heart infusion medium (BHI as a liquid culture medium in order to let the microorganisms grow. Incubation, purification and determination of bacteria were followed repeatedly to isolate the bacteriophage. Then it was tested on E.coli (ATCC 25922, Enterococcus faecalis (ATCC 19433, Staphylococcus aureus (ATCC 2392, and Yersinia enterocolitica (ATCC 9610 in order to determine the bacteriophage selectivity. Results: The E.coli bacteriophages were successfully isolated from all the eight samples, that were completely able to lyse and destroy E.coli bacterial cells, though no effect was observed on other types of bacteria. Conclusion: The study findings revealed that bacteriophages act selectively. Considering the raise of antibiotic resistance in the world, bacteriophages can serve as a good substitute for antibiotics in treating infectious diseases.

Optical molecular fluorescence determination of ultra-trace beryllium in occupational and environmental samples using highly alkaline conditions.

Science.gov (United States)

Adams, Lori; Agrawal, Anoop; Cronin, John P; Ashley, Kevin

2017-01-01

Exposures to beryllium (Be), even at extremely low levels, can cause severe health effects in a percentage of those exposed; consequently, occupational exposure limits (OELs) promulgated for this element are the lowest established for any element. This work describes the advantages of using highly alkaline dye solutions for determination of Be in occupational hygiene and environmental samples by means of an optical molecular fluorescence technique after sample extraction in 1-3% (w˖w -1 ) aqueous ammonium bifluoride (NH 4 HF 2 ). Improved attributes include the ability to further enhance the detection limits of Be in extraction solutions of high acidity with minimal dilution, which is particularly beneficial when NH 4 HF 2 solutions of higher concentration are used for extraction of Be from soil samples. Significant improvements in Be method detection limits (MDLs) are obtained at levels many-fold below those reported previously for this methodology. Notably, MDLs for Be of health organizations and regulatory agencies in the USA and internationally. Applications of enhanced Be measurements to air filter samples, surface wipe samples, soils and newly-designed occupational air sampler inserts are illustrated.

Pure zinc sulfide quantum dot as highly selective luminescent probe for determination of hazardous cyanide ion

Energy Technology Data Exchange (ETDEWEB)

Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Rajabi, Hamid Reza, E-mail: h.rajabi@mail.yu.ac.ir [Chemistry Department, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of)

2014-03-01

A rapid and simple fluorescence method is presented for selective and sensitive determination of hazardous cyanide ion in aqueous solution based on functionalized zinc sulfide (ZnS) quantum dot (QD) as luminescent prob. The ultra-small ZnS QDs were synthesized using a chemical co-precipitation method in the presence of 2-mercaptoethanol (ME) as an efficient capping agent. The prepared pure ZnS QDs was applied as an optical sensor for determination of cyanide ions in aqueous solutions. ZnS nanoparticles have exhibited a strong fluorescent emission at about 424 nm. The fluorescence intensity of QDs is linearly proportional to the cyanide ion concentration in the range 2.44 × 10{sup −6} to 2.59 × 10{sup −5} M with a detection limit of 1.70 × 10{sup −7} M at pH 11. The designed fluorescent sensor possesses remarkable selectivity for cyanide ion over other anions such as Cl{sup −}, Br{sup −}, F{sup −}, I{sup −}, IO{sub 3}{sup −}, ClO{sub 4}{sup −}, BrO{sub 3}{sup −}, CO{sub 3}{sup 2−}, NO{sub 2}{sup −}, NO{sub 3}{sup −}, SO{sub 4}{sup 2−}, S{sub 2}O{sub 4}{sup 2−}, C{sub 2}O{sub 4}{sup 2−}, SCN{sup −}, N{sub 3}{sup −}, citrate and tartarate with negligible influences on the cyanide detection by fluorescence spectroscopy. - Highlights: • Preparation of functionalized ZnS quantum dots in aqueous media • Highly selective quantum dot based luminescent probe for determination of cyanide • Fast and sensitive determination of hazardous CN{sup −} by fluorescence quenching.

Characterization of Angiotensin II Molecular Determinants Involved in AT1 Receptor Functional Selectivity.

Science.gov (United States)

Domazet, Ivana; Holleran, Brian J; Richard, Alexandra; Vandenberghe, Camille; Lavigne, Pierre; Escher, Emanuel; Leduc, Richard; Guillemette, Gaétan

2015-06-01

The octapeptide angiotensin II (AngII) exerts a variety of cardiovascular effects through the activation of the AngII type 1 receptor (AT1), a G protein-coupled receptor. The AT1 receptor engages and activates several signaling pathways, including heterotrimeric G proteins Gq and G12, as well as the extracellular signal-regulated kinases (ERK) 1/2 pathway. Additionally, following stimulation, βarrestin is recruited to the AT1 receptor, leading to receptor desensitization. It is increasingly recognized that specific ligands selectively bind and favor the activation of some signaling pathways over others, a concept termed ligand bias or functional selectivity. A better understanding of the molecular basis of functional selectivity may lead to the development of better therapeutics with fewer adverse effects. In the present study, we developed assays allowing the measurement of six different signaling modalities of the AT1 receptor. Using a series of AngII peptide analogs that were modified in positions 1, 4, and 8, we sought to better characterize the molecular determinants of AngII that underlie functional selectivity of the AT1 receptor in human embryonic kidney 293 cells. The results reveal that position 1 of AngII does not confer functional selectivity, whereas position 4 confers a bias toward ERK signaling over Gq signaling, and position 8 confers a bias toward βarrestin recruitment over ERK activation and Gq signaling. Interestingly, the analogs modified in position 8 were also partial agonists of the protein kinase C (PKC)-dependent ERK pathway via atypical PKC isoforms PKCζ and PKCι. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Application of ICP-QMS for the determination of ultratrace-levels of 226Ra in geothermal water and sediment samples

International Nuclear Information System (INIS)

Tsuey-Lin Tsai; Tsung-Yuan Wang; Hwa-Jou Wei; Lee-Chung Men; Chun-Chih Lin

2010-01-01

A rapid, accurate and less labor intensive approach to determining 226 Ra in environmental samples was examined; this utilized quadrupole-based inductively coupled plasma mass spectrometry (ICP-QMS). The procedure used chemical separation by ion exchange chromatography to remove most of the matrices after coprecipitation with BaSO 4 . The average chemical recovery of the NIST SRM preparation method ranged from 60.5 to 85.9% using 133 Ba as internal tracer by gamma counting. This technique was capable of completing a 226 Ra measurement within 3 min. It did not require an in-growth period to allow radon and its progeny to achieve secular equilibrium with the parent 226 Ra as is needed for liquid scintillation analyzer (LSA). The method detection limits for the determination of 226 Ra in geothermal water and sediment samples were 0.02 mBq L -1 (0.558 fg L -1 ) and 0.10 Bq kg -1 (2.79 fg g -1 ), respectively. The results obtained with various natural samples and the suitability of the method when applied to various environmental matrices such as geothermal water and sediment are discussed. When ICP-QMS was compared to double-focusing magnetic sector field inductively coupled plasma mass spectrometry (ICP-SFMS), good agreement was obtained with a correlation coefficient, r 2 = 0.982. (author)

Method validation for high resolution sector field inductively coupled plasma mass spectrometry determination of the emerging contaminants in the open ocean: Rare earth elements as a case study

Science.gov (United States)

Wysocka, Irena; Vassileva, Emilia

2017-02-01

Analytical procedure for the determination of fourteen rare earth elements (REEs) in the seawater samples has been developed and validated. The elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) at ultra-trace level were measured by high resolution sector field inductively coupled plasma mass spectrometry (HR ICP-SFMS) after off-line analytes pre-concentration and matrix separation. The sample pre-treatment was carried out by commercially available automated system seaFAST-pico™, which is a low-pressure ion chromatography technique, based on solid phase extraction principles. Efficient elimination of seawater matrix and up to 50-fold pre-concentration of REEs enabled their accurate and precise quantification at ng L- 1 level. A validation approach in line with the requirements of ISO/IEC 17025 standard and Eurachem guidelines were followed. With this in mind, selectivity, working range, linearity, recovery (from 92% to 102%), repeatability (1%-4%), intermediate precision (2%-6%), limits of detection (0.001-0.08 ng L- 1) were systematically assessed. The total uncertainty associated to each result was estimated and the main sources of uncertainty sorted out. All major contributions to the combined uncertainty of the obtained results were identified and propagated together, following the ISO/GUM guidelines. The relative expanded uncertainty was estimated at range from 10.4% to 11.6% (k = 2). Demonstration of traceability of measurement results was also presented. Due to the low limits of detection, this method enables the determination of ultra-low levels of REEs in the open seawater as well as small variations in their concentrations. The potential of the proposed analytical procedure, based on combination of seaFAST-pico™ for sample preparation and HR ICP-SFMS, was demonstrated by direct analysis of seawater form different regions of the world.

A novel ion selective sensor for promethium determination

International Nuclear Information System (INIS)

Gupta, Vinod K.; Jain, Rajeev; Hamdan, A.J.; Agarwal, Shilpi; Bharti, Arvind K.

2010-01-01

This is a first promethium 145 ion-selective sensor based on the comparative study of two Schiff base ligands (X 1 and X 2 ) as neutral ionophores. Effect of various plasticizers: 2-nitrophenyloctylether (o-NPOE), dibutyl phosphonate (DBP), dioctylphthalate (DOP), tri-(2-ethylhexyl) phosphate (TEHP), dibutyl butylphosphonate (DBBP), chloronaphthalene (CN) and anion excluders: potassium tetrakis (p-chloropheny1) borate (KTpClPB), sodiumtetraphenylborate (NaTPB) and oleic acid (OA) have been studied. The membrane with a composition of ionophore (X 1 /X 2 ):KTpClPB:PVC:o-NPOE (w/w, %) in the ratio of 5:5:30:60 exhibited best performance. The best responsive membrane sensors (8 and 21) exhibited working concentration range of 4.5 x 10 -7 -1.0 x 10 -2 M and 3.5 x 10 -6 -1.0 x 10 -2 M with a detection limits of 3.2 x 10 -7 M and 2.3 x 10 -6 M and Nernstian slopes of 20.0 ± 0.5, 19.5 ± 0.5 mV decade -1 of activity, respectively. The sensor no. 8 works satisfactorily in partially non-aqueous media up to 10% (v/v) content of methanol, ethanol and acetonitrile. Analytical application of the proposed sensor has been demonstrated in determination of promethium (III) ions in spiked water samples.

Indirect complexometric determination of mercury(II) using potassium bromide as selective masking agent

International Nuclear Information System (INIS)

Sreekumar, N.V.; Nazareth, R.A.; Narayana, B.; Hegde, P.; Manjunatha, B.R.

2002-01-01

A complexometric method for the determination of mercury in presence of other metal ions based on the selective masking ability of potassium bromide towards mercury is described. Mercury(II) present in a given sample solution is first complexed with a known excess of EDTA and the surplus EDTA is titrated against zinc sulfate solution at pH 5-6 using xylenol orange as the indicator. A known excess of 10 % solution of potassium bromide is then added and the EDTA released from Hg-EDTA complex is titrated against standard zinc sulfate solution. Reproducible and accurate results are obtained for 8 mg to 250 mg of mercury(II) with a relative error ±0.28 % and standard deviations /leg 0.5 mg. The interference of various ions is studied. This method was applied to the determination of mercury(II) in its alloys. (author)

A selective and regenerable voltammetric aptasensor for determination of homocysteine

International Nuclear Information System (INIS)

Saeed, Jaber; Mirzaei, Mohammad; Torkzadeh-Mahani, Masoud

2016-01-01

We describe an electrochemical aptasensor for the amino acid homocysteine (hCys). A gold electrode was modified with a highly specific aptamer against hCys (a 66-base DNA oligonucleotide) acting as the recognition probe. The method is highly selective over cysteine and methionine. The effects of accumulation time, type and concentration of accumulation buffer and pH, type and concentration of stripping buffer were studied. Under optimized conditions and a working potential of 1.07 V (vs. Ag/AgCl), the response to hCys is linear in the 0.2 to 10 μM concentration range. The detection limit is 10 nM, and the relative standard deviation is 3.1 % (at 1 μM of hCys). The electrode can be regenerated by immersing it into a 3 M solution of urea solution. The method was applied to the determination of hCys in (spiked) serum and urine and gave recoveries of 88.5 and 96.5 %, respectively. (author)

Polypyrrole Composite Film for Highly Sensitive and Selective Electrochemical Determination Sensors

International Nuclear Information System (INIS)

Zheng, Xiangli; Tian, Dong; Duan, Shuo; Wei, Maochao; Liu, Shan; Zhou, Changli; Li, Qing; Wu, Gang

2014-01-01

In this paper, polypyrrole (PPy) and benz[a]anthracene-7,12-dione (BaD) were electro-polymerized onto a pyrolytic graphite electrode (PGE), constructing a novel BaD/PPy/PGE platform for electrochemical sensoring. The morphology and electrochemical properties of the fabricated BaD/PPy/PGE were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Furthermore, the electrochemical behavior of benzo[k]fluoranthene (BkF) at the BaD/PPy/PGE was investigated. Due to the specific interactions between BkF and BaD, a wide linear range of BkF detection from 1.0 × 10 −12 to 1.0 × 10 −9 M with good linearity (R 2 = 0.9962) and a low detection limit (1.0 × 10 −13 M, S/N = 3) were demonstrated. Importantly, other similar aromatics which had one ring or more than two rings, such as benzo[a]anthracene, benzo[a]pyrene, pyrene, benzo[ghi]peryle, anthracene, phenanthrene, naphthalene and parachlorophenol, showed insignificant interference on BkF detection. Consequently, this novel BaD/PPy/PGE with excellent stability and selectivity holds promise as an effective BkF electrochemical sensor in aqueous solution. As an example for its practical application, the newly developed sensor was applied to quantitative determination of BkF in waste water samples obtained from a coking plant with satisfactory sensitivity, selectivity, and reversibility

Behaviour study of trace radioelements in the cycles of uranium conversion

International Nuclear Information System (INIS)

Bertaux, M.

1998-01-01

The aim of this work was to study the presence of ultra-trace radioelements in the cycles of uranium conversion. Radiochemical methods for determining ultra-trace amounts of various elements in uranium have been perfected. These methods are based on the chromatographic separation of anionic complexes and on the measurement of various activities by alpha spectrometry. Thus, the source of these traces has been determined and a work of tracing has been carried out in the Malvesi site (uranium purification unit). This work has revealed an accumulation of these traces in the uranium purification column, consequently to their extraction by the TBP. A decontamination process of weakly contaminated uranium batches has been proposed using the Parex computer model and tested at the industrial scale. This process is based on the U(VI) extraction by the TBP/ISOPAR mixture and on the use of oxalic acid as the complexing agent of the tetravalent actinides in aqueous phase. It has been tested with success during a purification study of a batch of about 4 tons of uranium contaminated by traces of various radioelements. The preliminary study had taken into account the influence of metallic impurities (iron, nickel, copper) on the radioelements complexation by the oxalate ions. (O.M.)

Determination of Selection Index of Cocoa (Theobroma Cacao L.) Yield Traits Using Regression Methods

OpenAIRE

Setyawan, Bayu; Taryono; Mitrowihardjo, Suyadi

2016-01-01

The increasing chocolate consumption has not been followed by growing production of dry cocoa beans. In order to support the increase in cocoa production, planting materials with high yield are needed. The objective of this research was to determine the components of cocoa traits affecting weight of dry cocoa beans, and set a selection index for superior cocoa trees. The experiment material were four cocoa hybrid populations of which their family ancestry were unknown, and were planted on Sam...

Highly Selective and Sensitized Spectrophotometric Determination of Iron (3) Following Potentiometric Study

International Nuclear Information System (INIS)

Shokrollahi, A.; Ghaedi, M.; Rajabi, H.R.

2007-01-01

A simple, selective and sensitized spectrophotometric method for determination of trace amounts of Fe 3+ ion in tap and waste water solutions has been described. The spectrophotometric determination of Fe 3+ ion using Ferron in the presence of N,N-Dodecy trimethylammonium bromide (DTAB) has been carried out. The Beer's law is obeyed over the concentration range of 0.05-2.6 μg mL -1 of Fe 3+ ion with the relative standard deviation (RSD %) 3 L mol -1 cm -1 . Potentiometric pH titration has been used for prediction of protonation constants of ferron, and evaluating its stoichiometry and respective stability constant with Fe 3+ ion. As it is obvious the most likely species of ferron alone and its complexes are LH (log=7.64), LH 2 (logK=10.52), LH 3 (logK=11.74) and ML 2 (logβ= 23.68), ML 3 (logβ23.68), ML 3 H (logβ= 23.68), ML 3 H 2 (logβ= 23.68) and ML(OH) 2 (logβ=23.68) respectively

Innovative sampling and extraction methods for the determination of nonsteroidal anti-inflammatory drugs in water.

Science.gov (United States)

Tanwar, Shivani; Di Carro, Marina; Magi, Emanuele

2015-03-15

Two different innovative approaches were used for the determination of nonsteroidal anti-inflammatory drugs (NSAIDs) in water: stir bar sorptive extraction (SBSE) and passive sampling, followed by electrospray ionization liquid chromatography-tandem mass spectrometry. SBSE was developed by comparing EG-Silicone and PDMS stir bars and optimizing main parameters to attain high preconcentration. Quantitative analysis was carried out by mass spectrometry in negative ionization mode and multiple reaction monitoring. The SBSE-LC-MS/MS method provided satisfactory figures of merit with LOD (7.5-71 ng L(-1)) and LOQ (22.5-213 ng L(-1)). The developed method was successfully applied to real samples collected from river water and wastewater effluents. The obtained results showed the presence of all analytes at trace levels, in a wide range of concentrations. The passive sampling approach was carried out by using Polar Organic Chemical Integrative Sampler (POCIS); samplers were deployed for 15 days in river and tap water, allowing to detect analytes at ultra-trace levels. Time-Weighted Average concentration of NSAIDs in river water was estimated in the range 0.33-0.46 ng L(-1), using the sampling rates previously obtained by means of a simple calibration system. Copyright © 2014 Elsevier B.V. All rights reserved.

The determination of small amounts of fluoride in uranium compounds by use of an ion-selective electrode

International Nuclear Information System (INIS)

Shelton, B.M.

1975-01-01

A method is presented for the determination of fluoride in uranium metal and oxide at levels from 16 p.p.m. upwards. Uranium is separated from fluoride by extraction into a solution of di(2-ethylhexyl)-phosphoric acid (HDEHP) in carbon tetrachloride. The fluoride remaining in the aqueous phase is determined by potentiometric measurement with an ion-selective electrode. A correction is made for the fluoride lost during the dissolution or extraction step, or both, which is based on a determination of the apparent loss of fluoride on spiked samples that are taken through the whole procedure [af

Ultra-trace determination of methylmercuy in seafood by atomic fluorescence spectrometry coupled with electrochemical cold vapor generation

Energy Technology Data Exchange (ETDEWEB)

Zu, Wenchuan, E-mail: zuhongshuai@126.com [Beijing Institute of Technology, College of Chemistry, Beijing 100081 (China); Beijing Center for Physical & Chemical Analysis, Beijing 100089 (China); Wang, Zhenghao [Beijing Normal University, College of Chemistry, Beijing 100875 (China)

2016-03-05

Highlights: • Methylmercury detection by ECVG-AFS without pre-separation by HPLC is proposed. • Methylmercury is atomized by direct electrochemical reduction with no reductant. • Remarkably better sensitivity is obtained than the traditional HPLC-UV-AFS method. • Glassy carbon is the best cathode material to generate Hg vapor from methylmercury. - Abstract: A homemade electrochemical flow cell was adopted for the determination of methylmercury. The cold vapor of mercury atoms was generated from the surface of glassycarbon cathode through the method of electrolytic reduction and detected by atomic fluorescence spectroscopy subsequently. The operating conditions were optimized with 2 ng mL{sup −1} methylmercury standard solution. The caliberation curve was favorably linear when the concentrations of standard HgCH{sub 3}{sup +} solutions were in the range of 0.2–5 ng mL{sup −1}(as Hg). Under the optimized conditions, the limit of detection (LOD) for methylmercury was 1.88 × 10{sup −3} ng mL{sup −1} and the precision evaluated by relative standard deviation was 2.0% for six times 2 ng mL{sup −1} standard solution replicates. The terminal analytical results of seafood samples, available from local market, showed that the methylmercury content ranged within 3.7–45.8 ng g{sup −1}. The recoveries for methylmercury spiked samples were found to be in the range of 87.6–103.6% and the relative standard deviations below 5% (n = 6)were acquired, which showed this method was feasible for real sample analysis.

Determination of Effective Criteria for Location Selection of Kiln Wood Drying Plants by AHP Technique

Directory of Open Access Journals (Sweden)

Rahim Mohebbi

2011-12-01

Full Text Available This study was aimed at determining the effective criteria for location selection of wood drying plants in Iran. For this purpose, after review and field visit of the industries, 35 key indicators were identified. These criteria were divided into five major groups as: materials, infrastructure, technical, economical and instructional indices. The priority rates of these criteria and sub-criteria were evaluated by AHP technique. The results indicated that among 35 effective sub-criteria in location selection of the plants, the sub-criteria of quality of raw materials(0.152, purchasing raw materials, land cost, profitability, reliability of supply, and sales had the highest priorities, which were rated as 0.118, 0.105, 0.067, 0.061 and 0.057, respectively

Radionuclide determination in environmental samples by inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Lariviere, Dominic; Taylor, Vivien F.; Evans, R. Douglas; Cornett, R. Jack

2006-01-01

The determination of naturally occurring and anthropogenic radionuclides in the environment by inductively coupled plasma mass spectrometry has gained recognition over the last fifteen years, relative to radiometric techniques, as the result of improvement in instrumental performance, sample introduction equipment, and sample preparation. With the increase in instrumental sensitivity, it is now possible to measure ultratrace levels (fg range) of many radioisotopes, including those with half-lives between 1 and 1000 years, without requiring very complex sample pre-concentration schemes. However, the identification and quantification of radioisotopes in environmental matrices is still hampered by a variety of analytical issues such as spectral (both atomic and molecular ions) and non-spectral (matrix effect) interferences and instrumental limitations (e.g., abundance sensitivity). The scope of this review is to highlight recent analytical progress and issues associated with the determination of radionuclides by inductively coupled plasma mass spectrometry. The impact of interferences, instrumental limitations (e.g., degree of ionization, abundance sensitivity, detection limits) and low sample-to-plasma transfer efficiency on the measurement of radionuclides by inductively coupled plasma mass spectrometry will be described. Solutions that overcome these issues will be discussed, highlighting their pros and cons and assessing their impact on the measurement of environmental radioactivity. Among the solutions proposed, mass and chemical resolution through the use of sector-field instruments and chemical reactions/collisions in a pressurized cell, respectively, will be described. Other methods, such as unique sample introduction equipment (e.g., laser ablation, electrothermal vaporisation, high efficiency nebulization) and instrumental modifications/optimizations (e.g., instrumental vacuum, radiofrequency power, guard electrode) that improve sensitivity and performance

Social determinants of health in selected slum areas in Jordan: challenges and policy directions.

Science.gov (United States)

Ajlouni, Musa T

2016-01-01

The unplanned urbanization in Jordan has over time created many informal settlements "slums" around big cities as Amman, Zerka and Aqaba. The purpose of this study was to highlight the most common challenges related to social determinants of health in two selected slum areas in Amman and Aqaba and suggest policy directions and interventions to meet these challenges. In addition to a prestructured interview with all household heads living in the two slum sites, focus group meetings with a purposefully selected sample of 12 slum dwellers in each site were used to assess the structural and intermediary determinants of health as perceived by slum residents in the two study locations. The study found that slum residents in the two locations suffer from many challenges as severe poverty; unemployment; illiteracy and low education attainments; gender discrimination; insufficient and poor diet; social and official exclusion; unhealthy environment; lack of water supply, electricity and basic sanitation facilities; high prevalence of diseases; and insufficient and inappropriate health services. Specific policy directions to meet these challenges were recommended and grouped into three main clusters: social protection, social inclusion and empowerment. New plans and tools should be developed by local authorities in Jordan to understand, protect, include and empower those vulnerable people who are forced to live in these unhealthy and inhuman environments. Copyright © 2014 John Wiley & Sons, Ltd.

Polytetrafluorethylene film-based liquid-three phase micro extraction coupled with differential pulse voltammetry for the determination of atorvastatin calcium.

Science.gov (United States)

Ensafi, Ali A; Khoddami, Elaheh; Rezaei, Behzad

2013-01-01

In this paper, we describe a new combination method based on polytetrafluorethylene (PTFE) film-based liquid three-phase micro extraction coupled with differential pulse voltammetry (DPV) for the micro extraction and quantification of atorvastatin calcium (ATC) at the ultra-trace level. Different factors affecting the liquid-three phases micro extraction of atorvastatin calcium, including organic solvent, pH of the donor and acceptor phases, concentration of salt, extraction time, stirring rate and electrochemical factors, were investigated, and the optimal extraction conditions were established. The final stable signal was achieved after a 50 min extraction time, which was used for analytical applications. An enrichment factor of 21 was achieved, and the relative standard deviation (RSD) of the method was 4.5% (n = 4). Differential pulse voltammetry exhibited two wide linear dynamic ranges of 20.0-1000.0 pmol L(-1) and 0.001-11.0 µmol L(-1) of ATC. The detection limit was found to be 8.1 pmol L(-1) ATC. Finally, the proposed method was used as a new combination method for the determination of atorvastatin calcium in real samples, such as human urine and plasma.

Determination of pigments in colour layers on walls of some selected historical buildings using optical and scanning electron microscopy

International Nuclear Information System (INIS)

Skapin, A. Sever; Ropret, P.; Bukovec, P.

2007-01-01

For successful restoration of painted walls and painted coloured finishing coats it is necessary to determine the composition of the original colour layers. Identification of the pigments used in The Cistercian Abbey of Sticna and The Manor of Novo Celje was carried out using optical and scanning electron microscopy. Selected samples of wall paintings were inspected by the combined application of an optical microscope and a low-vacuum Scanning Electron Microscope to determine their colour and structural features and to identify the position of individual pigment grains. Energy dispersive spectroscopy was used to determine the elemental distribution on selected surfaces and elemental composition of individual pigments. It was found that the most abundantly used pigments were iron oxide red, cinnabar, green earth, umber, calcium carbonate white, ultramarine, yellow ochre and carbon black. These identifications have allowed us to compare the use of various pigments in buildings from different historical periods

Determination of hepatocellular carcinoma grade by needle biopsy is unreliable for liver transplant candidate selection.

Science.gov (United States)

Court, Colin M; Harlander-Locke, Michael P; Markovic, Daniela; French, Samuel W; Naini, Bita V; Lu, David S; Raman, Steven S; Kaldas, Fady M; Zarrinpar, Ali; Farmer, Douglas G; Finn, Richard S; Sadeghi, Saeed; Tomlinson, James S; Busuttil, Ronald W; Agopian, Vatche G

2017-09-01

The objective of this article is to evaluate the utility of preoperative needle biopsy (PNB) grading of hepatocellular carcinoma (HCC) as a biomarker for liver transplantation (LT) candidate selection. Given the prognostic significance of HCC tumor grade, PNB grading has been proposed as a biomarker for LT candidate selection. Clinicopathologic characteristics of HCC LT recipients (1989-2014) with a PNB were analyzed, and the concordance of PNB grade to explant grade and vascular invasion was assessed to determine whether incorporation of PNB grade to accepted transplant criteria improved candidate selection. Of 965 patients undergoing LT for HCC, 234 (24%) underwent PNB at a median of 280 days prior to transplant. Grade by PNB had poor concordance to final explant pathology (κ = 0.22; P = 0.003), and low sensitivity (29%) and positive predictive value (35%) in identifying poorly differentiated tumors. Vascular invasion was predicted by explant pathologic grade (r s = 0.24; P Liver Transplantation 23 1123-1132 2017 AASLD. © 2017 by the American Association for the Study of Liver Diseases.

Ionic liquid solvent bar micro-extraction of CdCln(n-2)- species for ultra-trace Cd determination in seawater.

Science.gov (United States)

Herce-Sesa, Belén; López-López, José A; Moreno, Carlos

2018-02-01

Water analysis of trace metals has been benefited by recent studies on sample preparation by liquid micro-extraction. However, there are still limitations for its application to seawater, such as the need of additives to preserve the sample or the availability of chemical extractants for the selective extraction from highly saline samples. In this work, a three phase solvent bar micro-extraction (3SBME) system containing the ionic liquid trioctylmethylammonium chloride (Aliquat ® 336) has been used for isolation and pre-concentration of Cd from seawater samples, due to its ability for ionic exchange of CdCl n (n-2)- . The system was optimized to work at the natural pH of seawater, and conditions for application to real samples were 0.18 M Aliquat ® 336 dissolved in kerosene with 0.25 M dodecan-1-ol as organic solution, 1.5 M HNO 3 as acceptor solution, 60 min extraction time, and 800 rpm stirring speed in the sample. Loss of organic solution into the sample during extraction was evaluated and revealed its dependence on stirring rate and extraction time. Under optimum conditions samples containing Cd 0.09-0.90 nM were pre-concentrated 65 times. GF-AAS was used for metal quantification with a limit of detection of 0.04 nM. Accuracy was successfully evaluated measuring Cd in a seawater certified reference material BCR-403. Copyright © 2017 Elsevier Ltd. All rights reserved.

Potentiometric Determination of Ketotifen Fumarate in Pharmaceutical Preparations and Urine Using Carbon Paste and PVC Membrane Selective Electrodes

Directory of Open Access Journals (Sweden)

Eman Y. Z. Frag

2011-01-01

Full Text Available This study compares between unmodified carbon paste (CPE; the paste has no ion pair and polyvinyl chloride (PVC membrane selective electrodes that were used in potentiometric determination of ketotifen fumarate (KTF, where sodium tetraphenylborate (NaTPB was used as titrant. The performance characteristics of these sensors were evaluated according to IUPAC recommendations which reveal a fast, stable, and linear response for KTF over the concentration range of 10−7 to 10−2 mol L−1. The electrodes show Nernstian slope value of 52.51±0.20 and 51.51±0.25 mV decade−1 for CPE and PVC membrane electrodes at 30∘C, respectively. The potential is nearly stable over the pH range 3.0–6.0 and 2.0–7.0 for CPE and PVC membrane electrodes, respectively. Selectivity coefficient values towards different inorganic cations, sugars, and amino acids reflect high selectivity of the prepared electrodes. The electrodes responses at different temperatures were also studied, and long operational lifetime of 12 and 5 weeks for CPE and PVC membrane electrodes, respectively, were found. These are used for determination of ketotifen fumarate using potentiometric titration, calibration, and standard addition methods in pure samples, its pharmaceutical preparations (Zaditen tablets, and biological fluid (urine. The direct potentiometric determination of KTF using the proposed sensors gave recoveries % of 98.97±0.53 and 98.62±0.74 with RSD 1.42 and 0.63% for CPE and PVC membrane selective electrodes, respectively. Validation of the method shows suitability of the proposed sensors for use in quality control assessment of KTF. The obtained results were in a good agreement with those obtained using the reported spectrophotometric method.

Potentiometric determination of ketotifen fumarate in pharmaceutical preparations and urine using carbon paste and PVC membrane selective electrodes.

Science.gov (United States)

Frag, Eman Y Z; Mohamed, Gehad G; Khalil, Mohamed M; Hwehy, Mohammad M A

2011-01-01

This study compares between unmodified carbon paste (CPE; the paste has no ion pair) and polyvinyl chloride (PVC) membrane selective electrodes that were used in potentiometric determination of ketotifen fumarate (KTF), where sodium tetraphenylborate (NaTPB) was used as titrant. The performance characteristics of these sensors were evaluated according to IUPAC recommendations which reveal a fast, stable, and linear response for KTF over the concentration range of 10(-7) to 10(-2) mol L(-1). The electrodes show Nernstian slope value of 52.51 ± 0.20 and 51.51 ± 0.25 mV decade(-1) for CPE and PVC membrane electrodes at 30°C, respectively. The potential is nearly stable over the pH range 3.0-6.0 and 2.0-7.0 for CPE and PVC membrane electrodes, respectively. Selectivity coefficient values towards different inorganic cations, sugars, and amino acids reflect high selectivity of the prepared electrodes. The electrodes responses at different temperatures were also studied, and long operational lifetime of 12 and 5 weeks for CPE and PVC membrane electrodes, respectively, were found. These are used for determination of ketotifen fumarate using potentiometric titration, calibration, and standard addition methods in pure samples, its pharmaceutical preparations (Zaditen tablets), and biological fluid (urine). The direct potentiometric determination of KTF using the proposed sensors gave recoveries % of 98.97 ± 0.53 and 98.62 ± 0.74 with RSD 1.42 and 0.63% for CPE and PVC membrane selective electrodes, respectively. Validation of the method shows suitability of the proposed sensors for use in quality control assessment of KTF. The obtained results were in a good agreement with those obtained using the reported spectrophotometric method.

Ion-Selective Electrodes for the Potentiometric Determination of Pramoxine HCl Using Different Ionophores.

Science.gov (United States)

Ramadan, Nesrin K; Merey, Hanan A

2012-12-01

Four novel pramoxine HCl (PAM) selective electrodes were investigated with 2-nitrophenyl octylether as a plasticiser in a polymeric matrix of polyvinyl chloride (PVC). Sensor 1 was fabricated using sodium-tetraphenylborate (TPB) as an anionic exchanger without incorporation of an ionophore. Sensor 2 used 2-hydroxy propyl -cyclodextrin as an ionophore, while sensors 3 and 4 were constructed using 4-sulfocalix-6-arene and 4-sulfocalix-8-arene respectively as ionophores. Linear responses of PAM within the concentration ranges of 1.0 × 10-4 to 1.0 × 10-2 mol L-1 and 1.0 × 10-5 to 1.0 × 10-2 mol L-1 were obtained using sensors 1 and 2, respectively and 1.0 × 10-6 to 1.0 × 10-2 mol L-1 were obtained using sensors 3 and 4. Nernstian slopes of 50.4 ± 0.6, 54.3 ± 0.8, 56.3 ± 0.3 and 59.1 ± 0.5 mV/decade over the pH range of 3.0-6.0 were observed. The selectivity coefficients of the developed sensors indicated excellent selectivity for PAM. The utility of 2-hydroxy- propylcyclodextrin (2HP-β-CD) and 4-sulfocalix [6,8] arene (SC 6, 8) as ionophores had a significant influence on increasing the membrane sensitivity and selectivity of sensors 2, 3 and 4 compared to sensor 1. The proposed sensors displayed useful analytical characteristics for the determination of PAM in bulk powder, pharmaceutical formulation, and in biological fluid. Validation of the method showed the suitability of the proposed electrodes for the use in the quality control assessment of the drug. Furthermore, statistical comparison between the results obtained by the proposed method and the official method of the drug was performed and no significant difference was found.

Determining Selection across Heterogeneous Landscapes: A Perturbation-Based Method and Its Application to Modeling Evolution in Space.

Science.gov (United States)

Wickman, Jonas; Diehl, Sebastian; Blasius, Bernd; Klausmeier, Christopher A; Ryabov, Alexey B; Brännström, Åke

2017-04-01

Spatial structure can decisively influence the way evolutionary processes unfold. To date, several methods have been used to study evolution in spatial systems, including population genetics, quantitative genetics, moment-closure approximations, and individual-based models. Here we extend the study of spatial evolutionary dynamics to eco-evolutionary models based on reaction-diffusion equations and adaptive dynamics. Specifically, we derive expressions for the strength of directional and stabilizing/disruptive selection that apply both in continuous space and to metacommunities with symmetrical dispersal between patches. For directional selection on a quantitative trait, this yields a way to integrate local directional selection across space and determine whether the trait value will increase or decrease. The robustness of this prediction is validated against quantitative genetics. For stabilizing/disruptive selection, we show that spatial heterogeneity always contributes to disruptive selection and hence always promotes evolutionary branching. The expression for directional selection is numerically very efficient and hence lends itself to simulation studies of evolutionary community assembly. We illustrate the application and utility of the expressions for this purpose with two examples of the evolution of resource utilization. Finally, we outline the domain of applicability of reaction-diffusion equations as a modeling framework and discuss their limitations.

Separation of chloride and fluoride from uranium compounds and their determination by ion selective electrodes

International Nuclear Information System (INIS)

Pires, M.A.F.; Abrao, A.

1982-01-01

Fluoride and chloride must be rigorously controlled in uranium compounds, especially in ceramic grade UO 2 . Their determination is very difficult without previous uranium separation, particularly when both are at a low concentration. A simple procedure is described for this separation using a strong cationic resin to retain the uranyl ion. Both anions are determined in the effluent solution. Uranium compounds of nuclear fuel cycle, especially ammonium diuranate, ammonium uranyl tricarbonate, sodium diuranate, uranium trioxide and dioxide and uranium peroxide are dissolved in nitric acid and the solutions are percolated through the resin column. Chloride and fluoride are determined in the effluent by selective electrodes, the detection limits being 0.02 μg F - /ml and 1.0 μg Cl - /ml. The dissolution of the sample, the acidity of the solution, the measurement conditions and the sensitivity of the method are discussed. (Author) [pt

Using gold nanostars modified pencil graphite electrode as a novel substrate for design a sensitive and selective Dopamine aptasensor

Energy Technology Data Exchange (ETDEWEB)

Talemi, Rasoul Pourtaghavi, E-mail: rasoulpourtaghavi@gmail.com [Faculty of Chemistry, Kharazmi University, Tehran (Iran, Islamic Republic of); Mousavi, Seyed Mehdi [Faculty of Chemistry, Kharazmi University, Tehran (Iran, Islamic Republic of); Afruzi, Hossein [Department of Chemistry, Faculty of Science, Lorestan University, Lorestan (Iran, Islamic Republic of)

2017-04-01

For the first time, gold nanostars (GNS) were applied for electrostatic and covalent immobilizing a thiol modified Dopamine aptamer on the pencil graphite electrode and signal amplification. Dopamine aptamer was immobilized on the gold nanostars through electrostatic interaction between negatively charged phosphate groups of aptamer and positively charged gold nanostars and Au−S well known covalent interaction. In the presence of Dopamine in the test solution, the charge transfer resistance (R{sub CT}) on the electrode surface increased with the increase of the Dopamine concentration due to specific interaction between Dopamine aptamer and Dopamine molecules, which made a barrier for electrons and inhibited the electron-transfer. So, the proposed approach showed a high sensitivity and a wide linearity to Dopamine in the range from 1.0 (± 0.1) to 100.0 (± 0.3) ng L{sup −1} (ppt) with detection and quantification limits of 0.29 (± 0.10) and 0.90 (± 0.08) ng L{sup −1} (ppt), respectively. Finally, the sensor was successfully used for determination of Dopamine in biological (human blood plasma and urine) samples. The results open up the path for manufacturing cost effective aptasensors for other biomedical applications. - Highlights: • A novel impedimetric aptasensor was prepared for dopamine ultra-trace determination. • Gold nanostar used for electrostatic and covalent immobilization of a thiolated dopamine aptamer. • The proposed aptasensor had high sensitivity, specificity, and regeneration ability.

Using gold nanostars modified pencil graphite electrode as a novel substrate for design a sensitive and selective Dopamine aptasensor

International Nuclear Information System (INIS)

Talemi, Rasoul Pourtaghavi; Mousavi, Seyed Mehdi; Afruzi, Hossein

2017-01-01

For the first time, gold nanostars (GNS) were applied for electrostatic and covalent immobilizing a thiol modified Dopamine aptamer on the pencil graphite electrode and signal amplification. Dopamine aptamer was immobilized on the gold nanostars through electrostatic interaction between negatively charged phosphate groups of aptamer and positively charged gold nanostars and Au−S well known covalent interaction. In the presence of Dopamine in the test solution, the charge transfer resistance (R CT ) on the electrode surface increased with the increase of the Dopamine concentration due to specific interaction between Dopamine aptamer and Dopamine molecules, which made a barrier for electrons and inhibited the electron-transfer. So, the proposed approach showed a high sensitivity and a wide linearity to Dopamine in the range from 1.0 (± 0.1) to 100.0 (± 0.3) ng L −1 (ppt) with detection and quantification limits of 0.29 (± 0.10) and 0.90 (± 0.08) ng L −1 (ppt), respectively. Finally, the sensor was successfully used for determination of Dopamine in biological (human blood plasma and urine) samples. The results open up the path for manufacturing cost effective aptasensors for other biomedical applications. - Highlights: • A novel impedimetric aptasensor was prepared for dopamine ultra-trace determination. • Gold nanostar used for electrostatic and covalent immobilization of a thiolated dopamine aptamer. • The proposed aptasensor had high sensitivity, specificity, and regeneration ability.

Selective floatation-spectrophotometric determination of tellurium (4) with papaverine and butyl rhodamine B

International Nuclear Information System (INIS)

Skripchuk, V.G.

1981-01-01

It is shown, that papaverine reacts with a bromide complex of tellurium (4) to form a compound readily floated by toluene. The floatation is carried out from an aqueous solution, 5.2 M in H 2 SO 4 , 0.2 M in KBr and 5.4x10 -3 M in papaverine. The absorbance is a function of tellurium (4) concentration over a range of 5-100 μg Te/5 ml. Such a highly sensitive reagent as butylrhodamine B can be effectively substituted for papaverine. The floatation results in better selectivity. The method makes it possible to determine tellurium in blister, anodic and cathodic copper without matrix preseparation [ru

Highly selective direct determination of chlorate ions by using a newly developed potentiometric electrode based on modified smectite.

Science.gov (United States)

Topcu, Cihan

2016-12-01

A novel polyvinyl chloride membrane chlorate (ClO 3 - ) selective electrode based on modified smectite was developed for the direct determination of chlorate ions and the potentiometric performance characteristics of its were examined. The best selectivity and sensitivity for chlorate ions were obtained for the electrode membrane containing ionophore/polyvinylchloride/o-nitrophenyloctylether in composition of 12/28/60 (w/w%). The proposed electrode showed a Nernstian response toward chlorate ions at pH=7 in the concentration range of 1×10 -7 -1×10 -1 M and the limit of detection was calculated as 9×10 -8 M from the constructed response plot. The linear slope of the electrode was -61±1mVdecade -1 for chlorate activity in the mentioned linear working range. The selectivity coefficients were calculated according to both the matched potential method and the separate solution method. The calculated selectivity coefficients showed that the electrode performed excellent selectivity for chlorate ions. The potentiometric response of electrode toward chlorate ions was found to be highly reproducible. The electrode potential was stable between pH=4-10 and it had a dynamic response time of <5s. The potentiometric behavior of the electrode in partial non-aqueous medium was also investigated and the obtained results (up to 5% (v/v) alcohol) were satisfactory. The proposed electrode was used during 15 weeks without any significant change in its potential response. Additionally, the electrode was very useful in water analysis studies such as dam water, river water, tap water, and swimming pool water where the direct determination of chlorate ions was required. Copyright © 2016 Elsevier B.V. All rights reserved.

Extractive separation of uranium(VI) as perchlorate/chloroacetate complexes with 1-phenyl-2,3 dimethyl-5-pyrazolone and its applications

International Nuclear Information System (INIS)

Bose, R.; Murty, D.S.R.

2003-01-01

The extraction of U(VI) with 1-phenyl 2,3 dimethyl-5-pyrazolone, at a pH of 2.5, in the presence of common anions, like perchlorate and tri-, di-, and monochloroacetates has been investigated. The optimum experimental conditions have been evaluated by studying various parameters such as pH, equilibration period, reagent concentration, metal concentration, and solvents. Effect of diverse anions and cations on the extraction has also been studied. The extracted species, determined by log D - log R plots are represented as, [UO 2 (Apy) 4 (ClO 4 ) 2 ], [UO 2 (Apy) 2 (TCA) 2 ], [UO 2 (Apy) 2 (DCA) 2 ], [UO 2 (Apy)(H 2 O)(MCA) 2 ]. The conditional stability constants of the quantitatively extracted complexes are calculated. The proposed method allows the selective separation of uranium(VI) from multicomponent mixtures and geological matrices and is also applied for the separation and chemical characterization of impurities at trace and ultratrace levels. (author)

Determination of technetium-99, thorium-230 and uranium-234 in soils by inductively coupled plasma mass spectrometry using flow injection preconcentration

International Nuclear Information System (INIS)

Hollenbach, Mark; Grohs, James; Mamich, Stephen; Kroft, Marilyn; Denoyer, E.R.

1994-01-01

A new method is described for the determination of 99 Tc, 230 Th, and 234 U at ultra-trace levels in soils. The method used flow injection (FI) for on-line preconcentration of 99 Tc, 230 Th and 234 U prior to detection using inductively coupled plasma mass spectrometry (ICP-MS). The FI-ICP-MS method results in greater sensitivity and freedom from interferences compared with direct aspiration into an ICP mass spectrometer. Detection limits are improved by approximately a factor of 10. The FI-ICP-MS method is also faster, less labour intensive and generates less laboratory waste than traditional radiochemical methods. The accuracy of the method was tested for 99 Tc by comparison to liquid scintillation counting and for 230 Th and 234 U by analysis of a US Department of Energy reference soil. Detection limits in the soil for 99 Tc, 230 Th and 234 U were 11 mBq g -1 (0.02 ng g -1 ), 3.7 mBq g -1 (0.005 ng g -1 ) and 0.74 mBq g -1 (0.003 ng g -1 ), respectively. Sample preparation, analysis protocol, and method validation are described. (Author)

Measurement of volatile plant compounds in field ambient air by thermal desorption-gas chromatography-mass spectrometry.

Science.gov (United States)

Cai, Xiao-Ming; Xu, Xiu-Xiu; Bian, Lei; Luo, Zong-Xiu; Chen, Zong-Mao

2015-12-01

Determination of volatile plant compounds in field ambient air is important to understand chemical communication between plants and insects and will aid the development of semiochemicals from plants for pest control. In this study, a thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method was developed to measure ultra-trace levels of volatile plant compounds in field ambient air. The desorption parameters of TD, including sorbent tube material, tube desorption temperature, desorption time, and cold trap temperature, were selected and optimized. In GC-MS analysis, the selected ion monitoring mode was used for enhanced sensitivity and selectivity. This method was sufficiently sensitive to detect part-per-trillion levels of volatile plant compounds in field ambient air. Laboratory and field evaluation revealed that the method presented high precision and accuracy. Field studies indicated that the background odor of tea plantations contained some common volatile plant compounds, such as (Z)-3-hexenol, methyl salicylate, and (E)-ocimene, at concentrations ranging from 1 to 3400 ng m(-3). In addition, the background odor in summer was more abundant in quality and quantity than in autumn. Relative to previous methods, the TD-GC-MS method is more sensitive, permitting accurate qualitative and quantitative measurements of volatile plant compounds in field ambient air.

Ultratrace analysis for organolead compounds in Greenland snow

International Nuclear Information System (INIS)

Lobinski, R.; Szpunar-Lobinska, J.; Adams, F.C.

1994-01-01

The degradation products of tetraalkyllead compounds used as antiknock additives are unique indicators of automotive environmental pollution by lead. Recent dramatic improvements in species-specific ultrasensitive analytical procedures enabled the identification and quantification of organolead compounds in ancient Greenland snow which is considered as the archives of northern hemispheric pollution records. Organolead species determined in fresh and ancient polar snow demonstrate unambiguously the global range of petrol-related pollution not only with ionic Pb 2+ but also with more toxic metalloorganic compounds. (authors). 9 refs., 5 figs

Liquidity Determinants of the Selected Banking Sectors and their Size Groups

Directory of Open Access Journals (Sweden)

Jana Laštůvková

2016-01-01

Full Text Available The article focuses on the factors affecting the liquidity of selected bank sectors, as well as their size groups, using panel regression analysis. For higher complexity of the results, multiple dependent variables are used: liquidity creation, outflow and net change. The values are calculated based on the specific method of liquidity risk measurement – gross liquidity flows. The results indicate both multiple effects of some factors on the given variables, as well as isolated influence of factors on a single liquidity form or size group. Thus, when looking for determinants using just one form of liquidity, such as creation, the results need not necessarily comprehensively show the influence of the given factors, and can lead to erroneous conclusions. The results also point to the differing behaviours of the size groups and their different sensitivity on the factors; smaller banks have shown higher sensitivity on macroeconomic variables. Higher flexibility in regulation could lead to higher optimization.

A dihydrazone based fluorescent probe for selective determination of Al{sup 3+} ions

Energy Technology Data Exchange (ETDEWEB)

Pratap Singh, Divya; Singh, Vinod P., E-mail: singvp@yahoo.co.in

2014-11-15

A highly selective fluorescent sensor N,N′-bis((2-hydroxynaphthalen-1-yl)methylene) oxalohydrazide (H{sub 2}ohn) for the determination of Al{sup 3+} ions was synthesized and characterized by different physico-chemical and spectroscopic techniques. The single crystal structure of H{sub 2}ohn receptor has also been reported. The H{sub 2}ohn shows an enhanced fluorescence in the presence of Al{sup 3+} ions in ethanol–water (2:3 v/v) solution. Other cations viz. Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Mn{sup 2+}, Fe{sup 3+}, Co{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, Zn{sup 2+}, Pb{sup 2+}, Cd{sup 2+} and Hg{sup 2+} show no appreciable change in fluorescence intensity. The binding mode of H{sub 2}ohn receptor with Al{sup 3+} was studied by UV–visible, fluorescence and {sup 1}H NMR titrations. The receptor acts as a dibasic hexadentate ligand and interacts with two Al{sup 3+} ions with a high binding constant K{sub B}=2.62×10{sup 11} M{sup −2}. The lowest detection limit for Al{sup 3+} complex of H{sub 2}ohn was determined to be 8.56×10{sup −10} M. The structures of H{sub 2}ohn and its Al(III) complex were also optimized by DFT calculations. - Highlights: • A dihydrazone based fluorescent sensor is synthesized. • Characterized by IR, NMR, UV−visible and mass spectral analysis. • The receptor serves as a selective fluorescent sensor for Al{sup 3+} over other cations. • The sensing property is monitored by UV−visible, fluorescence and NMR spectroscopy. • A high binding constant of the receptor with Al{sup 3+} is reported here.

Ultra-Trace Analysis of Krypton-85

International Nuclear Information System (INIS)

Daerr, H.; Kalinowski, M.; Kohler, M.; Sahling, P.

2010-01-01

To strengthen the efficiency and effectiveness of nuclear safeguards for detecting undeclared nuclear material and activities we propose to use the radioactive krypton isotope Krypton-85 as a tracer for clandestine plutonium production. The main idea is to detect inexplicable atmospheric Kr85 concentration using the novel technology atom trap trace analysis (ATTA) in order to detect an undeclared reprocessing facility. The Additional Protocol (INFCIRC/540, 1997) establishes the possibility to take environmental samples. Krypton-85 has a combination of unique features which makes it an ideal tracer for plutonium separation activities anywhere in the world. It is always generated along with plutonium and 99.9% remains within the fuel cladding. Due to its half-life of 10.76 years, significant amounts of krypton-85 still remain in the spent fuel even after long cooling times. Krypton is not removed from the atmosphere by any processes like chemical reactions or wash-out. Furthermore, there are no other relevant sources of krypton-85 besides of reprocessing. The novel technology of atom trap trace analysis (ATTA) has been demonstrated by the physics group at Argonne National Laboratory in 1999. This is an ultra-sensitive trace analysis technique able to detect single krypton atoms. We are setting up an ATTA apparatus in our laboratory, which is designed to fulfill all requirements to detect clandestine plutonium production. Our goal is to determine Krypton-85 concentration of one liter samples of atmospheric air with an analysis time of 3 hours. This sample volume reduction is a significant step, since one liter can be taken as a grab sample by sucking it directly into pre-evacuated bottles at atmospheric pressure. The small samples size and the short analysis time of ATTA will make it possible to use krypton-85 as a tracer for clandestine plutonium production with routine operation. (author)

Determinants of Condom Use among Selected Migrant Commercial ...

African Journals Online (AJOL)

AJRH Managing Editor

among migrant men and women in selected commercial farms in two provinces of South Africa. The study analysed 943 ... employers and supervisors and their low-wage employees. ... The current study addresses two gaps in the literature.

Determination of laser cutting process conditions using the preference selection index method

Science.gov (United States)

Madić, Miloš; Antucheviciene, Jurgita; Radovanović, Miroslav; Petković, Dušan

2017-03-01

Determination of adequate parameter settings for improvement of multiple quality and productivity characteristics at the same time is of great practical importance in laser cutting. This paper discusses the application of the preference selection index (PSI) method for discrete optimization of the CO2 laser cutting of stainless steel. The main motivation for application of the PSI method is that it represents an almost unexplored multi-criteria decision making (MCDM) method, and moreover, this method does not require assessment of the considered criteria relative significances. After reviewing and comparing the existing approaches for determination of laser cutting parameter settings, the application of the PSI method was explained in detail. Experiment realization was conducted by using Taguchi's L27 orthogonal array. Roughness of the cut surface, heat affected zone (HAZ), kerf width and material removal rate (MRR) were considered as optimization criteria. The proposed methodology is found to be very useful in real manufacturing environment since it involves simple calculations which are easy to understand and implement. However, while applying the PSI method it was observed that it can not be useful in situations where there exist a large number of alternatives which have attribute values (performances) very close to those which are preferred.

Determination of specific activity of americium and plutonium in selected environmental samples

International Nuclear Information System (INIS)

Trebunova, T.

1999-01-01

The aim of this work was development of method for determination of americium and plutonium in environmental samples. Developed method was evaluated on soil samples and after they was applied on selected samples of fishes (smoked mackerel, herring and fillet from Alaska hake). The method for separation of americium is based on liquid separation with Aliquate-336, precipitation with oxalic acid and using of chromatographic material TRU-Spec TM .The intervals of radiochemical yields were from 13.0% to 80.9% for plutonium-236 and from 10.5% to 100% for americium-241. Determined specific activities of plutonium-239,240 were from (2.3 ± 1.4) mBq/kg to (82 ± 29) mBq/kg, the specific activities of plutonium-238 were from (14.2 ± 3.7) mBq/kg to (708 ± 86) mBq/kg. The specific activities of americium-241 were from (1.4 ± 0.9) mBq/kg to (3360 ± 210) mBq/kg. The fishes from Baltic Sea as well as from North Sea show highest specific activities then fresh-water fishes from Slovakia. Therefore the monitoring of alpha radionuclides in foods imported from territories with nuclear testing is recommended

Determination of terbium in phosphate rock by Tb3+-selective fluorimetric optode based on dansyl derivative as a neutral fluorogenic ionophore.

Science.gov (United States)

Hosseini, Morteza; Ganjali, Mohammad Reza; Veismohammadi, Bahareh; Faridbod, Farnoush; Abkenar, Shiva Dehghan; Norouzi, Parviz

2010-04-07

For the first time a highly sensitive and selective fluorimetric optode membrane was prepared for determination of trace amounts of Tb(III) ions in phosphate rock samples. The Tb(III) sensing system was constructed by incorporating 5-(dimethylamino)-N'-(2-hydroxy-1-naphthoyl) naphthalene-1-sulfonohydrazine (L) as a neutral Tb(III)-selective fluoroionophore, in the plasticized PVC membrane containing sodium tetraphenyl borate as a liphophilic anionic additive. The response of the optode is based on the strong fluorescence quenching of L by Tb(3+) ions. At a pH value of 5.0, the optode displays a wide concentration range of 1.0 x 10(-7) to 1.0 x 10(-2)M, with a relatively fast response time of less than 45 s. In addition, to high stability and reproducibility, the sensor shows a unique selectivity towards Tb(3+) ion with respect to common cations. The optode was applied successfully to the trace determination of terbium ion in binary mixture and water samples and the determination of Tb(3+) in phosphate rock samples. Crown Copyright 2010. Published by Elsevier B.V. All rights reserved.

Determination of the total nitrate content of thorium nitrate solution with a selective electrode

International Nuclear Information System (INIS)

Wirkner, F.M.

1979-01-01

The nitrate content of thorium nitrate solutions is determined with a liquid membrane nitrate selective electrode utilizing the known addition method in 0.1 M potassium fluoride medium as ionic strength adjustor. It is studied the influence of pH and the presence of chloride, sulphate, phosphate, meta-silicate, thorium, rare earths, iron, titanium, uranium and zirconium at the same concentrations as for the aqueous feed solutions in the thorium purification process. The method is tested in synthetic samples and in samples proceeding from nitric dissolutions of thorium hidroxide and thorium oxicarbonate utilized as thorium concentrates to be purified [pt

Porous glasses as a host of luminescent materials, their applications and site selective determination

Energy Technology Data Exchange (ETDEWEB)

Reisfeld, Renata, E-mail: renata.reisfeld@mail.huji.ac.il [Institute of Chemistry, Hebrew University of Jerusalem, Givat-Ram, Jerusalem 91904 (Israel); Jasinska, Bozena [Institute of Physics, Maria Curie-Sklodowska University, Pl. M. Curie-Skłodowsskiej 1, 20-031 Lublin (Poland); Levchenko, Viktoria [Institute of Chemistry, Hebrew University of Jerusalem, Givat-Ram, Jerusalem 91904 (Israel); Gorgol, Marek [Institute of Physics, Maria Curie-Sklodowska University, Pl. M. Curie-Skłodowsskiej 1, 20-031 Lublin (Poland); Saraidarov, Tsiala; Popov, Inna [Institute of Chemistry, Hebrew University of Jerusalem, Givat-Ram, Jerusalem 91904 (Israel); Antropova, Tatiana [I. V. Grebenshchikov Institute of the Chemistry of Silicates, Russian Academy of Sciences, Nab. Makarova, 2, Liter B, Saint-Petersburg 199034 (Russian Federation); Rysiakiewicz-Pasek, Ewa [Institute of Physics, Wroclaw University of Technology, W. Wyspianskiego 27, 50-370 Wroclaw (Poland)

2016-01-15

The site selective distribution of pore sizes in pure porous glasses and glasses doped by a luminescent colorant is determined by luminescent spectroscopy, SEM, SAXS and PALS. The potential applications of the studied materials as environmental and biological sensors are outlined. We suggest how luminescent porous glasses doped by complexes of Gd can act as solid scintillators in tracing elementary particles like neutrino. - Highlights: • Porous glasses are a medium for large number of luminescent materials. • Size distribution of empty and filled pores is studied. • The validity of data obtained by different methods is analyzed.

Total cyanide mass measurement with micro-ion selective electrode for determination of specific activity of carbon-11 cyanide.

Science.gov (United States)

Shea, Colleen; Alexoff, David L; Kim, Dohyun; Hoque, Ruma; Schueller, Michael J; Fowler, Joanna S; Qu, Wenchao

2015-08-01

In this research, we aim to directly measure the specific activity (SA) of the carbon-11 cyanide ([(11)C]CN¯) produced by our in-house built automated [(11)C]HCN production system and to identify the major sources of (12)C-cyanide ((12)CN¯). The [(11)C]CN¯ is produced from [(11)C]CO2, which is generated by the (14)N(p,α)(11)C nuclear reaction using a cyclotron. Direct measurement of cyanide concentrations was accomplished using a relatively inexpensive, and easy to use ion selective electrode (ISE) which offered an appropriate range of sensitivity for detecting mass. Multiple components of the [(11)C]HCN production system were isolated in order to determine their relative contributions to (12)CN¯ mass. It was determined that the system gases were responsible for approximately 30% of the mass, and that the molecular sieve/nickel furnace unit contributed approximately 70% of the mass. Beam on target (33µA for 1 and 10min) did not contribute significantly to the mass. Additionally, we compared the SA of our [(11)C]HCN precursor determined using the ISE to the SA of our current [(11)C]CN¯ derived radiotracers determined by HPLC to assure there was no significant difference between the two methods. These results are the first reported use of an ion selective electrode to determine the SA of no-carrier-added cyanide ion, and clearly show that it is a valuable, inexpensive and readily available tool suitable for this purpose. Copyright © 2015 Elsevier Ltd. All rights reserved.

Neuronal matrix metalloproteinase-9 is a determinant of selective neurodegeneration.

Science.gov (United States)

Kaplan, Artem; Spiller, Krista J; Towne, Christopher; Kanning, Kevin C; Choe, Ginn T; Geber, Adam; Akay, Turgay; Aebischer, Patrick; Henderson, Christopher E

2014-01-22

Selective neuronal loss is the hallmark of neurodegenerative diseases. In patients with amyotrophic lateral sclerosis (ALS), most motor neurons die but those innervating extraocular, pelvic sphincter, and slow limb muscles exhibit selective resistance. We identified 18 genes that show >10-fold differential expression between resistant and vulnerable motor neurons. One of these, matrix metalloproteinase-9 (MMP-9), is expressed only by fast motor neurons, which are selectively vulnerable. In ALS model mice expressing mutant superoxide dismutase (SOD1), reduction of MMP-9 function using gene ablation, viral gene therapy, or pharmacological inhibition significantly delayed muscle denervation. In the presence of mutant SOD1, MMP-9 expressed by fast motor neurons themselves enhances activation of ER stress and is sufficient to trigger axonal die-back. These findings define MMP-9 as a candidate therapeutic target for ALS. The molecular basis of neuronal diversity thus provides significant insights into mechanisms of selective vulnerability to neurodegeneration. Copyright © 2014 Elsevier Inc. All rights reserved.

On-line preconcentration of ultra-trace thallium(I in water samples with titanium dioxide nanoparticles and determination by graphite furnace atomic absorption spectrometry

Directory of Open Access Journals (Sweden)

Saeid Asadpour

2016-11-01

Full Text Available A new method has been developed for the determination of Tl(I based on simultaneous sorption and preconcentration with a microcolumn packed with TiO2 nanoparticle with a high specific surface area prepared by Sonochemical synthesis prior to its determination by graphite furnace atomic absorption spectrometry (GFAAS. The optimum experimental parameters for preconcentration of thallium, such as elution condition, pH, and sample volume and flow rate have been investigated. Tl(I can be quantitatively retained by TiO2 nanoparticles at pH 9.0, then eluted completely with 1.0 mol L−1 HCl. The adsorption capacity of TiO2 nanoparticles for Tl(I was found to be 25 mg g−1. Also detection limit, precision (RSD, n = 8 and enrichment factor for Tl(I were 87 ng L−1, 6.4% and 100, respectively. The method has been applied for the determination of trace amounts of Tl(I in some environmental water samples with satisfactory results.

Determination of terbium in phosphate rock by Tb{sup 3+}-selective fluorimetric optode based on dansyl derivative as a neutral fluorogenic ionophore

Energy Technology Data Exchange (ETDEWEB)

Hosseini, Morteza, E-mail: smhosseini@khayam.ut.ac.ir [Department of Chemistry, Islamic Azad University, Savadkooh Branch, Savadkooh (Iran, Islamic Republic of); Ganjali, Mohammad Reza [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Endocrinology and Metabolism Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Veismohammadi, Bahareh [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Faridbod, Farnoush [Endocrinology and Metabolism Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Abkenar, Shiva Dehghan [Department of Chemistry, Islamic Azad University, Savadkooh Branch, Savadkooh (Iran, Islamic Republic of); Norouzi, Parviz [Endocrinology and Metabolism Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of)

2010-04-07

For the first time a highly sensitive and selective fluorimetric optode membrane was prepared for determination of trace amounts of Tb(III) ions in phosphate rock samples. The Tb(III) sensing system was constructed by incorporating 5-(dimethylamino)-N'-(2-hydroxy-1-naphthoyl) naphthalene-1-sulfonohydrazine (L) as a neutral Tb(III)-selective fluoroionophore, in the plasticized PVC membrane containing sodium tetraphenyl borate as a liphophilic anionic additive. The response of the optode is based on the strong fluorescence quenching of L by Tb{sup 3+} ions. At a pH value of 5.0, the optode displays a wide concentration range of 1.0 x 10{sup -7} to 1.0 x 10{sup -2} M, with a relatively fast response time of less than 45 s. In addition, to high stability and reproducibility, the sensor shows a unique selectivity towards Tb{sup 3+} ion with respect to common cations. The optode was applied successfully to the trace determination of terbium ion in binary mixture and water samples and the determination of Tb{sup 3+} in phosphate rock samples.

A clean laboratory for ultratrace analysis: the ultratrace analytical facility (UTAF)

International Nuclear Information System (INIS)

Jadhav, S.G.; Sounderajan, Suvarna; Kumar, Sanjukta A.; Udas, A.C.; Ramanathan, M.; Palrecha, M.M.; Sudersanan, M.

2003-06-01

Thare has been an increasing demand for the quantification of various elements at extremely low concentrations in a variety of samples such as high purity materials, environmental and biological samples. The need for a controlled environment to obtain reliable and reproducible data necessitates the use of strategies and practices to minimize contamination during the analytical procedure. This report describes the protocol observed in our clean laboratory to eliminate contamination and ensure low laboratory blanks and some of the methodologies developed to carry out the analysis. The analysis is carried out by Graphite Furnace Atomic Absorption Spectrometry and electrochemical techniques such as Anodic/ Cathodic / Adsorptive Stripping Voltammetry. Characterisation of 5N (total impurities 10 ppm) arsenic is routinely carried out. Al in serum of patients suffering from end stage renal failure are also analyzed. Pine leaves, spinach, carrot puree and milk powder have been characterized for Al and Hg content and bovine serum has been characterized for Cu, Zn, Na, K in samples as part of intercomparison exercises. (author)

Potassium permanganate-glutaraldehyde chemiluminescence system catalyzed by gold nanoprisms toward selective determination of fluoride.

Science.gov (United States)

Abolhasani, Jafar; Hassanzadeh, Javad; Ghorbani-Kalhor, Ebrahim

2016-02-01

Gold and silver nanoparticles (NPs) are shown to exert a positive effect on the chemiluminescence (CL) reaction of permanganate aldehydes. Interestingly, between various shapes examined, Au nanoprisms have the highest beneficial effect. This effect is even more notable in the presence of sodium dodecyl sulfate (SDS) surfactant. UV-vis spectra and transmission electron microscopy were used to characterize the NP shapes and sizes. Furthermore, it was observed that iron(III) ions can slightly increase CL emission of this system. This intensification is very effective in the presence of fluoride ions (F(-)). These observations form the basis of the method for the high sensitive determination of F(-) in the 6-1200 nmol L(-1) concentration range, with a detection limit of 2.1 nmol L(-1). The proposed method has good precision and was satisfactorily used in the selective determination of low concentrations of fluoride ion in real samples. Copyright © 2015 John Wiley & Sons, Ltd.

Cell-selective determination of trace elements in testis by SR-XRF analysis with nanoprobe

International Nuclear Information System (INIS)

Homma-Takeda, Shino; Nishimura, Yoshikazu; Watanabe, Yoshito; Yukawa, Masae; Ueno, Shunji; Terada, Yasuko

2005-01-01

Organotin compounds are widely used in industry and its environmental contamination by these compounds has recently become a concern. It is known that they act as endocrine disruptors but details of the dynamics of Sn in reproductive organs are still unknown. In the present study, we attempted to determine Sn in the testis of rats exposed to tributyltin chloride (TBTC) cell-selectively by synchrotron radiation X-ray florescence analysis with nanoprobe. TBTC was orally administered to rats at a dose of 45 μmol/kg per day for 3 days. One day later, Sn was detected in spermatozoa at the stage VIII seminiferous tubule, which are the final step of spermatogenesis in the testis. Sn levels in the microdissectioned seminiferous tubules determined by inductively coupled argon plasma-mass spectrometry were approximately equivalent to that in the testis. These data indicate that Sn accumulates in germ cells as well as in spermatozoa in a short period of TBTC exposure. (author)

Selective and sensitive determination of lactose in low-lactose dairy products with HPAEC-PAD.

Science.gov (United States)

van Scheppingen, Wibo B; van Hilten, Piet H; Vijverberg, Marieke P; Duchateau, Alexander L L

2017-08-15

The demand for low lactose dairy products is increasing and more different lactose free food is commercially available. The level of lactose in these products decreased during the last years and nowadays a concentration of lactose free". For the determination of the lactose concentrations in these dairy products a sensitive analysis method is needed. We developed a method for the determination of low concentrations of lactose in a wide range of dairy products. A simple sample preparation with dilution, centrifugation and ultrafiltration is efficient for the isolation of lactose from the sample matrix. In this paper, a new HPAEC-PAD analysis on a CarboPac PA100 column gives a good separation of lactose from the other saccharides. This separation in combination with the PAD detector yields a selective and sensitive method for the quantification at the desired concentrations of lactose in low lactose dairy products. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Determinants Of Dividend Policy: A Study Of Selected Listed Firms In Nigeria

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Uwuigbe Olubukunola Ranti

2013-05-01

Full Text Available This study investigated the determinants of dividends policy in the Nigerian stock exchange market. To achieve the objectives of this study, a total of 50 listed firms in the Nigerian stock exchange market were selected and analyzed for the study using the judgmental sampling technique. Also, the corporate annual reports for the period 2006-2011 were used for the study. The paper was basically modeled to examine the effects of financial performance of firms, firm size, financial leverage and board independence on the dividend payout decisions of listed firms operating in the Nigerian stock exchange market using the regression analysis method. The study in its findings observed that there is a significant positive relationship between firms’ financial performance, size of firms and board independence on the dividend payouts decisions of listed firms in Nigeria.

Selected Factors Determining a Way of Coping with Stress in Type 2 Diabetic Patients

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Anna Beata Sobol-Pacyniak

2014-01-01

Full Text Available Objectives. The aim of the study was to examine factors which determine stress coping styles in type 2 diabetic (T2D patients, with regard to selected demographic variables, clinical diabetes-related variables and selected psychical variables (anxiety level and assessment of depressive disorders. Methods. 50 T2D patients, aged 59.9 ± 10.2 years were assessed by Coping Inventory for Stressful Situations (CISS, Spielberger State-Trait Anxiety Inventory (STAI, and Beck Depression Inventory (BDI. In the statistical analysis simple and multivariable logistic regression models were used. Results. Variables significantly increasing the selection risk of stress coping style different from preferred task-oriented strategy in a simple logistic regression model are: hypoglycemia within three months prior to the research: odds ratio (OR = 6.86 (95% confidence interval (CI 1.25–37.61, taking antidepressants or neuroleptics: OR =15.42 (95% CI 2.42–98.33, severe depression in Beck’s scale: OR = 84.00 (95% CI 6.51–1083.65, high state-anxiety level: OR = 9.60 (95% CI 1.08–85.16, and high trait-anxiety level: OR = 18.40 (95%CI 2.96–114.31, but in a multivariable model, diagnosed depression is the strongest factor: OR = 32.38 (95% CI 4.94–212.13. Conclusions. In T2D patients, the strategy to cope with stress appears to be mostly influenced by psychical predisposition.

Determinants of condom use among selected migrant commercial ...

African Journals Online (AJOL)

Using data from the Integrated Biological and Behavioural Surveillance Survey implemented by the International Organisation for Migration in 2010 among farm workers, this study seeks to investigate factors associated with condom use among migrant men and women in selected commercial farms in two provinces of ...

Officer Selection (la Selection des officiers)

National Research Council Canada - National Science Library

2000-01-01

.... The theme of this workshop, officer selection, is an issue of central importance to the military forces of all countries, since it determines which individuals, with what characteristics, will...

Electrocatalytic reduction of nitrite using ferricyanide; Application for its simple and selective determination

International Nuclear Information System (INIS)

Ojani, Reza; Raoof, Jahan-Bakhsh; Zarei, Ebrahim

2006-01-01

The electrocatalytic reduction of nitrite has been studied by ferricyanide at the surface of carbon paste electrode. Cyclic voltammetry and chronoamperometry techniques were used to investigate the suitability of ferricyanide as a mediator for the electrocatalytic nitrite reduction in aqueous solution with various pH. Results showed that pH 0.00 is the most suitable for this purpose. In the optimum pH, the electrocatalytic ability about 700 mV can be seen and the homogeneous second-order rate constant (k s ) for nitrite coupled catalytically to ferricyanide was calculated 2.75 x 10 3 M -1 s -1 by Nicholson-Shain method. Also, electron transfer coefficients (α) for ferricyanide was determined by using various electrochemical approaches such as Tafel plot in the absence and presence of nitrite 0.556 and 0.760, respectively. The catalytic reduction peak current was linearly dependent on the nitrite concentration and the linearity range obtained was 5.00 x 10 -5 to 1.00 x 10 -3 M. Detection limit has been found to be 2.63 x 10 -5 M (2σ). This method has been applied as a selective, simple and precise method for determination of nitrite in real sample

Direct phase selection of initial phases from single-wavelength anomalous dispersion (SAD) for the improvement of electron density and ab initio structure determination

International Nuclear Information System (INIS)

Chen, Chung-De; Huang, Yen-Chieh; Chiang, Hsin-Lin; Hsieh, Yin-Cheng; Guan, Hong-Hsiang; Chuankhayan, Phimonphan; Chen, Chun-Jung

2014-01-01

A novel direct phase-selection method to select optimized phases from the ambiguous phases of a subset of reflections to replace the corresponding initial SAD phases has been developed. With the improved phases, the completeness of built residues of protein molecules is enhanced for efficient structure determination. Optimization of the initial phasing has been a decisive factor in the success of the subsequent electron-density modification, model building and structure determination of biological macromolecules using the single-wavelength anomalous dispersion (SAD) method. Two possible phase solutions (ϕ 1 and ϕ 2 ) generated from two symmetric phase triangles in the Harker construction for the SAD method cause the well known phase ambiguity. A novel direct phase-selection method utilizing the θ DS list as a criterion to select optimized phases ϕ am from ϕ 1 or ϕ 2 of a subset of reflections with a high percentage of correct phases to replace the corresponding initial SAD phases ϕ SAD has been developed. Based on this work, reflections with an angle θ DS in the range 35–145° are selected for an optimized improvement, where θ DS is the angle between the initial phase ϕ SAD and a preliminary density-modification (DM) phase ϕ DM NHL . The results show that utilizing the additional direct phase-selection step prior to simple solvent flattening without phase combination using existing DM programs, such as RESOLVE or DM from CCP4, significantly improves the final phases in terms of increased correlation coefficients of electron-density maps and diminished mean phase errors. With the improved phases and density maps from the direct phase-selection method, the completeness of residues of protein molecules built with main chains and side chains is enhanced for efficient structure determination

A sequential extraction procedure to determine Ra and U isotopes by alpha-particle spectrometry in selective leachates

International Nuclear Information System (INIS)

Aguado, J.L.; Bolivar, J.P.; San-Miguel, E.G.; Garcia-Tenorio, R.

2003-01-01

A radiochemical sequential extraction procedure has been developed in our laboratory to determine 226 Ra and 234,238 U by alpha spectrometry in environmental samples. This method has been validated for both radionuclides by comparing in selected samples the values obtained through its application with the results obtained by applying alternative procedures. Recoveries obtained, counting periods applied and background levels found in the alpha spectra give suitable detection limits to allow the Ra and U determination in operational forms defined in riverbed contaminated sediments. Results obtained in these speciation studies show that 226 Ra and 234,238 U contamination tend to be associated to precipitated forms of the sediments. (author)

Laccase-catalyzed oxidation and intramolecular cyclization of dopamine: A new method for selective determination of dopamine with laccase/carbon nanotube-based electrochemical biosensors

International Nuclear Information System (INIS)

Xiang, Ling; Lin, Yuqing; Yu, Ping; Su, Lei; Mao, Lanqun

2007-01-01

This study demonstrates a new electrochemical method for the selective determination of dopamine (DA) with the coexistence of ascorbic acid (AA) and 3,4-dihydroxyphenylacetic acid (DOPAC) with laccase/multi-walled carbon nanotube (MWNT)-based biosensors prepared by cross-linking laccase into MWNT layer confined onto glassy carbon electrodes. The method described here is essentially based on the chemical reaction properties of DA including oxidation, intramolecular cyclization and disproportionation reactions to finally give 5,6-dihydroxyindoline quinone and on the uses of the two-electron and two-proton reduction of the formed 5,6-dihydroxyindoline quinone to constitute a method for the selective determination of DA at a negative potential that is totally separated from those for the redox processes of AA and DOPAC. Instead of the ECE reactions of DA with the first oxidation of DA being driven electrochemically, laccase is used here as the biocatalyst to drive the first oxidation of DA into its quinone form and thus initialize the sequential reactions of DA finally into 5,6-dihydroxyindoline quinone. In addition, laccase also catalyzes the oxidation of AA and DOPAC into electroinactive species with the concomitant reduction of O 2 . As a consequence, a combinational exploitation of the chemical properties inherent in DA and the multifunctional catalytic properties of laccase as well as the excellent electrochemical properties of carbon nanotubes substantially enables the prepared laccase/MWNT-based biosensors to be well competent for the selective determination of DA with the coexistence of physiological levels of AA and DOPAC. This demonstration offers a new method for the selective determination of DA, which could be potentially employed for the determination of DA in biological systems

Determination of Volatile Organic Compounds in Selected Strains of Cyanobacteria

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Ivan Milovanović

2015-01-01

Full Text Available Microalgal biomass can be used in creating various functional food and feed products, but certain species of microalgae and cyanobacteria are known to produce various compounds causing off-flavour. In this work, we investigated selected cyanobacterial strains of Spirulina, Anabaena, and Nostoc genera originating from Serbia, with the aim of determining the chemical profile of volatile organic compounds produced by these organisms. Additionally, the influence of nitrogen level during growth on the production of volatile compounds was investigated for Nostoc and Anabaena strains. In addition, multivariate techniques, namely, principal component analysis (PCA and hierarchical cluster analysis (HCA, were used for making distinction among different microalgal strains. The results show that the main volatile compounds in these species are medium chain length alkanes, but other odorous compounds such as 2-methylisoborneol (0.51–4.48%, 2-pentylfuran (0.72–8.98%, β-cyclocitral (0.00–1.17%, and β-ionone (1.15–2.72% were also detected in the samples. Addition of nitrogen to growth medium was shown to negatively affect the production of 2-methylisoborneol, while geosmin was not detected in any of the analyzed samples, which indicates that the manipulation of growth conditions may be useful in reducing levels of some unwanted odor-causing components.

Selective extraction and determination of chlorogenic acids as combined quality markers in herbal medicines using molecularly imprinted polymers based on a mimic template.

Science.gov (United States)

Ji, Wenhua; Zhang, Mingming; Yan, Huijiao; Zhao, Hengqiang; Mu, Yan; Guo, Lanping; Wang, Xiao

2017-12-01

We describe a solid-phase extraction adsorbent based on molecularly imprinted polymers (MIPs), prepared with use of a mimic template. The MIPs were used for the selective extraction and determination of three chlorogenic acids as combined quality markers for Lonicera japonica and Lianhua qingwen granules. The morphologies and surface groups of the MIPs were assessed by scanning electron microscopy, Brunauer-Emmett-Teller surface area analysis, and Fourier transform infrared spectroscopy. The adsorption isotherms, kinetics, and selectivity of the MIPs were systematically compared with those of non-molecularly imprinted polymers. The MIPs showed high selectivity toward three structurally similar chlorogenic acids (chlorogenic acid, cryptochlorogenic acid, and neochlorogenic acid). A procedure using molecularly imprinted solid-phase extraction coupled with high-performance liquid chromatography was established for the determination of three chlorogenic acids from Lonicera japonica and Lianhua qingwen granules. The recoveries of the chlorogenic acids ranged from 93.1% to 101.4%. The limits of detection and limits of quantification for the three chlorogenic acids were 0.003 mg g -1 and 0.01 mg g -1 , respectively. The newly developed method is thus a promising technique for the enrichment and determination of chlorogenic acids from herbal medicines. Graphical Abstract Mimic molecularly imprinted polymers for the selective extraction of chlorogenic acids.

Stuides on a Pb2+-selective electrode with a macrocyclic liquid membrane. Potentiometric determination of Pb2+ ions

Directory of Open Access Journals (Sweden)

MARIAN ISVORANU

2006-12-01

Full Text Available This paper presents experimental and theoretical data regarding the design, characterization and analytical applications of a non-expensive, liquid-membrane ion-selective electrode for Pb2+ ions. The membrane is a solution of the active complex formed by Pb2+ ions with dibenzo-18-crown-6-ionophore (DB-[18]-C-6 extracted in propylene carbonate (PC. The sucessful application of the developed electrode for the determination of Pb2+ ions in aqueos solution samples by direct potentiometry and potentiometric titration is presented. For the presented analytical results, there are insignificant systematic errors between the direct potentiometric method with the developed ion-selective electrode and atomic absorption spectrometry.

Determinants of Environmental Degradation under the Perspective of Globalization: A Panel Analysis of Selected MENA Nations

OpenAIRE

Audi, Marc; Ali, Amjad

2018-01-01

This paper has examined the determinants of environmental degradation under the perspective of globalization in the case of selected MENA nations (Jordan, United Arab Emirates, Saudi Arabia, Algeria, Qatar, Lebanon, Egypt, Bahrain, Iran, Morocco, Israel, Kuwait, Oman and Tunisia) over the period of 1980 to 2013. ADF - Fisher Chi-square, Im, Pesaran and Shin W-stat, Levin, Lin & Chu t*, and PP-Fisher Chi-square unit root tests are used for analyzing the stationarity of the variables. This stud...

Determination and evaluation of effective criteria to location selection the optimal for establishing fluting paper mills from agricultural residues of Mazandaran province

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Abdollah barimani

2013-11-01

Full Text Available Location selection for factory competitiveness in the market place plays an important role and should be chosen so that will leads achievement of the strategic advantages compared with other competitors. The objective of this study was determination of the effective criteria for decision making to select the most suitable location for establishing a fluting paper mills from agricultural residues. For this purpose, effective criteria were divided into five major groups: Material and Product, Facilities and limitations of regional (infrastructure, Technical and Human, Economical, Rules & Regulations as well as 33 sub-criteria, after preliminary investigation, preparatory observation, and an interview with some of the paper producers and relevant experts. A hierarchy was designed based on five major groups of criteria and then the priority rates of obtained criteria and sub-criteria were determined by Analytical Hierarchy Process (AHP after compiling expert's opinions via questionnaire. Results have shown that among 33 determined effective criteria in location selection of fluting paper mills from agricultural residues , the sub-criteria of Supply residual amount, Ensure the supply of residual, Cost purchasing of raw material, Cost of transporting raw material have the highest priorities, respectively

Selective Determination of Serotonin on Poly(3,4-ethylenedioxy pyrrole)-single-walled Carbon Nanotube-Modified Glassy Carbon Electrodes

International Nuclear Information System (INIS)

Kim, Seul Ki; Bae, Si Ra; Ahmed, Mohammad Shamsuddin; You, Jung Min; Jeon, Seung Won

2011-01-01

An electrochemically-modified electrode [P(EDOP-SWNTs)/GCE] was prepared by electropolymerization of 3,4-ethylenedioxy pyrrole (EDOP) single-walled carbon nanotubes (SWNTs) on the surface of a glassy carbon electrode (GCE) and characterized by SEM, CV, and DPV. This modified electrode was employed as an electrochemical biosensor for the selective determination of serotonin concentrations at pH 7.4 and exhibited a typical enhanced effect on the current response of serotonin with a lower oxidation overpotential. The linear response was in the range of 1.0 x 10"-"7 to 1.0 x 10"-"5 M, with a correlation coefficient of 0.998 on the anodic current. The lower detection limit was calculated as 5.0 nM. Due to the relatively low currents and difference of potentials in the electrochemical responses of uric acid (UA), ascorbic acid (AA), and dopamine (DA), the modified electrode was a useful and effective sensing device for the selective and sensitive serotonin determination in the presence of UA, AA, and DA

Selective Determination of Serotonin on Poly(3,4-ethylenedioxy pyrrole)-single-walled Carbon Nanotube-Modified Glassy Carbon Electrodes

Energy Technology Data Exchange (ETDEWEB)

Kim, Seul Ki; Bae, Si Ra; Ahmed, Mohammad Shamsuddin; You, Jung Min; Jeon, Seung Won [Chonnam National University, Gwangju (Korea, Republic of)

2011-04-15

An electrochemically-modified electrode [P(EDOP-SWNTs)/GCE] was prepared by electropolymerization of 3,4-ethylenedioxy pyrrole (EDOP) single-walled carbon nanotubes (SWNTs) on the surface of a glassy carbon electrode (GCE) and characterized by SEM, CV, and DPV. This modified electrode was employed as an electrochemical biosensor for the selective determination of serotonin concentrations at pH 7.4 and exhibited a typical enhanced effect on the current response of serotonin with a lower oxidation overpotential. The linear response was in the range of 1.0 x 10{sup -7} to 1.0 x 10{sup -5} M, with a correlation coefficient of 0.998 on the anodic current. The lower detection limit was calculated as 5.0 nM. Due to the relatively low currents and difference of potentials in the electrochemical responses of uric acid (UA), ascorbic acid (AA), and dopamine (DA), the modified electrode was a useful and effective sensing device for the selective and sensitive serotonin determination in the presence of UA, AA, and DA.

Use of magnesium silicate as a selective absorbent in radioimmunological method of determination of insulin level in human serum

Energy Technology Data Exchange (ETDEWEB)

Bogoniowska, Z; Stelmasiak, T [Wojskowy Instytut Higieny i Epidemiologii, Warsaw (Poland)

1974-01-01

The authors present a radioimmunological method for determination of insulin (IRI) level in the human serum using magnesium silicate (talc) as adsorbent. The method is based on the phenomenon of selective adsorption of the free radioactive hormone. The optimal parameters for the method were determined. The serum level of IRI in clinically healthy subjects after oral glucose loading was established. The obtained results were compared with the results obtained by the radioimmunological method of double antibodies in stochastically grouped samples.

A Simple Analytical Method Using HPLC with Fluorescence Detection to Determine Selected Polycyclic Aromatic Compounds in Filter Samples

International Nuclear Information System (INIS)

Garcia, S.; Perez, R. M.

2014-01-01

A study on the comparison and evaluation of a miniaturized extraction method for the determination of selected PACs in sample filters is presented. The main objective was the optimization and development of simple, rapid and low cost methods, minimizing the use of extracting solvent volume. The work also includes a study on the intermediate precision. (Author)

Determination of selected azaarenes in water by bonded-phase extraction and liquid chromatography

Science.gov (United States)

Steinheimer, T.R.; Ondrus, M.G.

1986-01-01

A method for the rapid and simple quantitative determination of quinoline, isoquinoline, and five selected three-ring azaarenes in water has been developed. The azaarene fraction is separated from its carbon analogues on n-octadecyl packing material by edition with acidified water/acetonitrile. Concentration as great as 1000-fold is achieved readily. Instrumental analysis involves high-speed liquid chromatography on flexible-walled, wide-bore columns with fluorescence and ultraviolet detection at several wavelengths employing filter photometers in series. Method-validation data is provided as azaarene recovery efficiency from fortified samples. Distilled water, river water, contaminated ground water, and secondary-treatment effluent have been tested. Recoveries at part-per-billion levels are nearly quantitative for the three-ring compounds, but they decrease for quinoline and isoquinoline. ?? 1986 American Chemical Society.

Determining fluoride ions in ammonium desulfurization slurry using an ion selective electrode method

Science.gov (United States)

Luo, Zhengwei; Guo, Mulin; Chen, Huihui; Lian, Zhouyang; Wei, Wuji

2018-02-01

Determining fluoride ions in ammonia desulphurization slurry using a fluoride ion selective electrode (ISE) is investigated. The influence of pH was studied and the appropriate total ionic strength adjustment buffer and its dosage were optimized. The impact of Fe3+ concentration on the detection results was analyzed under preferable conditions, and the error analysis of the ISE method’s accuracy and precision for measuring fluoride ion concentration in the range of 0.5-2000 mg/L was conducted. The quantitative recovery of F- in ammonium sulfate slurry was assessed. The results showed that when pH ranged from 5.5˜6 and the Fe3+ concentration was less than 750 mg/L, the accuracy and precision test results with quantitative recovery rates of 92.0%-104.2% were obtained.

A Pooled Data Analysis to Determine the Relationship between Selected Metals and Arsenic Bioavailability in Soil

OpenAIRE

Kaihong Yan; Ravi Naidu; Yanju Liu; Ayanka Wijayawardena; Luchun Duan; Zhaomin Dong

2018-01-01

Chronic exposure to arsenic (As) is a global concern due to worldwide exposure and adverse effects, and the importance of incorporating bioavailability in the exposure assessment and risk assessment of As is increasing acknowledged. The bioavailability of As is impacted by a number of soil properties, such as pH, clay and metal concentrations. By retrieving 485 data from 32 publications, the aim of this study was to determine the relationship between selected metals (Fe and Al) and As bioavai...

Determination of Free Fatty Acids and Triglycerides by Gas Chromatography Using Selective Esterification Reactions

Energy Technology Data Exchange (ETDEWEB)

Kail, Brian W; Link, Dirk D; Morreale, Bryan D

2012-11-01

A method for selectively determining both free fatty acids (FFA) and triacylglycerides (TAGs) in biological oils was investigated and optimized using gas chromatography after esterification of the target species to their corresponding fatty acid methyl esters (FAMEs). The method used acid catalyzed esterification in methanolic solutions under conditions of varying severity to achieve complete conversion of more reactive FFAs while preserving the concentration of TAGs. Complete conversion of both free acids and glycerides to corresponding FAMEs was found to require more rigorous reaction conditions involving heating to 120°C for up to 2 h. Method validation was provided using gas chromatography–flame ionization detection, gas chromatography–mass spectrometry, and liquid chromatography–mass spectrometry. The method improves on existing methods because it allows the total esterified lipid to be broken down by FAMEs contributed by FFA compared to FAMEs from both FFA and TAGs. Single and mixed-component solutions of pure fatty acids and triglycerides, as well as a sesame oil sample to simulate a complex biological oil, were used to optimize the methodologies. Key parameters that were investigated included: HCl-to-oil ratio, temperature and reaction time. Pure free fatty acids were found to esterify under reasonably mild conditions (10 min at 50°C with a 2.1:1 HCl to fatty acid ratio) with 97.6 ± 2.3% recovery as FAMEs, while triglycerides were largely unaffected under these reaction conditions. The optimized protocol demonstrated that it is possible to use esterification reactions to selectively determine the free acid content, total lipid content, and hence, glyceride content in biological oils. This protocol also allows gas chromatography analysis of FAMEs as a more ideal analyte than glyceride species in their native state.

Voltammetric determination of ultratrace levels of cerium(III) using a carbon paste electrode modified with nano-sized cerium-imprinted polymer and multiwalled carbon nanotubes

International Nuclear Information System (INIS)

Alizadeh, Taher; Ganjali, Mohammad Reza; Akhoundian, Maede; Norouzi, Parviz

2016-01-01

A carbon paste electrode was modified with a Ce(III)-imprinted polymer (Ce-IP) and used for voltammetric determination of Ce(III) ions in real water samples. Precipitation polymerization was used for synthesis of the nano-sized Ce-IP from vinylpyridine and methacrylic acid (acting as the complexing ligands and functional monomers), divinylbenzene (cross-linker) and AIBN as the radical starter. The Ce-IP was characterized by scanning electron microscopy and zeta potentials. A carbon paste electrode (CPE) was then impregnated with the Ce-IP and used for the extraction and subsequent determination of Ce(III). Oxidative square wave voltammetry showed the electrode to give a significantly better response than an electrode modified with the non-imprinted polymer. The addition of multiwalled carbon nanotubes to the Ce-IP-modified electrode further improves the signal, thereby increasing the sensitivity of the method. The effects of electrode composition, extraction pH value, volume and time were optimized. The electrode, if operated at a voltage of 1.05 V (vs. Ag/AgCl), displays a linear response to Ce(III) in the 1.0 μM to 25 pM concentration range, and the detection limit is 10 pM (at an S/N ratio of 3). The relative standard deviation of 5 separate determinations is 3.1 %. The method was successfully applied to the determination of Ce(III) in the spiked samples of drinking water and sea water. (author)

Determination of Nd3+ Ions in Solution Samples by a Coated Wire Ion-Selective Sensor

Directory of Open Access Journals (Sweden)

Hassan Ali Zamani

2012-01-01

Full Text Available A new coated wire electrode (CWE using 5-(methylsulfanyl-3-phenyl-1H-1,2,4-triazole (MPT as an ionophore has been developed as a neodymium ion-selective sensor. The sensor exhibits Nernstian response for the Nd3+ ions in the concentration range of 1.0×10−6-1.0×10−2 M with detection limit of 3.7×10−7 M. It displays a Nernstian slope of 20.2±0.2 mV/decade in the pH range of 2.7–8.1. The proposed sensor also exhibits a fast response time of ∼5 s. The sensor revealed high selectivity with respect to all common alkali, alkaline earth, transition and heavy metal ions, including members of the lanthanide family other than Nd3+. The electrode was used as an indicator electrode in the potentiometric titration of Nd(III ions with EDTA. The electrode was also employed for the determination of the Nd3+ ions concentration in water solution samples.

Ultrasensitive and Fast Voltammetric Determination of Iron in Seawater by Atmospheric Oxygen Catalysis in 500 μL Samples.

Science.gov (United States)

Caprara, Salvatore; Laglera, Luis M; Monticelli, Damiano

2015-06-16

A new method based on adsorptive cathodic stripping voltammetry with catalytic enhancement for the determination of total dissolved iron in seawater is reported. It was demonstrated that iron detection at the ultratrace level (0.1 nM) may be achieved in small samples (500 μL) with high sensitivity, no need for purging, no added oxidant, and a limit of detection of 5 pM. The proposed method is based on the adsorption of the complex Fe/2,3-dihydroxynaphthalene (DHN) exploiting the catalytic effect of atmospheric oxygen. As opposite to the original method (Obata, H.; van den Berg, C. M. Anal. Chem. 2001, 73, 2522-2528), atmospheric oxygen dissolved in solution replaced bromate ions in the oxidation of the iron complex: removing bromate reduces the blank level and avoids the use of a carcinogenic species. Moreover, the new method is based on a recently introduced hardware that enables the determinations to be performed in 500 μL samples. The analyses were carried out on buffered samples (pH 8.15, HEPPS 0.01 M), 10 μM DHN and iron quantified by the standard addition method. The sensitivity is 49 nA nM(-1) min(-1) with 30 s deposition time and the LOD is equal to 5 pM. As a result, the whole procedure for the quantification of iron in one sample requires around 7.5 min. The new method was validated via analysis on two reference samples (SAFe S and SAFe D2) with low iron content collected in the North Pacific Ocean.

Selective Flow Injection Analysis of Ultra-trace Amounts of Cr(VI), Preconcentration of It by Solvent Extraction, and Determination by Electrothermal Atomic Absorption Spectrometry (ETAAS)

DEFF Research Database (Denmark)

Nielsen, Steffen; Sturup, Stefan; Spliid, Henrik

1999-01-01

(IBMK). The Cr(VI) is complexed by reaction with ammonium pyrrolidine dithiocarbamate (APDC), and the non-charged Cr(VI)-PDC chelate formed is extracted into IBMK in a knotted reactor made from PTFE tubing. The organic extractant is separated from the aqueous phase by a gravity phase separator......(VI) was achieved after preconcentration for 99 s at a sample flow rate of 5.5 ml min-1, as compared to direct introduction of 55 mul of sample, yielding a detection limit (3sigma) of 3.3 ng l-1. The sampling frequency was 24.2 samples h-1. The proposed method was successfully evaluated by analyzing a NIST Cr...

Green Supplier Selection Criteria

DEFF Research Database (Denmark)

Nielsen, Izabela Ewa; Banaeian, Narges; Golinska, Paulina

2014-01-01

Green supplier selection (GSS) criteria arise from an organization inclination to respond to any existing trends in environmental issues related to business management and processes, so GSS is integrating environmental thinking into conventional supplier selection. This research is designed...... to determine prevalent general and environmental supplier selection criteria and develop a framework which can help decision makers to determine and prioritize suitable green supplier selection criteria (general and environmental). In this research we considered several parameters (evaluation objectives......) to establish suitable criteria for GSS such as their production type, requirements, policy and objectives instead of applying common criteria. At first a comprehensive and deep review on prevalent and green supplier selection literatures performed. Then several evaluation objectives defined to assess the green...

Explore the Most Potential Supplier’s Selection Determinants in Modern Supply Chain Management

Directory of Open Access Journals (Sweden)

Ming-Yuan Hsieh

2014-01-01

Full Text Available To increment the research reliability, validity, and representativeness, this study creatively cross-employed the factor analysis (FA and the grey relational analysis (GRA methods. The results of the 144 fully completed questionnaires are analyzed by FA and then these results were utilized in second questionnaires design of 15 experts. Furthermore, the results of these second questionnaires were further analyzed by GRA in order to explore the most potential supplier’s selection determinants in the modern supply chain management (MSCM. Beyond a series of measurements, the measured results have induced three contributive findings: (1 the empirical interviewed industrialists reported concern that suppliers have to provide a higher material yield rate and material delivery on time rate for the qualitative increment as well as a higher supplier’s gross margin ROI for the financial stabilization in MSCM; (2 the 15 experts concluded that material insurance rate is an important attribute to estimate risky assessments and the supplier’s gross margin ROI and warehouse operations cost as a percentage of sales are critical elements in the financial evaluations of potential suppliers; and (3 Supplier’s gross margin ROI, outbound freight cost as a percentage of sales, and material insurance rate are the three most decisive determinants in MSCM.

Determining the Effect of Natural Selection on Linked Neutral Divergence across Species.

Science.gov (United States)

Phung, Tanya N; Huber, Christian D; Lohmueller, Kirk E

2016-08-01

A major goal in evolutionary biology is to understand how natural selection has shaped patterns of genetic variation across genomes. Studies in a variety of species have shown that neutral genetic diversity (intra-species differences) has been reduced at sites linked to those under direct selection. However, the effect of linked selection on neutral sequence divergence (inter-species differences) remains ambiguous. While empirical studies have reported correlations between divergence and recombination, which is interpreted as evidence for natural selection reducing linked neutral divergence, theory argues otherwise, especially for species that have diverged long ago. Here we address these outstanding issues by examining whether natural selection can affect divergence between both closely and distantly related species. We show that neutral divergence between closely related species (e.g. human-primate) is negatively correlated with functional content and positively correlated with human recombination rate. We also find that neutral divergence between distantly related species (e.g. human-rodent) is negatively correlated with functional content and positively correlated with estimates of background selection from primates. These patterns persist after accounting for the confounding factors of hypermutable CpG sites, GC content, and biased gene conversion. Coalescent models indicate that even when the contribution of ancestral polymorphism to divergence is small, background selection in the ancestral population can still explain a large proportion of the variance in divergence across the genome, generating the observed correlations. Our findings reveal that, contrary to previous intuition, natural selection can indirectly affect linked neutral divergence between both closely and distantly related species. Though we cannot formally exclude the possibility that the direct effects of purifying selection drive some of these patterns, such a scenario would be possible only

Selective catalyst reduction light-off strategy

Science.gov (United States)

Gonze, Eugene V [Pinckney, MI

2011-10-18

An emissions control system includes a temperature determination module and an emissions control module. The temperature determination module determines a first temperature of a heater element of a diesel particulate filter (DPF) assembly in an exhaust system and determines a second temperature of a catalyst of the DPF assembly. The emissions control module selectively activates the heater element, selectively initiates a predefined combustion process in an engine based upon the first temperature, and selectively starts a reductant injection process based upon the second temperature.

Determination of the radon Concentration in underground water in selected areas in and around Kumasi

International Nuclear Information System (INIS)

Owusu, Seth Adjei

2012-06-01

Radon (Rn-222) is a radioactive noble gas of natural origin that may be found anywhere in soil, air and different types of water: surface, borehole, well and spring. It is worth to carry out surveys for the radon in water for radiation protection as well as for geological considerations. The research presenters here was carried out in selected towns in and around Kumasi for the determination of radon concentration in groundwater. The major towns from which samples were taken are , Mowire, Kronum, Aburaso, Medoma, Kenyase, Buokrom, Bomfa, Ayeduase, Kotei, Tikrom. All the samples are used for domestic purposes such as cooking, drinking, bathing and washing. Waters from boreholes and wells in the selected towns were sampled and the radon concentration level measured. The Roll’s method was used for the radon concentration analysis on all the 100 samples. The results shows that, the minimum radon concentration in groundwater was 13015.934 Bq/m3 and it was found at Bomfa, and the highest was found to be 964628.480 Bq/m3, recorded at Mowire. It is believed that this variation of levels is mainly due to the difference in rock type, soil type and geology of the area as well as the depth of the water samples. This information can be used to estimate the possible health hazards from radon in the selected towns in the future from environmental point of view. The data would promote public awareness related to risk of radon exposure. (au)

Dichotomies of collectivism and individualism in bioethics: selective abortion debates and issues of self-determination in Japan and 'the West'

NARCIS (Netherlands)

Kato, M.; Sleeboom-Faulkner, M.

2011-01-01

This article examines the dichotomies of collectivism and individualism in the debates on the selective abortion of disabled fetuses, which have occurred over the last four decades in Japan. Disagreements in debates on abortion in Japan have often revolved around the concept of self-determination

Multi-Criteria Decision Making For Determining A Simple Model of Supplier Selection

Science.gov (United States)

Harwati

2017-06-01

Supplier selection is a decision with many criteria. Supplier selection model usually involves more than five main criteria and more than 10 sub-criteria. In fact many model includes more than 20 criteria. Too many criteria involved in supplier selection models sometimes make it difficult to apply in many companies. This research focuses on designing supplier selection that easy and simple to be applied in the company. Analytical Hierarchy Process (AHP) is used to weighting criteria. The analysis results there are four criteria that are easy and simple can be used to select suppliers: Price (weight 0.4) shipment (weight 0.3), quality (weight 0.2) and services (weight 0.1). A real case simulation shows that simple model provides the same decision with a more complex model.

Determination of contaminants in boric acid used as neutron moderator by means of ion chromatography and selective electrodes

International Nuclear Information System (INIS)

Pires, M.A.F.; Abrao, A.

1988-07-01

The boric acid used as neutron moderator in reactors must observe restrictions about the concentration of some impurities. According to Westinghouse (1) specification, the highest limits for sodium, sulphate, phosphate, fluoride, and chlorine are: Na + - 0,003%; SO 4 -2 - 0,0006%; PO 4 -3 - 0,003%; F - - 0,00002%; Cl - - 0,00004%. This paper describes the determination of ions above mentioned directly in the boric acid solution. The sample is dissolved in water or in an appropriate eluent and is injected in the ion chromatograph. Na + and F - are determined by means of selective electrodes. The determination limits found for F - (0,0002%) and Cl - (0,0002%) are not sufficiently low to attent the specifications. The determination limits found for SO 4 -2 (0,0005%), PO 4 -3 (0,0003%) and Na + (0,0005%) are good enough for nuclear pure boric acid analysis. In some samples nitrate (detection limit 0,0015%) was found as well. Boric acid from different suppliers were analysed. (author) [pt

solid phase extraction method for selective determination

African Journals Online (AJOL)

FATOKI

determination of phthalate ester plasticizers in rivers and marine water samples. Of the ... samples that receive effluent from industries that use phthalate esters. ... Keywords Phthalates, Plasticizers, Solid Phase Gas Chromatography.

Total sulfur determination in residues of crude oil distillation using FT-IR/ATR and variable selection methods

Science.gov (United States)

Müller, Aline Lima Hermes; Picoloto, Rochele Sogari; Mello, Paola de Azevedo; Ferrão, Marco Flores; dos Santos, Maria de Fátima Pereira; Guimarães, Regina Célia Lourenço; Müller, Edson Irineu; Flores, Erico Marlon Moraes

2012-04-01

Total sulfur concentration was determined in atmospheric residue (AR) and vacuum residue (VR) samples obtained from petroleum distillation process by Fourier transform infrared spectroscopy with attenuated total reflectance (FT-IR/ATR) in association with chemometric methods. Calibration and prediction set consisted of 40 and 20 samples, respectively. Calibration models were developed using two variable selection models: interval partial least squares (iPLS) and synergy interval partial least squares (siPLS). Different treatments and pre-processing steps were also evaluated for the development of models. The pre-treatment based on multiplicative scatter correction (MSC) and the mean centered data were selected for models construction. The use of siPLS as variable selection method provided a model with root mean square error of prediction (RMSEP) values significantly better than those obtained by PLS model using all variables. The best model was obtained using siPLS algorithm with spectra divided in 20 intervals and combinations of 3 intervals (911-824, 823-736 and 737-650 cm-1). This model produced a RMSECV of 400 mg kg-1 S and RMSEP of 420 mg kg-1 S, showing a correlation coefficient of 0.990.

Determination of total mercury in seafood by ion-selective electrodes based on a thiol functionalized ionic liquid

Directory of Open Access Journals (Sweden)

Juan Miao

2018-04-01

Full Text Available A mercury(II ion-selective electrode with an ionic liquid (IL, 1-methyl-2-butylthioimidazolium bis(trifluoromethanesulphonylimide ([C1C4Sim]NTf2 as active material was constructed. Parameters affecting the performance of the electrodes such as the dosages of the IL and carbon nanotubes and the aqueous pH values were investigated. Experimental results indicated that the optimal composition of the electrode filling material was 47.6% [C1C4Sim]NTf2, 47.6% tetrabutylphosphonium bis(trifluoromethanesulphonylimide (TBPNTf2 and 4.8% carboxylic multi-walled carbon nanotubes (MWCNTs-COOH. Under the selected conditions, the proposed electrodes showed a good linear response in the concentration range of 10−10–10−5 mol L−1 and had a detection limit of 4.1 × 10−11 mol L−1. No great interference from common metal ions was found. The proposed electrodes were applied to determine Hg2+ in seafood samples; the results were comparable to those of the direct mercury analyzer. Keywords: Ionic liquids (ILs, Mercury, Ion-selective electrodes, Carbon nanotubes, Seafood

A polymeric membrane ion selective electrode based on organic-inorganic composite ion exchanger for the determination of thorium(IV)

International Nuclear Information System (INIS)

Chandra, Sulekh; Agarwal, Himanshu; Chandan Kumar, Singh; Sindhu, Susheel Kumar; Pankaj Kumar

2005-01-01

A poly(vinyl chloride) membrane electrode based on organic- inorganic composite ion exchanger, tin(IV) tungstoselenate-pyridine, has been prepared and tested for the selective determination of thorium(IV) ions. The PVC membrane electrode comprising 16% composite ion exchanger as the electroactive phase, 50% o-dioctyl phthalate as plasticizer, 4% tetraphenyl borate as anionic excluder and 30% poly(vinylchloride) displays a linear response to thorium(IV) ions over a wide concentration range of 1.0 x 10 -1 -8.0 x 10 -6 M with a Nernstain slope of 14.2 mV/ decade. The electrode shows a very short response time (∼15 s) and may be used in the pH range 2.5-9.0. The selectivity coefficient for alkali, alkaline earth and transition is smaller than 4.0 x 10 -4 . The sensor has been successfully used as an indicator electrode in the potentiometric titration of Th 4+ with EDTA as well as also for the determination of Th 4+ in the binary mixtures. (author)

Determination of Selection Method in Genetic Algorithm for Land Suitability

Directory of Open Access Journals (Sweden)

Irfianti Asti Dwi

2016-01-01

Full Text Available Genetic Algoirthm is one alternative solution in the field of modeling optimization, automatic programming and machine learning. The purpose of the study was to compare some type of selection methods in Genetic Algorithm for land suitability. Contribution of this research applies the best method to develop region based horticultural commodities. This testing is done by comparing the three methods on the method of selection, the Roulette Wheel, Tournament Selection and Stochastic Universal Sampling. Parameters of the locations used in the test scenarios include Temperature = 27°C, Rainfall = 1200 mm, hummidity = 30%, Cluster fruit = 4, Crossover Probabiitiy (Pc = 0.6, Mutation Probabilty (Pm = 0.2 and Epoch = 10. The second test epoch incluides location parameters consist of Temperature = 30°C, Rainfall = 2000 mm, Humidity = 35%, Cluster fruit = 5, Crossover Probability (Pc = 0.7, Mutation Probability (Pm = 0.3 and Epoch 10. The conclusion of this study shows that the Roulette Wheel is the best method because it produces more stable and fitness value than the other two methods.

Ion-Selective Electrode for the Determination of Iron(III in Vitamin Formulations

Directory of Open Access Journals (Sweden)

Teixeira Marcos Fernando de S.

1998-01-01

Full Text Available A coated graphite-epoxy ion-selective electrode for iron(III, based on the ion-pair formed between [Fe(citrate2]3- and the tricaprylylmethylammonium cation (Aliquat 336 in a poly(vinylchloride (PVC matrix has been constructed. A thin membrane film of this ion-pair, dibutylphthalate (DBPh in PVC was deposited directly onto a Perspex® tube, which contained a graphite-epoxy conductor substrate. The coating solution was prepared by dissolving 30% (w/w of PVC in 10 mL of tetrahydrofuran following addition of 65% (w/w DBPh and 5% (w/w of the ionic pair. The effect of pH, citrate concentration and some cations on the electrode response has been investigated. The E(mV vs. log [Fe(citrate2]3- electrode response was linear for iron(III concentration from 1.0 x 10-3 mol/L to 1.0 x 10-1 mol/L in 1.0 mol/L citrate medium, with a slope of 19.3 ± 0.5 mV/decade and a useful lifetime of at least six months (more than 800 determinations for each polymeric membrane used. The detection limit was 7.5 x 10-4 mol/L and the relative standard deviation was less than 3% for a solution containing 5.0 x 10-3 mol/L of iron(III (n = 10. The application of this electrode for iron(III determination in samples of vitamin formulations is described. The results obtained with this procedure are in close agreement with those obtained using AA spectrophotometry (r = 0.9999.

Consumers' price awareness at the point-of-selection: What constitutes the most appropriate measure of consumers' price awareness and what determines the differences?

DEFF Research Database (Denmark)

Jensen, Birger Boutrup

This paper focuses on consumers' price information processing at the point-of-selection. Specifically, it updates past results of consumers' price awareness at the point-of-selection - applying both a price-recall and a price-recognition test - and tests hypotheses on potential determinants...... of consumers' price awareness at the point-of-selection. Both price-memory tests resulted in higher measured price awareness than in any of the past studies. Results also indicate that price recognition is not the most appropiate measure. Finally, a discriminant analysis shows that consumers who are aware...

Determination of Diffusion Coefficients and Activation Energy of Selected Organic Liquids using Reversed-Flow Gas Chromatographic Technique

International Nuclear Information System (INIS)

Khalisanni Khalid; Rashid Atta Khan; Sharifuddin Mohd Zain

2012-01-01

Evaporation of vaporize organic liquid has ecological consequences when the compounds are introduced into both freshwater and marine environments through industrial effluents, or introduced directly into the air from industrial unit processes such as bioreactors and cooling towers. In such cases, a rapid and simple method are needed to measure physicochemical properties of the organic liquids. The Reversed-Flow Gas Chromatography (RF-GC) sampling technique is an easy, fast and accurate procedure. It was used to measure the diffusion coefficients of vapors from liquid into a carrier gas and at the same time to determine the rate coefficients for the evaporation of the respective liquid. The mathematical expression describing the elution curves of the samples peaks was derived and used to calculate the respective parameters for the selected liquid pollutants selected such as methanol, ethanol, 1-propanol, 1-butanol, n-pentane, n-hexane, n-heptane and n-hexadecane, evaporating into the carrier gas of nitrogen. The values of diffusion coefficients found were compared with those calculated theoretically or reported in the literature. The values of evaporation rate were used to determine the activation energy of respective samples using Arrhenius equation. An interesting finding of this work is by using an alternative mathematical analysis based on equilibrium at the liquid-gas interphase, the comparison leads to profound agreement between theoretical values of diffusion coefficients and experimental evidence. (author)

Analytical Evaluation to Determine Selected PAHs by HPLC in a Type 2 Fuel

International Nuclear Information System (INIS)

Garcia Alonso, S.; Perez Pastor, R. M.; Sevillano Castano, M. L.; Escolano Segovia, O.; Garcia Frutos, F. J.

2009-01-01

An evaluation of analytical parameters to determine selected PAHs in a fuel oil type II by HPLC coupled to fluorescence and diode detectors is presented. The study was focused on four conventional treatments of these kinds of oil samples and the main objective was giving a measure of confidence level of PAH results in the fuel oil. This study was performed in the frame of the project Assessment of natural attenuation of PAHs in agricultural soil contaminated with fuel from an accidental spill (Spanish National Plain I+D+I, CTM2007-64537). This paper is presented as follows: Analysis of reference material 1582 (NIST) by using the four kinds of sample treatments of interest. Application of variance analysis to compare results obtained from type II fuel by using each sample treatment and chromatographic detector. Finally, a statistic calculation was performed to measure uncertainty components in chromatographic analysis. (Author)

Comparison study of RNAA and ICP-MS for the determination of ultra-traces of Th and U in geological and cosmochemical samples

International Nuclear Information System (INIS)

Chai, J.; Oura, Y.; Ebihara, M.

2003-01-01

In order to determine thorium and uranium traces in geochemical and cosmochemical samples, we developed an ICP-MS procedure, in which an anion-exchange step was introduced after sample digestion to separate major matrix elements, leading to decrease the dilution factor and increase the sensitivity for Th and U. The ICP-MS procedure was compared to the RNAA procedure which we recently developed for the same purpose. Both ICP-MS and RNAA procedures developed were found to yield similar detection limits (sub ppb) for Th and U. (author)

Toxic metal levels in cocoa powder and chocolate by ICP-MS method after microwave-assisted digestion.

Science.gov (United States)

Lo Dico, Gianluigi Maria; Galvano, Fabio; Dugo, Giacomo; D'ascenzi, Carlo; Macaluso, Andrea; Vella, Antonio; Giangrosso, Giuseppe; Cammilleri, Gaetano; Ferrantelli, Vincenzo

2018-04-15

The Commission Regulation (EC) Regulation N. 488/2014, established the concentration limits for cadmium in specific products based on cocoa and chocolate products as from January 2019. Based on this information there is a need to determine ultratrace levels of elements that might be presents in cocoa and chocolate products. In this work, the concentrations of Arsenic, Antimony, Cadmium, Chromium, Lead, Selenium and Vanadium were evaluated in cocoa powder and chocolate by the validation of an ICP-MS method. Good selectivity/specificity, recovery, repeatability and within-laboratory reproducibility, LOD, LOQ, range of linearity, standard measurement uncertainty parameters for method validation were achieved, in accordance with Commission Regulation. The cocoa powder revealed the maximum metal concentrations of 0.303 ± 0.035 mg/kg for cadmium, 1.228 ± 0.146 mg/kg for lead and 0.094 ± 0.013 mg/kg for arsenic. A significant difference was found between cocoa powder and chocolate samples (p < .05). Copyright © 2017 Elsevier Ltd. All rights reserved.

PVC membrane, coated-wire, and carbon-paste ion-selective electrodes for potentiometric determination of galantamine hydrobromide in physiological fluids.

Science.gov (United States)

Abdel-Haleem, Fatehy M; Saad, Mohamed; Barhoum, Ahmed; Bechelany, Mikhael; Rizk, Mahmoud S

2018-08-01

We report on highly-sensitive ion-selective electrodes (ISEs) for potentiometric determining of galantamine hydrobromide (GB) in physiological fluids. Galantamine hydrobromide (GB) was selected for this study due to its previous medical importance for treating Alzheimer's disease. Three different types of ISEs were investigated: PVC membrane electrode (PVCE), carbon-paste electrode (CPE), and coated-wire electrode (CWE). In the construction of these electrodes, galantaminium-reineckate (GR) ion-pair was used as a sensing species for GB in solutions. The modified carbon-paste electrode (MCPE) was prepared using graphene oxide (MCPE-GO) and sodium tetrakis (trifluoromethyl) phenyl borate (MCPE-STFPB) as ion-exchanger. The potentiometric modified CPEs (MCPE-GO and MCPE-STFPB) show an improved performance in term of Nernstian slope, selectivity, response time, and response stability compared to the unmodified CPE. The prepared electrodes PVCE, CWE, CPE, MCPE-GO and MCPE-STFPB show Nernstian slopes of 59.9, 59.5, 58.1, 58.3 and 57.0 mV/conc. decade, and detection limits of 5.0 × 10 -6 , 6.3 × 10 -6 , 8.0 × 10 -6 , 6.0 × 10 -6 and 8.0 × 10 -6  mol L -1 , respectively. The prepared ISEs also show high selectivity against cations (i.e. Na + , K + , NH 4 + , Ca 2+ , Al 3+ , Fe 3+ ), amino acids (i.e. glycine, L-alanine alanine), and sugars (i.e. fructose, glucose, maltose, lactose). The prepared ISEs are applicable for determining GB in spiked serums, urines, and pharmaceutical preparations, using a standard addition and a direct potentiometric method. The fast response time (<10 s), long lifetime (1-5 weeks), reversibility and stability of the measured signals facilitate the application of these sensors for routine analysis of the real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Determination of Effective Criteria for location Selection of WPC Plants from agricultural residues in Iran by AHP Technique

Directory of Open Access Journals (Sweden)

hasan alizadeh

2017-02-01

Full Text Available This study was aimed at determining the effective criteria for location selection of WPC Plants from agricultural residues in Iran. For this purpose, after review and studies papers and books, Six criteria" products and materials, regulations, technical and human, economic, infrastructure and environmental and also 30 sub-criteria were identified. The priority rates of these criteria and sub-criteria were evaluated by AHP technique. The results indicated that among 30 effective sub-criteria in location selection of the WPC plants from agricultural residues, amount of wastes supply (0.087, continuity of wastes supply, cost of wastes supply, amount of sales and export, granted facilities and less Hazards for the environment and forest had the highest priorities, which were rated as 0.071, 0.067, 0.065, 0.064 and 0.062 respectively.

[Rapid determination of componential contents and calorific value of selected agricultural biomass feedstocks using spectroscopic technology].

Science.gov (United States)

Sheng, Kui-Chuan; Shen, Ying-Ying; Yang, Hai-Qing; Wang, Wen-Jin; Luo, Wei-Qiang

2012-10-01

Rapid determination of biomass feedstock properties is of value for the production of biomass densification briquetting fuel with high quality. In the present study, visible and near-infrared (Vis-NIR) spectroscopy was employed to build prediction models of componential contents, i. e. moisture, ash, volatile matter and fixed-carbon, and calorific value of three selected species of agricultural biomass feedstock, i. e. pine wood, cedar wood, and cotton stalk. The partial least squares (PLS) cross validation results showed that compared with original reflection spectra, PLS regression models developed for first derivative spectra produced higher prediction accuracy with coefficients of determination (R2) of 0.97, 0.94 and 0.90, and residual prediction deviation (RPD) of 6.57, 4.00 and 3.01 for ash, volatile matter and moisture, respectively. Good prediction accuracy was achieved with R2 of 0.85 and RPD of 2.55 for fixed carbon, and R2 of 0.87 and RPD of 2.73 for calorific value. It is concluded that the Vis-NIR spectroscopy is promising as an alternative of traditional proximate analysis for rapid determination of componential contents and calorific value of agricultural biomass feedstock

Determination of soluble ultra-trace metals and metalloids in rainwater and atmospheric deposition fluxes: a 2-year survey and assessment.

Science.gov (United States)

Montoya-Mayor, R; Fernández-Espinosa, A J; Seijo-Delgado, I; Ternero-Rodríguez, M

2013-08-01

The present work investigates the relationships between composition of rainwater and dry deposition fluxes by trace metals and metalloids. A modification in automatic "wet-only" and "dry-only" samplers was applied, which allowed the collection and conservation of samples separately. ICP-MS technique was used for the determination of analytes in samples. Concentrations of soluble elements in rainwater were measured directly in filtered samples. A sequential acid treatment with nitric, hydrofluoric and finally perchloric acids was used to measure the total contents of metals and metalloids in coarse particles. Variation between periods of heavy and light rains was assessed. Almost all of the metals and metalloids - B, Tl, Th, U, Al, Cs, Be, Ti and others - studied in dry deposition showed important decreases in concentrations (40-92%) during periods of heavy rainfall. Most of these metals and metalloids - As, Cr, Co, Ni - presented their highest levels (53-90%) in heavy rainfall periods in rainwater samples. Sources were identified in both types of samples collected using a new chemometric tool (SPCA). Urban traffic, surrounding contaminated soils and local anthropogenic sources were identified for rainwater samples. Natural and contaminated soils and general anthropogenic emissions were the sources identified for dry deposition fluxes. Copyright © 2013 Elsevier Ltd. All rights reserved.

Analytical Evaluation to Determine Selected PAHs in a Contaminated Soil With Type II Fuel

International Nuclear Information System (INIS)

Garcia Alonso, S.; Perez Pastor, R. M.; Sevillano Castano, M. L.; Garcia Frutos, F. J.

2010-01-01

A study on the optimization of an ultrasonic extraction method for selected PAHs determination in soil contaminated by type II fuel and by using HPLC with fluorescence detector is presented. The main objective was optimize the analytical procedure, minimizing the volume of solvent and analysis time and avoiding possible loss by evaporation. This work was carried out as part of a project that investigated a remediation process of agricultural land affected by an accidental spillage of fuel (Plan Nacional I + D + i, CTM2007-64 537). The paper is structured as: Optimization of wavelengths in the chromatographic conditions to improve resolution in the analysis of fuel samples. Optimization of the main parameters affecting in the extraction process by sonication. Comparison of results with those obtained by accelerated solvent extraction. (Author) 3 refs.

Determination of Some Heavy Metals in Selected Beauty and ...

African Journals Online (AJOL)

Several epidemiologic studies have investigated the potential carcinogenicity of human exposure to heavy metals from diverse sources but few or none was on African black and beauty soaps. Hence, this study examines the presence of some heavy metals in selected African black and beauty soaps commonly used in ...

Determination of Selected Polycyclic Aromatic Compounds in Particulate Matter Samples with Low Mass Loading: An Approach to Test Method Accuracy

Directory of Open Access Journals (Sweden)

Susana García-Alonso

2017-01-01

Full Text Available A miniaturized analytical procedure to determine selected polycyclic aromatic compounds (PACs in low mass loadings (<10 mg of particulate matter (PM is evaluated. The proposed method is based on a simple sonication/agitation method using small amounts of solvent for extraction. The use of a reduced sample size of particulate matter is often limiting for allowing the quantification of analytes. This also leads to the need for changing analytical procedures and evaluating its performance. The trueness and precision of the proposed method were tested using ambient air samples. Analytical results from the proposed method were compared with those of pressurized liquid and microwave extractions. Selected PACs (polycyclic aromatic hydrocarbons (PAHs and nitro polycyclic aromatic hydrocarbons (NPAHs were determined by liquid chromatography with fluorescence detection (HPLC/FD. Taking results from pressurized liquid extractions as reference values, recovery rates of sonication/agitation method were over 80% for the most abundant PAHs. Recovery rates of selected NPAHs were lower. Enhanced rates were obtained when methanol was used as a modifier. Intermediate precision was estimated by data comparison from two mathematical approaches: normalized difference data and pooled relative deviations. Intermediate precision was in the range of 10–20%. The effectiveness of the proposed method was evaluated in PM aerosol samples collected with very low mass loadings (<0.2 mg during characterization studies from turbofan engine exhausts.

Extended-gate field-effect transistor (EG-FET) with molecularly imprinted polymer (MIP) film for selective inosine determination.

Science.gov (United States)

Iskierko, Zofia; Sosnowska, Marta; Sharma, Piyush Sindhu; Benincori, Tiziana; D'Souza, Francis; Kaminska, Izabela; Fronc, Krzysztof; Noworyta, Krzysztof

2015-12-15

A novel recognition unit of chemical sensor for selective determination of the inosine, renal disfunction biomarker, was devised and prepared. For that purpose, inosine-templated molecularly imprinted polymer (MIP) film was deposited on an extended-gate field-effect transistor (EG-FET) signal transducing unit. The MIP film was prepared by electrochemical polymerization of bis(bithiophene) derivatives bearing cytosine and boronic acid substituents, in the presence of the inosine template and a thiophene cross-linker. After MIP film deposition, the template was removed, and was confirmed by UV-visible spectroscopy. Subsequently, the film composition was characterized by spectroscopic techniques, and its morphology and thickness were determined by AFM. The finally MIP film-coated extended-gate field-effect transistor (EG-FET) was used for signal transduction. This combination is not widely studied in the literature, despite the fact that it allows for facile integration of electrodeposited MIP film with FET transducer. The linear dynamic concentration range of the chemosensor was 0.5-50 μM with inosine detectability of 0.62 μM. The obtained detectability compares well to the levels of the inosine in body fluids which are in the range 0-2.9 µM for patients with diagnosed diabetic nephropathy, gout or hyperuricemia, and can reach 25 µM in certain cases. The imprinting factor for inosine, determined from piezomicrogravimetric experiments with use of the MIP film-coated quartz crystal resonator, was found to be 5.5. Higher selectivity for inosine with respect to common interferents was also achieved with the present molecularly engineered sensing element. The obtained analytical parameters of the devised chemosensor allow for its use for practical sample measurements. Copyright © 2015 Elsevier B.V. All rights reserved.

Motivation of medical students: selection by motivation or motivation by selection.

Science.gov (United States)

Wouters, Anouk; Croiset, Gerda; Galindo-Garre, Francisca; Kusurkar, Rashmi A

2016-01-29

Medical schools try to implement selection procedures that will allow them to select the most motivated students for their programs. Though there is a general feeling that selection stimulates student motivation, conclusive evidence for this is lacking. The current study aims to use the perspective of Self-determination Theory (SDT) of motivation as a lens to examine how medical students' motivation differs in relation to different selection procedures. The hypotheses were that 1) selected students report higher strength and autonomous motivation than non-selected students, and 2) recently selected students report higher strength and autonomous motivation than non-selected students and students who were selected longer ago. First- (Y1) and fourth-year (Y4) medical students in the six-year regular programme and first-year students in the four-year graduate entry programme (GE) completed questionnaires measuring motivation strength and type (autonomous-AM, controlled-CM). Scores were compared between students admitted based on selection, lottery or top pre-university GPA (top GPA) using ANCOVAs. Selected students' answers on open-ended questions were analysed using inductive thematic analysis to identify reasons for changes in motivation. The response rate was 61.4 % (n = 357). Selected students (Y1, Y4 and GE) reported a significantly higher strength of motivation than non-selected students (Y1 and Y4 lottery and top GPA) (p motivation as they felt autonomous, competent and that they belonged to a special group. These reported reasons are in alignment with the basic psychological needs described by Self-Determination Theory as important in enhancing autonomous motivation. A comprehensive selection procedure, compared to less demanding admission procedures, does not seem to yield a student population which stands out in terms of autonomous motivation. The current findings indicate that selection might temporarily enhance students' motivation. The mechanism

Determination of arsenate in water by anion selective membrane electrode using polyurethane–silica gel fibrous anion exchanger composite

Energy Technology Data Exchange (ETDEWEB)

Khan, Asif Ali, E-mail: asifkhan42003@yahoo.com; Shaheen, Shakeeba, E-mail: shakeebashaheen@ymail.com

2014-01-15

Highlights: • PU–Si gel is new anion exchanger material synthesized and characterized. • This material used as anion exchange membrane is applied for electroanalytical studies. • The method for detection and determination of AsO{sub 4}{sup 3−} in traces amounts discussed. • The results are also verified from arsenic analyzer. -- Abstract: Polyurethane (PU)–silica (Si gel) based fibrous anion exchanger composites were prepared by solid–gel polymerization of polyurethane in the presence of different amounts of silica gel. The formation of PU–Si gel fibrous anion exchanger composite was characterized by Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTA), scanning electron microscopy (SEM) and elemental analysis. The membrane having a composition of 5:3 (PU:Si gel) shows best results for water content, porosity, thickness and swelling. Our studies show that the present ion selective membrane electrode is selective for arsenic, having detection limit (1 × 10{sup −8} M to 1 × 10{sup −1} M), response time (45 s) and working pH range (5–8). The selectivity coefficient values for interfering ions indicate good selectivity for arsenate (AsO{sub 4}{sup 3−}) over interfering anions. The accuracy of the detection limit results was compared by PCA-Arsenomat.

Determinants of capital structure: An empirical study of companies from selected post-transition economies

Directory of Open Access Journals (Sweden)

Sasho Arsov

2016-06-01

Full Text Available The goal of this paper is to examine if there are any determinants that systematically influence the capital structure of the companies in the Balkan countries and to determine if any of the existing capital structure theories are relevant in their case. We apply a panel regression on a sample consisting of the largest and most frequently traded joint-stock companies from four countries. The results show that the larger companies and those with higher fixed asset investments exhibit higher leverage, while the more profitable companies and those with more tangible assets use less debt financing. Other variables, such as the concentration of company ownership, the riskiness of its operating profits and the effective tax rates have not been found statistically significant. These results, supported by the robustness tests, have confirmed our expectation that the managers in these countries do not set specific target leverage ratios, but instead follow a particular order in the selection of the sources of financing. In other words, the companies behave in accordance with the pecking order theory, which is a confirmation of our initial hypothesis. The governments of these countries should put more effort on stimulating the use of other sources of financing to relieve the possible excessive company dependence on the banking sector.

Biomarker selection for determining bone biocompatibility of pure magnesium processed by equal channel angular pressing (ECAP) using immunohistochemistry

Science.gov (United States)

Handayani, Lisa; Sulistyani, Lilies Dwi; Supriadi, Sugeng; Priosoeryanto, Bambang Pontjo; Latief, Benny Syariefsyah

2018-02-01

Since grain refinement is proved to be favorable to improve mechanical properties and corrosion resistance, a new conceptual metal forming process, equal channel angular pressing (ECAP), has been carried out on magnesium, a very promising biodegradable material in the field of oral and maxillofacial surgery. The popularity of immunohisto-chemistry (IHC) has been rising following the discovery of biomarker. In the meantime, more antibodies being produced for research have been continuously rising and becoming more varied. This review provides a conceptual framework to understand the roles of IHC on determination of bone biocompatibility to ECAP magnesium by selecting biomarker and point needed to either select or make an antibody to the target. From the review, it has been concluded that the most suitable biomarkers for biocompatibility test of bone implanted with ECAP magnesium are collagen-1, osteocalcin, smooth muscle actin, and CD68.

Determinants of Habitat Selection by Hatchling Australian Freshwater Crocodiles

Science.gov (United States)

Somaweera, Ruchira; Webb, Jonathan K.; Shine, Richard

2011-01-01

Animals almost always use habitats non-randomly, but the costs and benefits of using specific habitat types remain unknown for many types of organisms. In a large lake in northwestern Australia (Lake Argyle), most hatchling (banks rather than the more widely available open banks. Mean body sizes of young crocodiles did not differ among the three habitat types. We tested four potential explanations for non-random habitat selection: proximity to nesting sites, thermal conditions, food availability, and exposure to predation. The three alternative habitat types did not differ in proximity to nesting sites, or in thermal conditions. Habitats with higher food availability harboured more hatchlings, and feeding rates (obtained by stomach-flushing of recently-captured crocodiles) were highest in such areas. Predation risk may also differ among habitats: we were twice as likely to capture a crocodile after seeing it in open-bank sites than in the other two habitat types. Thus, habitat selection of hatchling crocodiles in this system may be driven both by prey availability and by predation risk. PMID:22163308

Direct phase selection of initial phases from single-wavelength anomalous dispersion (SAD) for the improvement of electron density and ab initio structure determination.

Science.gov (United States)

Chen, Chung-De; Huang, Yen-Chieh; Chiang, Hsin-Lin; Hsieh, Yin-Cheng; Guan, Hong-Hsiang; Chuankhayan, Phimonphan; Chen, Chun-Jung

2014-09-01

Optimization of the initial phasing has been a decisive factor in the success of the subsequent electron-density modification, model building and structure determination of biological macromolecules using the single-wavelength anomalous dispersion (SAD) method. Two possible phase solutions (φ1 and φ2) generated from two symmetric phase triangles in the Harker construction for the SAD method cause the well known phase ambiguity. A novel direct phase-selection method utilizing the θ(DS) list as a criterion to select optimized phases φ(am) from φ1 or φ2 of a subset of reflections with a high percentage of correct phases to replace the corresponding initial SAD phases φ(SAD) has been developed. Based on this work, reflections with an angle θ(DS) in the range 35-145° are selected for an optimized improvement, where θ(DS) is the angle between the initial phase φ(SAD) and a preliminary density-modification (DM) phase φ(DM)(NHL). The results show that utilizing the additional direct phase-selection step prior to simple solvent flattening without phase combination using existing DM programs, such as RESOLVE or DM from CCP4, significantly improves the final phases in terms of increased correlation coefficients of electron-density maps and diminished mean phase errors. With the improved phases and density maps from the direct phase-selection method, the completeness of residues of protein molecules built with main chains and side chains is enhanced for efficient structure determination.

What Are the Environmental Determinants of Phenotypic Selection? A Meta-analysis of Experimental Studies.

Science.gov (United States)

Caruso, Christina M; Martin, Ryan A; Sletvold, Nina; Morrissey, Michael B; Wade, Michael J; Augustine, Kate E; Carlson, Stephanie M; MacColl, Andrew D C; Siepielski, Adam M; Kingsolver, Joel G

2017-09-01

Although many selection estimates have been published, the environmental factors that cause selection to vary in space and time have rarely been identified. One way to identify these factors is by experimentally manipulating the environment and measuring selection in each treatment. We compiled and analyzed selection estimates from experimental studies. First, we tested whether the effect of manipulating the environment on selection gradients depends on taxon, trait type, or fitness component. We found that the effect of manipulating the environment was larger when selection was measured on life-history traits or via survival. Second, we tested two predictions about the environmental factors that cause variation in selection. We found support for the prediction that variation in selection is more likely to be caused by environmental factors that have a large effect on mean fitness but not for the prediction that variation is more likely to be caused by biotic factors. Third, we compared selection gradients from experimental and observational studies. We found that selection varied more among treatments in experimental studies than among spatial and temporal replicates in observational studies, suggesting that experimental studies can detect relationships between environmental factors and selection that would not be apparent in observational studies.

Determination of TNT explosive based on its selectively interaction with creatinine-capped CdSe/ZnS quantum dots

International Nuclear Information System (INIS)

Carrillo-Carrión, Carolina; Simonet, Bartolomé M.; Valcárcel, Miguel

2013-01-01

Graphical abstract: -- Highlights: •Creatinine-modified CdSe/ZnS quantum dots fluorescent probe has been prepared. •This modified QDs has been used for sensing 2,4,6,-trinitrotoluene explosive (TNT). •The selectivity of fluorescence quenching of creatinine-QD for TNT has been evaluated. •The potential application of the proposed methodology for the determination of TNT in spiked soils has been demonstrated. -- Abstract: Here, a creatinine-modified CdSe/ZnS quantum dots fluorescent probe has been prepared and used for sensing 2,4,6,-trinitrotoluene explosive (TNT). The proposed method is based on the selective interaction between creatinine and nitroaromatic compounds according to the well-known Jaffé reaction. The procedure for the synthesis of creatinine-CdSe/ZnS reagent is very simple and reproducible and its fluorescent characteristics are reported. We found that the presence of TNT quenches the original fluorescence of creatinine-QD according to the Stern–Volmer model. Under the working conditions, the calibration plot of I o /I versus concentration of TNT was linear in the range 10–300 μg L −1 (R 2 = 0.996). The mechanism interaction is discussed. The selectivity of fluorescence quenching of creatinine-QD for TNT has been evaluated. Finally, the potential application of the proposed methodology for the determination of TNT in spiked soils is demonstrated. For the analysis of soil samples a solid-liquid extraction is carried out and a four-point standard addition protocol is used to correct the matrix effect. The method, which is simple and rapid, allows the detection of 0.057 μg g −1 of TNT in soil samples. This sensor could be a useful tool for environmental studies, a crucial topic for nanotechnology nowadays

Comparative study on the selectivity of various spectrophotometric techniques for the determination of binary mixture of fenbendazole and rafoxanide.

Science.gov (United States)

Saad, Ahmed S; Attia, Ali K; Alaraki, Manal S; Elzanfaly, Eman S

2015-11-05

Five different spectrophotometric methods were applied for simultaneous determination of fenbendazole and rafoxanide in their binary mixture; namely first derivative, derivative ratio, ratio difference, dual wavelength and H-point standard addition spectrophotometric methods. Different factors affecting each of the applied spectrophotometric methods were studied and the selectivity of the applied methods was compared. The applied methods were validated as per the ICH guidelines and good accuracy; specificity and precision were proven within the concentration range of 5-50 μg/mL for both drugs. Statistical analysis using one-way ANOVA proved no significant differences among the proposed methods for the determination of the two drugs. The proposed methods successfully determined both drugs in laboratory prepared and commercially available binary mixtures, and were found applicable for the routine analysis in quality control laboratories. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of membrane-selective electrodes for the determination of Tiemonium methylsulphate

Directory of Open Access Journals (Sweden)

Lobna A. Hussein

2017-06-01

Full Text Available Three ion selective electrodes were developed for the quantification of Tiemonium methylsulphate (TIM. Two of these sensors involve the construction of water insoluble ion-association complexes; namely sensor1 TIM-phosphotungstate (TIM-PT and sensor 2 TIM-Reinecke (TIM-R. Molecular recognition elements have extensive applications in electrochemical sensors with a significant potential for future development thus a third electrode utilizing molecularly imprinted polymer was constructed; sensor 3 TIM-MIP. The proposed sensors showed fast, stable Nernstian responses of 56.4, 56.1and 57.5 mV/decade for sensors 1, 2 and 3, respectively, across a relatively wide TIM concentration range (1 × 10−4 to 1 × 10−2 mol L−1 for sensors 1 and 2 and 1 × 10–5 to 1 × 10–2 mol L−1 for sensor 3 in the pH range of 2–7. Sensor 1 and sensor 2 can be used for five weeks while sensor 3 for 65 days without a significant change in sensitivity. The suggested method was used to determine TIM in dosage forms. No measurable difference was obtained when the result statistically compared with respect to accuracy and precision with reported HPLC method.

Collection/concentration of trace uranium for spectrophotometric detection using activated carbon and first-derivative spectrophotometry

International Nuclear Information System (INIS)

El-Sayed, A.A.; Hamed, M.M.; El-Reefy, S.; Hmmad, H.A.

2007-01-01

The need exists for preconcentration of trace and ultratrace amounts of uranium from environmental, geological and biological samples. The adsorption of uranium on various solids is important from the purification, environmental, and radioactivity waste disposal points of view. A method is described for the determination of traces of uranium using first-derivative spectrophotometry after adsorptive preconcentration of uranium on activated carbon. Various parameters that influence the adsorptive preconcentration of uranium on activated carbon, viz., pH, amounts of activated carbon and time of stirring and interference of metals have been studied. First-derivative spectrophotometry in conjunction with adsorptive preconcentration of uranium on activated carbon is used for determining uranium at concentration levels down to 20 ppb (w/v). (orig.)

Highly sensitive and selective determination of methylergometrine maleate using carbon nanofibers/silver nanoparticles composite modified carbon paste electrode.

Science.gov (United States)

Kalambate, Pramod K; Rawool, Chaitali R; Karna, Shashi P; Srivastava, Ashwini K

2016-12-01

A highly sensitive and selective voltammetric method for determination of Methylergometrine maleate (MM) in pharmaceutical formulations, urine and blood serum samples has been developed based on enhanced electrochemical response of MM at carbon nanofibers and silver nanoparticles modified carbon paste electrode (CNF-AgNP-CPE). The electrode material was characterized by various techniques viz., X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The electrocatalytic response of MM at CNF-AgNP-CPE was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the proposed sensor exhibits excellent electrochemical response towards MM. The DPV study shows greatly enhanced electrochemical signal for MM at CNF-AgNP-CPE lending high sensitivity to the proposed sensor for MM detection. The peak (Ip) current for MM is found to be rectilinear in the range 4.0×10(-8)-2.0×10(-5)M with a detection limit of 7.1×10(-9)M using DPV. The feasibility of the proposed sensor in analytical applications was investigated by conducting experiments on commercial pharmaceutical formulations, human urine and blood serum samples, which yielded satisfactory recoveries of MM. The proposed electrochemical sensor offers high sensitivity, selectivity, reproducibility and practical utility. We recommend it as an authentic and productive electrochemical sensor for successful determination of MM. Copyright © 2016. Published by Elsevier B.V.

Ion-selective electrode reviews

CERN Document Server

Thomas, J D R

1985-01-01

Ion-Selective Electrode Reviews, Volume 7 is a collection of papers that covers the applications of electrochemical sensors, along with the versatility of ion-selective electrodes. The coverage of the text includes solid contact in membrane ion-selective electrodes; immobilized enzyme probes for determining inhibitors; potentiometric titrations based on ion-pair formation; and application of ion-selective electrodes in soil science, kinetics, and kinetic analysis. The text will be of great use to chemists and chemical engineers.

Determinants of habitat selection by hatchling Australian freshwater crocodiles.

Directory of Open Access Journals (Sweden)

Ruchira Somaweera

Full Text Available Animals almost always use habitats non-randomly, but the costs and benefits of using specific habitat types remain unknown for many types of organisms. In a large lake in northwestern Australia (Lake Argyle, most hatchling (<12-month-old freshwater crocodiles (Crocodylus johnstoni are found in floating vegetation mats or grassy banks rather than the more widely available open banks. Mean body sizes of young crocodiles did not differ among the three habitat types. We tested four potential explanations for non-random habitat selection: proximity to nesting sites, thermal conditions, food availability, and exposure to predation. The three alternative habitat types did not differ in proximity to nesting sites, or in thermal conditions. Habitats with higher food availability harboured more hatchlings, and feeding rates (obtained by stomach-flushing of recently-captured crocodiles were highest in such areas. Predation risk may also differ among habitats: we were twice as likely to capture a crocodile after seeing it in open-bank sites than in the other two habitat types. Thus, habitat selection of hatchling crocodiles in this system may be driven both by prey availability and by predation risk.

Determination of Anti-nutrients and Toxic Substances of Selected ...

African Journals Online (AJOL)

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ABSTRACT: Determination of antinutrients and toxic substances in leafy vegetables is an imperative facet in nutritional studies as it establishes the baseline concentrations index for phytotoxins in the vegetables. Concentrations of cyanide, nitrate, soluble and total oxalates were quantitatively determined in the common ...

Determination of the ion-exchange capacity of anion-selective membranes

Czech Academy of Sciences Publication Activity Database

Karas, F.; Hnát, J.; Paidar, M.; Schauer, Jan; Bouzek, K.

2014-01-01

Roč. 39, č. 10 (2014), s. 5054-5062 ISSN 0360-3199 Institutional support: RVO:61389013 Keywords : ion-exchange capacity * anion-selective membranes * titration Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.313, year: 2014

Natural selection and molecular evolution in primate PAX9 gene, a major determinant of tooth development.

Science.gov (United States)

Pereira, Tiago V; Salzano, Francisco M; Mostowska, Adrianna; Trzeciak, Wieslaw H; Ruiz-Linares, Andrés; Chies, José A B; Saavedra, Carmen; Nagamachi, Cleusa; Hurtado, Ana M; Hill, Kim; Castro-de-Guerra, Dinorah; Silva-Júnior, Wilson A; Bortolini, Maria-Cátira

2006-04-11

Large differences in relation to dental size, number, and morphology among and within modern human populations and between modern humans and other primate species have been observed. Molecular studies have demonstrated that tooth development is under strict genetic control, but, the genetic basis of primate tooth variation remains unknown. The PAX9 gene, which codes for a paired domain-containing transcription factor that plays an essential role in the development of mammal dentition, has been associated with selective tooth agenesis in humans and mice, which mainly involves the posterior teeth. To determine whether this gene is polymorphic in humans, we sequenced approximately 2.1 kb of the entire four-exon region (exons 1, 2, 3 and 4; 1,026 bp) and exon-intron (1.1 kb) boundaries of 86 individuals sampled from Asian, European, and Native American populations. We provided evidence that human PAX9 polymorphisms are limited to exon 3 only and furnished details about the distribution of a mutation there in 350 Polish subjects. To investigate the pattern of selective pressure on exon 3, we sequenced ortholog regions of this exon in four species of New World monkeys and one gorilla. In addition, orthologous sequences of PAX9 available in public databases were also analyzed. Although several differences were identified between humans and other species, our findings support the view that strong purifying selection is acting on PAX9. New World and Old World primate lineages may, however, have different degrees of restriction for changes in this DNA region.

Ultratrace determination of lead in whole blood using electrothermal atomization laser-excited atomic fluorescence spectrometry.

Science.gov (United States)

Wagner, E P; Smith, B W; Winefordner, J D

1996-09-15

Laser-excited atomic fluorescence has been used to detect lead that was electrothermally atomized from whole blood in a graphite furnace. A 9 kHz repetition rate copper vapor laser pumped dye laser was used to excite the lead at 283.3 nm, and the resulting atomic fluorescence was detected at 405.8 nm. No matrix modification was used other than a 1:21 dilution of the whole blood with high-purity water. Using the atomic fluorescence peak area as the analytical measure and a background correction technique based upon a simultaneous measurement of the transmitted laser intensity, excellent agreement for NIST and CDC certified whole blood reference samples was obtained with aqueous standards. A limit of detection in blood of 10 fg/mL (100 ag absolute) was achieved.

Liquid phase micro-extraction: Towards the green methodology for ultratrace metals determination in aquatic ecosystems

Directory of Open Access Journals (Sweden)

López-López J. A.

2013-04-01

Full Text Available Heavy metals are normally found, in natural waters, in very low concentrations. Some of them are essential for life in low level; however, in higher level they are toxic. Therefore, analyzing their bio-available fraction is of main interest. Standard methodology is based in the collection of a number of samples from a water body. Collected samples must be stored, pre-treated and then analyzed. Pre-treatment usually involves pre-concentrating the metal, with the corresponding risk of contamination or loss of analyte. This way, punctual information is obtained from every sampling campaign. As an alternative, passive sampling techniques allow the continuous and coupled sampling-pre-treatment for heavy metals analysis, giving a better approach in the characterization of the studied water body. Liquid phase micro-extraction (LPME is a green analytical alternative for liquid-liquid extraction that promotes a reduction of sample volume, solvent needed and waste generation. Using these systems, polypropylene hollow fibers (HF with pores in their walls can be used. A few micro-liters of organic solvent are supported in the pores. The sample is placed in the outer part of the fiber and a receiving phase is placed in its inner part, allowing continuous liquid extraction of the metal from the sample. Several fibers with different physical features have been employed to analyzed total concentration and bio-availability of some heavy metals (Ag, Ni, Cu in natural water samples. Thanks to fibers configuration, devices for passive sampling based in HF-LPME could be designed. Advantages of this methodology over existing ones are supported because the receiving phase is liquid. As a consequence, retained metals do not need to be eluted from the acceptor prior to instrumental analysis.

A novel bi-enzyme electrochemical biosensor for selective and sensitive determination of methyl salicylate.

Science.gov (United States)

Fang, Yi; Umasankar, Yogeswaran; Ramasamy, Ramaraja P

2016-07-15

An amperometric sensor based on a bi-enzyme modified electrode was fabricated to detect methyl salicylate, a volatile organic compound released by pathogen-infected plants via systemic response. The detection is based on cascadic conversion reactions that result in an amperometric electrochemical signal. The bi-enzyme electrode is made of alcohol oxidase and horseradish peroxidase enzymes immobilized on to a carbon nanotube matrix through a molecular tethering method. Methyl salicylate undergoes hydrolysis to form methanol, which is consumed by alcohol oxidase to form formaldehyde while simultaneously reducing oxygen to hydrogen peroxide. The hydrogen peroxide will be further reduced to water by horseradish peroxidase, which results in an amperometric signal via direct electron transfer. The bi-enzyme biosensor was evaluated by cyclic voltammetry and constant potential amperometry using hydrolyzed methyl salicylate as the analyte. The sensitivity of the bi-enzyme biosensor as determined by cyclic voltammetry and constant potential amperometry were 112.37 and 282.82μAcm(-2)mM(-1) respectively, and the corresponding limits of detection were 22.95 and 0.98μM respectively. Constant potential amperometry was also used to evaluate durability, repeatability and interference from other compounds. Wintergreen oil was used for real sample study to establish the application of the bi-enzyme sensor for selective determination of plant pathogen infections. Copyright © 2016 Elsevier B.V. All rights reserved.

VENDOR SELECTION AND DETERMINING PROCUREMENT QUOTAS IN CONDITIONS WHEN DISCOUNTS ARE OFFERED ON THE TOTAL VALUE OF THE CONTRACTED PROCUREMENT OF MANY DIFFERENT PRODUCTS

Directory of Open Access Journals (Sweden)

Zoran Babic

2012-04-01

Full Text Available Vendor selection is a very significant business problem for ensuring the competitiveness on the market. That is why companies pay great attention to this problem. To solve the vendor selection problems can be applied to a number of quantitative methods. Depending on the goals of the company the vendor selection can be a mono-criterion or multi-criterion programming problem. This paper deals with the problem of vendor selection and determining procurement quotas from selected vendors under conditions where vendors offer discounts to the total order value within a specified period where the buyer buys more products from the vendors. The total value of procurement costs in a given period is taken as an optimization criterion. In this paper the specific flour purchase problem is solved for a company that manufactures bakery products

VENDOR SELECTION AND DETERMINING PROCUREMENT QUOTAS IN CONDITIONS WHEN DISCOUNTS ARE OFFERED ON THE TOTAL VALUE OF THE CONTRACTED PROCUREMENT OF MANY DIFFERENT PRODUCTS

Directory of Open Access Journals (Sweden)

Zoran Babić

2012-04-01

Full Text Available Vendor selection is a very significant business problem for ensuring the competitiveness on the market. That is why companies pay great attention to this problem. To solve the vendor selection problems can be applied to a number of quantitative methods. Depending on the goals of the company the vendor selection can be a mono-criterion or multi-criterion programming problem. This paper deals with the problem of vendor selection and determining procurement quotas from selected vendors under conditions where vendors offer discounts to the total order value within a specified period where the buyer buys more products from the vendors. The total value of procurement costs in a given period is taken as an optimization criterion. In this paper the specific flour purchase problem is solved for a company that manufactures bakery products.

Highly selective and sensitive determination of copper ion by two novel optical sensors

Directory of Open Access Journals (Sweden)

Mehrorang Ghaedi

2017-05-01

Full Text Available New optical sensors for the determination of copper ion by incorporation of 1,1′-(4-nitro-1,2-phenylenebis(azan-1-yl-1-ylidenebis(methan-1-yl-1-lidenedinaphthalen-2-ol(L1, 1,1′-2,2′-(1,2-phenylenebis(ethene-2,1-diyldinaphthalen-2-ol 1(L2, dibutylphthalate (DBP and sodium tetraphenylborate (Na-TPB to the plasticized polyvinyl chloride matrices were prepared. The tendency of both ionophores (L2 and L1 as chromoionophore was significantly enhanced by the addition of DBP to the membrane. The proposed sensors benefit from advantages such as high stability, reproducibility and relatively long lifetime, good selectivity for Cu2+ ion determination over a large number of alkali, alkaline earth, transition and heavy metal ions. At optimum values of membrane compositions and experimental conditions, both sensors’ response was linear over a concentration range of 7.98 × 10−6 to 1.31 × 10−4mol L−1 and 1.99 × 10−6 to 5.12 × 10−5 mol L−1 for L2 and L1, respectively. Sensor detection limit based on the definition that the concentration of the sample leads to a signal equal to the blank signal plus three times of its standard deviation was found to be 3.99 × 10−7 and 5.88 × 10−7 mol L−1 for L2 and L1, respectively. The response time of the optodes (defined as the time required reaching the 90% of the peak signal was found to be 5–8 min for L2 and 20–25 min for L1 based sensor. The proposed optical sensors were applied successfully for the determination of Cu2+ ion content in water samples.

Sensitive and selective determination of Cu2+ at D-penicillamine functionalized nano-cellulose modified pencil graphite electrode

Science.gov (United States)

Taheri, M.; Ahour, F.; Keshipour, S.

2018-06-01

A novel electrochemical sensor based on D-penicillamine anchored nano-cellulose (DPA-NC) modified pencil graphite electrode was fabricated and used for highly selective and sensitive determination of copper (II) ions in the picomolar concentration by square wave adsorptive stripping voltammetric (SWV) method. The modified electrode showed better and increased SWV response compared to the bare and NC modified electrodes which may be related to the porous structure of modifier along with formation of complex between Cu2+ ions and nitrogen or oxygen containing groups in DPA-NC. Optimization of various experimental parameters influence the performance of the sensor, were investigated. Under optimized condition, DPA-NC modified electrode was used for the analysis of Cu2+ in the concentration range from 0.2 to 50 pM, and a lower detection limit of 0.048 pM with good stability, repeatability, and selectivity. Finally, the practical applicability of DPA-NC-PGE was confirmed via measuring trace amount of Cu (II) in tap and river water samples.

A nanosized cadmium(II)-imprinted polymer for use in selective trace determination of cadmium in complex matrices

International Nuclear Information System (INIS)

Behbahani, Mohammad; Bagheri, Akbar; Barati, Mozhgan; Pourali, Ali Reza; Tapeh, Nasim Akbari Ghareh; Bojdi, Majid Kalate

2013-01-01

We describe a nanosized Cd(II)-imprinted polymer that was prepared from 4-vinyl pyridine (the functional monomer), ethyleneglycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the radical initiator), neocuproine (the ligand), and Cd(II) (the template ion) by precipitation polymerization in acetonitrile as the solvent. The imprinted polymer was characterized by X-ray diffraction, thermogravimetric analysis, differential thermal analysis, and scanning electron microscopy. The maximum adsorption capacity of the nanosized sorbent was calculated to be 64 mg g −1 . Cadmium(II) was then quantified by FAAS. The relative standard deviation and limit of detection are 4.2 % and 0.2 μg L −1 , respectively. The imprinted polymer displays improve selectivity for Cd(II) ions over a range of competing metal ions with the same charge and similar ionic radius. This nanosized sorbent is an efficient solid phase for selective extraction and preconcentration of Cd(II) in complex matrices. The method was successfully applied to the trace determination of Cd(II) in food and water samples. (author)

Sales Tax Compliance and Audit Selection

OpenAIRE

Murray, Matthew N.

1995-01-01

Uses sample selection estimation techniques to identify systematic audit selection rules and determinants of sales tax underreporting. Though based on data from only one state (Tennessee), outcomes are useful in developing and evaluating audit selection results.

Social determinants and the classification of disease: descriptive epidemiology of selected socially mediated disease constellations.

Directory of Open Access Journals (Sweden)

Robert S Levine

Full Text Available Most major diseases have important social determinants. In this context, classification of disease based on etiologic or anatomic criteria may be neither mutually exclusive nor optimal.Units of analysis comprised large metropolitan central and fringe metropolitan counties with reliable mortality rates--(n = 416. Participants included infants and adults ages 25 to 64 years with selected causes of death (1999 to 2006. Exposures included that residential segregation and race-specific social deprivation variables. Main outcome measures were obtained via principal components analyses with an orthogonal rotation to identify a common factor. To discern whether the common factor was socially mediated, negative binomial multiple regression models were developed for which the dependent variable was the common factor. Results showed that infant deaths, mortality from assault, and malignant neoplasm of the trachea, bronchus and lung formed a common factor for race-gender groups (black/white and men/women. Regression analyses showed statistically significant, positive associations between low socio-economic status for all race-gender groups and this common factor.Between 1999 and 2006, deaths classified as "assault" and "lung cancer", as well as "infant mortality" formed a socially mediated factor detectable in population but not individual data. Despite limitations related to death certificate data, the results contribute important information to the formulation of several hypotheses: (a disease classifications based on anatomic or etiologic criteria fail to account for social determinants; (b social forces produce demographically and possibly geographically distinct population-based disease constellations; and (c the individual components of population-based disease constellations (e.g., lung cancer are phenotypically comparable from one population to another but genotypically different, in part, because of socially mediated epigenetic variations

7th international conference ''Modern trends in activation analysis''

International Nuclear Information System (INIS)

Obrusnik, I.

1987-01-01

The conference was held on 23-27 June, 1986 in Copenhagen (DK) with the participation of specialists from 42 countries. 175 papers were submitted covering the wide field of applications of neutron activation analysis, from novel techniques to sample preparation, information processes and control, activation techniques, light element and rare earth element determination, ultratracer analysis, quality assurance, comparator methods, and reference materials. The poster session was mainly oriented to industrial applications of activation analysis, biological applications, in vivo use of neutron activation analysis, the applications of neutron activation analysis in environmental control, criminology, etc. (E.S.)

Selective enrichment and determination of monoamine neurotransmitters by CU(II) immobilized magnetic solid phase extraction coupled with high-performance liquid chromatography-fluorescence detection.

Science.gov (United States)

He, Maofang; Wang, Chaozhan; Wei, Yinmao

2016-01-15

In this paper, iminodiacetic acid-Cu(II) functionalized Fe3O4@SiO2 magnetic nanoparticles were prepared and used as new adsorbents for magnetic solid phase extraction (MSPE) of six monoamine neurotransmitters (MNTs) from rabbit plasma. The selective enrichment of MNTs at pH 5.0 was motivated by the specific coordination interaction between amino groups of MNTs and the immobilized Cu(II). The employed weak acidic extraction condition avoided the oxidation of MNTs, and thus facilitated operation and ensured higher recoveries. Under optimal conditions, the recoveries of six MNTs from rabbit plasma were in the range of 83.9-109.4%, with RSD of 2.0-10.0%. When coupled the Cu(II) immobilized MSPE with high-performance liquid chromatography-fluorescence detection, the method exhibited relatively lower detection limits than the previously reported methods, and the method was successfully used to determine the endogenous MNTs in rabbit plasma. The proposed method has potential application for the determination of MNTs in biological samples. Also, the utilization of coordination interaction to improve the selectivity might open another way to selectively enrich small alkaloids from complex samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of tellurium at ultra-trace levels in drinking water by on-line solid phase extraction coupled to graphite furnace atomic absorption spectrometer

International Nuclear Information System (INIS)

Pedro, Juana; Stripekis, Jorge; Bonivardi, Adrian; Tudino, Mabel

2008-01-01

In this paper, two time-based flow injection (FI) separation pre-concentration systems coupled to graphite furnace atomic absorption spectrometry (GFAAS) for tellurium determination are studied and compared. The first alternative involves the pre-concentration of the analyte onto Dowex 1X8 employed as packaging material of a micro-column inserted in the flow system. The second set-up is based on the co-precipitation of tellurium with La(OH) 3 followed by retention onto XAD resins. Both systems are compared in terms of limit of detection, linear range, RSD%, sample throughput, micro-columns lifetime and aptitude for fully automatic operation. The features of the Dowex system are: 37% efficiency of retention and an enhancement factor of 42 for a pre-concentration time of 180 seconds (sample flow rate = 3 ml min -1 ) with acetic acid elution volumes of 80 μl. The detection limit (3 s) is 7 ng l -1 and the relative standard deviation (n = 7200 ng l -1 ) is 5.8%. The analytical performance of the XAD system is: 72% efficiency of retention and an enhancement factor of 25 for a pre-concentration time of 180 s (sample flow rate = 3 ml min -1 ) with nitric acid elution volumes of 300 μl. The detection limit is 66 ng l -1 and the relative standard deviation (n = 7200 ng l -1 ) is 8.3%. Applications to the determination of tellurium in tap water and the validation of the analytical methodology employing SRM 1643e as certified reference material are shown

Recruiter Selection Model

National Research Council Canada - National Science Library

Halstead, John B

2006-01-01

.... The research uses a combination of statistical learning, feature selection methods, and multivariate statistics to determine the better prediction function approximation with features obtained...

Spectrophotometric Determination of Chromium (III) in Egyptian 11 manite from phosphate solution using Ewes as a selective adsorbent

International Nuclear Information System (INIS)

Abdu, A. A.

2012-12-01

Egyptian white sand (EWS) was used as an adsorbent for the selective separation of Cr(III) from phosphate solution to be determined colorimetrically using 1,5-diphenylcarbazide. The experimental factors affecting maximum selective adsorption/desorption of Cr(III) on / from EWS were the amount of adsorption (g), pH of initial concentration of Cr(III) in solution, contact time temperature and initial concentration of Cr(III) in solution were investigated. No effect of [PO 4 ] 3- , Ti(IV) and Fe(III) on Cr(III) sorption were verified. Accuracy and relative standard deviations (RSD) were acceptable for all analyses. The maximum sorption capacity, Q e , of adsorbed Cr(III) per gram of sand was 93.5 mg/g, at EWS concentration 20 g/1, pH 0.8 contact time 120 min and temperature 30 o C for adsorption of Cr(III) on EWS and pH 0.4, contact time 6 min and temperature 25o C for desorption of Cr(III) from EWS. (Author)

Determination of trace Np and Pu by ICP-MS with extraction chromatography in emergency situations

International Nuclear Information System (INIS)

Yanqin, Ji; Qing, Tian; Baoming, Shen; Xianzhang, Shao

2008-01-01

Full text: An accurate determination of radioculides from various sources in the environmental samples is essential for assessment of the potential hazards and suitable countermeasures both in case of accidents, authorised release and routine surveillance. However, the concentrationof neptunium and plutonium is extremely low in environmental samples, and such samples have a complex matrix composition, which is to be taken into account for a proper analysis. Conventional radiochemical methods such as alpha spectrometry, neutron activation analysis, liquid, liquid scintillation system, fission track and gamma spectrometry for the quantitative determination of neptunium and plutonium often require complicated and time-consuming sample preparation and separation procedures. Due to the large amount of the complex and often unknown matrix, the analysis may also be covered by naturally occurring radionuclides. With the development of new analysis techniques, non-radioactive methods are increasingly used for the determination of trace or ultra-trace radionuclides in environmental samples. Inductively coupled plasma mass spectrometry (ICP-MS) is one of the most suitable analysis techniques for the measurement of the long-lived radionuclides with its high sensitivity, low detection limits, short analysis time, less chemical interferences and multi-elemental capability. The throughput is therefore very high (approx.100 samples a day). The main objective of the present study was to set up of a simple, fast separation procedure to measure Np and Pu in the environmental samples ICP-MS. An unique extraction chromatographic column (TOA: tri-n-octylamine on Teflon powder) with a two-stage sample loading was prepared to separate Np and Pu from the environmental matrix. Np and Pu were efficiently retained in 4 M HNO 3 medium on the column and easiy eluted with 0.02 M oxalic acid 0.16 M HNO 3 at 95 C degree. The separated solutions were free from most of the matrix elements and were

Simultaneous visualization of the subfemtomolar expression of microRNA and microRNA target gene using HILO microscopy.

Science.gov (United States)

Lin, Yi-Zhen; Ou, Da-Liang; Chang, Hsin-Yuan; Lin, Wei-Yu; Hsu, Chiun; Chang, Po-Ling

2017-09-01

The family of microRNAs (miRNAs) not only plays an important role in gene regulation but is also useful for the diagnosis of diseases. A reliable method with high sensitivity may allow researchers to detect slight fluctuations in ultra-trace amounts of miRNA. In this study, we propose a sensitive imaging method for the direct probing of miR-10b (miR-10b-3p, also called miR-10b*) and its target ( HOXD10 mRNA) in fixed cells based on the specific recognition of molecular beacons combined with highly inclined and laminated optical sheet (HILO) fluorescence microscopy. The designed dye-quencher-labelled molecular beacons offer excellent efficiencies of fluorescence resonance energy transfer that allow us to detect miRNA and the target mRNA simultaneously in hepatocellular carcinoma cells using HILO fluorescence microscopy. Not only can the basal trace amount of miRNA be observed in each individual cell, but the obtained images also indicate that this method is useful for monitoring the fluctuations in ultra-trace amounts of miRNA when the cells are transfected with a miRNA precursor or a miRNA inhibitor (anti-miR). Furthermore, a reasonable causal relation between the miR-10b and HOXD10 expression levels was observed in miR-10b* precursor-transfected cells and miR-10b* inhibitor-transfected cells. The trends of the miRNA alterations obtained using HILO microscopy completely matched the RT-qPCR data and showed remarkable reproducibility (the coefficient of variation [CV] = 0.86%) and sensitivity (<1.0 fM). This proposed imaging method appears to be useful for the simultaneous visualisation of ultra-trace amounts of miRNA and target mRNA and excludes the procedures for RNA extraction and amplification. Therefore, the visualisation of miRNA and the target mRNA should facilitate the exploration of the functions of ultra-trace amounts of miRNA in fixed cells in biological studies and may serve as a powerful tool for diagnoses based on circulating cancer cells.

What should we be selecting for? A systematic approach for determining which personal characteristics to assess for during admissions

Directory of Open Access Journals (Sweden)

Conlon Peter

2012-11-01

Full Text Available Abstract Background Admission committees are responsible for creating fair, defensible, reliable, and valid processes that assess those attributes considered important for professional success. There is evidence for the continuing use of academic ability as a selection criterion for health professional schools; however, there is little evidence for the reliability and validity of measures currently in place to assess personal characteristics. The Ontario Veterinary College (OVC initiated a review of its admissions criteria in order to implement an evidence-based method to determine which characteristics veterinary stakeholders consider important to assess for admission. Methods Eleven characteristics were identified by the OVC Admissions Committee and a survey was sent to all licensed veterinarians in Ontario (n=4,068, OVC students (n=450, and OVC faculty, interns and residents (n=192. A paired comparison method was used to identify the relative rank order of the characteristics, and multivariate analysis of variance with post hoc analyses was used to determine between group differences in the returned survey data. Results Surveys were returned from 1,312 participants (27.86% response rate; female 59.70%. The relative rank of the characteristics was reasonably consistent among participant groups, with ethical behaviour, sound judgment, communication, and critical and creative thinking being ranked as the top four. However, the importance of certain characteristics like communication and empathy were perceived differently by groups. For instance, females scored communication (F(1, 1289 = 20.24, p d = .26 and empathy (F(1, 1289 = 55.41, p d = 0.42 significantly higher than males, while males scored knowledge of profession (F(1, 1289 = 12.81, p d = 0.20, leadership (F(1, 1289 = 10.28, p = .001, d = 0.18, and sound judgment (F(1, 1289 = 13.56, p d = 0.21 significantly higher than females. Conclusions The data from the paired comparison method

Determination of Sugar and Some Trace Metals Content in Selected ...

African Journals Online (AJOL)

Ten brands of commercial fruit juices were analyzed for pH, specific gravity, total solids, reducing sugar and total sugar trace metals contents. The pH was determined using a Hanna pH meter. Sugar content was determined using the Lane and Eynon method. Sodium and potassium were determined by flame photometry ...

Using of multi-walled carbon nanotubes electrode for adsorptive stripping voltammetric determination of ultratrace levels of RDX explosive in the environmental samples.

Science.gov (United States)

Rezaei, Behzad; Damiri, Sajjad

2010-11-15

A study of the electrochemical behavior and determination of RDX, a high explosive, is described on a multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE) using adsorptive stripping voltammetry and electrochemical impedance spectroscopy (EIS) techniques. The results indicated that MWCNTs electrode remarkably enhances the sensitivity of the voltammetric method and provides measurements of this explosive down to the sub-mg/l level in a wide pH range. The operational parameters were optimized and a sensitive, simple and time-saving cyclic voltammetric procedure was developed for the analysis of RDX in ground and tap water samples. Under optimized conditions, the reduction peak have two linear dynamic ranges of 0.6-20.0 and 8.0-200.0 mM with a detection limit of 25.0 nM and a precision of <4% (RSD for 8 analysis). Copyright © 2010 Elsevier B.V. All rights reserved.

Selective and sensitive fluorimetric determination of carbendazim in apple and orange after preconcentration with magnetite-molecularly imprinted polymer

Science.gov (United States)

İlktaç, Raif; Aksuner, Nur; Henden, Emur

2017-03-01

In this study, magnetite-molecularly imprinted polymer has been used for the first time as selective adsorbent before the fluorimetric determination of carbendazim. Adsorption capacity of the magnetite-molecularly imprinted polymer was found to be 2.31 ± 0.63 mg g- 1 (n = 3). Limit of detection (LOD) and limit of quantification (LOQ) of the method were found to be 2.3 and 7.8 μg L- 1, respectively. Calibration graph was linear in the range of 10-1000 μg L- 1. Rapidity is an important advantage of the method where re-binding and recovery processes of carbendazim can be completed within an hour. The same imprinted polymer can be used for the determination of carbendazim without any capacity loss repeatedly for at least ten times. Proposed method has been successfully applied to determine carbendazim residues in apple and orange, where the recoveries of the spiked samples were found to be in the range of 95.7-103%. Characterization of the adsorbent and the effects of some potential interferences were also evaluated. With the reasonably high capacity and reusability of the adsorbent, dynamic calibration range, rapidity, simplicity, cost-effectiveness and with suitable LOD and LOQ, the proposed method is an ideal method for the determination of carbendazim.

Separation and determination of arsenic species in water by selective exchange and hybrid resins

Energy Technology Data Exchange (ETDEWEB)

Issa, Nureddin Ben [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, Belgrade (Serbia); Rajakovic-Ognjanovic, Vladana N. [Faculty of Civil Engineering, University of Belgrade, Bulevar Kralja Aleksandra 73, Belgrade (Serbia); Marinkovic, Aleksandar D. [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, Belgrade (Serbia); Rajakovic, Ljubinka V., E-mail: ljubinka@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, Belgrade (Serbia)

2011-11-07

Highlights: {yields} A simple and efficient method for separation and determination of arsenic species. {yields} A new hybrid resin HY-AgCl is effective for iAs and oAs analytical separation. {yields} SBAE resin was convenient for the separation of As(III) from As(V) and oAs species. {yields} HY-Fe resin was convenient for the separation of DMAs(V). - Abstract: A simple and efficient method for separation and determination of inorganic arsenic (iAs) and organic arsenic (oAs) in drinking, natural and wastewater was developed. If arsenic is present in water prevailing forms are inorganic acids of As(III) and As(V). oAs can be found in traces as monomethylarsenic acid, MMA(V), and dimethylarsenic acid, DMAs(V). Three types of resins: a strong base anion exchange (SBAE) and two hybrid (HY) resins: HY-Fe and HY-AgCl, based on the activity of hydrated iron oxides and a silver chloride were investigated. It was found that the sorption processes (ion exchange, adsorption and chemisorptions) of arsenic species on SBAE (ion exchange) and HY resins depend on pH values of water. The quantitative separation of molecular and ionic forms of iAs and oAs was achieved by SBAE and pH adjustment, the molecular form of As(III) that exists in the water at pH <8.0 was not bonded with SBAE, which was convenient for direct determination of As(III) concentration in the effluent. HY-Fe resin retained all arsenic species except DMAs(V), which makes possible direct measurements of this specie in the effluent. HY-AgCl resin retained all iAs which was convenient for direct determination of oAs species concentration in the effluent. The selective bonding of arsenic species on three types of resins makes possible the development of the procedure for measuring and calculation of all arsenic species in water. In order to determine capacity of resins the preliminary investigations were performed in batch system and fixed bed flow system. Resin capacities were calculated according to breakthrough

Species dependent studies of no-carrier-added 93mMo: A green method

International Nuclear Information System (INIS)

Mandal, Swadesh; Nayak, Dalia

2010-01-01

The present paper reports a combination of radioanalytical and green methodology for the ultra-trace scale speciation of molybdenum. The differential attitude of iron-doped calcium alginate (Fe-CA) and chitosan biopolymers towards no-carrier-added 93m Mo radionuclide was studied to develop environmentally sustainable speciation methodology in ultra-trace scale. The affinity of 93m Mo towards the Fe-CA beads is greater than that of chitosan. Species information was obtained by comparing the adsorption profile of 93m Mo on Fe-CA and chitosan biopolymer with the software code CHEAQS PRO program. From the experimental results it is concluded that no-carrier-added 93m Mo radionuclide form mononuclear species instead of polynuclear species in aqueous solution. Use of biodegradable, non-toxic biopolymer makes this method a step forward towards green chemistry.

Determination of selected quaternary ammonium compounds by liquid chromatography with mass spectrometry. Part II. Application to sediment and sludge samples in Austria

International Nuclear Information System (INIS)

Martinez-Carballo, Elena; Gonzalez-Barreiro, Carmen; Sitka, Andrea; Kreuzinger, Norbert; Scharf, Sigrid; Gans, Oliver

2007-01-01

Soxhlet extraction and high-performance liquid chromatography (HPLC) coupled to tandem mass spectrometry detection (MS/MS) was used for the determination of selected quaternary ammonium compounds (QACs) in solid samples. The method was applied for the determination of alkyl benzyl, dialkyl and trialkyl quaternary ammonium compounds in sediment and sludge samples in Austria. The overall method quantification limits range from 0.6 to 3 μg/kg for sediments and from 2 to 5 μg/kg for sewage sludges. Mean recoveries between 67% and 95% are achieved. In general sediments were especially contaminated by C12 chain benzalkonium chloride (BAC-C12) as well as by the long C-chain dialkyldimethylammonium chloride (DDAC-C18) with a maximum concentration of 3.6 mg/kg and 2.1 mg/kg, respectively. Maxima of 27 mg/kg for DDAC-C10, 25 mg/kg for BAC-C12 and 23 mg/kg for BAC-C14 were determined for sludge samples. The sums of the 12 selected target compounds range from 22 mg/kg to 103 mg/kg in the sludge samples. - The presence of quaternary ammonium surfactants in sediment and sludge samples is reported for the first time in Austria

All-Solid-State, PVC Membrane, and Carbon Paste Ion-Selective Electrodes for Determination of Donepezil Hydrochloride in Pharmaceutical Formulation.

Science.gov (United States)

Khamees, Nesreen; Mohamed, Tagreed Abdel-Fattah; Derar, Abeer Rashad; Aziz, Azza

2017-09-01

All-solid-state, polyvinyl chloride (PVC) membrane, and carbon paste potentiometric ion-selective electrodes (ISEs) were proposed for the determination of donepezil hydrochloride (DON) in the drug substance and a pharmaceutical formulation. The potentiometric response toward DON was based on the existence of donepezil-tetraphenyl borate (DON-TPB) in a PVC membrane or a carbon paste in the presence of dioctylphthalate. In contrast, the solid-state electrode was prepared by direct incorporation of DON-TPB into a commercial nail varnish without external additives. The electrodes exhibited Nernstian slopes of 55.0, 57.0, and 53.0 mV/decade over the concentration ranges of 1 × 10-5 to 1 × 10-3, 1 × 10-4 to 10-2, and 1 × 10-4 to 5 × 10-3 for the solid-state, PVC membrane, and carbon paste electrodes, respectively. The response of the electrodes is independent of pH in the range of 2-≤8. The electrodes showed good selectivity for DON with respect to a number of inorganic cations and amino acids. The electrodes were used for the determination of DON in pure solution and in pharmaceutical tablets with high accuracy (±2%) and precision (RSD ≤2%). The solid-state electrode is simple, economical, and rapid when compared to the PVC membrane and carbon paste electrodes.

A simple route to Develop Highly porous Nano Polypyrrole/Reduced Graphene Oxide Composite film for Selective Determination of Dopamine

International Nuclear Information System (INIS)

Daniel Arulraj, Abraham; Arunkumar, Arumugam; Vijayan, Muthunanthevar; Balaji Viswanath, Kamatchirajan; Vasantha, Vairathevar Sivasamy

2016-01-01

A highly selective sensor was developed for dopamine with electrochemically treated sodium dodecyl benzene sulfonate doped nano polypyrrole (ET-SDBS-NPPy)/reduced graphene oxide (RGO) film. First, graphene oxide (GO) was reduced on the electrode surface electrochemically and then, SDBS-NPPy film was polymerized electrochemically on the ERGO coated GCE and bare GCE also. The SDBS-NPPy/ERGO and SDBS-NPPy films were treated electrochemically in phosphate buffer solution to replace macro SDBS- anions by smaller phosphate anions. Then, the physical properties of the above composite films were characterized by scanning electron microscope (SEM) and water wettability test. The replacement of SDBS- anions by phosphate anions leaves porous structure in the polymer films and also increases the hydrophobicity in the films. Then, these composite films were applied for the determination of dopamine in the presence of ascorbic acid and uric acid. Under the optimal conditions, the linear range for dopamine detection is 0.1 μM-100.0 μM with the detection limit of 20 nM at S/N = 3. Generally, conducting polypyrrole film could sense ascorbic acid and dopamine simultaneously. However, we have proposed a simple route to synthesis a porous and hydrophobic polypyrrole composite film for selective determination of dopamine in the presence of higher concentration (five orders) of ascorbic acid and uric acid.

Microplate Bioassay for Determining Substrate Selectivity of "Candida rugosa" Lipase

Science.gov (United States)

Wang, Shi-zhen; Fang, Bai-shan

2012-01-01

Substrate selectivity of "Candida rugosa" lipase was tested using "p"-nitrophenyl esters of increasing chain length (C[subscript 1], C[subscript 7], C[subscript 15]) using the high-throughput screening method. A fast and easy 96-well microplate bioassay was developed to help students learn and practice biotechnological specificity screen. The…

Multielement ultratrace analysis in tungsten using secondary ion mass spectrometry

International Nuclear Information System (INIS)

Wilhartitz, P.; Virag, A.; Friedbacher, G.; Grasserbauer, M.

1987-01-01

The ever increasing demands on properties of materials create a trend also towards ultrapure products. Characterization of these materials is only possible with modern, highly sophisticated analytical techniques such as activation analysis and mass spectrometry, particularly SSMS, SIMS and GDMS. Analytical strategies were developed for the determination of about 40 elements in a tungsten matrix with high-performance SIMS. Difficulties like the elimination of interferences had to be overcome. Extrapolated detection limits were established in the range of pg/g (alkali metals, halides) to ng/g (e.g. Ta, Th). Depth profiling and ion imaging gave additional information about the lateral and the depth distribution of the elements. (orig.)

Trace and ultratrace level elemental and speciation analysis

International Nuclear Information System (INIS)

Arunachalam, J.

2012-01-01

Accurate determination of elements present at parts per million and billion levels in various matrices is a growing requirement in different fields. In environmental sciences various trace elements need to be analyzed so as establish the dispersal models of pollutants or the adequacy of effluent treatment prior to discharge into water bodies. The issues of bioaccumulation and magnification are important in aquatic systems. In nutrition and biochemistry one has to establish the bio-availability of essential and toxic elemental species as toxic elements prevent assimilation of essential elements. Fission and fusion technologies use a variety of structural materials requiring many trace elements to be present at levels strictly below the specified levels. Ultra-pure bulk semiconductor materials are required for fabrication devices. In metallurgy and materials sciences too, various trace elements are known to influence the properties. In the emerging fields like nanotechnology, it is necessary to understand the passage and accumulation of nano-particles inside the cells, through trace analysis. Many analytical techniques exist which can provide the concentration information in the bulk materials with good accuracy. They include ICP-AES, FAAS, and ICP-MS, which are solution based techniques. Direct solid state analytical techniques are Glow Discharge Mass Spectrometry (GDMS) and XRF. Accelerator based ion-beam analysis techniques can provide information on concentration and depth profiles of different elements in layered structures. Hyphenated techniques such as HPLC/lC-ICPMS, are helpful in identifying various chemical oxidation states in which a given element might be present in a matrix, which is termed as speciation analysis. This presentation will include the existing analytical competencies and the laboratory requirements for trace and ultra trace element elemental and speciation analyses and their applications. (author)

Time-dependent integrity during storage of natural surface water samples for the trace analysis of pharmaceutical products, feminizing hormones and pesticides

Directory of Open Access Journals (Sweden)

Prévost Michèle

2010-04-01

Full Text Available Abstract Monitoring and analysis of trace contaminants such as pharmaceuticals and pesticides require the preservation of the samples before they can be quantified using the appropriate analytical methods. Our objective is to determine the sample shelf life to insure proper quantification of ultratrace contaminants. To this end, we tested the stability of a variety of pharmaceutical products including caffeine, natural steroids, and selected pesticides under refrigerated storage conditions. The analysis was performed using multi-residue methods using an on-line solid-phase extraction combined with liquid chromatography tandem mass spectrometry (SPE-LC-MS/MS in the selected reaction monitoring mode. After 21 days of storage, no significant difference in the recoveries was observed compared to day 0 for pharmaceutical products, while for pesticides, significant losses occurred for DIA and simazine after 10 days (14% and 17% reduction respectively and a statistically significant decrease in the recovery was noted for cyanazine (78% disappearance. However, the estrogen and progestogen steroids were unstable during storage. The disappearance rates obtained after 21 days of storage vary from 63 to 72% for the feminizing hormones. Overall, pharmaceuticals and pesticides seem to be stable for refrigerated storage for up to about 10 days (except cyanazine and steroidal hormones can be quite sensitive to degradation and should not be stored for more than a few days.

Fuzzy target selection using RFM variables

NARCIS (Netherlands)

Kaymak, U.

2001-01-01

An important data mining problem from the world of direct marketing is target selection. The main task in target selection is the determination of potential customers for a product from a client database. Target selection algorithms identify the profiles of customer groups for a particular product,

Selected Problems of Determining the Course of Railway Routes by Use of GPS Network Solution

Science.gov (United States)

Koc, Władysław; Specht, Cezary

2011-09-01

The main problem related to railroad surveying design and its maintenance is the necessity to operate in local geodetic reference systems caused by the long rail sections with straight lines and curvatures of the running edge. Due to that reason the geodetic railroad classical surveying methods requires to divide all track for a short measurement section and that caused additional errors. Development of the Global Navigational Satellite Systems (GNSS) positioning methods operating in the standardized World Geodetic System (WGS-84) allowed verification of capability of utilization GPS measurements for railroad surveying. It can be stated that implemented satellite measurement techniques opens a whole new perspective on applied research and enables very precise determination of data for railway line determining, modernization and design. The research works focused on implementation GNSS multi-receivers measurement positioning platform for projecting and stock-taking working based on polish active geodesic network ASG-EUPOS, as a reference frame. In order to eliminate the influence of random measurement errors and to obtain the coordinates representing the actual shape of the track few campaigns were realized in 2009 and 2010. Leica GPS Total station system 1200 SmartRover (with ATX1230 GG antennas) receivers were located in the diameter of the measurement platform. Polish Active Geodetic Network ASG-EUPOS was used as a reference network transmitted Real Time Kinematic Positioning Service according to RTCM 3.1 standard. Optimum time period were selected for GNSS campaign and testing area was chosen without large obstructions. The article presents some surveying results of the measurement campaigns and also discusses the accuracy of the course determination. Analyzes and implementation of results in railroad design process are also discussed.

Bacterial selection for biological control of plant disease: criterion determination and validation

Directory of Open Access Journals (Sweden)

Monalize Salete Mota

Full Text Available Abstract This study aimed to evaluate the biocontrol potential of bacteria isolated from different plant species and soils. The production of compounds related to phytopathogen biocontrol and/or promotion of plant growth in bacterial isolates was evaluated by measuring the production of antimicrobial compounds (ammonia and antibiosis and hydrolytic enzymes (amylases, lipases, proteases, and chitinases and phosphate solubilization. Of the 1219 bacterial isolates, 92% produced one or more of the eight compounds evaluated, but only 1% of the isolates produced all the compounds. Proteolytic activity was most frequently observed among the bacterial isolates. Among the compounds which often determine the success of biocontrol, 43% produced compounds which inhibit mycelial growth of Monilinia fructicola, but only 11% hydrolyzed chitin. Bacteria from different plant species (rhizosphere or phylloplane exhibited differences in the ability to produce the compounds evaluated. Most bacterial isolates with biocontrol potential were isolated from rhizospheric soil. The most efficient bacteria (producing at least five compounds related to phytopathogen biocontrol and/or plant growth, 86 in total, were evaluated for their biocontrol potential by observing their ability to kill juvenile Mesocriconema xenoplax. Thus, we clearly observed that bacteria that produced more compounds related to phytopathogen biocontrol and/or plant growth had a higher efficacy for nematode biocontrol, which validated the selection strategy used.

Systematic wavelength selection for improved multivariate spectral analysis

Science.gov (United States)

Thomas, Edward V.; Robinson, Mark R.; Haaland, David M.

1995-01-01

Methods and apparatus for determining in a biological material one or more unknown values of at least one known characteristic (e.g. the concentration of an analyte such as glucose in blood or the concentration of one or more blood gas parameters) with a model based on a set of samples with known values of the known characteristics and a multivariate algorithm using several wavelength subsets. The method includes selecting multiple wavelength subsets, from the electromagnetic spectral region appropriate for determining the known characteristic, for use by an algorithm wherein the selection of wavelength subsets improves the model's fitness of the determination for the unknown values of the known characteristic. The selection process utilizes multivariate search methods that select both predictive and synergistic wavelengths within the range of wavelengths utilized. The fitness of the wavelength subsets is determined by the fitness function F=.function.(cost, performance). The method includes the steps of: (1) using one or more applications of a genetic algorithm to produce one or more count spectra, with multiple count spectra then combined to produce a combined count spectrum; (2) smoothing the count spectrum; (3) selecting a threshold count from a count spectrum to select these wavelength subsets which optimize the fitness function; and (4) eliminating a portion of the selected wavelength subsets. The determination of the unknown values can be made: (1) noninvasively and in vivo; (2) invasively and in vivo; or (3) in vitro.

A Novel Ion - selective Polymeric Membrane Sensor for Determining Thallium(I) With High Selectivity

International Nuclear Information System (INIS)

Kassim, Anuar; Rezayi, Majid; Ahmadzadeh, Saeid; Yusof, Noor Azah; Tee, Tan Wee; Abdullah, Abd Halim; Rounaghi, Gholamhossein; Mohajeri, Masoomeh; Heng, Lee Yook

2011-01-01

Thallium is a toxic metal that introduced into the environment mainly as a waste from the production of zinc, cadmium, and lead and by combustion of coal. Thallium causes gastrointestinal irritation and nerve damage when people are exposed to it for relatively short period of time. For long term, thallium has the potential to cause the following effects: change in blood chemistry, damage to liver, kidney, intestinal and testicular tissue, and hair loss. In this work a membrane was prepared by use of 4'-nitrobenzo -18-crown-6 (4'NB18C6) as an ion carrier, polyvinylchloride (PVC) as a matrix, and diocthylphetalate (DOP) as a plasticizer for making an ion selective electrode for measurement of Tl + cation in solutions. The amount of 4'-nitrobenzo-18C6 and polyvinylchloride were optimized in the preparation of the membrane. The response of the electrode was Nernstian within the concentration range 1.0 x 10 -8 to 1.0 x 10 -1 M. This sensor displays a drift in Nernstian response for this cation with increasing the amount of ionophore and decreasing the amount of polyvinylchloride.The results of potentiometric measurements showed that, this electrode also responses to Cu 2+ Ni 2+ and Pb 2+ cations, but the electrode has a wider dynamic range and a lower detection limit to Tl + cation. The effects of various parameters such as pH, different cations interferences, effect of the amount of ionophore and polyvinylchloride and time on response of the coated ion selective electrode were investigated. Finally the constructed electrode was used in complexometric and precipitation titrations of Tl + cation with EDTA and KBr, respectively. The response of the fabricated electrode at concentration range from 1.0 x 10 -8 to 1.0 x 10 -1 M is linear with a Nernstian slope of 57.27 mV.

A Novel Ion - selective Polymeric Membrane Sensor for Determining Thallium(I) With High Selectivity

Science.gov (United States)

Kassim, Anuar; Rezayi, Majid; Ahmadzadeh, Saeid; Rounaghi, Gholamhossein; Mohajeri, Masoomeh; Azah Yusof, Noor; Tee, Tan Wee; Yook Heng, Lee; Halim Abdullah, Abd

2011-02-01

Thallium is a toxic metal that introduced into the environment mainly as a waste from the production of zinc, cadmium, and lead and by combustion of coal. Thallium causes gastrointestinal irritation and nerve damage when people are exposed to it for relatively short period of time. For long term, thallium has the potential to cause the following effects: change in blood chemistry, damage to liver, kidney, intestinal and testicular tissue, and hair loss. In this work a membrane was prepared by use of 4'-nitrobenzo -18-crown-6 (4'NB18C6) as an ion carrier, polyvinylchloride (PVC) as a matrix, and diocthylphetalate (DOP) as a plasticizer for making an ion selective electrode for measurement of Tl+ cation in solutions. The amount of 4'-nitrobenzo-18C6 and polyvinylchloride were optimized in the preparation of the membrane. The response of the electrode was Nernstian within the concentration range 1.0 × 10-8 to 1.0 × 10-1M. This sensor displays a drift in Nernstian response for this cation with increasing the amount of ionophore and decreasing the amount of polyvinylchloride.The results of potentiometric measurements showed that, this electrode also responses to Cu2+ Ni2+ and Pb2+ cations, but the electrode has a wider dynamic range and a lower detection limit to Tl+ cation. The effects of various parameters such as pH, different cations interferences, effect of the amount of ionophore and polyvinylchloride and time on response of the coated ion selective electrode were investigated. Finally the constructed electrode was used in complexometric and precipitation titrations of Tl+ cation with EDTA and KBr, respectively. The response of the fabricated electrode at concentration range from 1.0 × 10-8 to 1.0 × 10-1M is linear with a Nernstian slope of 57.27 mV.

Novel and validated titrimetric method for determination of selected angiotensin-II-receptor antagonists in pharmaceutical preparations and its comparison with UV spectrophotometric determination

Directory of Open Access Journals (Sweden)

Shrikant H. Patil

2012-12-01

Full Text Available A novel and simple titrimetric method for determination of commonly used angiotensin-II-receptor antagonists (ARA-IIs is developed and validated. The direct acid base titration of four ARA-IIs, namely eprosartan mesylate, irbesartan, telmisartan and valsartan, was carried out in the mixture of ethanol:water (1:1 as solvent using standardized sodium hydroxide aqueous solution as titrant, either visually using phenolphthalein as an indicator or potentiometrically using combined pH electrode. The method was found to be accurate and precise, having relative standard deviation of less than 2% for all ARA-IIs studied. Also, it was shown that the method could be successfully applied to the assay of commercial pharmaceuticals containing the above-mentioned ARA-IIs. The validity of the method was tested by the recovery studies of standard addition to pharmaceuticals and the results were found to be satisfactory. Results obtained by this method were found to be in good agreement with those obtained by UV spectrophotometric method. For UV spectrophotometric analysis ethanol was used as a solvent and wavelength of 233 nm, 246 nm, 296 nm, and 250 nm was selected for determination of eprosartan mesylate, irbesartan, telmisartan, and valsartan respectively. The proposed titrimetric method is simple, rapid, convenient and sufficiently precise for quality control purposes. Keywords: Angiotensin-II-receptor antagonists, Titrimetric assay, UV spectrophotometry, Validation

Ultratrace analysis of actinides via coprecipitation/laser-induced fluorescence spectroscopy

International Nuclear Information System (INIS)

Miller, S.M.

1982-01-01

Actinides were selectively preconcentrated by coprecipitating each out of solution with a fluoride matrix and calcining each sample at 800 0 C. The fluorescence spectrum of each sample was recorded by illuminating the sample with laser light and detecting fluorescence with either a fluorescence/Raman spectrometer, an infrared spectrometer or in certain cases a filter fluorimeter. Three previously unobserved actinide spectra were recorded. Narrow lines at 546.9 nm, 564.6 nm, and 569.6 nm were found for CaF 2 :PuO 2++ at 10K. CaF 2 :Am + 3 displayed two broadband fluorescent peaks at 625 nm and 746 nm at room temperature and CaF 2 :Pu + 3 possessed a fluorescent peak at 1.22 microns at 10K. Energy transfer was observed in the form of Tb fluorescence quenching in TbF 3 :Pu + 3 when Pu was present in quantities of 10 ppM or more and in the form of Tb fluorescence enhancement in TbF 3 :Am + 3 when 1 ppM or more of Am was present. Careful sample preparation and the use of temporal as well as a spectral discrimination system extended the detection limit of U from 1 ml samples to the subfemtogram level. The fluorescence detection limits for Pu and Am were extended to 0.48 and 0.032 pg/ml. 39 figures, 9 tables

Valence States Modulation Strategy for Picomole Level Assay of Hg2+ in Drinking and Environmental Water by Directional Self-Assembly of Gold Nanorods.

Science.gov (United States)

Chen, Lu; Lu, Linlin; Wang, Sufan; Xia, Yunsheng

2017-06-23

In this study, we present a valence states modulation strategy for picomole level assay of Hg 2+ using directional self-assembly of gold nanorods (AuNRs) as signal readout. Hg 2+ ions are first controllably reduced to Hg + ions by appropriate ascorbic acid, and the reduced Hg + ions react with the tips of the preadded AuNRs and form gold amalgam. Such Hg + decorated AuNRs then end-to-end self-assemble into one-dimensional architectures by the bridging effects of lysine based on the high affinity of NH 2 -Hg + interactions. Correspondingly, the AuNRs' longitudinal surface plasmon resonance is gradually reduced and a new broad band appears at 900-1100 nm region simultaneously. The resulting distinctly ratiometric signal output is not only favorable for Hg 2+ ions detection but competent for their quantification. Under optimal conditions, the linear range is 22.8 pM to 11.4 nM, and the detection limit is as low as 8.7 pM. Various transition/heavy metal ions, such as Pb 2+ , Ti 2+ , Co 2+ , Fe 3+ , Mn 2+ , Ba 2+ , Fe 2+ , Ni 2+ , Al 3+ , Cu 2+ , Ag + , and Au 3+ , do not interfere with the assay. Because of ultrahigh sensitivity and excellent selectivity, the proposed system can be employed for assaying ultratrace of Hg 2+ containing in drinking and commonly environmental water samples, which is difficult to be achieved by conventional colorimetric systems. These results indicate that the present platform possesses specific advantages and potential applications in the assay of ultratrace amounts of Hg 2+ ions.

Determination of the Mutant Selection Window and Evaluation of the Killing of Mycoplasma gallisepticum by Danofloxacin, Doxycycline, Tilmicosin, Tylvalosin and Valnemulin

OpenAIRE

Zhang, Nan; Ye, Xiaomei; Wu, Yuzhi; Huang, Zilong; Gu, Xiaoyan; Cai, Qinren; Shen, Xiangguang; Jiang, Hongxia; Ding, Huanzhong

2017-01-01

Mycoplasma gallisepticum is a common etiological cause of a chronic respiratory disease in chickens; its increasing antimicrobial resistance compromises the use of tetracyclines, macrolides and quinolones in the farm environment. Mutant selection window (MSW) determination was used to investigate the propensity for future resistance induction by danofloxacin, doxycycline, tilmicosin, tylvalosin and valnemulin. Killing of M. gallisepticum strain S6 by these antimicrobials was also studied by i...

Structure of the Human FANCL RING-Ube2T Complex Reveals Determinants of Cognate E3-E2 Selection

Science.gov (United States)

Hodson, Charlotte; Purkiss, Andrew; Miles, Jennifer Anne; Walden, Helen

2014-01-01

Summary The combination of an E2 ubiquitin-conjugating enzyme with an E3 ubiquitin-ligase is essential for ubiquitin modification of a substrate. Moreover, the pairing dictates both the substrate choice and the modification type. The molecular details of generic E3-E2 interactions are well established. Nevertheless, the determinants of selective, specific E3-E2 recognition are not understood. There are ∼40 E2s and ∼600 E3s giving rise to a possible ∼24,000 E3-E2 pairs. Using the Fanconi Anemia pathway exclusive E3-E2 pair, FANCL-Ube2T, we report the atomic structure of the FANCL RING-Ube2T complex, revealing a specific and extensive network of additional electrostatic and hydrophobic interactions. Furthermore, we show that these specific interactions are required for selection of Ube2T over other E2s by FANCL. PMID:24389026

Protein structure and ionic selectivity in calcium channels: selectivity filter size, not shape, matters.

Science.gov (United States)

Malasics, Attila; Gillespie, Dirk; Nonner, Wolfgang; Henderson, Douglas; Eisenberg, Bob; Boda, Dezso

2009-12-01

Calcium channels have highly charged selectivity filters (4 COO(-) groups) that attract cations in to balance this charge and minimize free energy, forcing the cations (Na(+) and Ca(2+)) to compete for space in the filter. A reduced model was developed to better understand the mechanism of ion selectivity in calcium channels. The charge/space competition (CSC) mechanism implies that Ca(2+) is more efficient in balancing the charge of the filter because it provides twice the charge as Na(+) while occupying the same space. The CSC mechanism further implies that the main determinant of Ca(2+) versus Na(+) selectivity is the density of charged particles in the selectivity filter, i.e., the volume of the filter (after fixing the number of charged groups in the filter). In this paper we test this hypothesis by changing filter length and/or radius (shape) of the cylindrical selectivity filter of our reduced model. We show that varying volume and shape together has substantially stronger effects than varying shape alone with volume fixed. Our simulations show the importance of depletion zones of ions in determining channel conductance calculated with the integrated Nernst-Planck equation. We show that confining the protein side chains with soft or hard walls does not influence selectivity.

New solid phase extractors for selective separation and preconcentration of mercury (II) based on silica gel immobilized aliphatic amines 2-thiophenecarboxaldehyde Schiff's bases

International Nuclear Information System (INIS)

Soliman, Ezzat M.; Saleh, Mohamed B.; Ahmed, Salwa A.

2004-01-01

2-Thiophenecarboxaldhyde is chemically bonded to silica gel surface immobilized monoamine, ethylenediamine and diethylenetriamine by a simple Schiff's base reaction to produce three new SP-extractors, phases (I-III). The selectivity properties of these phases toward Hg(II) uptake as well as eight other metal ions: Ca(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) were extensively studied and evaluated as a function of pH of metal ion solution and equilibrium shaking time by the batch equilibrium technique. The data obtained clearly indicate that the new SP-extractors have the highest affinity for retention of Hg(II) ion. Their Hg(II) uptake in mmol g -1 and distribution coefficient as log K d values are always higher than the uptake of any other metal ion along the range of pH used (pH 1.0-10.0). The uptake of Hg(II) using phase I was 2.0 mmol g -1 (log K d 6.6) at pH 1.0 and 2.0. 1.8 mmol g -1 (log K d 4.25), 1.6 mmol g -1 (log K d 3.90) and 1.08 mmol g -1 (log K d 3.37) at pH 3.0, 5.0 and 8.0, respectively. Selective separation of Hg(II) from the other eight coexisting metal ions under investigation was achieved successfully using phase I at pH 2.0 either under static or dynamic conditions. Hg(II) was completely retained while Ca(II), Co(II) and Cd(II) ions were not retained. Ni(II), Cu(II), Zn(II), Pb(II) and Fe(III) showed very low percentage retention values to be 0.74, 0.97, 3.5 and 6.3%, respectively. Moreover, the high recovery values (95.5 ± 0.5, 95.8 ± 0.5 and 99.0% ± 1.0) of percolating two liters of doubly distilled water, drinking tap water and Nile river water spiked with 5 ng/l of Hg(II) over 100 mg of phase I packed in a minicolumn and used as a thin layer enrichment bed demonstrate the accuracy and validity of the new SP-extractors for preconcentration of the ultratrace amount of spiked Hg(II) prior to the determination by borohydride generation atomic absorption spectrometry (AAS) with no matrix interference. The detection

Oesophageal cancer in the Transkei. Determination of trace element concentrations in selected plant material by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Renan, M.J.; Drennan, B.D.; Keddy, R.J.; Sellschop, J.P.F.

1979-01-01

The results of the analysis by instrumental neutron activation for the concentration of trace elements in plant materials from certain areas in the Transkei region of southern Africa are presented. These areas are selected for their characteristic high or low incidence of carcinoma of the oesophagus. To broaden the suite of elements for which analysed and to overcome some of the limitations of neutron activation analysis, certain other nuclear analyses and methods are suggested which, if utilized, would increase the number of elements determined, and so improve the information available. (author)

A composite material based on nanoparticles of yttrium (III) oxide for the selective and sensitive electrochemical determination of acetaminophen

International Nuclear Information System (INIS)

Baytak, Aysegul Kutluay; Teker, Tugce; Duzmen, Sehriban; Aslanoglu, Mehmet

2016-01-01

An electrochemical sensor was prepared by modifying a glassy carbon electrode (GCE) with a composite of yttrium (III) oxide nanoparticles (Y_2O_3NPs) and carbon nanotubes (CNTs) for the determination of acetaminophen (ACT). Compared with a bare GCE and CNTs/GCE, the Y_2O_3NPs/CNTs/GCE exhibited a well-defined redox couple for ACT and highly enhanced the current response. The separations in the anodic and cathodic peak potentials (ΔE_p) for ACT were 552 mV, 24 mV and 10 mV at ba4re GCE, CNTs/GCE and Y_2O_3NPs/CNTs/GCE, respectively. The observation of only 10 mV of ΔE_p for ACT at Y_2O_3NPs/CNTs/GCE was a clear indication of a great acceleration of the electrode process compared to bare GCE and GCE modified with CNTs. Also, L-ascorbic acid (L-AA) and L-tyrosine (L-TRY) did not interfere with the selective determination of ACT. Square wave voltammetry (SWV) was performed for the quantification of ACT. A linear plot was obtained for current responses versus the concentrations of ACT over the range from 1.0 × 10"−"1"0 to 1.8 × 10"−"8 M with a detection limit of 3.0 × 10"−"1"1 M (based on 3S_b/m). The proposed composite material provided high electrocatalytic activity, improved voltammetric behavior, good selectivity and good reproducibility. The accurate quantification of ACT makes the proposed electrode of great interest for the public health. - Highlights: • A voltammetric sensor based on yttrium oxide was prepared for the detection of ACT. • The proposed electrode has greatly accelerated the voltammetric process of ACT. • A detection limit of 0.03 nM was obtained for ACT. • The proposed electrode exhibited great selectivity for ACT in the presence of L-AA and L-TRY. • The composite material exhibited high sensitivity, good stability and excellent reproducibility.

On subset selection from Logistic populations

NARCIS (Netherlands)

Laan, van der P.

1990-01-01

Some distributional results are derived for subset selection from Logistic populations, differing only in their location parameter. The probability of correct selection is determined. Exact and numerical results concerning the expected subset size are presented.

Molecularly imprinted polymer for selective extraction of malachite green from seawater and seafood coupled with high-performance liquid chromatographic determination

International Nuclear Information System (INIS)

Lian Ziru; Wang Jiangtao

2012-01-01

Highlights: ► The malachite green molecularly imprinted polymer (MG-MIP) was prepared. ► The characteristics and regeneration property of MIP were studied. ► An off-line method for MG was developed using MIP as solid-phase extraction. ► The MG concentrations from seawater and seafood samples were determined. - Abstract: In this paper, a highly selective sample cleanup procedure combining molecular imprinting technique (MIT) and solid-phase extraction (SPE) was developed for the isolation of malachite green in seawater and seafood samples. The molecularly imprinted polymer (MIP) was prepared using malachite green as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linking monomer. The imprinted polymer and non-imprinted polymer were characterized by scanning electron microscope and static adsorption experiments. The MIP showed a high adsorption capacity and was used as selective sorbent for the SPE of malachite green. An off-line molecularly imprinted solid-phase extraction (MISPE) method followed by high-performance liquid chromatography with diodearray detection for the analysis of malachite green in seawater and seafood samples was also established. Finally, five samples were determined. The results showed that malachite green concentration in one seawater sample was at 1.30 μg L −1 and the RSD (n = 3) was 4.15%.

Liquid chromatographic-tandem mass spectrometric determination of selected sulphonamides in milk

NARCIS (Netherlands)

Rhijn, van J.A.; Lasaroms, J.J.P.; Berendsen, B.J.A.; Brinkman, U.A.Th.

2002-01-01

Liquid chromatography–tandem mass spectrometry is used for the quantitative analysis of selected sulphonamides in milk. Ultrafiltration is the only sample pre-treatment technique which is required. Consequently, sample throughput is much higher than with conventional procedures, and analyte

A Novel Ion - selective Polymeric Membrane Sensor for Determining Thallium(I) With High Selectivity

Energy Technology Data Exchange (ETDEWEB)

Kassim, Anuar; Rezayi, Majid; Ahmadzadeh, Saeid; Yusof, Noor Azah; Tee, Tan Wee; Abdullah, Abd Halim [Department of Chemistry Faculty of Science, Universiti Putra Malaysia 43400 Serdang, Selangor (Malaysia); Rounaghi, Gholamhossein; Mohajeri, Masoomeh [Department of Chemistry, Factuality of Sciences, Islamic Azad University of Mashhad, Mashhad (Iran, Islamic Republic of); Heng, Lee Yook, E-mail: anuar@science.upm.edu.my [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E. (Malaysia)

2011-02-15

Thallium is a toxic metal that introduced into the environment mainly as a waste from the production of zinc, cadmium, and lead and by combustion of coal. Thallium causes gastrointestinal irritation and nerve damage when people are exposed to it for relatively short period of time. For long term, thallium has the potential to cause the following effects: change in blood chemistry, damage to liver, kidney, intestinal and testicular tissue, and hair loss. In this work a membrane was prepared by use of 4'-nitrobenzo -18-crown-6 (4'NB18C6) as an ion carrier, polyvinylchloride (PVC) as a matrix, and diocthylphetalate (DOP) as a plasticizer for making an ion selective electrode for measurement of Tl{sup +} cation in solutions. The amount of 4'-nitrobenzo-18C6 and polyvinylchloride were optimized in the preparation of the membrane. The response of the electrode was Nernstian within the concentration range 1.0 x 10{sup -8} to 1.0 x 10{sup -1}M. This sensor displays a drift in Nernstian response for this cation with increasing the amount of ionophore and decreasing the amount of polyvinylchloride.The results of potentiometric measurements showed that, this electrode also responses to Cu{sup 2+} Ni{sup 2+} and Pb{sup 2+} cations, but the electrode has a wider dynamic range and a lower detection limit to Tl{sup +} cation. The effects of various parameters such as pH, different cations interferences, effect of the amount of ionophore and polyvinylchloride and time on response of the coated ion selective electrode were investigated. Finally the constructed electrode was used in complexometric and precipitation titrations of Tl{sup +} cation with EDTA and KBr, respectively. The response of the fabricated electrode at concentration range from 1.0 x 10{sup -8} to 1.0 x 10{sup -1}M is linear with a Nernstian slope of 57.27 mV.

Facile synthesis of N-acetyl-L-cysteine capped CdHgSe quantum dots and selective determination of hemoglobin.

Science.gov (United States)

Wang, Qingqing; Zhan, Guoqing; Li, Chunya

2014-01-03

Using N-acetyl-L-cysteine (NAC) as a stabilizer, well water-dispersed, high-quality and stable CdHgSe quantum dots were facilely synthesized via a simple aqueous phase method. The as-prepared NAC capped CdHgSe quantum dots were thoroughly characterized by fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. A novel method for the selective determination of hemoglobin (Hb) was developed based on fluorescence quenching of the NAC capped CdHgSe quantum dots. A number of key factors including pH value of phosphate buffer solution, quantum dots concentration, the adding sequence of reagents and reaction time that influence the analytical performance of the NAC capped CdHgSe quantum dots in Hb determination were investigated. Under the optimal experimental conditions, the change of fluorescence intensity (ΔI) was linearly proportional to the concentration of Hb in the range of 4.0×10(-9)-4.4×10(-7) mol L(-1) with a detection limit of 2.0×10(-9) mol L(-1). The developed method has been successfully employed to determine Hb in human urine samples. Copyright © 2013. Published by Elsevier B.V.

Determinants of Propranolol's Selective Effect on Loss Aversion.

Science.gov (United States)

Sokol-Hessner, Peter; Lackovic, Sandra F; Tobe, Russell H; Camerer, Colin F; Leventhal, Bennett L; Phelps, Elizabeth A

2015-07-01

Research on emotion and decision making has suggested that arousal mediates risky decisions, but several distinct and often confounded processes drive such choices. We used econometric modeling to separate and quantify the unique contributions of loss aversion, risk attitudes, and choice consistency to risky decision making. We administered the beta-blocker propranolol in a double-blind, placebo-controlled within-subjects study, targeting the neurohormonal basis of physiological arousal. Matching our intervention's pharmacological specificity with a quantitative model delineating decision-making components allowed us to identify the causal relationships between arousal and decision making that do and do not exist. Propranolol selectively reduced loss aversion in a baseline- and dose-dependent manner (i.e., as a function of initial loss aversion and body mass index), and did not affect risk attitudes or choice consistency. These findings provide evidence for a specific, modulatory, and causal relationship between precise components of emotion and risky decision making. © The Author(s) 2015.

Polymeric membrane sensors based on Cd(II) Schiff base complexes for selective iodide determination in environmental and medicinal samples.

Science.gov (United States)

Singh, Ashok Kumar; Mehtab, Sameena

2008-01-15

The two cadmium chelates of schiff bases, N,N'-bis(salicylidene)-1,4-diaminobutane, (Cd-S(1)) and N,N'-bis(salicylidene)-3,4-diaminotoluene (Cd-S(2)), have been synthesized and explored as ionophores for preparing PVC-based membrane sensors selective to iodide(I) ion. Potentiometric investigations indicate high affinity of these receptors for iodide ion. Polyvinyl chloride (PVC)-based membranes of Cd-S(1) and Cd-S(2) using as hexadecyltrimethylammonium bromide (HTAB) cation discriminator and o-nitrophenyloctyl ether (o-NPOE), dibutylphthalate (DBP), acetophenone (AP) and tributylphosphate (TBP) as plasticizing solvent mediators were prepared and investigated as iodide-selective sensors. The best performance was shown by the membrane of composition (w/w) of (Cd-S(1)) (7%):PVC (31%):DBP (60%):HTAB (2%). The sensor works well over a wide concentration range 5.3x10(-7) to 1.0x10(-2)M with Nernstian compliance (59.2mVdecade(-1) of activity) within pH range 2.5-9.0 with a response time of 11s and showed good selectivity for iodide ion over a number of anions. The sensor exhibits adequate life (3 months) with good reproducibility (S.D.+/-0.24mV) and could be used successfully for the determination of iodide content in environmental water samples and mouth wash samples.

Determination of ultra-trace contaminants on silicon wafer surfaces using TXRF. Present state of the art

International Nuclear Information System (INIS)

Pahlke, S.; Fabry, L.; Kotz, L.; Mantler, C.; Ehmann, T.

2000-01-01

Recently, TXRF became a standard, on-line inspection tool for controlling the cleanliness of polished Si wafers for semiconductor use now up to 300 diameter. Wafer makers strive for an all-over metallic cleanliness of 10 atoms x cm -2 . Therefore an analytical tools must cover LOD in a range 9 atoms x cm -2 or lower. The all-over cleanliness of the whole wafer surface can analyzed using VPD/TXRF. For this chemical wafer-pre-preparation under cleanroom conditions class 1 we have developed a full automatic 'Wafer Surface Preparation System' coupled with a new generation TXRF. We have also combined this system with other independent methods for Na, Al, anions and cations. Only the combination of automatic wafer handling systems, modem analytical tools, ultra-pure water, ULSI chemicals and special cleanroom conditions provides us a chance to achieve the present and the future demands for semiconductor industry. (author)

Liquid-liquid extraction in flow analysis: A critical review

Energy Technology Data Exchange (ETDEWEB)

Silvestre, Cristina I.C.; Santos, Joao L.M. [REQUIMTE, Servico de Quimica-Fisica, Faculdade de Farmacia, Universidade do Porto, R. Anibal Cunha, 164, 4099-030 Porto (Portugal); Lima, Jose L.F.C., E-mail: limajlfc@ff.up.pt [REQUIMTE, Servico de Quimica-Fisica, Faculdade de Farmacia, Universidade do Porto, R. Anibal Cunha, 164, 4099-030 Porto (Portugal); Zagatto, Elias A.G. [Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, P.O. Box 96, Piracicaba 13400-970 (Brazil)

2009-10-12

Liquid-liquid extractions (LLE) are a common sample pre-treatment in many analytical applications. This review aims at providing a critical overview of the distinct automated continuous flow-based approaches that were developed for liquid-liquid extraction with the purpose of pre-concentration and/or separation of multiple analytes, such as ultra-trace metal and metalloid species, phenolic compounds, surfactants, pharmaceuticals, etc., hyphenated with many detection technique such as UV/vis spectrophotometry, atomic spectrometric detection systems and luminescent detectors, including distinct extraction strategies and applications like single and multiple extraction schemes, wetting film extraction, supported liquid membrane extraction, back extraction, closed-loop systems and the utilisation of zone sampling, chromatomembranes and iterative reversal techniques. The analytical performance of the developed flow-based LLE methods and the influence of flow manifold components such as the segmenter, extraction coil and phase separator, is emphasised and object of discussion. An overall presentation of each system components, selectivity, advantages and shortcomings is carried out and exemplified with selected applications.

Hydrothermal synthesis of Fe2O3/graphene nanocomposite for selective determination of ascorbic acid in the presence of uric acid

International Nuclear Information System (INIS)

Yu, Zhiyuan; Li, Hejun; Lu, Jinhua; Zhang, Xinmeng; Liu, Ningkun; Zhang, Xu

2015-01-01

In this study, we had demonstrated a hydrothermal method to prepare Fe 2 O 3 /graphene (RG) nanocomposite for the determination of ascorbic acid (AA) in the presence of uric acid (UA). The synthesized materials were characterized by scanning electron microscopy (SEM), X-ray diffraction measurements (XRD), transmission electron microscopy (TEM) and inductively coupled plasma atomic emission spectrometry (ICP-AES). As a sensor, the Fe 2 O 3 /RG nanocomposite modified electrode exhibited synergistic effects which not only improved the electrochemical catalytic oxidation of AA, but also resolved the overlapping anodic peaks of AA and UA. And the results showed that Fe 2 O 3 /RG could be used for the determination of AA in the presence of low concentration of UA. Using the modified electrode with different concentrations of AA, the linear response range for the determination of AA in the presence UA was 0.57–3.97 mM (R = 0.9994). The detection limit (S/N = 3) was found to be 0.543 μM for the determination of AA. The results suggested that the Fe 2 O 3 /RG nanocomposite had the advantages of simplicity, high sensitivity and good selectivity for determination of AA

Boron Heterocycle High-Fidelity Estrogen Mimics as Novel Antiestrogens for the Treatment of Breast Cancer

Science.gov (United States)

2001-10-01

placement therapy and prevention of osteoporosis and wechselprodukte von Mikroorganismen. Boromycin. cardiovascular disease in postmenopausal women. Helv...Perspect t1.Nieularsreen ce toathletminerals. Nutrhecalt elixirsoru- 1994;102 (Suppl 7):1-141. 21. Nielen3: Ultratrace minerals: mythical elixirs or nu

Bovine nucleus caudatus acetylcholinesterase: active site determination and investigation of a dimeric form obtained by selective proteolysis

Energy Technology Data Exchange (ETDEWEB)

Landauer, P.; Ruess, K.P.; Lieflaender, M.

1984-09-01

The number of catalytic subunits of purified bovine nucleus caudatus acetylcholinesterase (E.C. 3.1.1.7) has been determined by active site labelling with (3H)diisopropyl fluorophosphate ((3H)DFP). The 10.5 S, 16 S, and 20 S forms were estimated to contain two, four, and six active sites, respectively, per molecule. A 4.8 S form, which showed a weak amphiphile-dependent activity behavior, was obtained by selective proteolytic digestion with pronase. The inability of the purified 4.8 S form to aggregate after detergent removal, and the molecular mass in the range of 130-165 kD under nondenaturating conditions, indicate that this form is a dimeric form, lacking those hydrophobic regions responsible for aggregation.

Ultratrace analysis of {sup 129}I in sediments by ICP-MS with collision cell

Energy Technology Data Exchange (ETDEWEB)

Izmer, A.V.; Becker, J.S. [Research Center Juelich (Germany). Central Div. of Analytical Chemistry; Boulyga, S.F. [Mainz Univ. (Germany). Inst. for Inorganic Chemistry and Analytical Chemistry; Zoriy, M.V. [Research Center Juelich (Germany). Central Div. of Analytical Chemistry]|[Research Center Juelich (Germany). Dept. for Safety and Radiation Protection

2004-07-01

The aim of the work was the development of a rapid and high-sensitive analytical method using ICP-MS with hexapole collision cell (ICP-CC-MS) for the determination of low 129I+/127I+ isotope ratios in synthetic lab standards and environmental samples. A special direct sample introduction device for iodine extraction via the gas phase from solid environmental material coupled on-line to ICP-CC-QMS was developed. The detection limit for 129I+ determination in aqueous solution and soil samples via gas-phase extraction was determined to be of 0.8 pg/g and 30 pg/g, respectively. (orig.)

A Simple and Sensitive Plant-Based Western Corn Rootworm Bioassay Method for Resistance Determination and Event Selection.

Science.gov (United States)

Wen, Zhimou; Chen, Jeng Shong

2018-05-26

We report here a simple and sensitive plant-based western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), bioassay method that allows for examination of multiple parameters for both plants and insects in a single experimental setup within a short duration. For plants, injury to roots can be visually examined, fresh root weight can be measured, and expression of trait protein in plant roots can be analyzed. For insects, in addition to survival, larval growth and development can be evaluated in several aspects including body weight gain, body length, and head capsule width. We demonstrated using the method that eCry3.1Ab-expressing 5307 corn was very effective against western corn rootworm by eliciting high mortality and significantly inhibiting larval growth and development. We also validated that the method allowed determination of resistance in an eCry3.1Ab-resistant western corn rootworm strain. While data presented in this paper demonstrate the usefulness of the method for selection of events of protein traits and for determination of resistance in laboratory populations, we envision that the method can be applied in much broader applications.

Optimization of the Analytical Method Using HPLC with Fluorescence Detection to Determine Selected Polycyclic Aromatic Compounds in Clean Water Samples

International Nuclear Information System (INIS)

Garcia Alonso, S.; Perez Pastor, R. M.

2013-01-01

A study on the comparison and evaluation of 3 miniaturized extraction methods for the determination of selected PACs in clear waters is presented. Three types of liquid-liquid extraction were used for chromatographic analysis by HPLC with fluorescence detection. The main objective was the optimization and development of simple, rapid and low cost methods, minimizing the use of extracting solvent volume. The work also includes a study on the scope of the methods developed at low and high levels of concentration and intermediate precision. (Author)

Application of isotope-dilution laser ablation ICP-MS for direct determination of Pu concentrations in soils at pg g(-1) levels.

Science.gov (United States)

Boulyga, Sergei F; Tibi, Markus; Heumann, Klaus G

2004-01-01

The methods available for determination of environmental contamination by plutonium at ultra-trace levels require labor-consuming sample preparation including matrix removal and plutonium extraction in both nuclear spectroscopy and mass spectrometry. In this work, laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was applied for direct analysis of Pu in soil and sediment samples. Application of a LINA-Spark-Atomizer system (a modified laser ablation system providing high ablation rates) coupled with a sector-field ICP-MS resulted in detection limits as low as 3x10(-13) g g(-1) for Pu isotopes in soil samples containing uranium at a concentration of a few microg g(-1). The isotope dilution (ID) technique was used for quantification, which compensated for matrix effects in LA-ICP-MS. Interferences by UH+ and PbO2+ ions and by the peak tail of 238U+ ions were reduced or separated by use of dry plasma conditions and a mass resolution of 4000, respectively. No other effects affecting measurement accuracy, except sample inhomogeneity, were revealed. Comparison of results obtained for three contaminated soil samples by use of alpha-spectrometry, ICP-MS with sample decomposition, and LA-ICP-IDMS showed, in general, satisfactory agreement of the different methods. The specific activity of (239+240)Pu (9.8 +/- 3.0 mBq g(-1)) calculated from LA-ICP-IDMS analysis of SRM NIST 4357 coincided well with the certified value of 10.4 +/- 0.2 mBq g(-1). However, the precision of LA-ICP-MS for determination of plutonium in inhomogeneous samples, i.e. if "hot" particles are present, is limited. As far as we are aware this paper reports the lowest detection limits and element concentrations yet measured in direct LA-ICP-MS analysis of environmental samples.

Application of isotope-dilution laser ablation ICP-MS for direct determination of Pu concentrations in soils at pg g-1 levels

International Nuclear Information System (INIS)

Boulyga, Sergei F.; Tibi, Markus; Heumann, Klaus G.

2004-01-01

The methods available for determination of environmental contamination by plutonium at ultra-trace levels require labor-consuming sample preparation including matrix removal and plutonium extraction in both nuclear spectroscopy and mass spectrometry. In this work, laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was applied for direct analysis of Pu in soil and sediment samples. Application of a LINA-Spark-Atomizer system (a modified laser ablation system providing high ablation rates) coupled with a sector-field ICP-MS resulted in detection limits as low as 3 x 10 -13 g g -1 for Pu isotopes in soil samples containing uranium at a concentration of a few μg g -1 . The isotope dilution (ID) technique was used for quantification, which compensated for matrix effects in LA-ICP-MS. Interferences by UH + and PbO 2 + ions and by the peak tail of 238 U + ions were reduced or separated by use of dry plasma conditions and a mass resolution of 4000, respectively. No other effects affecting measurement accuracy, except sample inhomogeneity, were revealed. Comparison of results obtained for three contaminated soil samples by use of α-spectrometry, ICP-MS with sample decomposition, and LA-ICP-IDMS showed, in general, satisfactory agreement of the different methods. The specific activity of 239+240 Pu (9.8±3.0 mBq g -1 ) calculated from LA-ICP-IDMS analysis of SRM NIST 4357 coincided well with the certified value of 10.4±0.2 mBq g -1 . However, the precision of LA-ICP-MS for determination of plutonium in inhomogeneous samples, i.e. if ''hot'' particles are present, is limited. As far as we are aware this paper reports the lowest detection limits and element concentrations yet measured in direct LA-ICP-MS analysis of environmental samples. (orig.)

Simultaneous visualization of the subfemtomolar expression of microRNA and microRNA target gene using HILO microscopy† †Electronic supplementary information (ESI) available: The LED device for the sample photobleaching, a schematic presentation of HILO microscopy, fluorescence spectra and hybridization curves of the molecular beacons, the linear correlation between the miRNA fluorescence intensity and the miRNA copy number, a validation of the miRNA adsorption and miRNA target gene expression via RT-qPCR, a validation of RT-qPCR using capillary electrophoresis, the reproducibility of RT-qPCR and Poisson distribution of the miRNA pipetting as well as a complete list of the oligonucleotides used in this study. See DOI: 10.1039/c7sc02701j Click here for additional data file.

Science.gov (United States)

Lin, Yi-Zhen; Ou, Da-Liang; Chang, Hsin-Yuan; Lin, Wei-Yu; Hsu, Chiun

2017-01-01

The family of microRNAs (miRNAs) not only plays an important role in gene regulation but is also useful for the diagnosis of diseases. A reliable method with high sensitivity may allow researchers to detect slight fluctuations in ultra-trace amounts of miRNA. In this study, we propose a sensitive imaging method for the direct probing of miR-10b (miR-10b-3p, also called miR-10b*) and its target (HOXD10 mRNA) in fixed cells based on the specific recognition of molecular beacons combined with highly inclined and laminated optical sheet (HILO) fluorescence microscopy. The designed dye-quencher-labelled molecular beacons offer excellent efficiencies of fluorescence resonance energy transfer that allow us to detect miRNA and the target mRNA simultaneously in hepatocellular carcinoma cells using HILO fluorescence microscopy. Not only can the basal trace amount of miRNA be observed in each individual cell, but the obtained images also indicate that this method is useful for monitoring the fluctuations in ultra-trace amounts of miRNA when the cells are transfected with a miRNA precursor or a miRNA inhibitor (anti-miR). Furthermore, a reasonable causal relation between the miR-10b and HOXD10 expression levels was observed in miR-10b* precursor-transfected cells and miR-10b* inhibitor-transfected cells. The trends of the miRNA alterations obtained using HILO microscopy completely matched the RT-qPCR data and showed remarkable reproducibility (the coefficient of variation [CV] = 0.86%) and sensitivity (<1.0 fM). This proposed imaging method appears to be useful for the simultaneous visualisation of ultra-trace amounts of miRNA and target mRNA and excludes the procedures for RNA extraction and amplification. Therefore, the visualisation of miRNA and the target mRNA should facilitate the exploration of the functions of ultra-trace amounts of miRNA in fixed cells in biological studies and may serve as a powerful tool for diagnoses based on circulating cancer cells. PMID:28989695

The Multi-Template Molecularly Imprinted Polymer Based on SBA-15 for Selective Separation and Determination of Panax notoginseng Saponins Simultaneously in Biological Samples

Directory of Open Access Journals (Sweden)

Chenghong Sun

2017-11-01

Full Text Available The feasible, reliable and selective multi-template molecularly imprinted polymers (MT-MIPs based on SBA-15 (SBA-15@MT-MIPs for the selective separation and determination of the trace level of ginsenoside Rb1 (Rb1, ginsenoside Rg1 (Rg1 and notoginsenoside R1 (R1 simultaneously from biological samples were developed. The polymers were constructed by SBA-15 as support, Rb1, Rg1, R1 as multi-template, acrylamide (AM as functional monomer and ethylene glycol dimethacrylate (EGDMA as cross-linker. The new synthetic SBA-15@MT-MIPs were satisfactorily applied to solid-phase extraction (SPE coupled with high performance liquid chromatography (HPLC for the separation and determination of trace Rb1, Rg1 and R1 in plasma samples. Under the optimized conditions, the limits of detection (LODs and quantitation (LOQs of the proposed method for Rb1, Rg1 and R1 were in the range of 0.63–0.75 ng·mL−1 and 2.1–2.5 ng·mL−1, respectively. The recoveries of R1, Rb1 and Rg1 were obtained between 93.4% and 104.3% with relative standard deviations (RSDs in the range of 3.3–4.2%. All results show that the obtained SBA-15@MT-MIPs could be a promising prospect for the practical application in the selective separation and enrichment of trace Panax notoginseng saponins (PNS in the biological samples.

Site selection handbook: Workshop on site selection for low-level radioactive waste disposal facilities

International Nuclear Information System (INIS)

1987-10-01

The Low-Level Radioactive Waste Policy Amendments Act of 1985 (LLRWPAA) requires the Department of Energy (DOE) to provide technical assistance to ''...those compact regions, host States and nonmember States determined by the Secretary to require assistance.'' Technical assistance has been defined to include, but not be limited to, ''technical guidelines for site selection.'' This site selection workshop was developed to assist States and Compacts in developing new low-level radioactive waste (LLW) disposal sites in accordance with the requirements of the LLRWPAA. The workshop comprises a series of lectures, discussion topics, and exercises, supported by this Site Selection Workshop Handbook, designed to examine various aspects of a comprehensive site selection program. It is not an exhaustive treatment of all aspects of site selection, nor is it prescriptive. The workshop focuses on the major elements of site selection and the tools that can be used to implement the site selection program

Highly sensitive and selective determination of methylergometrine maleate using carbon nanofibers/silver nanoparticles composite modified carbon paste electrode

International Nuclear Information System (INIS)

Kalambate, Pramod K.; Rawool, Chaitali R.; Karna, Shashi P.; Srivastava, Ashwini K.

2016-01-01

A highly sensitive and selective voltammetric method for determination of Methylergometrine maleate (MM) in pharmaceutical formulations, urine and blood serum samples has been developed based on enhanced electrochemical response of MM at carbon nanofibers and silver nanoparticles modified carbon paste electrode (CNF-AgNP-CPE). The electrode material was characterized by various techniques viz., X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The electrocatalytic response of MM at CNF-AgNP-CPE was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the proposed sensor exhibits excellent electrochemical response towards MM. The DPV study shows greatly enhanced electrochemical signal for MM at CNF-AgNP-CPE lending high sensitivity to the proposed sensor for MM detection. The peak (I p ) current for MM is found to be rectilinear in the range 4.0 × 10 −8 –2.0 × 10 −5 M with a detection limit of 7.1 × 10 −9 M using DPV. The feasibility of the proposed sensor in analytical applications was investigated by conducting experiments on commercial pharmaceutical formulations, human urine and blood serum samples, which yielded satisfactory recoveries of MM. The proposed electrochemical sensor offers high sensitivity, selectivity, reproducibility and practical utility. We recommend it as an authentic and productive electrochemical sensor for successful determination of MM. - Highlights: • Voltammetric sensor for methylergometrine maleate using carbon nanofibers and silver nanoparticle - carbon paste electrode • Wide working range, good reproducibility, fast response and high stability were the main advantages of the proposed sensor • Analysis of methylergometrine maleate in pharmaceutical formulations, urine and blood serum samples • Lowest limit of detection obtained for methylergometrine maleate

A simple and selective spectrophotometric flow injection determination of trace amounts of ruthenium by catalytic oxidation of safranin-O

Energy Technology Data Exchange (ETDEWEB)

Rezaei, Behzad [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-84111 (Iran, Islamic Republic of)], E-mail: rezaei@cc.iut.ac.ir; Keyvanfard, Mohsen [Faculty of Science, Majlesi Campus, Islamic Azad University, Isfahan (Iran, Islamic Republic of)

2008-03-01

In this work, a simple, selective and rapid flow injection method has been developed for determination of ruthenium. The method is based on its catalytic effect on the oxidation of safranin-O by metaperiodate. The reaction was monitored spectrophotometrically by measuring safranin-O absorbance at {lambda}{sub max} = 521. The reagents and manifold variables, which have influences on the sensitivity, were investigated and the optimum conditions were established. The optimized conditions made it possible to determine ruthenium in the ranges of 0.4-20.0 ng/mL ({delta}A = 0.2819C{sub Ru} + 1.1840) and 20.0-100.0 ng/mL ({delta}A = 0.0984C{sub Ru} + 7.9391) with a detection limit of 0.095 ng/mL and a sample rate of 30 {+-} 5 samples/h. Relative standard deviation for the five replicate measurements was less than 1.84%. The proposed method has been successfully applied for analysis of ultra trace amounts of ruthenium in real samples.

A simple and selective spectrophotometric flow injection determination of trace amounts of ruthenium by catalytic oxidation of safranin-O

International Nuclear Information System (INIS)

Rezaei, Behzad; Keyvanfard, Mohsen

2008-01-01

In this work, a simple, selective and rapid flow injection method has been developed for determination of ruthenium. The method is based on its catalytic effect on the oxidation of safranin-O by metaperiodate. The reaction was monitored spectrophotometrically by measuring safranin-O absorbance at λ max = 521. The reagents and manifold variables, which have influences on the sensitivity, were investigated and the optimum conditions were established. The optimized conditions made it possible to determine ruthenium in the ranges of 0.4-20.0 ng/mL (ΔA = 0.2819C Ru + 1.1840) and 20.0-100.0 ng/mL (ΔA = 0.0984C Ru + 7.9391) with a detection limit of 0.095 ng/mL and a sample rate of 30 ± 5 samples/h. Relative standard deviation for the five replicate measurements was less than 1.84%. The proposed method has been successfully applied for analysis of ultra trace amounts of ruthenium in real samples

Facial attractiveness, sexual selection, and personnel selection : when evolved preferences matter

NARCIS (Netherlands)

Luxen, MF; Van de Vijver, FJR

Using an evolutionary perspective, we looked at sex differences in the influence of facial attractiveness of applicants in hiring decisions, and determined whether expected contact intensity with applicants and experience in personnel selection moderated this influence. We found effects of evolved

Nanomolar determination of Pb (II ions by selective templated electrode

Directory of Open Access Journals (Sweden)

Mazloum-Ardakani Mohammad

2012-01-01

Full Text Available Polypyrrole modified electrode, prepared by electropolymerization of pyrrole in the presence of methyl red as a dopant, was templated with respect to Pb2+ ion and applied for potentiometric and voltammetric detection of this ion. The templating process improved the analytical response characteristics of the electrode, specially their selectivity, with respect to Pb2+ ion. The improvement depends on both the incorporated ligand (dopant and the templating process, with the latter being more vital. The potentiometric response of the electrode was linear within the Pb2+ concentration range of 2.0×10-6 to 5.0×10-2 M with a near-Nernstian slope of 28.6 mV decade-1 and a detection limit of 7.0 ×10-7 M. The electrode was also used for preconcentration differential pulse anodic stripping voltammetry (DPASV and results showed that peak currents for the incorporated lead species were dependent on the metal ion concentration in the range of 1.0×10-8 to 1.0×10-3 M. The detection limit of DPASV method was 3.5 ×10-9 M. The selectivity of the electrode with respect to some transition metal ions was investigated. The modified-templated electrode was used for the successful assay of lead in two standard reference material samples.

Synchronous scanning phosphorimetry for the selective determination of chrysene: a metrological study

Directory of Open Access Journals (Sweden)

Alessandra L. M. C. da Cunha

2010-01-01

Full Text Available Room-temperature phosphorimetry was used to quantify trace levels of chrysene in sugar-cane spirits and in fish bile. A selective phosphorescence enhancer (AgNO3 and synchronous scanning allowed the detection of ng amounts of chrysene. Accuracy (113 ± 17% and selectivity was evaluated using the CRM-NIST-1647d - Priority Pollutant Polycyclic Aromatic Hydrocarbons in acetonitrile. Analysis of sugar-cane spirit samples enabled recovery of 108 ± 18% which agreed with the one achieved using HPLC. Method's uncertainty was equivalent to 3.4 ng of the analyte, however, the analyte pre-concentration (SPE improved sensibility and minimized the relative uncertainty. Characterization and homogeneity studies in fish bile were also performed.

Calibration Variable Selection and Natural Zero Determination for Semispan and Canard Balances

Science.gov (United States)

Ulbrich, Norbert M.

2013-01-01

Independent calibration variables for the characterization of semispan and canard wind tunnel balances are discussed. It is shown that the variable selection for a semispan balance is determined by the location of the resultant normal and axial forces that act on the balance. These two forces are the first and second calibration variable. The pitching moment becomes the third calibration variable after the normal and axial forces are shifted to the pitch axis of the balance. Two geometric distances, i.e., the rolling and yawing moment arms, are the fourth and fifth calibration variable. They are traditionally substituted by corresponding moments to simplify the use of calibration data during a wind tunnel test. A canard balance is related to a semispan balance. It also only measures loads on one half of a lifting surface. However, the axial force and yawing moment are of no interest to users of a canard balance. Therefore, its calibration variable set is reduced to the normal force, pitching moment, and rolling moment. The combined load diagrams of the rolling and yawing moment for a semispan balance are discussed. They may be used to illustrate connections between the wind tunnel model geometry, the test section size, and the calibration load schedule. Then, methods are reviewed that may be used to obtain the natural zeros of a semispan or canard balance. In addition, characteristics of three semispan balance calibration rigs are discussed. Finally, basic requirements for a full characterization of a semispan balance are reviewed.

Simple and Selective HPLC-UV/Vis Bioanalytical Method to Determine Aluminum Phthalocyanine Chloride in Skin Permeation Studies

Directory of Open Access Journals (Sweden)

Thaiene Avila Reis

2018-01-01

Full Text Available Considering the feasibility of the aluminum phthalocyanine chloride (AlPcCl application in the topical photodynamic therapy of cutaneous tumors and the lack of HPLC methods capable of supporting skin permeation experiments using this compound, the aim of this study was to obtain a simple and selective chromatographic method for AlPcCl determination in skin matrices. A HPLC-UV/Vis method was developed using a normal-phase column operating at 30°C, an isocratic mobile phase of methanol : phosphoric acid (0.01 M at 1.5 mL/min, and detection at 670 nm. The method exhibited (i selectivity against various contaminants found in the different skin layers, (ii high drug extraction capacity from the hair follicle (>70% and remaining skin (>80%, and (iii low limits of detection and of quantification (0.03 and 0.09 μg/mL, resp.. The method was also linear in the range from 0.1 to 5.0 µg/mL (r = 0.9994 and demonstrated robustness with regard to experimental chromatographic parameters according to a factorial design. Lastly, the developed method was successfully tested in in vitro skin permeation studies of AlPcCl, proving its effectiveness in the development of pharmaceutical delivery systems containing this drug for topical photodynamic therapy of skin cancers.

The determination of iodine in cheese by neutron activation combined with separation of iodine by selective retention on Dowex 2-X8

International Nuclear Information System (INIS)

Nordbye, P.I.; Augustson, J.H.

1980-03-01

Iodine has been determined in Norwegian cheese by combination of neutron activation and subsequent separation of radioiodine ( 128 I) by selective retention on Dowex 2-X8 anion exchange resin. Iodine may be detected down to 5ng in terms of absolute amounts. In terms of concentration the detection limit was 10ppb. Results showed a precision of 5 percent at a concentration level of 1ppm. (Auth.)

The evolution of sex ratios and sex-determining systems

NARCIS (Netherlands)

Uller, Tobias; Pen, Ido; Wapstra, Erik; Beukeboom, Leo W.; Komdeur, Jan

Sex determination is a fundamental process governed by diverse mechanisms. Sex ratio selection is commonly implicated in the evolution of sex-determining systems, although formal models are rare. Here, we argue that, although sex ratio selection can induce shifts in sex determination, genomic

Hand-held optical sensor using denatured antibody coated electro-active polymer for ultra-trace detection of copper in blood serum and environmental samples.

Science.gov (United States)

Chandra, Sutapa; Dhawangale, Arvind; Mukherji, Soumyo

2018-07-01

An optimum copper concentration in environment is highly desired for all forms of life. We have developed an ultrasensitive copper sensor which functions from femto to micro molar concentration accurately (R 2 = 0.98). The sensor is based on denatured antibody immunoglobulin G (IgG), immobilized on polyaniline (PAni) which in turn is the coating on the core of an optical fiber. The sensing relies on changes in evanescent wave absorbance in the presence of the analyte. The sensor showed excellent selectivity towards Cu (II) ions over all other metal ions. The sensor was tested with lake and marine water samples to determine unknown concentrations of copper ions and the recovery results were within 90-115%, indicating reasonable accuracy. We further integrated the fiber-optic sensor with a miniaturized hand-held instrumentation platform to develop an accurate and field deployable device which can broadly be applicable to determine Cu (II) concentration in a wide range of systems - natural water bodies, soil as well as blood serum. Copyright © 2018 Elsevier B.V. All rights reserved.

A composite material based on nanoparticles of yttrium (III) oxide for the selective and sensitive electrochemical determination of acetaminophen

Energy Technology Data Exchange (ETDEWEB)

Baytak, Aysegul Kutluay [Department of Medical Laboratory, Vocational School of Health Services, Harran University, Şanlıurfa 63510 (Turkey); Teker, Tugce; Duzmen, Sehriban [Department of Chemistry, Harran University, Şanlıurfa 63510 (Turkey); Aslanoglu, Mehmet, E-mail: maslanoglu@harran.edu.tr [Department of Chemistry, Harran University, Şanlıurfa 63510 (Turkey)

2016-09-01

An electrochemical sensor was prepared by modifying a glassy carbon electrode (GCE) with a composite of yttrium (III) oxide nanoparticles (Y{sub 2}O{sub 3}NPs) and carbon nanotubes (CNTs) for the determination of acetaminophen (ACT). Compared with a bare GCE and CNTs/GCE, the Y{sub 2}O{sub 3}NPs/CNTs/GCE exhibited a well-defined redox couple for ACT and highly enhanced the current response. The separations in the anodic and cathodic peak potentials (ΔE{sub p}) for ACT were 552 mV, 24 mV and 10 mV at ba4re GCE, CNTs/GCE and Y{sub 2}O{sub 3}NPs/CNTs/GCE, respectively. The observation of only 10 mV of ΔE{sub p} for ACT at Y{sub 2}O{sub 3}NPs/CNTs/GCE was a clear indication of a great acceleration of the electrode process compared to bare GCE and GCE modified with CNTs. Also, L-ascorbic acid (L-AA) and L-tyrosine (L-TRY) did not interfere with the selective determination of ACT. Square wave voltammetry (SWV) was performed for the quantification of ACT. A linear plot was obtained for current responses versus the concentrations of ACT over the range from 1.0 × 10{sup −10} to 1.8 × 10{sup −8} M with a detection limit of 3.0 × 10{sup −11} M (based on 3S{sub b}/m). The proposed composite material provided high electrocatalytic activity, improved voltammetric behavior, good selectivity and good reproducibility. The accurate quantification of ACT makes the proposed electrode of great interest for the public health. - Highlights: • A voltammetric sensor based on yttrium oxide was prepared for the detection of ACT. • The proposed electrode has greatly accelerated the voltammetric process of ACT. • A detection limit of 0.03 nM was obtained for ACT. • The proposed electrode exhibited great selectivity for ACT in the presence of L-AA and L-TRY. • The composite material exhibited high sensitivity, good stability and excellent reproducibility.

Highly selective and sensitive optical sensor for determination of Pb2+and Hg2+ ions based on the covalent immobilization of dithizone on agarose membrane

Science.gov (United States)

Zargoosh, Kiomars; Babadi, Fatemeh Farhadian

2015-02-01

A highly sensitive and selective optical membrane for determination of Hg2+ and Pb2+ was prepared by covalent immobilization of dithizone on agarose membrane. In addition to its high stability, reproducibility and relatively long lifetime, the proposed optical sensor revealed good selectivity for target ions over a large number of alkali, alkaline earth, transition, and heavy metal ions. The proposed optical membrane displays linear responses from 1.1 × 10-8 to 2.0 × 10-6 mol L-1 and 1.2 × 10-8 to 2.4 × 10-6 mol L-1 for Hg2+ and Pb2+, respectively. The limits of detection (LOD) were 2.0 × 10-9 mol L-1 and 4.0 × 10-9 mol L-1 for Hg2+ and Pb2, respectively. The prepared optical membrane was successfully applied to the determination of Hg2+ and Pb2+ in industrial wastes, spiked tap water and natural waters without any preconcentration step.

Limb-segment selection in drawing behaviour

NARCIS (Netherlands)

Meulenbroek, R G; Rosenbaum, D A; Thomassen, A.J.W.M.; Schomaker, L R

How do we select combinations of limb segments to carry out physical tasks? Three possible determinants of limb-segment selection are hypothesized here: (1) optimal amplitudes and frequencies of motion for the effectors; (2) preferred movement axes for the effectors; and (3) a tendency to continue

LIMB-SEGMENT SELECTION IN DRAWING BEHAVIOR

NARCIS (Netherlands)

MEULENBROEK, RGJ; ROSENBAUM, DA; THOMASSEN, AJWM; SCHOMAKER, LRB; Schomaker, Lambertus

How do we select combinations of limb segments to carry out physical tasks? Three possible determinants of limb-segment selection are hypothesized here: (1) optimal amplitudes and frequencies of motion for the effectors; (2) preferred movement axes for the effectors; and (3) a tendency to continue

Mixed ion-exchanger chemically modified carbon paste ion-selective electrodes for determination of triprolidine hydrochloride

Directory of Open Access Journals (Sweden)

Yousry M. Issa

2010-01-01

Full Text Available Triprolidine hydrochloride (TpCl ion-selective carbon paste electrodes were constructed using Tp-TPB/Tp-CoN and Tp-TPB/Tp-PTA as ion-exchangers. The two electrodes revealed Nernstian responses with slopes of 58.4 and 58.1 mV decade−1 at 25 °C in the ranges 6 × 10−6–1 × 10−2 and 2 × 10−5–1 × 10−2 M for Tp-TPB/Tp-CoN and Tp-TPB/Tp-PTA, respectively. The potentials of these electrodes were independent of pH in the ranges of 2.5–7.0 and 4.5–7.0, and detection limits were 6 × 10−6 and 1 × 10−5 M for Tp-TPB/Tp-CoN and Tp-TPB/Tp-PTA, respectively. The electrodes showed a very good selectivity for TpCl with respect to a large number of inorganic cations and compounds. The standard addition, potentiometric titration methods and FIA were applied to the determination of TpCl in pure solutions and pharmaceutical preparations. The results obtained were in close agreement with those found by the official method. The mean recovery values were 100.91% and 97.92% with low coefficient of variation values of 0.94%, and 0.56% in pure solutions, 99.82% and 98.53% with coefficient of variation values of 2.20%, and 0.73% for Actifed tablet and Actifed syrup, respectively, using the Tp-TPB/Tp-CoN electrode, and 98.85%, and 99.18% with coefficient of variation values of 0.48% and 0.85% for Actifed tablet and Actifed syrup, respectively, using the Tp-TPB/Tp-PTA electrode.

Analytical application of solid contact ion-selective electrodes for determination of copper and nitrate in various food products and drinking water.

Science.gov (United States)

Wardak, Cecylia; Grabarczyk, Malgorzata

2016-08-02

A simple, fast and cheap method for monitoring copper and nitrate in drinking water and food products using newly developed solid contact ion-selective electrodes is proposed. Determination of copper and nitrate was performed by application of multiple standard additions technique. The reliability of the obtained results was assessed by comparing them using the anodic stripping voltammetry or spectrophotometry for the same samples. In each case, satisfactory agreement of the results was obtained, which confirms the analytical usefulness of the constructed electrodes.

Synthesis of Fe–Cu/TiO2 nanostructure and its use in construction of a sensitive and selective sensor for metformin determination

International Nuclear Information System (INIS)

Gholivand, Mohammad Bagher; Shamsipur, Mojtaba; Paimard, Giti; Feyzi, Mostafa; Jafari, Fataneh

2014-01-01

A carbon paste electrode modified with Fe-Cu/TiO 2 was prepared and used for low level determination of metformin (MET) using square wave adsorptive stripping voltammetry (SWAdSV). The Fe-Cu/TiO 2 nanoparticle was synthesized by a modified sol–gel method. The surface structure and composition of nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction analysis (XRD) and N 2 physisorption. Also, electrochemical properties of the prepared nanocomposite modified electrode were investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) techniques. Under optimized conditions, the modified electrode exhibited a linear response over the concentration range of 15 nM to 75 μM MET, with a detection limit of 3 nM. The proposed sensor exhibited a high sensitivity, good selectivity and was successfully applied for MET determination in real samples such as human urine and pharmaceutical formulations. - Highlights: • A carbon paste modified electrode for determination of MET was developed. • The synthesized Fe-Cu/TiO 2 nanocomposite was used as a modifier. • The sensor was successfully applied for MET determination in real samples. • Square wave adsorptive stripping voltammetric method was used for MET determination

Determination of chloride in MOX samples using chloride ion selective electrode

Energy Technology Data Exchange (ETDEWEB)

Govindan, R; Das, D K; Mallik, G K; Sumathi, A; Patil, Sangeeta; Raul, Seema; Bhargava, V K; Kamath, H S [Bhabha Atomic Research Centre, Tarapur (India). Advanced Fuel Fabrication Facility

1997-09-01

The chloride present in the MOX fuel is separated from the matrix by pyrohydrolysis at a temperature of 950 {+-} 50 degC and is then analyzed by chloride ion selective electrode (Cl-ISE). The range covered is 0.4-4 ppm with a precision of better than {+-}5% R.S.D. (author). 4 refs., 1 tab.

A dye laser with a partial-selective resonator

Energy Technology Data Exchange (ETDEWEB)

Makogon, M M; Sukhanov, V B

1977-04-01

The possibility of controlling the width and spectral position of the generation line of an organic dye laser (Rhodamine 6Zh) whose resonator represents a combination of selective and non-selective channels is demonstrated. The selective channel entails an unsymmetrically mounted prism with whose angular displacement the spectral width can be changed within broad ranges; the non-selective channel maintains the resonator's quality at a sufficiently high level. An expression is given which makes it possible to determine the generation's spectral width when fixing the prism's angular position. The change in the rearrangement band was studied in relation to the qualities of the selective and non-selective channels as determined by the form of the active medium's amplification contour (a narrowing of the spectrum from 0.15 to 0.0019 nm led to a reduction of the rearrangement area from 38.4 to 28.3 nm).

Treatment of selective mutism: focus on selective serotonin reuptake inhibitors.

Science.gov (United States)

Kaakeh, Yaman; Stumpf, Janice L

2008-02-01

Abstract Selective mutism is a pediatric psychiatric disorder that occurs when a child consistently fails to speak in specific situations in which speaking is expected, such as at school and social gatherings, but speaks appropriately in other settings. Selective mutism often is diagnosed when a child starts school and does not talk to teachers or peers, but talks to family members at home; the condition is frequently accompanied by anxiety and shyness. Although the underlying etiology of the condition remains unclear, psychotherapy is the preferred initial treatment, with the support of parents and teachers. If the child does not respond to psychotherapy, addition of pharmacologic treatment should be considered, depending on the severity of symptoms and presence of other illnesses. Although data are limited to case reports and trials with small patient populations and short follow-up periods, some patients with selective mutism respond to therapy with selective serotonin reuptake inhibitors (SSRIs). Fluoxetine is the most studied SSRI as treatment for the condition, although further investigation is required to determine the optimal dosage and duration of therapy.

Ultra-trace plutonium determination in small volume seawater by sector field inductively coupled plasma mass spectrometry with application to Fukushima seawater samples.

Science.gov (United States)

Bu, Wenting; Zheng, Jian; Guo, Qiuju; Aono, Tatsuo; Tagami, Keiko; Uchida, Shigeo; Tazoe, Hirofumi; Yamada, Masatoshi

2014-04-11

Long-term monitoring of Pu isotopes in seawater is required for assessing Pu contamination in the marine environment from the Fukushima Dai-ichi Nuclear Power Plant accident. In this study, we established an accurate and precise analytical method based on anion-exchange chromatography and SF-ICP-MS. This method was able to determine Pu isotopes in seawater samples with small volumes (20-60L). The U decontamination factor was 3×10(7)-1×10(8), which provided sufficient removal of interfering U from the seawater samples. The estimated limits of detection for (239)Pu and (240)Pu were 0.11fgmL(-1) and 0.08fgmL(-1), respectively, which corresponded to 0.01mBqm(-3) for (239)Pu and 0.03mBqm(-3) for (240)Pu when a 20L volume of seawater was measured. We achieved good precision (2.9%) and accuracy (0.8%) for measurement of the (240)Pu/(239)Pu atom ratio in the standard Pu solution with a (239)Pu concentration of 11fgmL(-1) and (240)Pu concentration of 2.7fgmL(-1). Seawater reference materials were used for the method validation and both the (239+240)Pu activities and (240)Pu/(239)Pu atom ratios agreed well with the expected values. Surface and bottom seawater samples collected off Fukushima in the western North Pacific since March 2011 were analyzed. Our results suggested that there was no significant variation of the Pu distribution in seawater in the investigated areas compared to the distribution before the accident. Copyright © 2014 Elsevier B.V. All rights reserved.

Direct determination of Ti content in sunscreens with laser-induced breakdown spectroscopy: Line selection method for high TiO{sub 2} nanoparticle concentration

Energy Technology Data Exchange (ETDEWEB)

Menneveux, Jérôme; Wang, Fang; Lu, Shan; Bai, Xueshi; Motto-Ros, Vincent [Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex (France); Gilon, Nicole [Institut des Sciences Analytiques, UMR5280 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex (France); Chen, Yanping [Department of Physics and Astrophysics, Shanghai Jiao Tong University, Shanghai 200240 (China); Yu, Jin, E-mail: jin.yu@univ-lyon1.fr [Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex (France); Department of Physics and Astrophysics, Shanghai Jiao Tong University, Shanghai 200240 (China)

2015-07-01

Sunscreen represents a large variety of creams which, in the analytical point of view, exhibit a similar matrix. Such matrix corresponds to a semi-solid emulsion of mixture of oil and water. The formulation of a cream can include metal and nonmetal elements in different contents in order to realize specific pharmaceutical or cosmetic functions designed for the product. The complex matrix of these materials makes their analysis challenging for classical elemental analytical techniques with specific and complicated sample pretreatment procedures needed for reliable quantification. In this work we demonstrate and assess direct determination, without any pretreatment, of elemental content, especially for metallic element such as titanium, in a sunscreen using laser-induced breakdown spectroscopy (LIBS). The used configuration corresponds to that of indirect ablation of a thin film of cream applied on the surface of a pure aluminum target. We especially focused, in this work, on the case of high concentration of TiO{sub 2} nanoparticle in cream. Such choice was justified first by the fact that such concentration level is usually found in commercial sunscreens. On the other hand, titanium presents a large number of lines, neutral as well as singly ionized, in the spectral range from the near UV to the near IR. It provides therefore an ideal case to study line selection method to manage the effect of self-absorption, which becomes unavoidable at high concentration level, and to optimize measurement precision. Through such study, we try to deduce a quantifiable and generalizable line selection method for high performance LIBS measurements. More specifically, calibration curves were first established using 6 laboratory-prepared samples. The quadratic term of the curves was then studied as a function of the intensity of the used lines and their type (neutral or ion, resonant or non-resonant). The prediction performance of the lines was assessed with 2 validation samples with

Determinant factors for Brebes shallot farmers in selecting shallot varieties (Case study in Brebes, Central Java Indonesia)

Science.gov (United States)

Sembiring, A.

2017-03-01

The using of a high quality seed is very important for a successfully cultivation and an increasing of vegetable production. The vegetable productions, including for shallot are much more affected by seed varieties. Previous studies showed that production rate, shape, colour, resistant to pest and disease, number of bulbs and demanding by market were factors that influence farmers to choose shallot variety. The aim of the study is to observe determinant factors that influence shallot farmers to change their shallot varieties and persist to use certain varieties. The study was conducted in June to December 2014 in Wanasari, Tanjung, Kemukten and Limbangan villages, Brebes District. Brebes was selected as it is the biggest shallot production in Indonesia. Data were collected from 35 shallot farmers through survey by using the structural questionnaire. The data then analysed with the descriptive statistic.

Determine the optimal carrier selection for a logistics network based on multi-commodity reliability criterion

Science.gov (United States)

Lin, Yi-Kuei; Yeh, Cheng-Ta

2013-05-01

From the perspective of supply chain management, the selected carrier plays an important role in freight delivery. This article proposes a new criterion of multi-commodity reliability and optimises the carrier selection based on such a criterion for logistics networks with routes and nodes, over which multiple commodities are delivered. Carrier selection concerns the selection of exactly one carrier to deliver freight on each route. The capacity of each carrier has several available values associated with a probability distribution, since some of a carrier's capacity may be reserved for various orders. Therefore, the logistics network, given any carrier selection, is a multi-commodity multi-state logistics network. Multi-commodity reliability is defined as a probability that the logistics network can satisfy a customer's demand for various commodities, and is a performance indicator for freight delivery. To solve this problem, this study proposes an optimisation algorithm that integrates genetic algorithm, minimal paths and Recursive Sum of Disjoint Products. A practical example in which multi-sized LCD monitors are delivered from China to Germany is considered to illustrate the solution procedure.

Determination of vitamins D2 and D3 in selected food matrices by online high-performance liquid chromatography-gas chromatography-mass spectrometry (HPLC-GC-MS).

Science.gov (United States)

Nestola, Marco; Thellmann, Andrea

2015-01-01

An online normal-phase liquid chromatography-gas chromatography-mass spectrometry (HPLC-GC-MS) method was developed for the determination of vitamins D2 and D3 in selected food matrices. Transfer of the sample from HPLC to GC was realized by large volume on-column injection; detection was performed with a time-of-flight mass spectrometer (TOF-MS). Typical GC problems in the determination of vitamin D such as sample degradation or sensitivity issues, previously reported in the literature, were not observed. Determination of total vitamin D content was done by quantitation of its pyro isomer based on an isotopically labelled internal standard (ISTD). Extracted ion traces of analyte and ISTD showed cross-contribution, but non-linearity of the calibration curve was not determined inside the chosen calibration range by selection of appropriate quantifier ions. Absolute limits of detection (LOD) and quantitation (LOQ) for vitamins D2 and D3 were calculated as approximately 50 and 150 pg, respectively. Repeatability with internal standard correction was below 2 %. Good agreement between quantitative results of an established high-performance liquid chromatography with UV detection (HPLC-UV) method and HPLC-GC-MS was found. Sterol-enriched margarine was subjected to HPLC-GC-MS and HPLC-MS/MS for comparison, because HPLC-UV showed strong matrix interferences. HPLC-GC-MS produced comparable results with less manual sample cleanup. In summary, online hyphenation of HPLC and GC allowed a minimization in manual sample preparation with an increase of sample throughput.

Molecularly imprinted polymer for selective extraction of malachite green from seawater and seafood coupled with high-performance liquid chromatographic determination.

Science.gov (United States)

Lian, Ziru; Wang, Jiangtao

2012-12-01

In this paper, a highly selective sample cleanup procedure combining molecular imprinting technique (MIT) and solid-phase extraction (SPE) was developed for the isolation of malachite green in seawater and seafood samples. The molecularly imprinted polymer (MIP) was prepared using malachite green as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linking monomer. The imprinted polymer and non-imprinted polymer were characterized by scanning electron microscope and static adsorption experiments. The MIP showed a high adsorption capacity and was used as selective sorbent for the SPE of malachite green. An off-line molecularly imprinted solid-phase extraction (MISPE) method followed by high-performance liquid chromatography with diodearray detection for the analysis of malachite green in seawater and seafood samples was also established. Finally, five samples were determined. The results showed that malachite green concentration in one seawater sample was at 1.30 μg L⁻¹ and the RSD (n=3) was 4.15%. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

A sensitive and selective chemiluminescence sensor for the determination of dopamine based on silanized magnetic graphene oxide-molecularly imprinted polymer.

Science.gov (United States)

Duan, Huimin; Li, Leilei; Wang, Xiaojiao; Wang, Yanhui; Li, Jianbo; Luo, Chuannan

2015-03-15

Based on silanized magnetic graphene oxide-molecularly imprinted polymer (Si-MG-MIP), a sensitive and selective chemiluminescence sensor for dopamine measurement was developed. Si-MG-MIP, in which silanes was introduced to improve the mass transfer, graphene oxide was employed to improve absorption capacity, Fe3O4 nanoparticles were applied for separation easily and molecularly imprinted polymer was used to improve selectivity, demonstrated the advantages of the sensor. All the composites were confirmed by SEM, TEM, XRD and FTIR. Under the optimal conditions of chemiluminescence, dopamine could be assayed in the range of 8.0-200.0 ng/mL with a correlation coefficient of linear regression of 0.9970. The detection limit was 1.5 ng/mL (3δ) and the precision for 11 replicate detections of 80.0 ng/mL dopamine was 3.4% (RSD). When the sensor was applied in determining dopamine in actual samples, recovery ranged from 94% to 110%, which revealed that the results were satisfactory. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of Selected Aromas in Marquette and Frontenac Wine Using Headspace-SPME Coupled with GC-MS and Simultaneous Olfactometry

Directory of Open Access Journals (Sweden)

Somchai Rice

2018-03-01

Full Text Available Understanding the aroma profile of wines made from cold climate grapes is needed to help winemakers produce quality aromatic wines. The current study aimed to add to the very limited knowledge of aroma-imparting compounds in wines made from the lesser-known Frontenac and Marquette cultivars. Headspace solid-phase microextraction (SPME and gas chromatography-mass spectrometry (GC-MS with simultaneous olfactometry was used to identify and quantify selected, aroma-imparting volatile organic compounds (VOC in wines made from grapes harvested at two sugar levels (22° Brix and 24° Brix. Aroma-imparting compounds were determined by aroma dilution analysis (ADA. Odor activity values (OAV were also used to aid the selection of aroma-imparting compounds. Principal component analysis and hierarchical clustering analysis indicated that VOCs in wines produced from both sugar levels of Marquette grapes are similar to each other, and more similar to wines produced from Frontenac grapes harvested at 24° Brix. Selected key aroma compounds in Frontenac and Marquette wines were ethyl hexanoate, ethyl isobutyrate, ethyl octanoate, and ethyl butyrate. OAVs >1000 were reported for three aroma compounds that impart fruity aromas to the wines. This study provides evidence that aroma profiles in Frontenac wines can be influenced by timing of harvesting the berries at different Brix. Future research should focus on whether this is because of berry development or accumulation of aroma precursors and sugar due to late summer dehydration. Simultaneous chemical and sensory analyses can be useful for the understanding development of aroma profile perceptions for wines produced from cold-climate grapes.

The interaction properties of the human Rab GTPase family--comparative analysis reveals determinants of molecular binding selectivity.

Directory of Open Access Journals (Sweden)

Matthias Stein

Full Text Available Rab GTPases constitute the largest subfamily of the Ras protein superfamily. Rab proteins regulate organelle biogenesis and transport, and display distinct binding preferences for effector and activator proteins, many of which have not been elucidated yet. The underlying molecular recognition motifs, binding partner preferences and selectivities are not well understood.Comparative analysis of the amino acid sequences and the three-dimensional electrostatic and hydrophobic molecular interaction fields of 62 human Rab proteins revealed a wide range of binding properties with large differences between some Rab proteins. This analysis assists the functional annotation of Rab proteins 12, 14, 26, 37 and 41 and provided an explanation for the shared function of Rab3 and 27. Rab7a and 7b have very different electrostatic potentials, indicating that they may bind to different effector proteins and thus, exert different functions. The subfamily V Rab GTPases which are associated with endosome differ subtly in the interaction properties of their switch regions, and this may explain exchange factor specificity and exchange kinetics.We have analysed conservation of sequence and of molecular interaction fields to cluster and annotate the human Rab proteins. The analysis of three dimensional molecular interaction fields provides detailed insight that is not available from a sequence-based approach alone. Based on our results, we predict novel functions for some Rab proteins and provide insights into their divergent functions and the determinants of their binding partner selectivity.

The role of positive selection in determining the molecular cause of species differences in disease

Directory of Open Access Journals (Sweden)

Foord Steven M

2008-10-01

Full Text Available Abstract Background Related species, such as humans and chimpanzees, often experience the same disease with varying degrees of pathology, as seen in the cases of Alzheimer's disease, or differing symptomatology as in AIDS. Furthermore, certain diseases such as schizophrenia, epithelial cancers and autoimmune disorders are far more frequent in humans than in other species for reasons not associated with lifestyle. Genes that have undergone positive selection during species evolution are indicative of functional adaptations that drive species differences. Thus we investigate whether biomedical disease differences between species can be attributed to positively selected genes. Results We identified genes that putatively underwent positive selection during the evolution of humans and four mammals which are often used to model human diseases (mouse, rat, chimpanzee and dog. We show that genes predicted to have been subject to positive selection pressure during human evolution are implicated in diseases such as epithelial cancers, schizophrenia, autoimmune diseases and Alzheimer's disease, all of which differ in prevalence and symptomatology between humans and their mammalian relatives. In agreement with previous studies, the chimpanzee lineage was found to have more genes under positive selection than any of the other lineages. In addition, we found new evidence to support the hypothesis that genes that have undergone positive selection tend to interact with each other. This is the first such evidence to be detected widely among mammalian genes and may be important in identifying molecular pathways causative of species differences. Conclusion Our dataset of genes predicted to have been subject to positive selection in five species serves as an informative resource that can be consulted prior to selecting appropriate animal models during drug target validation. We conclude that studying the evolution of functional and biomedical disease differences

Highly active antiretroviral therapy adherence and its determinants in selected regions in Indonesia

Directory of Open Access Journals (Sweden)

Felix F. Widjaja

2011-02-01

Full Text Available Background: Highly active antiretroviral therapy (HAART can reduce morbidity and mortality of HIV-infected patients. However, it depends upon adherence to medication. The objective of this study was to examine the adherence to HAART and to evaluate individual patient characteristics i.e. self-efficacy, depression level, and social support and to finally determine HAART adherence in selected regions in Indonesia.Methods: This cross-sectional study was conducted in Jakarta, Malang, Bandung, Makasar and Banda Aceh. The subject of the study was HIV-infected patients who were older than 13 years old and had taken HAART for at least a month. They were recruited consecutively then asked how many pills they had missed during the previous month. Poor adherence can be stated if the percentage of adherence rate is below 95%. HIV treatment adherence self-efficacy scale  (HIVASES, Beck Depression Inventory (BDI-II and Interpersonal Support Evaluation List (ISEL was adapted to assess self-efficacy, depression level and social support, respectively.Results: We found that 96% (n=53 of the subjects adhered to HAART. There were no associations between adherence with self-efficacy, depression level, and social support. The main cause of non-adherence in this study was ‘simply  forget’.Conclusion: Adherence to HAART was found to be high and not associated with self-efficacy, depression level and social support in some central regions in Indonesia. (Med J Indones 2011; 20:50-5Keywords: adherence, depression, HAART, HIV, self-efficacy, social support

Application of resonance ionization mass spectrometry for trace analysis and in fundamental research

International Nuclear Information System (INIS)

Passler, G.

1997-01-01

Resonance ionization mass spectrometry (RIMS) has been used for ultra-trace analysis on long-lived radioisotopes like Pu, Tc and 89,90 Sr in various environmental samples. The experimental approaches cover pulsed laser spectroscopy on a thermal atomic beam and subsequent time-of-flight mass analysis, a pulsed laser ion source combined with conventional mass spectrometry, and collinear resonance ionization on a mass-separated fast atomic beam. The high sensitivity of RIMS also enables atomic spectroscopy on rare isotopes. For the first time experimental values for the ionization potential of actinides up to Cf have been determined. The paper reviews the dependency of the different experimental approaches on the analytical problem. copyright 1997 American Institute of Physics

Study on the identification of organic and common anions in the pyrohydrolysis distillate of mixed uranium-plutonium carbide for the interference free determination of chlorine and fluorine by ion chromatography

Energy Technology Data Exchange (ETDEWEB)

Jeyakumar, Subbiah; Mishra, Vivekchandra Guruprasad; Das, Mrinal Kanti; Raut, Vaibhavi Vishwajeet; Sawant, Ramesh Mahadeo [Bhabha Atomic Research Centre, Mumbai (India). Radioanalytical Chemistry Div.; Ramakumar, Karanam Lakshminarayana [Bhabha Atomic Research Centre, Mumbai (India). Radiochemistry and Isotope Group

2014-07-01

Identification of various soluble organic acids formed during the pyrohydrolysis of uranium-plutonium mixed carbide [(U,Pu)C] was carried out using ion chromatography. This has significant importance as the soluble organic acids can cause severe interferences during the ion chromatography separation and determination of Cl{sup -} and F{sup -} in the pyrohydrolysis distillate of (U,Pu)C. Determination of Cl and F is important in the chemical quality control of nuclear materials as these two elements can cause corrosion and hence, their concentrations in all nuclear materials are restricted to certain specified values. Since the pyrohydrolysis distillates contain both inorganic and organic acid anions, for the sake of separating and identifying organic acid anions from the common inorganic anions, three independent isocratic elutions using varying concentrations of NaOH eluent were employed for the separation of weakly, moderately and strongly retained anions. It was observed that pyrohydrolysis of (U,Pu)C also produced soluble organic acids as in the case of nitric acid dissolution of UC. The present investigation revealed the presence of formic, acetic, propionic, butyric, oxalic acid anions in the pyrohydrolysis distillate of (U,Pu)C in trace or ultra-trace concentrations. The presence of each organic acid identified in the chromatogram was confirmed with spike addition as well as by separating them by capillary electrophoresis method. The presence of lower aliphatic acids viz. formic and acetic acids was reconfirmed by carrying out an independent separation with tetraborate eluent. It is suggested that nitric acid being formed during pyrohydrolysis could be responsible for the formation of organic acids. Based on the findings, an ion chromatography separation method has been proposed for the interference-free determination of chloride and fluoride in pyrohydrolysis distillate of (U,Pu)C. (orig.)

Dispersive solid phase microextraction with magnetic graphene oxide as the sorbent for separation and preconcentration of ultra-trace amounts of gold ions.

Science.gov (United States)

Kazemi, Elahe; Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad

2015-08-15

A selective, simple and rapid dispersive solid phase microextraction was developed using magnetic graphene oxide (MGO) as an efficient sorbent for the separation and preconcentration of gold ions. The MGO was synthesized by means of the simple one step chemical coprecipitation method, characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Gold ions retained by the sorbent were eluted using 0.5mol L(-)(1) thiourea in 0.1mol L(-1) HCl solution and determined by the flow injection flame atomic absorption spectrometry (FI-FAAS). The factors affecting the separation and preconcentration of gold were investigated and optimized. Under the optimized conditions, the method exhibited a linear dynamic range of 0.02-100.0µg L(-)(1) with a detection limit of 4ng L(-1) and an enrichment factor of 500. The relative standard deviations of 3.2% and 4.7% (n=6) were obtained at 20µg L(-1) level of gold ions for the intra and the inter day analysis, respectively. The method was successfully applied to the determination of gold ions in water and waste water samples as well as a certified reference material (CCU-1b, copper flotation concentrate). Copyright © 2015 Elsevier B.V. All rights reserved.

Selective flotation-spectrophotometric determination of trace copper(II) in natural waters, human blood and drug samples using phenanthraquinone monophenylthiosemicarbazone.

Science.gov (United States)

Khalifa, M E; Akl, M A; Ghazy, S E

2001-06-01

Copper(II) forms 1:1 and 1:2 intense red complexes with phenanthraquinone monophenylthiosemicarbazone (PPT) at pH 3-3.5 and > or =6.5, respectively. These complexes exhibit maximal absorbance at 545 and 517 nm, the molar absorptivity being 2.3 x 10(4) and 4.8 x 10(4) l mol(-1) cm(-1), respectively. However, the 1:1 complex was quantitatively floated with oleic acid (HOL) surfactant in the pH range 4.5-5.5, providing a highly selective and sensitive procedure for the spectrophotometric determination of CuII. The molar absorptivity of the floated Cu-PPT complex was 1.5 x 10(5) l mol)(-1) cm(-1). Beer's law was obeyed over the range 3-400 ppb at 545 nm. The analytical parameters affecting the flotation process and hence the determination of copper traces were reported. Also, the structure of the isolated solid complex and the mechanism of flotation were suggested. Moreover, the procedure was successfully applied to the analysis of CuII in natural waters, serum blood and some drug samples.

High Selectivity Oxygen Delignification

Energy Technology Data Exchange (ETDEWEB)

Lucian A. Lucia

2005-11-15

Project Objective: The objectives of this project are as follows: (1) Examine the physical and chemical characteristics of a partner mill pre- and post-oxygen delignified pulp and compare them to lab generated oxygen delignified pulps; (2) Apply the chemical selectivity enhancement system to the partner pre-oxygen delignified pulps under mill conditions (with and without any predetermined amounts of carryover) to determine how efficiently viscosity is preserved, how well selectivity is enhanced, if strength is improved, measure any yield differences and/or bleachability differences; and (3) Initiate a mill scale oxygen delignification run using the selectivity enhancement agent, collect the mill data, analyze it, and propose any future plans for implementation.

Molecularly imprinted sol-gel nanofibers based solid phase microextraction coupled on-line with high performance liquid chromatography for selective determination of acesulfame.

Science.gov (United States)

Moein, Mohammad Mahdi; Javanbakht, Mehran; Karimi, Mohammad; Akbari-Adergani, Behrouz

2015-03-01

Sol-gel based molecularly imprinted polymer (MIP) nanofiber was successfully fabricated by electrospinning technique on the surface of a stainless steel bar. The manufactured tool was applied for on-line selective solid phase microextraction (SPME) and determination of acesulfame (ACF) as an artificial sweetener with high performance liquid chromatography (HPLC). The selective ability of method for the extraction of ACF was investigated in the presence of some selected sweeteners such as saccharine (SCH), aspartame (ASP) and caffeine (CAF). Electrospinning of MIP sol-gel solution on the stainless steel bar provided an unbreakable sorbent with high thermal, mechanical, and chemical stability. Moreover, application of the MIP-SPME tool revealed a unique approach for the selective microextraction of the analyte in beverage samples. In this work, 3-(triethoxysilyl)-propylamine (TMSPA) was chosen as a precursor due to its ability to imprint the analyte by hydrogen bonding, Van der Walls, and dipole-dipole interactions. Nylon 6 was also added as a backbone and support for the precursor in which sol could greatly growth during the sol-gel process and makes the solution electrospinable. Various effective parameters in the extraction efficiency of the MIP-SPME tool such as loading time, flow rate, desorption time, selectivity, and the sample volume were evaluated. The linearity for the ACF in beverage sample was in the range of 0.78-100.5 ng mL(-1). Limit of detection (LOD) and quantification (LOQ) were 0.23 and 0.78 ng mL(-1) respectively. The RSD values (n=5) were all below 3.5%at the 20 ng mL(-1) level. Copyright © 2014 Elsevier B.V. All rights reserved.

Selective dispersive liquid–liquid microextraction and preconcentration of Ni(II) into a micro droplet followed by ETAAS determination using a yellow Schiff's base bisazanyl derivative

International Nuclear Information System (INIS)

Alizadeh, Kamal; Nemati, Hadi; Zohrevand, Somaieh; Hashemi, Payman; Kakanejadifard, Ali; Shamsipur, Mojtaba; Ganjali, Mohammad Reza; Faridbod, Farnoush

2013-01-01

A simple, rapid and sensitive method was developed for the selective separation and preconcentration of Ni(II) using dispersive liquid–liquid microextraction, by a yellow Schiff's base bisazanyl derivative, as a selective complexing agent. In this method, a mixture of 45 μL chloroform (extraction solvent) and 450 μL tetrahydrofuran (dispersive solvent) is rapidly injected by syringe into a 5 mL aqueous sample containing 3% (w/v) sodium chloride and an appropriate amount of the Schiff's base. As a result, a cloudy solution is formed by entire dispersion of the extraction solvent into the aqueous phase. After centrifuging for 5 min at 5000 rpm, the sedimented phase is directly injected into the electrothermal atomic absorption spectrometry for Ni(II) determination. Some important parameters, such as kind and volume of extraction and dispersive solvents, extraction time, salt effect, pH and concentration of the chelating agent have been optimized. Under the optimum conditions, the enrichment factor for the presented method is 138. The calibration curve was linear over a nickel concentration range of 10–50 ng mL −1 . The detection limit and relative standard deviation were 0.04 ng mL −1 and 2.1%, respectively. The method was successfully applied to the extraction and determination of Ni(II) in different water samples. - Highlights: ► A new synthesized schiff's base was used for selective separation of Ni(II) ions. ► The method based on DLLME was successfully applied to the determination of Ni(II). ► A cloudy solution is formed by entire dispersion of the extraction solvent into the aqueous phase. ► In this work, the response surface analysis was used for the optimization purpose. ► The curvature of response surface reflects the interactive effect of the variables.

Highly selective solid phase extraction and preconcentration of Azathioprine with nano-sized imprinted polymer based on multivariate optimization and its trace determination in biological and pharmaceutical samples

Energy Technology Data Exchange (ETDEWEB)

Davarani, Saied Saeed Hosseiny, E-mail: ss-hosseiny@cc.sbu.ac.ir [Faculty of Chemistry, Shahid Beheshti University, G. C., P.O. Box 19839-4716, Tehran (Iran, Islamic Republic of); Rezayati zad, Zeinab [Faculty of Chemistry, Shahid Beheshti University, G. C., P.O. Box 19839-4716, Tehran (Iran, Islamic Republic of); Taheri, Ali Reza; Rahmatian, Nasrin [Islamic Azad University, Ilam Branch, Ilam (Iran, Islamic Republic of)

2017-02-01

In this research, for first time selective separation and determination of Azathioprine is demonstrated using molecularly imprinted polymer as the solid-phase extraction adsorbent, measured by spectrophotometry at λ{sub max} 286 nm. The selective molecularly imprinted polymer was produced using Azathioprine and methacrylic acid as a template molecule and monomer, respectively. A molecularly imprinted solid-phase extraction procedure was performed in column for the analyte from pharmaceutical and serum samples. The synthesized polymers were characterized by infrared spectroscopy (IR), field emission scanning electron microscopy (FESEM). In order to investigate the effect of independent variables on the extraction efficiency, the response surface methodology (RSM) based on Box–Behnken design (BBD) was employed. The analytical parameters such as precision, accuracy and linear working range were also determined in optimal experimental conditions and the proposed method was applied to analysis of Azathioprine. The linear dynamic range and limits of detection were 2.5–0.01 and 0.008 mg L{sup ‐1} respectively. The recoveries for analyte were higher than 95% and relative standard deviation values were found to be in the range of 0.83–4.15%. This method was successfully applied for the determination of Azathioprine in biological and pharmaceutical samples. - Graphical abstract: A new-nano sized imprinted polymer was synthesized and applied as sorbent in SPE in order to selective recognition, preconcentration, and determination of Azathioprine with the response surface methodology based on Box–Behnken design and was successfully investigated for the clean-up of human blood serum and pharmaceutical samples. - Highlights: • The nanosized-imprinted polymer has been synthesized by precipitation polymerization technique. • A molecularly imprinted solid-phase extraction procedure was performed for determination of Azathioprine. • The Azathioprine

Highly selective solid phase extraction and preconcentration of Azathioprine with nano-sized imprinted polymer based on multivariate optimization and its trace determination in biological and pharmaceutical samples

International Nuclear Information System (INIS)

Davarani, Saied Saeed Hosseiny; Rezayati zad, Zeinab; Taheri, Ali Reza; Rahmatian, Nasrin

2017-01-01

In this research, for first time selective separation and determination of Azathioprine is demonstrated using molecularly imprinted polymer as the solid-phase extraction adsorbent, measured by spectrophotometry at λ max 286 nm. The selective molecularly imprinted polymer was produced using Azathioprine and methacrylic acid as a template molecule and monomer, respectively. A molecularly imprinted solid-phase extraction procedure was performed in column for the analyte from pharmaceutical and serum samples. The synthesized polymers were characterized by infrared spectroscopy (IR), field emission scanning electron microscopy (FESEM). In order to investigate the effect of independent variables on the extraction efficiency, the response surface methodology (RSM) based on Box–Behnken design (BBD) was employed. The analytical parameters such as precision, accuracy and linear working range were also determined in optimal experimental conditions and the proposed method was applied to analysis of Azathioprine. The linear dynamic range and limits of detection were 2.5–0.01 and 0.008 mg L ‐1 respectively. The recoveries for analyte were higher than 95% and relative standard deviation values were found to be in the range of 0.83–4.15%. This method was successfully applied for the determination of Azathioprine in biological and pharmaceutical samples. - Graphical abstract: A new-nano sized imprinted polymer was synthesized and applied as sorbent in SPE in order to selective recognition, preconcentration, and determination of Azathioprine with the response surface methodology based on Box–Behnken design and was successfully investigated for the clean-up of human blood serum and pharmaceutical samples. - Highlights: • The nanosized-imprinted polymer has been synthesized by precipitation polymerization technique. • A molecularly imprinted solid-phase extraction procedure was performed for determination of Azathioprine. • The Azathioprine-molecular imprinting

A New Platform for Profiling Degradation-Related Impurities Via Exploiting the Opportunities Offered by Ion-Selective Electrodes: Determination of Both Diatrizoate Sodium and Its Cytotoxic Degradation Product.

Science.gov (United States)

Riad, Safaa M; Abd El-Rahman, Mohamed K; Fawaz, Esraa M; Shehata, Mostafa A

2018-05-01

Although the ultimate goal of administering active pharmaceutical ingredients (APIs) is to save countless lives, the presence of impurities and/or degradation products in APIs or formulations may cause harmful physiological effects. Today, impurity profiling (i.e., the identity as well as the quantity of impurity in a pharmaceutical) is receiving critical attention from regulatory authorities. Despite the predominant use of spectroscopic and chromatographic methods over electrochemical methods for impurity profiling of APIs, this work investigates the opportunities offered by electroanalytical methods, particularly, ion-selective electrodes (ISEs), for profiling degradation-related impurities (DRIs) compared with conventional spectroscopic and chromatographic methods. For a meaningful comparison, diatrizoate sodium (DTA) was chosen as the anionic X-ray contrast agent based on its susceptibility to deacetylation into its cytotoxic and mutagenic degradation product, 3,5-diamino-2,4,6 triiodobenzoic acid (DTB). This cationic diamino compound can be also detected as an impurity in the final product because it is used as a synthetic precursor for the synthesis of DTA. In this study, four novel sensitive and selective sensors for the determination of both DTA and its cytotoxic degradation products are presented. Sensors I and II were developed for the determination of the anionic drug, DTA, and sensors III and IV were developed for the determination of the cationic cytotoxic impurity. The use of these novel sensors not only provides a stability-indicating method for the selective determination of DTA in the presence of its degradation product, but also permits DRI profiling. Moreover, a great advantage of these proposed ISE systems is their higher sensitivity for the quantification of DTB relative to other spectroscopic and chromatographic methods, so it can measure trace amounts of DTB impurities in DTA bulk powder and pharmaceutical formulation without a need for

Selecting Personal Computers.

Science.gov (United States)

Djang, Philipp A.

1993-01-01

Describes a Multiple Criteria Decision Analysis Approach for the selection of personal computers that combines the capabilities of Analytic Hierarchy Process and Integer Goal Programing. An example of how decision makers can use this approach to determine what kind of personal computers and how many of each type to purchase is given. (nine…

Development of a highly sensitive MIP based-QCM nanosensor for selective determination of cholic acid level in body fluids

International Nuclear Information System (INIS)

Gültekin, Aytaç; Karanfil, Gamze; Sönmezoğlu, Savaş; Say, Rıdvan

2014-01-01

Determination of cholic acid is very important and necessary in body fluids due to its both pharmaceutical and clinical significance. In this study, a quartz crystal microbalance (QCM) nanosensor, which is imprinted cholic acid, has been developed for the assignation of cholic acid. The cholic acid selective memories have been generated on QCM electrode surface by using molecularly imprinted polymer (MIP) based on methacryloylamidohistidine-copper (II) (MAH-Cu(II)) pre-organized monomer. The cholic acid imprinted nanosensor was characterized by atomic force microscopy (AFM) and then analytical performance of the cholic acid imprinted QCM nanosensor was studied. The detection limit was found to be 0.0065 μM with linear range of 0.01–1000 μM. Moreover, the high value of Langmuir constant (b) (7.3 * 10 5 ) obtained by Langmuir graph showed that the cholic acid imprinted nanosensor had quite strong binding sites affinity. At the last step of this procedure, cholic acid levels in body fluids were determined by the prepared imprinted QCM nanosensor. - Graphical abstract: QCM responses of the cholic acid imprinted and non-imprinted nanosensors (C CA = 0.1 μM). - Highlights: • The purpose is to synthesize a new cholic acid imprinted QCM nanosensor by MIP. • Analytical applications of QCM nanosensor were investigated. • The cholic acid levels in body fluids were determined by prepared QCM nanosensor

Highly selective ionic liquid-based microextraction method for sensitive trace cobalt determination in environmental and biological samples

International Nuclear Information System (INIS)

Berton, Paula; Wuilloud, Rodolfo G.

2010-01-01

A simple and rapid dispersive liquid-liquid microextraction procedure based on an ionic liquid (IL-DLLME) was developed for selective determination of cobalt (Co) with electrothermal atomic absorption spectrometry (ETAAS) detection. Cobalt was initially complexed with 1-nitroso-2-naphtol (1N2N) reagent at pH 4.0. The IL-DLLME procedure was then performed by using a few microliters of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium hexafluorophosphate [C 6 mim][PF 6 ] as extractant while methanol was the dispersant solvent. After microextraction procedure, the Co-enriched RTIL phase was solubilized in methanol and directly injected into the graphite furnace. The effect of several variables on Co-1N2N complex formation, extraction with the dispersed RTIL phase, and analyte detection with ETAAS, was carefully studied in this work. An enrichment factor of 120 was obtained with only 6 mL of sample solution and under optimal experimental conditions. The resultant limit of detection (LOD) was 3.8 ng L -1 , while the relative standard deviation (RSD) was 3.4% (at 1 μg L -1 Co level and n = 10), calculated from the peak height of absorbance signals. The accuracy of the proposed methodology was tested by analysis of a certified reference material. The method was successfully applied for the determination of Co in environmental and biological samples.

From the Phenix irradiation end to the analytical results: PROFIL R target destructive characterization

International Nuclear Information System (INIS)

Ferlay, G.; Dancausse, J. Ph.

2009-01-01

In the French long-lived radionuclide (LLRN) transmutation program, several irradiation experiments were initiated in the Phenix fast neutron reactor to obtain a better understanding of the transmutation processes. The PROFIL experiments are performed in order to collect accurate information on the total capture integral cross sections of the principal heavy isotopes and some important fission products in the spectral range of fast reactors. One of the final goals is to diminish the uncertainties on the capture cross-section of the fission products involved in reactivity losses in fast reactors. This program includes two parts: PROFIL-R irradiated in a standard fast reactor spectrum and PROFIL-M irradiated in a moderated spectrum. The PROFIL-R and PROFIL-M irradiations were completed in August 2005 and May 2008, respectively. For both irradiations more than a hundred containers with isotopes of pure actinides and other elements in different chemical forms must be characterized. This raises a technical and analytical challenge: how to recover by selective dissolution less than 5 mg of isotope powder from a container with dimensions of only a few millimeters using hot cell facilities, and how to determine analytically both trace and ultra-trace elemental and isotopic compositions with sufficient accuracy to be useful for code calculations. (authors)

Determinants of propranolol’s selective effect on loss aversion

Science.gov (United States)

Sokol-Hessner, Peter; Lackovic, Sandra F.; Tobe, Russell H.; Camerer, Colin F.; Leventhal, Bennett L.; Phelps, Elizabeth A.

2015-01-01

Research on emotion and decision-making has suggested that arousal mediates risky decisions (e.g., Bechara et al., 1997), but several distinct and often confounded processes drive such choices. Here, we used econometric modeling to separate and quantify the unique contributions of loss aversion, risk sensitivity and choice consistency to risky decision-making. We administered the beta-blocker propranolol in a double-blind, placebo-controlled within-subjects study, targeting the neurohormonal basis of physiological arousal. Matching our intervention’s pharmacological specificity with a quantitative model delineating decision-making components allowed us to identify the causal relationships between arousal and decision-making that do and do not exist. Propranolol selectively reduced loss aversion in a baseline- and dose-dependent manner (i.e. as a function of initial loss aversion and body-mass index), and did not affect risk sensitivity or choice consistency. These findings provide evidence for a specific, modulatory, and causal relationship between precise components of both emotion and risky decision-making. PMID:26063441

Aqueous nitrite ion determination by selective reduction and gas phase nitric oxide chemiluminescence

Science.gov (United States)

Dunham, A. J.; Barkley, R. M.; Sievers, R. E.; Clarkson, T. W. (Principal Investigator)

1995-01-01

An improved method of flow injection analysis for aqueous nitrite ion exploits the sensitivity and selectivity of the nitric oxide (NO) chemilluminescence detector. Trace analysis of nitrite ion in a small sample (5-160 microL) is accomplished by conversion of nitrite ion to NO by aqueous iodide in acid. The resulting NO is transported to the gas phase through a semipermeable membrane and subsequently detected by monitoring the photoemission of the reaction between NO and ozone (O3). Chemiluminescence detection is selective for measurement of NO, and, since the detection occurs in the gas-phase, neither sample coloration nor turbidity interfere. The detection limit for a 100-microL sample is 0.04 ppb of nitrite ion. The precision at the 10 ppb level is 2% relative standard deviation, and 60-180 samples can be analyzed per hour. Samples of human saliva and food extracts were analyzed; the results from a standard colorimetric measurement are compared with those from the new chemiluminescence method in order to further validate the latter method. A high degree of selectivity is obtained due to the three discriminating steps in the process: (1) the nitrite ion to NO conversion conditions are virtually specific for nitrite ion, (2) only volatile products of the conversion will be swept to the gas phase (avoiding turbidity or color in spectrophotometric methods), and (3) the NO chemiluminescence detector selectively detects the emission from the NO + O3 reaction. The method is free of interferences, offers detection limits of low parts per billion of nitrite ion, and allows the analysis of up to 180 microL-sized samples per hour, with little sample preparation and no chromatographic separation. Much smaller samples can be analyzed by this method than in previously reported batch analysis methods, which typically require 5 mL or more of sample and often need chromatographic separations as well.

Selective decontamination of the digestive tract and selective oropharyngeal decontamination in intensive care unit patients: a cost-effectiveness analysis

NARCIS (Netherlands)

Oostdijk, E.A.; Wit, G.A. de; Bakker, M; Smet, A.M. de; Bonten, M.J.; Hoeven, J.G. van der; Pickkers, P.; Sturm, P.D.J.; Voss, A.; et al.,

2013-01-01

OBJECTIVE: To determine costs and effects of selective digestive tract decontamination (SDD) and selective oropharyngeal decontamination (SOD) as compared with standard care (ie, no SDD/SOD (SC)) from a healthcare perspective in Dutch Intensive Care Units (ICUs). DESIGN: A post hoc analysis of a

Selective decontamination of the digestive tract and selective oropharyngeal decontamination in intensive care unit patients : a cost-effectiveness analysis

NARCIS (Netherlands)

Oostdijk, Evelien A. N.; de Wit, G. A.; Bakker, Marina; de Smet, Anne-Marie; Bonten, M. J. M.

2013-01-01

Objective: To determine costs and effects of selective digestive tract decontamination (SDD) and selective oropharyngeal decontamination (SOD) as compared with standard care (ie, no SDD/SOD (SC)) from a healthcare perspective in Dutch Intensive Care Units (ICUs). Design: A post hoc analysis of a

Genetic algorithm-based wavelength selection in multicomponent spectrophotometric determination by PLS: Application on sulfamethoxazole and trimethoprim mixture in bovine milk

Directory of Open Access Journals (Sweden)

Givianrad Hadi Mohammad

2013-01-01

Full Text Available The simultaneous determination of sulfamethoxazole (SMX and trimethoprim (TMP mixtures in bovine milk by spectrophotometric method is a difficult problem in analytical chemistry, due to spectral interferences. By means of multivariate calibration methods, such as partial least square (PLS regression, it is possible to obtain a model adjusted to the concentration values of the mixtures used in the calibration range. Genetic algorithm (GA is a suitable method for selecting wavelengths for PLS calibration of mixtures with almost identical spectra without loss of prediction capacity using the spectrophotometric method. In this study, the calibration model based on absorption spectra in the 200-400 nm range for 25 different mixtures of SMX and TMP Calibration matrices were formed form samples containing 0.25-20 and 0.3-21 μg mL-1 for SMX and TMP, at pH=10, respectively. The root mean squared error of deviation (RMSED for SMX and TMP with PLS and genetic algorithm partial least square (GAPLS were 0.242, 0.066 μgmL-1 and 0.074, 0.027 μg mL-1, respectively. This procedure was allowed the simultaneous determination of SMX and TMP in synthetic and real samples and good reliability of the determination was proved.

Selective Mutism Questionnaire: Measurement Structure and Validity

Science.gov (United States)

Letamendi, Andrea M.; Chavira, Denise A.; Hitchcock, Carla A.; Roesch, Scott C.; Shipon-Blum, Elisa; Stein, Murray B.

2008-01-01

The psychometric properties of the Selective Mutism Questionnaire (SMQ) are evaluated using a clinical sample of children with selective mutism (SM). The study shows that SMQ is useful in determining the severity of a child's nonspeaking behaviors, the scope of these behaviors and necessary follow up assessment.

DETERMINATION OF DIVERSE ENVIRONMENTAL POLLUTION LEVEL FROM SELECTED AREAS OF RAWALPINDI, PAKISTAN

Directory of Open Access Journals (Sweden)

S. Pervez

2017-08-01

Full Text Available Anthropogenic contaminants arising from both stationary (power plants, industries and residential heating and mobile sources (road traffic can harm ambient air quality in urban areas. Depending upon their physical state, these pollutants are classified as liquid and vapor phases and are subsequently transported to the Earth’s surface through dry and wet deposition. After the deposition of these pollutants onto the surface of earth various health effects caused by these pollutants occurred like cardiovascular diseases and hypertension. In this study four different locations/sites were selected from the Rawalpindi city depending upon the population, traffic rush and industries to examine the noise level, concentration of carbon dioxide and heavy metals. Air sampler was used for the collection of air sample to analyze the heavy metal concentration, Quest electronic sound meter for measuring sound level and SIBATA for CO2 measurement. The study findings revealed that noise level was higher at all selected locations as described by WHO limit (70 dB being highest at Industrial area due to heavy machinery and lowest at green area. Concentration of all four heavy metals were high as compared with the prescribed limits. CO2 level reaches up to 300 ppm because of coal consumption during the winter season. The threshold values of all these selected parameters well above the prescribed limits defined by the authorities so to combat with this situation we should move towards more energy efficient fuels, proper maintenance of vehicles and machineries, traffic management and installation of noise barriers in industries as well as installation of catalytic convertors in vehicles to stop further air pollution.

Determinants of Bank Selection Choices in Malaysia: A Demographic based Investigation

OpenAIRE

Celestine Fernandez, Dominic

2008-01-01

Banking is an important contributor to the economic growth around the world. The benefits of understanding consumer selection decisions will provide bankers with a competitive advantage as it has the ability to influence the marketing mix. With rising overheads and price competition, the profit margins earned from bank services are being narrowed. Banks will have to capture a sizeable customer base to sustain their profitability and turnover. Malaysia was chosen for this study as banks have b...

Sex selection: treating different cases differently.

Science.gov (United States)

Dickens, B M; Serour, G I; Cook, R J; Qiu, R-Z

2005-08-01

This paper contrasts ethical approaches to sex selection in countries where discrimination against women is pervasive, resulting in selection against girl children, and in countries where there is less general discrimination and couples do not prefer children of either sex. National sex ratio imbalances where discrimination against women is common have resulted in laws and policies, such as in India and China, to deter and prevent sex selection. Birth ratios of children can be affected by techniques of prenatal sex determination and abortion, preconception sex selection and discarding disfavored embryos, and prefertilization sperm sorting, when disfavored sperm remain unused. Incentives for son preference are reviewed, and laws and policies to prevent sex selection are explained. The elimination of social, economic and other discrimination against women is urged to redress sex selection against girl children. Where there is no general selection against girl children, sex selection can be allowed to assist families that want children of both sexes.

A novel dual-function molecularly imprinted polymer on CdTe/ZnS quantum dots for highly selective and sensitive determination of ractopamine

International Nuclear Information System (INIS)

Liu, Huilin; Liu, Dongrui; Fang, Guozhen; Liu, Fangfang; Liu, Cuicui; Yang, Yukun; Wang, Shuo

2013-01-01

Highlights: ► We have developed a novel dual-function MIP-coated QDs material. ► The MIP-coated QDs combine the advantage of molecular imprinting and QDs. ► We used MIP-coated QDs as fluorescence sensing material for recognize RAC. ► We used QDs@MIP as sorbent to combine SPE with HPLC for the determination. -- Abstract: A novel dual-function material was synthesized by anchoring a molecularly imprinted polymer (MIP) layer on CdTe/ZnS quantum dots (QDs) using a sol–gel with surface imprinting. The material exhibited highly selective and sensitive determination of ractopamine (RAC) through spectrofluorometry and solid-phase extraction (SPE) coupled with high performance liquid chromatography (HPLC). A series of adsorption experiments revealed that the material showed high selectivity, good adsorption capacity and a fast mass transfer rate. Fluorescence from the MIP-coated QDs was more strongly quenched by RAC than that of the non-imprinted polymer, which indicated that the MIP-coated QDs acted as a fluorescence sensing material could recognize RAC. In addition, the MIP-coated QDs as a sorbent was also shown to be promising for SPE coupled with HPLC for the determination of trace RAC in feeding stuffs and pork samples. Under optimal conditions, the spectrofluorometry and SPE-HPLC methods using the MIP-coated QDs had linear ranges of 5.00 × 10 −10 –3.55 × 10 −7 and 1.50 × 10 −10 –8.90 × 10 −8 mol L −1 , respectively, with limits of detection of 1.47 × 10 −10 and 8.30 × 10 −11 mol L −1 , the relative standard deviations for six repeat experiments of RAC (2.90 × 10 −9 mol L −1 ) were below 2.83% and 7.11%

A novel dual-function molecularly imprinted polymer on CdTe/ZnS quantum dots for highly selective and sensitive determination of ractopamine

Energy Technology Data Exchange (ETDEWEB)

Liu, Huilin; Liu, Dongrui; Fang, Guozhen; Liu, Fangfang; Liu, Cuicui; Yang, Yukun [Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin Key Laboratory of Food Nutrition and Safety, Tianjin University of Science and Technology, Tianjin 300457 (China); Wang, Shuo, E-mail: s.wang@tust.edu.cn [Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin Key Laboratory of Food Nutrition and Safety, Tianjin University of Science and Technology, Tianjin 300457 (China)

2013-01-31

Highlights: ► We have developed a novel dual-function MIP-coated QDs material. ► The MIP-coated QDs combine the advantage of molecular imprinting and QDs. ► We used MIP-coated QDs as fluorescence sensing material for recognize RAC. ► We used QDs@MIP as sorbent to combine SPE with HPLC for the determination. -- Abstract: A novel dual-function material was synthesized by anchoring a molecularly imprinted polymer (MIP) layer on CdTe/ZnS quantum dots (QDs) using a sol–gel with surface imprinting. The material exhibited highly selective and sensitive determination of ractopamine (RAC) through spectrofluorometry and solid-phase extraction (SPE) coupled with high performance liquid chromatography (HPLC). A series of adsorption experiments revealed that the material showed high selectivity, good adsorption capacity and a fast mass transfer rate. Fluorescence from the MIP-coated QDs was more strongly quenched by RAC than that of the non-imprinted polymer, which indicated that the MIP-coated QDs acted as a fluorescence sensing material could recognize RAC. In addition, the MIP-coated QDs as a sorbent was also shown to be promising for SPE coupled with HPLC for the determination of trace RAC in feeding stuffs and pork samples. Under optimal conditions, the spectrofluorometry and SPE-HPLC methods using the MIP-coated QDs had linear ranges of 5.00 × 10{sup −10}–3.55 × 10{sup −7} and 1.50 × 10{sup −10}–8.90 × 10{sup −8} mol L{sup −1}, respectively, with limits of detection of 1.47 × 10{sup −10} and 8.30 × 10{sup −11} mol L{sup −1}, the relative standard deviations for six repeat experiments of RAC (2.90 × 10{sup −9} mol L{sup −1}) were below 2.83% and 7.11%.

PVC-Membrane Potentiometric Electrochemical Sensor Based on 2-(4-Oxopentan-2-ylideneaminoisoindoline-1,3-dione for Selective Determination of Holmium(III

Directory of Open Access Journals (Sweden)

Hassan Ali Zamani

2011-01-01

Full Text Available 2-(4-Oxopentan-2-ylideneamino isoindoline-1,3-dione (OID was found to be a suitable neutral ionophore in the fabrication of a highly selective Ho3+ membrane sensor. The electrode has a near-Nernstian slope of 19.6±0.5 mV per decade with a wide concentration range between 1.0×10-6 and 1.0×10-2 mol/L in the pH range of 3.5–8.8, having a fast response time (∼5 s and a detection limit of 5.8×10-7 mol/L. This electrode presented very good selectivity and sensitivity towards the Ho3+ ions over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The practical utility of the electrode has been demonstrated by its use as an indicator electrode for the potentiometric titration of a Ho3+ solution with EDTA and for the determination of Ho3+ ions concentration in mixtures of two and three different ions.