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1.
Tatyana S. Baptista Marcelo M. Redígolo Cibele B. Zamboni Ivone M. Sato Jose R. Marcelino 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(2):399-403
The World Health Organization states that envenomation is responsible for a high number of deaths per year, especially in
equatorial areas. The only effective specific treatment is the use of hyperimmune serum (antivenom). In Brazil, Crioula breed
horses are used for antivenom production, with great importance in the maintenance of public health programs. A strict biochemical
and metabolic control is required to attain specificity in antiserum. Inorganic elements represent only a small fraction of
whole blood. Nonetheless, they play important roles in mammalian metabolism, being responsible for controlling enzymatic reactions,
respiratory and cardiac functions and ageing. In this work, whole blood samples from Crioula breed horses were analyzed by
EDXRF technique. The reference interval values were determined for the elements Na (1955–2013 μg g−1), Mg (51–75 μg g−1), P (523–555 μg g−1), S (1628–1730 μg g−1), Cl (2388–2574 μg g−1), K (1649–1852 μg g−1), Ca (202–213 μg g−1), Cu (4.1–4.5 μg g−1) and Zn (2.4–2.8 μg g−1) and a comparative study with NAA results was outlined. The samples were obtained from Instituto Butantan. Both techniques
showed to be appropriate for whole blood sample analyses and offer a new perspective in Veterinary Medicine. 相似文献
2.
Borges KB de Oliveira AR Barth T Jabor VA Pupo MT Bonato PS 《Analytical and bioanalytical chemistry》2011,399(2):915-925
The purpose of this study was the development and validation of an LC–MS–MS method for simultaneous analysis of ibuprofen
(IBP), 2-hydroxyibuprofen (2-OH-IBP) enantiomers, and carboxyibuprofen (COOH-IBP) stereoisomers in fungi culture medium, to
investigate the ability of some endophytic fungi to biotransform the chiral drug IBP into its metabolites. Resolution of IBP
and the stereoisomers of its main metabolites was achieved by use of a Chiralpak AS-H column (150 × 4.6 mm, 5 μm particle
size), column temperature 8 °C, and the mobile phase hexane–isopropanol–trifluoroacetic acid (95: 5: 0.1, v/v) at a flow rate of 1.2 mL min−1. Post-column infusion with 10 mmol L−1 ammonium acetate in methanol at a flow rate of 0.3 mL min−1 was performed to enhance MS detection (positive electrospray ionization). Liquid–liquid extraction was used for sample preparation
with hexane–ethyl acetate (1:1, v/v) as extraction solvent. Linearity was obtained in the range 0.1–20 μg mL−1 for IBP, 0.05–7.5 μg mL−1 for each 2-OH-IBP enantiomer, and 0.025–5.0 μg mL−1 for each COOH-IBP stereoisomer (r ≥ 0.99). The coefficients of variation and relative errors obtained in precision and accuracy studies (within-day and between-day)
were below 15%. The stability studies showed that the samples were stable (p > 0.05) during freeze and thaw cycles, short-term exposure to room temperature, storage at −20 °C, and biotransformation
conditions. Among the six fungi studied, only the strains Nigrospora sphaerica (SS67) and Chaetomium globosum (VR10) biotransformed IBP enantioselectively, with greater formation of the metabolite (+)-(S)-2-OH-IBP. Formation of the COOH-IBP stereoisomers, which involves hydroxylation at C3 and further oxidation to form the
carboxyl group, was not observed. 相似文献
3.
Zang X Wang J Wang O Wang M Ma J Xi G Wang Z 《Analytical and bioanalytical chemistry》2008,392(4):749-754
A novel method was developed for the determination of captan, folpet, and captafol in apples by dispersive liquid–liquid microextraction
(DLLME) coupled with gas chromatography–electron capture detection (GC–ECD). Some experimental parameters that influence the
extraction efficiency, such as the type and volume of the disperser solvents and extraction solvents, extraction time, and
addition of salt, were studied and optimized to obtain the best extraction results. Under the optimum conditions, high enrichment
factors for the compounds were achieved ranging from 824 to 912. The recoveries of fungicides in apples at spiking levels
of 20.0 μg kg−1 and 70.0 μg kg−1 were 93.0–109.5% and 95.4–107.7%, respectively. The relative standard deviations (RSDs) for the apple samples at 30.0 μg kg−1 of each fungicide were in the range from 3.8 to 4.9%. The limits of detection were between 3.0 and 8.0 μg kg−1. The linearity of the method ranged from 10 to 100 μg kg−1 for the three fungicides, with correlation coefficients (r
2) varying from 0.9982 to 0.9997. The obtained results show that the DLLME combined with GC–ECD can satisfy the requirements
for the determination of fungicides in apple samples.
Figure Dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography–electron capture detection (GC–ECD) allows
satisfactory determination of fungicides in apple samples 相似文献
4.
Rodrigues TH Rocha MV de Macedo GR Gonçalves LR 《Applied biochemistry and biotechnology》2011,164(6):929-943
In this work, the potential of microwave-assisted alkali pretreatment in order to improve the rupture of the recalcitrant
structures of the cashew able bagasse (CAB), lignocellulosic by-product in Brazil with no commercial value, is obtained from
cashew apple process to juice production, was studied. First, biomass composition of CAB was determined, and the percentage
of glucan and lignin was 20.54 ± 0.70% and 33.80 ± 1.30%, respectively. CAB content in terms of cellulose, hemicelluloses,
and lignin, 19.21 ± 0.35%, 12.05 ± 0.37%, and 38.11 ± 0.08%, respectively, was also determined. Results showed that, after
enzymatic hydrolysis, alkali concentration exerted influence on glucose formation, after pretreatment with 0.2 and 1.0 mo L−1 of NaOH (372 ± 12 and 355 ± 37 mg gglucan−1) when 2% (w/v) of cashew apple bagasse pretreated by microwave-assisted alkali pretreatment (CAB-M) was used. On the other hand, pretreatment
time (15–30 min) and microwave power (600–900 W) exerted no significant effect on hydrolysis. On enzymatic hydrolysis step,
improvement on solid percentage (16% w/v) and enzyme load (30 FPU gCAB-M−1) increased glucose concentration to 15 g L−1. The fermentation of the hydrolyzate by Saccharomyces cerevesiae resulted in ethanol concentration and productivity of 5.6 g L−1 and 1.41 g L−1 h−1, respectively. 相似文献
5.
A simple and efficient method, based on ultrasound-enhanced surfactant-assisted dispersive liquid–liquid microextraction (UESA-DLLME)
followed by high-performance liquid chromatography (HPLC) has been developed for extraction and determination of ketoconazole
and econazole nitrate in human blood samples. In this method, a common cationic surfactant, cetyltrimethylammonium bromide
(CTAB), was used as dispersant. Chloroform (40 μL) as extraction solvent was added rapidly to 5 mL blood containing 0.068 mg mL−1 CTAB. The mixture was then sonicated for 2 min to disperse the organic chloroform phase. After the extraction procedure,
the mixture was centrifuged to sediment the organic chloroform phase, which was collected for HPLC analysis. Several conditions,
including type and volume of extraction solvent, type and concentration of the surfactant, ultrasound time, extraction temperature,
pH, and ionic strength were studied and optimized. Under the optimum conditions, linear calibration curves were obtained in
the ranges 4–5000 μg L−1 for ketoconazole and 8–5000 μg L−1 for econazole nitrate, with linear correlation coefficients for both >0.99. The limits of detection (LODs, S/N = 3) and enrichment factors (EFs) were 1.1 and 2.3 μg L−1, and 129 and 140 for ketoconazole and econazole nitrate, respectively. Reproducibility and recovery were good. The method
was successfully applied to the determination of ketoconazole and econazole nitrate in human blood samples. 相似文献
6.
A rapid, sensitive and environmentally friendly method for the analysis of 14 anilines in water samples by dispersive liquid–liquid
microextraction based on solidification of floating organic drop (DLLME-SFO) prior to gas chromatography–mass spectrometry
(GC-MS) was developed and optimized. In the proposed method, cyclohexane was used as the extraction solvent as its toxicity
was much lower than that of the solvent usually used in dispersive liquid–liquid microextraction (DLLME). In the optimized
conditions, the method exhibited good analytical performance. Based on a signal-to-noise ratio of 3, limits of detection for
anilines were in the range of 0.07 to 0.29 μg L−1, and the linear range was 0.5–200 μg L−1 with regression coefficients (r
2) higher than 0.9977. It was efficient for qualitative and quantitative analysis of anilines in water samples. The relative
standard deviations varied from 2.9 to 8.6 % depending on different compounds indicating good precision. Tap water and river
water were selected for evaluating the application to real water samples. The relative recoveries of anilines for the two
real samples spiked with 10 μg L−1 anilines were in the scope of 78.2–114.6 % and 77.3–115.6 %, respectively. 相似文献
7.
Viñas P López-García I Bravo-Bravo M Briceño M Hernández-Córdoba M 《Analytical and bioanalytical chemistry》2012,403(4):1059-1066
A miniaturized dispersive liquid–liquid microextraction (DLLME) procedure coupled to liquid chromatography (LC) with fluorimetric
detection was evaluated for the preconcentration and determination of thiamine (vitamin B1). Derivatization was carried out by chemical oxidation of thiamine with 5 × 10−5 M ferricyanide at pH 13 to form fluorescent thiochrome. For DLLME, 0.5 mL of acetonitrile (dispersing solvent) containing
90 μL of tetrachloroethane (extraction solvent) was rapidly injected into 10 mL of sample solution containing the derivatized
thiochrome and 24% (w/v) sodium chloride, thereby forming a cloudy solution. Phase separation was carried out by centrifugation, and a volume of
20 μL of the sedimented phase was submitted to LC. The mobile phase was a mixture of a 90% (v/v) 10 mM KH2PO4 (pH 7) solution and 10% (v/v) acetonitrile at 1 mL min−1. An amide-based stationary phase involving a ligand with amide groups and the endcapping of trimethylsilyl was used. Specificity,
linearity, precision, recovery, and sensitivity were satisfactory. Calibration graph was carried out by the standard additions
method and was linear between 1 and 10 ng mL−1. The detection limit was 0.09 ng mL−1. The selectivity of the method was judged from the absence of interfering peaks at the thiamine elution time for blank chromatograms
of unspiked samples. A relative standard deviation of 3.2% was obtained for a standard solution containing thiamine at 5 ng mL−1. The esters thiamine monophosphate and thiamine pyrophosphate can also be determined by submitting the sample to successive
acid and enzymatic treatments. The method was applied to the determination of thiamine in different foods such as beer, brewer’s
yeast, honey, and baby foods including infant formulas, fermented milk, cereals, and purees. For the analysis of solid samples,
a previous extraction step was applied based on an acid hydrolysis with trichloroacetic acid. The reliability of the procedure
was checked by analyzing a certified reference material, pig’s liver (CRM 487). The value obtained was 8.76 ± 0.2 μg g−1 thiamine, which is in excellent agreement with the certified value, 8.6 ± 1.1 μg g−1. 相似文献
8.
Ligang Chen Qinglei Zeng Xiaobo Du Xin Sun Xiaopan Zhang Yang Xu Aimin Yu Hanqi Zhang Lan Ding 《Analytical and bioanalytical chemistry》2009,395(5):1533-1542
In this work, a new method was developed for the determination of melamine (MEL) in animal feed. The method was based on the
on-line coupling of dynamic microwave-assisted extraction (DMAE) to strong cation-exchange (SCX) resin clean-up. The MEL was
first extracted by 90% acidified methanol aqueous solution (v/v, pH = 3) under the action of microwave energy, and then the extract was cooled and passed through the SCX resin. Thus, the
protonated MEL was retained on the resin through ion exchange interaction and the sample matrixes were washed out. Some obvious
benefits were achieved, such as acceleration of analytical process, together with reduction in manual handling, risk of contamination,
loss of analyte, and sample consumption. Finally, the analyte was separated by a liquid chromatograph with a SCX analytical
column, and then identified and quantitatived by a tandem mass spectrometry with positive ionization mode and multiple-reaction
monitoring. The DMAE parameters were optimized by the Box–Behnken design. The linearity of quantification obtained by analyzing
matrix-matched standards is in the range of 50–5,000 ng g−1. The limit of detection and limit of quantification obtained are 12.3 and 41.0 ng g−1, respectively. The mean intra- and inter-day precisions expressed as relative standard deviations with three fortified levels
(50, 250, and 500 ng g−1) are 5.1% and 7.3%, respectively, and the recoveries of MEL are in the range of 76.1–93.5%. The proposed method was successfully
applied to determine MEL in different animal feeds obtained from the local market. MEL was detectable with the contents of
279, 136, and 742 ng g−1 in three samples.
相似文献
9.
Autopsy of 29-year old woman suspicious of committing suicide by the ingestion of As2O3 yielded contradictory findings. All pathological findings as well as clinical symptoms suggested acute poisoning, while a
highly elevated As level of 26.4 μg g−1 in her hair collected at the autopsy, which was determined with inductively coupled plasma mass spectrometry indicated chronic
poisoning. To elucidate this discrepancy, instrumental neutron activation analysis (INAA) with proven accuracy was performed
of another set of sectioned hair samples. Levels of As found by INAA in the range of 0.16–0.26 μg g−1 excluded chronic poisoning, because the person died after approximately 14 h after the As2O3 ingestion. Two reasons for the discordant As results obtained by ICP-MS and INAA are considered: (1) accidental, non-removed
contamination of hair on the As2O3 ingestion; (2) erroneous performance of ICP-MS. 相似文献
10.
A weak cation-exchange monolithic column has been prepared in stainless steel tubing and used as the solid-phase extraction
material in quantitative analysis of caffeine and theophylline in urine. Column switching, with water as mobile phase, was
used for on-line cleaning and screening of human urine samples. Reversed-phase high-performance liquid chromatography was
then performed on a C18 column with methanol–water 30:70 (v/v) as mobile phase at a flow rate of 0.5 mL min−1. Ultraviolet detection was performed at 274 nm. Good linear relationships were obtained between response and concentrations
of caffeine and theophylline in the range 0.1–50 μg mL−1. Absolute recovery ranged from 77.4 to 82.3% and inter-day and intra-day relative standard deviations were less than 5%.
The method was suitable for analysis of caffeine and theophylline in human urine, because it eliminated tedious pretreatment
and enabled rapid, economic, repeatable, and effective assay of traces of the drugs in biological samples. 相似文献
11.
Zhou Y Han L Cheng J Guo F Zhi X Hu H Chen G 《Analytical and bioanalytical chemistry》2011,399(5):1901-1906
A method for analysis of diethofencarb and pyrimethanil in apple pulp and peel was developed by using dispersive liquid–liquid
microextraction based on solidification of a floating organic droplet (DLLME-SFO) and high-performance liquid chromatography
with diode-array detection (HPLC–DAD). Acetonitrile was used as the solvent to extract the two fungicides from apple pulp
and peel, assisted by microwave irradiation. When the extraction process was finished, the target analytes in the extraction
solvent were rapidly transferred from the acetonitrile extract to another extraction solvent (1-undecanol) by using DLLME-SFO.
Because of the lower density of 1-undecanol than that of water, the finely dispersed droplets of 1-undecanol collected on
the top of aqueous sample and solidified at low temperature. Meanwhile, the tiny particles of apple cooled and precipitated.
Recovery was tested for a concentration of 8 μg kg−1. Recovery of diethofencarb and pyrimethanil from apple pulp and peel was in the range 83.5–101.3%. The repeatability of the
method, expressed as relative standard deviation, varied between 4.8 and 8.3% (n = 6). Detection limits of the method for apple pulp and peel varied from 1.2–1.6 μg kg−1 for the two fungicides. Compared with conventional sample preparation, the method has the advantage of rapid speed and simple
operation, and has high enrichment factors and low consumption of organic solvent. 相似文献
12.
Seebunrueng K Santaladchaiyakit Y Soisungnoen P Srijaranai S 《Analytical and bioanalytical chemistry》2011,401(5):1707-1716
A mixed anionic–cationic surfactant cloud point extraction (CPE) has been developed using sodium dodecyl sulfate (SDS) and
tetrabutylammonium bromide (TBABr) for the extraction and preconcentration of organophosphorus pesticides (OPPs) at ambient
temperature before analysis by high-performance liquid chromatography. The studied OPPs were azinphos-methyl, parathion-methyl,
fenitrothion, diazinon, chlorpyrifos, and prothiophos. The optimum conditions of the mixed anionic–cationic CPE were 50 mmol L−1 SDS, 100 mmol L−1 TBABr, and 10% (w/v) NaCl. The extracted OPPs were successfully separated within 11 min using the conditions of a Waters Symmetry C8 column,
a flow rate of 0.8 mL min−1, a gradient elution of methanol and water, and detection at 210 nm. Linearity was found over the range 0.05–5 μg mL−1, with the correlation coefficients higher than 0.996. The enrichment factor of the target analytes was in the range 6–11,
which corresponds to their limits of detection from 1 to 30 ng mL−1. High precisions (intra-day and inter-day) were obtained with relative standard deviation <1.5% (t
R) and 10% (peak area). Accuracies (% recovery) of the different spiked OPP concentrations were 82.7–109.1% (water samples)
and 80.3–113.3% (fruit juice samples). No contamination by the OPPs was observed in any studied samples. 相似文献
13.
L. Giannetti F. Longo F. Buiarelli M. V. Russo B. Neri 《Analytical and bioanalytical chemistry》2010,398(2):1017-1023
A specific, sensitive and robust liquid chromatography tandem mass spectrometry method for determining oxytetracycline, tetracycline,
chlortetracycline and doxycycline in royal jelly and honey samples is presented. Extraction of drug residues was performed
by ammonium acetate buffer as extractant followed by a clean-up with metal chelate affinity chromatography and solid-phase
extraction. Tetracycline analysis was performed using liquid chromatography–electrospray ionisation–tandem mass spectrometry.
The presented method is the first validated for royal jelly and in accordance with the requirements set by Commission Decision
2002/657/EC. Recoveries of the methods, calculated spiking the samples at 5.0, 10.0, 20.0 and 30.0 μg kg−1, were 79% to 90% for honey and 77% to 90% for royal jelly. The intra-day precision (RSD) ranged between 8.1% and 15.0% for
honey and from 9.1% to 16.3% for royal jelly, while inter-day precision values were from 10.2% to 17.6% and from 10.6% to
18.4% respectively for honey and royal jelly. Linearity for the four analytes was calculated from 5.0 to 50.0 μg kg−1. The decision limits (CCα) ranged from 6.2 to 6.4 μg kg−1 and from 6.1 to 6.5 μg kg−1 for honey and royal jelly, respectively. Detection capabilities values (CCβ) ranged between 7.2 and 7.7 μg kg−1 and from 7.3 to 7.9 μg kg−1 respectively for honey and royal jelly. The developed method is currently in use for confirmation of the official control
analysis of honey and royal jelly samples. 相似文献
14.
Ru-Song Zhao Xia Wang Jing Sun Shan-Shan Wang Jin-Peng Yuan Xi-Kui Wang 《Analytical and bioanalytical chemistry》2010,397(4):1627-1633
A novel and environmentally friendly microextraction method, termed ionic liquid dispersive liquid-phase microextraction (IL-DLPME),
has been developed for rapid enrichment of triclosan and triclocarban before analysis by high-performance liquid phase chromatography–electrospray
tandem mass spectrometry (HPLC–ESI-MS–MS). Instead of using toxic organic solvents, an ionic liquid was used as a green extraction
solvent. This also avoided the instability of the suspending drop in single-drop liquid-phase microextraction, and the heating
and cooling step in temperature-controlled ionic liquid dispersive liquid phase microextraction. Factors that may affect the
enrichment efficiency, for example volume of ionic liquid, type and volume of dispersive solvent, pH, extraction time, and
NaCl content were investigated in detail and optimized. Under optimum conditions, linearity of the method was observed over
the range 0.2–12 μg L−1 for triclocarban and 1–60 μg L−1 for triclosan with correlation coefficients ranging from 0.9980 to 0.9990, respectively. The sensitivity of the proposed
method was found to be excellent, with limits of detection in the range 0.040–0.58 μg L−1 and precision in the range 7.0–8.8% (RSD, n = 5). This method has been successfully used to analyze real environmental water samples and satisfactory results were achieved.
Average recoveries of spiked compounds were in the range 70.0–103.5%. All these results indicated that the developed method
would be a green method for rapid determination of triclosan and triclocarban at trace levels in environmental water samples. 相似文献
15.
Consuelo Cháfer-Pericás Ángel Maquieira Rosa Puchades Javier Miralles Amelia Moreno 《Analytical and bioanalytical chemistry》2010,396(2):911-921
An indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed in plate to detect three sulfonamide residues
(sulfamerazine (SMR), sulfadimetoxine (SDM), and sulfadiazine (SDZ)) in gilthead sea bream (Sparus aurata) samples. Different extraction methodologies—using methanol/water 1:1 (v/v) + ethylene diamine tetraacetic acid (EDTA) 0.5% (m/v), acetonitrile, phosphate-buffered saline (PBS) 10 mmol L−1 pH 7 and acetate buffer 100 mmol L−1 pH 5—and cleanup steps, based on solid-phase extraction (C18, SCX, Si) or liquid extraction with hexane, were assayed. As optimum, a fast and simple method using acetonitrile was selected
to extract the sulfonamide residues from the edible muscle of fish. Due to matrix effects, a standard addition calibration
curve in fish extract is necessary for quantification purposes. Sulfonamide-free samples were spiked at different concentration
levels (between 30 and 90 ng g−1, 5–15 ng mL−1 in plate) and average recoveries (n = 8), ranging from 71% to 95%, 65% to 79%, and 72% to 95%, were obtained for SMR, SDM, and SDZ, respectively. The assay detection
limits for these antibiotics were lower than 100 μg kg−1 (maximum residue level established by the European Union). The accuracy was evaluated by spiking blank fish extracts at different
concentrations (10–40 ng mL−1, 5–20 ng mL−1 in plate), and the relative errors ranged between ±20%. Finally, in order to confirm the utility of the developed ELISA as
a screening methodology, fish samples from different supermarkets were analyzed, and results were compared with those obtained
by a validated high-performance liquid chromatography (HPLC) method. The correlation between the results obtained by both
ELISA and HPLC methods is satisfactory.
相似文献
16.
Lina Kantiani Marinella Farré Josep Manuel Grases i Freixiedas Damià Barceló 《Analytical and bioanalytical chemistry》2010,398(3):1195-1205
A fully automated method has been developed for analysis of eighteen antibacterial compounds, including penicillins, cephalosporins
and sulfonamides, in animal feed with limits of quantification in the range 0.25–5.79 μg kg−1. The method is based on pressurized liquid extraction of 3 g homogenized feed with water and online clean-up of 500 μL of
the extract with C18HD cartridges. The purified sample was directly analysed by liquid chromatography–electrospray tandem mass spectrometry (SPE–LC–ESI-MS–MS).
Chromatographic separation was achieved within 10 min by use of a C12 Phenomenex Hydro-RP reversed-phase analytical column and a mobile phase gradient (water + 0.1% formic acid–methanol + 0.1%
formic acid). The method was validated, revealing capability for detection of concentrations as low as 0.09 μg kg−1, decision limits (CCα) and detection capabilities (CCβ) in the range 10–174 μg kg−1 and 22–182 μg kg−1, respectively, and inter-day precision ranging from 0.7 to 8.3%. Recovery, with internal standard correction, was in the
range 93–134% for all analytes. The method was then applied to analysis of fifteen feed samples, nine of which contained at
least one antimicrobial at concentrations between 0.006 and 1.526 mg kg−1. The performance data and results from the method were compared with those from a previous method developed by our group,
using offline SPE, by analyzing the same set of samples by both methods. The online SPE approach resulted in slightly improved
sensitivity, with LODs of 0.09–2.12 μg kg−1 compared with 0.12–3.94 μg kg−1 by the offline approach. In general, better recovery was achieved by use of online purification (for 72% of the analytes)
and the correlation between the two methods was good. The main advantages of the new online method are rapid and automated
sample pre-treatment, and reduction of sample manipulation, enabling high-throughput analysis and highly accurate results.
Because of all these characteristics, the proposed method is applicable and could be deemed necessary within the field of
food control and safety. 相似文献
17.
M N Matos Reyes M L Cervera M de la Guardia 《Analytical and bioanalytical chemistry》2009,394(6):1557-1562
A sensitive and simple analytical method has been developed for determination of Sb(III), Sb(V), Se(IV), Se(VI), Te(IV), Te(VI),
and Bi(III) in garlic samples by using hydride-generation–atomic-fluorescence spectrometry (HG–AFS). The method is based on
a single extraction of the inorganic species by sonication at room temperature with 1 mol L−1 H2SO4 and washing of the solid phase with 0.1% (w/v) EDTA, followed by measurement of the corresponding hydrides generated under two different experimental conditions directly
and after a pre-reduction step. The limit of detection of the method was 0.7 ng g−1 for Sb(III), 1.0 ng g−1 for Sb(V), 1.3 ng g−1 for Se(IV), 1.0 ng g−1 for Se(VI), 1.1 ng g−1 for Te(IV), 0.5 ng g−1 for Te(VI), and 0.9 ng g−1 for Bi(III), in all cases expressed in terms of sample dry weight. 相似文献
18.
Clémens S Monperrus M Donard OF Amouroux D Guérin T 《Analytical and bioanalytical chemistry》2011,401(9):2699-2711
Methylmercury (MeHg) and total mercury (THg) in seafood were determined using species-specific isotope dilution analysis and
gas chromatography combined with inductively coupled plasma mass spectrometry. Sample preparation methods (extraction and
derivation step) were evaluated on certified reference materials using isotopically enriched Hg species. Solid–liquid extraction,
derivation by propylation and automated agitation gave excellent accuracy and precision results. Satisfactory figures of merit
for the selected method were obtained in terms of limit of quantification (1.2 μg Hg kg−1 for MeHg and 1.4 μg Hg kg−1 for THg), repeatability (1.3–1.7%), intermediate precision reproducibility (1.5% for MeHg and 2.2% for THg) and trueness
(bias error less than 7%). By means of a recent strategy based on accuracy profiles (β-expectation tolerance intervals), the
selected method was successfully validated in the range of approximately 0.15–5.1 mg kg−1 for MeHg and 0.27–5.2 mg kg−1 for THg. Probability β was set to 95% and the acceptability limits to ±15%. The method was then applied to 62 seafood samples
representative of consumption in the French population. The MeHg concentrations were generally low (1.9–588 μg kg−1), and the percentage of MeHg varied from 28% to 98% in shellfish and from 84% to 97% in fish. For all real samples tested,
methylation and demethylation reactions were not significant, except in one oyster sample. The method presented here could
be used for monitoring food contamination by MeHg and inorganic Hg in the future to more accurately assess human exposure. 相似文献
19.
A new adsorbent is proposed for the solid-phase extraction of phenol and 1-naphthol from polluted water. The adsorbent (TX-SiO2) is an organosilica composite made from a bifunctional immobilized layer comprising a major fraction (91%) of hydrophilic
diol groups and minor fraction (9%) of the amphiphilic long-chain nonionic surfactant Triton X-100 (polyoxyethylated isooctylphenol)
(TX). Under static conditions phenol was quantitatively extracted onto TX-SiO2 in the form of a 4-nitrophenylazophenolate ion associate with cetyltrimethylammonium bromide. The capacity of TX-SiO2 for phenol is 2.4 mg g−1 with distribution coefficients up to 3.4 × 104 mL g−1; corresponding data for 1-naphthol are 1.5 mg g−1 and 3 × 103 mL g−1. The distribution coefficient does not change significantly for solution volumes of 0.025–0.5 L and adsorbent mass less than
0.03 g; 1–90 μg analyte can be easily eluted by 1–3 mL acetonitrile with an overall recovery of 98.2% and 78.3% for phenol
and 1-naphthol, respectively. Linear correlation between acetonitrile solution absorbance (A
540) and phenol concentration (C) in water was found according to the equation A
540 = (6 ± 1) × 10−2 + (0.9 ± 0.1)C (μmol L−1) with a detection range from 1 × 10−8 mol L−1 (0.9 μL g−1) to 2 × 10−7 mol L−1 (19 μL g−1), a limit of quantification of 1 μL g−1 (preconcentration factor 125), correlation coefficient of 0.936, and relative standard deviation of 2.5%. A solid-phase colorimetric
method was developed for quantitative determination of 1-naphthol on adsorbent phase using scanner technology and RGB numerical
analysis. The detection limit of 1-naphthol with this method is 6 μL g−1 while the quantification limit is 20 μL g−1. A test system was developed for naked eye monitoring of 1-naphthol impurities in water. The proposed test kit allows one
to observe changes in the adsorbent color when 1-naphthol concentration in water is 0.08–3.2 mL g−1. 相似文献
20.
A novel method for the determination of five sulfonylurea herbicides in soil was developed by a dispersive solid-phase extraction
(DSPE) clean-up followed by dispersive liquid–liquid microextraction (DLLME), prior to sweeping micellar electrokinetic chromatography
(MEKC). In the DSPE-DLLME, 10 g of soil sample was first extracted with 10 mL of acetonitrile containing 5% formic acid (pH 3.0).
The extract was then cleaned-up by a DSPE with C18 as sorbent. A 1 mL aliquot of the resulting extract was then added into a centrifuge tube containing 5 mL of water adjusted
to pH 2.0 and 60.0 μL chlorobenzene (as extraction solvent) for DLLME procedure. Then, the organic sample extraction solution
was evaporated to dryness, and reconstituted with 20.0 μL of 1.0 mmol L−1 Na2HPO4 (pH 10.0) for sweeping-MEKC analysis after DLLME. Under optimized conditions, the method provided as high as 3,000- to 5,000-fold
enrichments factors. The linearity of the method was in the range of 3.3–200 ng g−1 for chlorimuron ethyl and bensulfuron methyl, and in the range of 1.7–200 ng g−1 for tribenuron methyl, chlorsulfuron and metsulfuron methyl, with the correlation coefficients (r) ranging from 0.9965 to 0.9983, respectively. The limits of detection (LODs) ranged from 0.5 to 1.0 ng g−1. The intraday relative standard deviations (RSDs, n = 5) were below 5.3% and interday RSDs (n = 15) within 6.8%. The recoveries of the method for the five sulfonylureas from soil samples at spiking levels of 5.0, 20.0,
and 100.0 ng g−1 were 76.0–93.5%, respectively. The developed method has been successfully applied to the analysis of the target sulfonylurea
herbicide residues in soil samples with a satisfactory result. 相似文献