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1.
The present work describes a headspace single-drop microextraction (HS-SDME) method in conjunction with gas chromatography
electron capture detection (GC–ECD) for the determination of an organophosphate insecticide, chlorpyrifos-ethyl (CPF), in
rat liver. Sample preparation included tissue homogenization with methanol in the presence of anhydrous sodium sulfate in
order to isolate CPF from the matrix, followed by dilution with 10 mL of 0.1 M H2SO4 and headspace microextraction to a 2-μL drop of 1-octanol. The main factors affecting extraction efficiency were optimized
[temperature 90 °C, preheating and extraction times of eight and six minutes, respectively, 2 g of (NH4)2SO4, stirring rate of 1000 rpm, 200 μL of methanolic extract]. The method allows for the separation and quantitation of residue
levels of CPF in the livers of rats exposed orally to that insecticide. Using internal standardization (with chlorpyrifos-methyl
used as an internal standard), the linearity of the method was demonstrated in the range 10–2500 ng g−1 with a correlation coefficient R > 0.996 and a satisfactory level of precision (RSD 3.85%, n = 6). Moreover, the results obtained with the new method do not differ from those obtained with the conventional residue
method used in our laboratory. The feasibility of this HS-SDME approach as an equivalent analytical method for the determination
of CPF in rat liver that possessess advantages such as low cost, low solvent consumption and high throughput was confirmed.
Figure Headspace single-drop microextraction 相似文献
2.
A photometric method for the determination of silicon based on the yellow color of α-silicomolybdic acid is described. The pH must be kept within the range 3.0–3.7, and the equilibrium state is established by beating the solution. Since the color of this modification is remarkably stable and reproducible, a high degree of precision can be attained. 相似文献
3.
Pérez-Serradilla JA Luque de Castro MD 《Analytical and bioanalytical chemistry》2007,389(5):1541-1547
Sorbent material packed in a PTFE laboratory-made flow cell located in the specimen holder of an energy-dispersive X-ray fluorescence
(EDXRF) detector has been used for in situ solid-phase extraction (SPE) preconcentration–detection of metals. The flow cell
was connected to a single-channel flow-injection (FI) manifold (for full automation of the steps and proper development of
the method) by two PTFE tubes of 0.5-mm inner diameter introduced into the spectrometer specimen holder by a small orifice
without distortion or modification of the instrument. The optical window open in the PTFE flow cell was adjusted to the X-ray
irradiation zone of the spectrometer and fixed to it. The approach was tested by using both Pb and Cd aqueous solutions and
a Dowex 50 cation-exchange resin as a sorbent, and flushing the sample through the flow cell for EDXRF measurements after
removal of the sample matrix. The limits of detection and the limits of quantification (LOQs) thus obtained were 0.15 and
0.5 μg for Pb and 0.3 and 0.8 μg for Cd, respectively, values that allow the approach to be used for the analysis of drinking
water by injecting a 100-mL sample into the FI manifold, taking into account the EC drinking water directives. The linear
dynamic ranges are between the LOQ and 600 μg for both analytes. The method was validated by the standard addition method
using tap-water samples. In addition, the integrated SPE–EDXRF approach enables the study of the variables influencing the
sorption step–namely the effects of the volume of sample flushed through the column, concentrations of the analytes in the
sample, breakthrough volume of the resin, elution profiles, sample pH and retention and elution flow rates–in an automatic,
cheap, fast and precise way. 相似文献
4.
Roya Mirzajani Nahid Pourreza Alireza R. Kiasat Samira S. Najjar 《International journal of environmental analytical chemistry》2013,93(7):800-810
Immobilization of β-cyclodextrin on Dowex resin as an insoluble polymeric matrix by covalent bond presents a new solid-phase medium for preconcentration of Pb (II) at trace level in environmental samples prior to its flame atomic absorption spectrometric determination. The method is based on the sorption of lead after passing on modified Dowex sorbent in a column. The effect of several parameters such as pH, flow rate of sample, eluent kind and volume was investigated. The sorption capacity of the matrix has been found to be 0.4996?mg?g?1 of adsorbent with the preconcentration factor of 250 for Pb (II). Nitric acid (3 M) as an eluent was sufficient to obtain quantitative recovery (>95%) for Pb (II). The optimum flow rate was 10?ml?min ?1. The calibration curve was linear in the range of (3–250?ng?mL?1) with a correlation coefficient of 0.9995. The limit of detection (LOD) based on three times the standard deviation of the blank was 1.37?ng?mL?1. The relative standard deviation (RSD) for determination of 10?ng?mL?1 and 100?ngmL?1 of Pb (II) was 3.00 % and 0.58 % (n?=?10), respectively. The method was successfully applied to determination of lead in some environmental samples such as tap water, river water, soil and rice. 相似文献
5.
M. Rada V. Maties M. Culea S. Rada E. Culea 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(2):507-510
Transparent glasses were prepared by conventional melting–quenching method in the xMoO3·(100 ? x)[3B2O3·PbO] system where 0 ≤ x ≤ 15 mol%. By increasing the MoO3 content up to 20 mol% the PbMoO4 crystalline phase appears. These systems exhibit a photochromic effect which can be induced through laser exposures (λ = 633 nm) directly on the bulk sample. Structural investigations by FTIR spectroscopy show that the photosensitive effect is due to a reduction of Mo6+ to Mo4+ and/or Mo5+ promoted by the oxidation of Pb2+ and some structural changes of the borate network. 相似文献
6.
A simple and cost effective sample pre-treatment method, dispersive liquid–liquid microextraction (DLLME), has been developed for the extraction of six fluoroquinolones (FQs) from chicken liver samples. Clean DLLME extracts were analyzed for fluoroquinolones using liquid chromatography with diode array detection (LC-DAD). Parameters such as type and volume of disperser solvent, type and volume of extraction solvent, concentration and composition of phosphoric acid in the disperser solvent and pH were optimized. Linearity in the concentration range of 30–500 μg kg−1 was obtained with regression coefficients ranging from 0.9945 to 0.9974. Intra-day repeatability expressed as % RSD was between 4 and 7%. The recoveries determined in spiked blank chicken livers at three concentration levels (i.e. 50, 100 and 300 μg kg−1) ranged from 83 to 102%. LODs were between 5 and 19 μg kg−1 while LOQs ranged between 23 and 62 μg kg−1. All of the eight chicken liver samples obtained from the local supermarkets were found to contain at least one type of fluoroquinolone with enrofloxacin being the most commonly detected. Only one sample had four fluoroquinolone antibiotics (ciprofloxacin, difloxacin, enrofloxacin, norfloxacin). Norfloxacin which is unlicensed for use in South Africa was also detected in three of the eight chicken liver samples analyzed. The concentration levels of all FQs antibiotics in eight samples ranged from 8.8 to 35.3 μg kg−1, values which are lower than the South African stipulated maximum residue limits (MRL). 相似文献
8.
N. L. Koryagina E. I. Savel’eva N. S. Khlebnikova A. I. Ukolov E. S. Ukolova G. V. Karakashev A. S. Radilov 《Journal of Analytical Chemistry》2016,71(14):1309-1318
The potentials of different chromatography–mass spectrometry methods for the determination of alkyl methylphosphonic acids (AMPAs)—the chemical markers of nerve agents in urine—are compared. The gas chromatography–mass spectrometry (GC–MS) characteristics of various volatile AMPA derivatives are studied. The preference of perfluorobenzyl derivatives over methyl, trimethylsilyl and tert-butyldimethylsilyl esters for the GC–MS determination of AMPAs in urine is demonstrated. An optimal technique for the determination of AMPAs in urine is HPLC combined with high-resolution MS2 mass spectrometry with the isotope–labeled forms of target compounds as internal standards. The detection limits of AMPAs in the proposed analytical procedures vary from 0.1 to 1.0 ng/mL. 相似文献
9.
A new liquid chromatography–mass spectrometry (LC/MS) method has been developed for the quantitative analysis of plasmalogens
in human plasma using a nonendogenous plasmalogen (1-O-1′-(Z)-tricosenyl-2-oleoyl-rac-glycero-3-phosphocholine, PLS 23:0/18:1) as an internal standard. 1-O-1′-(Z)-Tricosenyl glyceryl ether was prepared by reacting lithioalkoxyallyl with 1-iodoeicosane as the key intermediate in the
formation of PLS 23:0/18:1. In LC/MS analyses, PLS 23:0/18:1 generated significant fragment ions in positive and negative
modes. In positive ion mode, the [M+H]+ of PLS 23:0/18:1 yielded unique fragments with cleavages at the sn-1 and sn-2 positions of the glycerol backbone. In negative ion mode, the [M+CH3COO]− of PLS 23:0/18:1 resulted in characteristic fragmentation at the sn-2 and sn-3 positions. 1-O-1′-(Z)-Hexadecenyl-2-linoleoyl-rac-glycero-3-phosphocholine (PLS 16:0/18:2) and 2-arachidonoyl-O-1′-(Z)-hexadecenyl-rac-glycero-3-phosphocholine (PLS 16:0/20:4) were chemically synthesized as PLS 23:0/18:1. The calibration curves obtained for
PLS 16:0/18:2 and PLS 16:0/20:4 were linear throughout the calibration range (0.04–1.60 pmol). The LOD (S/N = 5:1) was 0.008 pmol
and the LOQ (S/N = 6:1) was 0.01 pmol for both PLS 16:0/18:2 and PLS 16:0/20:4. Plasma concentrations of PLS 16:0/18:2 and
PLS 16:0/20:4 were 4.0 ± 1.3 μM and 3.5 ± 1.2 μM (mean ± SD), respectively, in five healthy volunteers. 相似文献
10.
《Chemical physics letters》1986,128(4):354-357
We have determined from X-ray diffraction that lead stearate, which like many hydrocarbon compounds does not form good crystals in bulk, can be grown epitaxially on mica using the Langmuir—Blodgett technique. The strong alternation in intensities of the (11l) peaks cannot be explained by considering the lead ions only, and imply that the hydrocarbon chains do not close-pack into a triangular array but reproduce the in-plane structure of the lead ions. 相似文献
11.
B. B. Alchagirov F. F. Dyshekova R. Kh. Arkhestov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(11):2262-2269
The temperature and concentration dependences of the surface tension of lithium alloys based on lead are experimentally determined for the first time in a field of compositions with up to 20 at % lithium in lead in the temperature range from the liquidus up to 700 K. The isotherm of surface tension of the studied alloys in the range of compositions with ~10 at % Li in lead contains a minimum, as does the adsorption isotherm of lithium in the sub-eutectic area of PbLi compounds. 相似文献
12.
Tiago Augusto Donegatti Alnilan Lobato Eliana A. R. Duek Luís Moreira Gonçalves Elisabete Alves Pereira 《Electrophoresis》2020,41(18-19):1576-1583
Aminoglycosides are a relevant class of antibiotics widely used by medics and veterinaries. There are a variety of reasons that make their determination relevant, such as quality control, environment and food contamination assessment, drug-release studies, among others. The lack of a chromophore makes aminoglycoside spectrophotometric detection particularly challenging, often requiring derivatization. In this work, an indirect detection method, making use of imidazole as a probe, applying CZE was successfully tested. It did not require derivatization, which simplified the sample preparation. Suitable figures of merit were obtained; recoveries between 95 and 105%, adequate repeatability and precision, correlation coefficients (r) above 0.998, and limits of detection (LODs) of 3.2 and 11 mg/L for gentamicin and paromomycin, respectively. As a proof-of-concept, it was also applied in a simple controlled release experiment that was well fitted using the Hill equation. 相似文献
13.
Barrett B Borek-Dohalský V Fejt P Vaingátová S Huclová J Nemec B Jelínek I 《Analytical and bioanalytical chemistry》2005,383(2):210-217
A validated, highly sensitive, and selective HPLC method with MS–MS detection has been developed for quantitative determination
of azithromycin (AZI) in human Na2EDTA plasma. Roxithromycin (ROX) was used as internal standard. Human plasma containing AZI and internal standard was ultrafiltered
through Centrifree Micropartition devices and the concentration of AZI was determined by isocratic HPLC–MS–MS. Multiple reaction
monitoring mode (MRM) was used for MS–MS detection. The calibration plot was linear in the concentration range 2.55–551.43 ng mL−1. Inter-day and Intra-day precision and accuracy of the proposed method were characterized by R.S.D and percentage deviation,
respectively; both were less than 8%. Limit of quantification was 2.55 ng mL−1. The proposed method was used to determine the pharmacokinetic profile of AZI (250-mg tablets). 相似文献
14.
Benzene, toluene, ethylbenzene, three isomers of xylene, and cumene have been isolated and enriched from soil samples by a combination of water extraction at room and elevated temperature and headspace–solid-phase microextraction before their gas chromatographic–mass spectrometric (GC–MS) determination. The conditions used for all stages of sample preparation and chromatographic analysis were optimized. Analytes sampled on a polydimethylsiloxane-coated solid-phase microextraction fiber were thermally desorbed in the split/splitless injector of a gas chromatograph (GC) coupled with a mass spectrometer (MS). The desorption temperature was optimized. The GC separation was performed in a capillary column. Detection limits were found to be of the order of ca. 1 ng g–1. Relative recoveries of the analytes from soils were found to be highly dependent on soil organic-matter content and on compound identity; they ranged from ca 92 to 96% for sandy soil (extraction at room temperature) and from ca 27 to 55% for peaty soil (extraction at elevated temperature). A few real-world soil samples were analyzed; the individual monoaromatic hydrocarbon content ranged from below detection limits to 6.4 ng g–1 for benzene and 8.1 for the total of p- + m-xylene. 相似文献
15.
E. Beceiro-González A. Guimaraes M.F. Alpendurada 《Journal of chromatography. A》2009,1216(29):5563-5569
In this work, a headspace-solid-phase micro-extraction (HS-SPME) combined with gas chromatography–mass spectrometry (GC–MS) method for multielemental speciation of organometallic compounds of mercury, lead and tin in water samples was upgraded by the introduction of tandem mass spectrometry (MS/MS) as detection technique. The analytical method is based on the ethylation with NaBEt4 and simultaneous headspace-solid-phase micro-extraction of the derivative compounds followed by GC–MS/MS analysis. The main experimental parameters influencing the extraction efficiency such as derivatisation time, extraction time and extraction temperature were optimized. The overall optimum extraction conditions were the following: a 50 μm/30 μm divinyl-benzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) SPME fibre, 150 min derivatisation time, 15 min extraction time, sample agitation at 250 rpm and 40 °C extraction temperature. The analytical characteristics of the HS-SPME method combined with GC–MS and GC–MS/MS were evaluated. The combination of both techniques HS-SPME and GC–MS/MS allowed to attain lower limits of detection (4–33 ng l−1) than those obtained by HS-SPME–GC–MS (17–45 ng l−1). The proposed method presented good linear regression coefficients (r2 > 0.9970) and repeatability (4.8–21.0%) for all the compounds under study. The accuracy of the method measured as the average percentage recovery of the compounds in spiked river water and seawater samples was higher than 80% for all the compounds studied, except for monobutyltin in the river water sample. A study of the uncertainty associated with the analytical results was also carried out. 相似文献
16.
Tribalat L Paisse O Dessalces G Grenier-Loustalot MF 《Analytical and bioanalytical chemistry》2006,386(7-8):2161-2168
In the framework of developing analyses for exogenous contaminants in food matrices such as honey, we have compared data obtained
by high-performance liquid chromatography coupled with mass spectrometry (LC–MS) to those provided by high-performance liquid
chromatography and tandem mass spectrometry (LC–MS–MS). Initial results obtained with LC–MS showed that the technique lacked
selectivity, which is why the method was validated by LC–MS–MS. This method involves a solid-phase extraction (SPE) of nitrofuran
metabolites and nitrofuran parent drugs, a derivatization by 2-nitrobenzaldehyde for 17 h, and finally a clean-up by SPE.
The data obtained show that the limits of detection varied between 0.2 and 0.6 μg kg−1 for the metabolites and between 1 and 2 μg kg−1 for nitrofuran parent drugs. The method was applied to different flower honeys. The results showed that nitrofurans (used
as antibiotics) are consistently present in this matrix, the predominant compound being furazolidone.
Figure Working bees 相似文献
17.
Manuel Sergi Sabino Napoletano Camilla Montesano Roberto Iofrida Roberta Curini Dario Compagnone 《Analytical and bioanalytical chemistry》2013,405(2-3):725-735
An LC–MS–MS-based procedure for determination in hair of 14 different drugs of abuse belonging to the classes cocaine, amphetamine-like compounds, opiates, and hallucinogens has been developed. A pressurized-liquid extraction procedure was used and proved useful for quantitative recovery of all the analytes tested. This procedure, in conjunction with a simple decontamination step, performed to avoid false-positive samples, enabled the detection of all the analytes with LOQ ranging from 1.8 to 16 pg mg?1 and accuracy varying from 85 to 111 %. The procedure was validated in accordance with the SOFT/AAFS guidelines and seems to be suitable for routine determination of the drugs tested in hair. 相似文献
18.
19.
Mari Ataee Toraj Ahmadi-Jouibari 《International journal of environmental analytical chemistry》2016,96(3):271-283
This study was designed to determine the ultra-trace amounts of lead (Pb) and cadmium (Cd) in various cereals (rice, wheat, barley, peas, beans, corn and lentil) obtained from the markets in Kermanshah city, West Iran. An efficient microextraction method was applied to separation and preconcentration of metal ions. This method is dispersive liquid–liquid microextraction based on solidification of floating organic drop, which overcomes the most important problems of other microextraction techniques. Some effective parameters on extraction were studied and, under optimised conditions, the enhancement factors were 122 and 115 for Cd and Pb, respectively. The calibration graphs were linear in the range of 0.1–50 µg kg?1 with correlation coefficient more than 0.992. The detection limit was 0.05 µg kg?1. The values of intra-day relative standard deviations and inter-day relative standard deviations were in the range of 4.7?5.3% and 6.0?6.8%, respectively. The Pb concentrations in rice and wheat samples were considerably higher than the allowable limits set by World Health Organization. The method was successfully applied to determination of the Pb and Cd in cereals, and application of the proposed method to the analysis of two certified reference materials produced results that were in good agreement with the certified values. 相似文献
20.
Ivan Notardonato Pasquale Avino Angela Centola Giuseppe Cinelli Mario Vincenzo Russo 《Analytical and bioanalytical chemistry》2013,405(18):6137-6141
This paper proposes a new method for quantitative analysis of acrylamide in cereal-based foods and potato chips. The method uses reaction with trifluoroacetic anhydride, and analyses the resulting derivative by use of gas chromatography with electron-capture detection (GC–ECD). The effects of derivatization conditions, including temperature, reaction time, and catalyst, on the acylation reaction were evaluated. Chromatographic analysis was performed on an SE-54 capillary column. Under the optimum conditions, good retention and peak response were achieved for the acrylamide derivative. The analytical method was fully validated by assessment of LODs and LOQs (1 ng g?1 and 25 ng g?1, with relative standard deviations (RSD) 2.1 and 3.6, respectively), linearity (R?=?0.9935 over the range 0.03–10 μg g?1), and extraction recovery (>96 %, with RSD below 2.0, for acrylamide spiked at 1, 20, 50, and 100 ng g?1; 99.8 % for acrylamide content >1000 ng g?1). The method requires no clean-up of the acrylamide derivative before injection. The method has been successfully used to determine acrylamide levels in different commercial cereal-based foods, French fries, and potato chips. Figure
Novel derivatization method and GC-ECD analysis of acrylamide in cooked foods 相似文献