共查询到20条相似文献,搜索用时 31 毫秒
1.
R. Rahnama Kozani Y. Assadi F. Shemirani M. R. Milani Hosseini M. R. Jamali 《Chromatographia》2007,66(1-2):81-86
Dispersive liquid–liquid microextraction (DLLME) has been used for preconcentration of trihalomethanes (THMs) in drinking
water. In DLLME an appropriate mixture of an extraction solvent (20.0 μL carbon disulfide) and a disperser solvent (0.50 mL
acetone) was used to form a cloudy solution from a 5.00-mL aqueous sample containing the analytes. After phase separation
by centrifugation the enriched analytes in the settled phase (6.5 ± 0.3 μL) were determined by gas chromatography with electron-capture
detection (GC–ECD). Different experimental conditions, for example type and volume of extraction solvent, type and volume
of disperser solvent, extraction time, and use of salt, were investigated. After optimization of the conditions the enrichment
factor ranged from 116 to 355 and the limit of detection from 0.005 to 0.040 μg L−1. The linear range was 0.01–50 μg L−1 (more than three orders of magnitude). Relative standard deviations (RSDs) for 2.00 μg L−1 THMs in water, with internal standard, were in the range 1.3–5.9% (n = 5); without internal standard they were in the range 3.7–8.6% (n = 5). The method was successfully used for extraction and determination of THMs in drinking water. The results showed that
total concentrations of THMs in drinking water from two areas of Tehran, Iran, were approximately 10.9 and 14.1 μg L−1. Relative recoveries from samples of drinking water spiked at levels of 2.00 and 5.00 μg L−1 were 95.0–107.8 and 92.2–100.9%, respectively. Comparison of this method with other methods indicates DLLME is a very simple
and rapid (less than 2 min) method which requires a small volume of sample (5 mL). 相似文献
2.
Uttam Mandal Amlan Kanti Sarkar Kadagi Veeran Gowda Sangita Agarwal Anirbandeep Bose Uttam Bhaumik Debotri Ghosh Tapan Kumar Pal 《Chromatographia》2008,67(3-4):237-243
A bioanalytical method has been developed and validated for determination of pregabalin in human plasma. The analytical method
consists in the precipitation of plasma sample with trichloro acetic acid (20% v/v solution in water), followed by the determination of pregabalin by an LC-MS-MS method using gabapentin as internal standard.
Separation was achieved on a Gemini C18 50 mm × 2.0 mm (3 μm) column with an isocratic mobile phase consisting of methanol–water (98:2, v/v) with 0.5% v/v formic acid. Protonated ions formed by a turbo ionspray in positive mode were used to detect analyte and internal standard.
The MS-MS detection was by monitoring the fragmentation of 160.2→55.1 (m/z) for pregabalin and 172.2→67.1 (m/z) for gabapentin on a triple quadrupole mass spectrometer. The assay was calibrated over the range 0.1–15.0 μg mL−1 with correlation coefficient of 0.9998. Validation data showed intra-batch (n = 6) CV% ≤ 6.89 and RE (%) between −4.17 and +3.08 and inter-batch (n = 18) CV% < 9.09 and RE (%) between −3.0 and +10.00. Mean extraction recovery were 80.45–89.12% for three QC samples and 87.56%
for IS. Plasma samples were stable for three freeze–thaw cycles, or 24 h ambient storage, or 1 and 3 months storage at −20 °C.
Processed sample (ready for injection) were stable up to 72 h at autosampler (4 °C). This method has been used for analyzing
plasma samples from a bioequivalence study with 18 volunteers. 相似文献
3.
A method based on solid phase extraction was developed for the determination of the herbicide triallate and its metabolite
2,3,3-trichloro-prop-2-en-sulfonic acid (TCPSA). Soil samples were extracted with methanol and diluted with water to yield
a methanol/water ratio of 1 : 4. Triallate was adsorbed on C18 cartridges while TCPSA was enriched on quaternary amine anion exchange resins. Cartridges were eluted with methanol/ethyl
acetate and methanol/sulfuric acid mixture, respectively. TCPSA methyl ester was formed using trimethyl orthoformate and subsequently
analyzed by GC/ECD. Determination limits of both target compounds were 5 μg/kg soil with recoveries of 100 ± 12% for triallate
and 57 ± 5% for TCPSA. In water analysis, determination limits were 0.05 μg/L with recoveries of 84 ± 14% for triallate and
100 ± 22% for TCPSA. In laboratory batch experiments, concentration of triallate decreased from 2690 to 1550 μg/kg soil within
59 days. 14 days after triallate application, TCPSA was determined to be 14 μg/kg which increased to 98 μg/kg soil at the
end of the incubation period. Soil/water distribution coefficients in loamy sand soil were 102 for triallate and 0.02 for
TCPSA which indicated a higher leaching tendency of the polar metabolite.
Received: 2 July 1997 / Revised: 15 September 1997 / Accepted: 25 September 1997 相似文献
4.
Directly suspended droplet liquid–liquid–liquid microextraction (LLLME) has been used to determine residues of diclofenac
(2-[2-(2,6-dichlorophenyl) aminophenyl] ethanoic acid), in environmental water samples. In this technique a free suspended
droplet of an aqueous solvent is delivered to the top-center position of an immiscible organic solvent floating on the top
of an aqueous sample while being agitated by a stirring bar placed on the bottom of the sample cell. Recently, diclofenac
was found as an environmental contaminant in sewage, surface, ground and drinking water samples. In the present work, diclofenac
was extracted from water samples by LLLME and analysed by HPLC with UV detection at 281 nm. Factors such as organic solvent,
extraction and back extraction times, stirring rate and the pH of acceptor and donor phases were optimized. Enrichment factor
and detection limit (LOD, n = 7) were 102 and 0.1 μg L−1, respectively. The linearity ranged from 0.5 to 2,000 μg−1 with a %RSD (n = 5) of 7.2 at S/N = 3. All experiments were carried out at room temperature (22 ± 0.5 °C). 相似文献
5.
Al-Hamdi AM Williams JR Al-Kindy SM Pillay AE 《Applied biochemistry and biotechnology》2006,135(3):209-218
A rapid reversed-phase (RP) high-performance liquid chromatography method for the isolation of bilirubin from its photoproducts
(e.g., biliverdin) is reported. The method is based on isocratic elution using methanol:water as the mobile phase. A 24 full-factorial experimental design approach was adopted. For the optimization, the best separation was obtained using a flow
rate of 1.50 mL/min, a mobile phase of 99∶1 methanol:water (v/v) at pH 3.60, and a 150×4.6 mm id RP (C18) column containing 5-μm particles. These conditions produced the fastest total retention time of 3.38±0.055 min, and other
chromatographic parameters were acceptable. Under the optimum conditions, a linear calibration curve for bilirubin was obtained
over the 1.0–40.0 μg/L concentration range studied. The limit of quantification was 0.79 g/L and the limit of detection was
0.24 μg/L. Bilirubin in solution was monitored by ultraviolet detection at 450 nm. 相似文献
6.
J. W. Bae C. S. Myung C. I. Choi S. M. Moon C. G. Jang S. Y. Lee 《Journal of Analytical Chemistry》2010,65(12):1261-1265
The purpose of this study was to validate a reliable analytical method for pharmacokinetic study of ceftibuten in human plasma
by high performance liquid chromatography (HPLC) system with UV detection. Ceftizoxime was used as the internal standard.
After plasma sample was precipitated with acetonitrile and dichloromethane, the supernatant was directly injected into the
HPLC system. Separation was performed on a Capcell Pak C18 UG120 column (4.6 mm × 250 mm, 5 μm particles) with a mobile phase of acetonitrile/50 mM ammonium acetate (5: 95, v/v) and
UV detection at a wavelength of 262 nm. The intra- and inter-day precision expressed as the relative standard deviation was
less than 15%. The lower limit of quantification was 0.5 hg/mL of ceftibuten using 0.5 mL of plasma. The calibration curve
was linear in concentration range of 0.5–30 μg/mL (r
2 = 0.9998). The mean accuracy was 96–102%. The coefficient of variation (precision) in the intra- and inter-day validation
was 0.9–3.9 and 0.9–2.4%, respectively. The pharmacokinetics of ceftibuten was evaluated after a single oral administration
of 400 mg to healthy volunteers. The AUC0–9 h, c
max, T
max, and T
1/2 were 86.6 ± 12.7 μg h/mL, 18.4 ± 1.5 μg/mL, 2.63 ± 0.83 and 2.65 ± 0.41 h, respectively. The method was demonstrated to be
highly reproducible and feasible for pharmacokinetic studies of ceftibuten in eight volunteers after oral administration (400
mg as ceftibuten). 相似文献
7.
Hüseyin Ba Mustafa Lale A. Rehber Türker 《Fresenius' Journal of Analytical Chemistry》1999,363(3):224-230
By using the adsorbent Saccharomyces cerevisiae immobilized on sepiolite an adsorption-elution method was developed for the preconcentration of Cu, Zn, and Cd followed by
flame atomic absorption spectrometry (FAAS). Recoveries were 98.3 ± 0.4% for Cu, 94.2 ± 0.3% for Zn, and 99.04 ± 0.04% for
Cd at 95% confidence level obtained by the column method. The influence of sea water matrix elements on the separation of
the trace elements was also assessed by using the column procedure. The breakthrough capacities were found to be 74 μmol/g
for copper, 128 μmol/g for zinc and 97 μmol/g for cadmium. After optimization the proposed method was applied to the trace
metal determination in sea and river water.
Received: 8 June 1998 / Revised: 8 September 1998 / Accepted: 16 September 1998 相似文献
8.
Brandão GP de Campos RC Luna AS de Castro EV de Jesus HC 《Analytical and bioanalytical chemistry》2006,385(8):1562-1569
A procedure for the determination of As in diesel, gasoline and naphtha at μg L−1 levels by GFAAS is proposed. Sample stabilization was achieved by the formation of three component solutions prepared by
mixing appropriate volumes of the samples propan-1-ol and nitric acid aqueous solution. This mixture resulted in a one-phase
medium, which was indefinitely stable. No changes in the analyte signals were observed over several days in spiked samples,
proving long-term stabilization ability. The use of conventional (Pd) and permanent (Ir) modification was investigated and
the former was preferred. Central composite design multivariate optimization defined the optimum microemulsion composition
as well as the temperature program. In this way, calibration using aqueous analytical solutions was possible, since the same
sensitivity was observed in the investigated microemulsion media and in 0.2% v/v HNO3. Coefficients of correlation larger than 0.999 and an As characteristic mass of 22 pg were observed. Recoveries (n=4) obtained from spiked samples were 98±4, 99±3 and 103±5%, and the limits of detection in the original samples were 1.8,
1.2 and 1.5 μg L−1 for diesel, gasoline and naphtha, respectively. Validation was performed by the analysis of a set of commercial samples by
independent comparative procedures. No significant difference (Student’s t-test, p<0.05) was observed between comparative and proposed procedure results. The total determination cycle lasted 4 min for diesel
and 3 min for gasoline and naphtha, equivalent to a sample throughput of 7 h−1 for diesel and 10 h−1 for gasoline and naphtha. 相似文献
9.
Evaluation of a novel ELISA for serotonin: urinary serotonin as a potential biomarker for depression
Nichkova MI Huisman H Wynveen PM Marc DT Olson KL Kellermann GH 《Analytical and bioanalytical chemistry》2012,402(4):1593-1600
Depression is a common disorder with physical and psychological manifestations often associated with low serotonin. Since
noninvasive diagnostic tools for depression are sparse, we evaluated the clinical utility of a novel ELISA for the measurement
of serotonin in urine from depressed subjects and from subjects under antidepressant therapy. We developed a competitive ELISA
for direct measurement of serotonin in derivatized urine samples. Assay performance was evaluated and applied to clinical
samples. The analytical range of the assay was from 6.7 to 425 μg serotonin/g creatinine (Cr). The limit of quantification
was 4.7 μg/g Cr. The average recovery for spiked urine samples was 104.4%. Average intra-assay variation was 4.4%, and inter-assay
variation was <20%. The serotonin analysis was very specific. No significant interferences were observed for 44 structurally
and nonstructurally related urinary substances. Very good correlation was observed between urinary serotonin levels measured
by ELISA and liquid chromatography tandem mass spectrometry (LC-MS/MS; ELISA = 1.16 × LC-MS/MS − 53.8; r = 0.965; mean % bias = 11%; n = 18). Serotonin was stable in acidified urine for 30 days at room temperature and at −20 °C. The established reference range
for serotonin was 54–366 μg/g Cr (n = 64). Serotonin levels detected in depressed patients (87.53 ± 4.89 μg/g Cr; n = 60) were significantly lower (p < 0.001) than in nondepressed subjects (153.38 ± 7.99 μg/g Cr). Urinary excretion of serotonin in depressed individuals significantly
increased after antidepressant treatment by 5-hydroxy-tryptophane and/or selective serotonin re-uptake inhibitor (p < 0.01). The present ELISA provides a convenient and robust method for monitoring urinary serotonin. It is suitable to monitor
serotonin imbalances and may be particularly helpful in evaluating antidepressant therapies. 相似文献
10.
Determination of tetracycline residues in soil by pressurized liquid extraction and liquid chromatography tandem mass spectrometry 总被引:2,自引:0,他引:2
Vicente Andreu Pablo Vazquez-Roig Cristina Blasco Yolanda Picó 《Analytical and bioanalytical chemistry》2009,394(5):1329-1339
An optimized extraction and cleanup method for the analysis of chlortetracycline (CTC), doxycycline (DC), oxytetracycline
(OTC) and tetracycline (TC) in soil is presented. Soil extraction in a pressurized liquid extraction system, followed by extract
clean up using solid-phase extraction (SPE) and tetracycline determination by liquid chromatography tandem mass spectrometry
(LC-MS/MS) provided appropriate efficiency and reproducibility. Different dispersing agents and solvents for soil extraction
and several SPE cartridges for cleanup were compared. The best extraction results were obtained using ethylenediamine tetraacetic
acid-treated sand as dispersing agent, and water at 70 °C. The most effective cleanup was obtained using Strata-XTM sorbent in combination with a strong anion exchange cartridge. Recoveries ranged from 71% to 96% and precision, as indicated
by the relative standard deviations, was within the range of 8–15%. The limits of quantification (LOQs) by using LC-MS/MS,
based on signal-to-noise ratio (S/N) of 10, ranged from 1 μg kg−1 for TC to 5 μg kg−1 for CTC. These results pointed out that this technique is appropriate to determine tetracyclines in soils. Analysis of 100
samples taken in the Valencian Community revealed that, in soil, up to 5 μg kg−1 CTC, 15 μg kg−1 OTC, 18 μg kg−1 TC, and 12 μg kg−1 DC could be detected. Detection of the analytes in several samples, which typify great part of the Spanish agricultural soils,
should be outlined as most important result of this study.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. 相似文献
11.
Minakata K Nozawa H Gonmori K Yamagishi I Suzuki M Hasegawa K Watanabe K Suzuki O 《Analytical and bioanalytical chemistry》2011,400(7):1945-1951
An electrospray ionization tandem mass spectrometric (ESI-MS-MS) method has been developed for the determination of cyanide
(CN–) in blood. Five microliters of blood was hemolyzed with 50 μL of water, then 5 μL of 1 M tetramethylammonium hydroxide solution
was added to raise the pH of the hemolysate and to liberate CN– from methemoglobin. CN– was then reacted with NaAuCl4 to produce dicyanogold, Au(CN)2–, that was extracted with 75 μL of methyl isobutyl ketone. Ten microliters of the extract was injected directly into an ESI-MS-MS
instrument and quantification of CN– was performed by selected reaction monitoring of the product ion CN– at m/z 26, derived from the precursor ion Au(CN)2– at m/z 249. CN– could be measured in the quantification range of 2.60 to 260 μg/L with the limit of detection at 0.56 μg/L in blood. This
method was applied to the analysis of clinical samples and the concentrations of CN– in the blood were as follows: 7.13 ± 2.41 μg/L for six healthy non-smokers, 3.08 ± 1.12 μg/L for six CO gas victims, 730 ± 867 μg
for 21 house fire victims, and 3,030 ± 97 μg/L for a victim who ingested NaCN. The increase of CN– in the blood of a victim who ingested NaN3 was confirmed using MS-MS for the first time, and the concentrations of CN– in the blood, gastric content and urine were 78.5 ± 5.5, 11.8 ± 0.5, and 11.4 ± 0.8 μg/L, respectively. 相似文献
12.
Ahn KC Gee SJ Kim HJ Aronov PA Vega H Krieger RI Hammock BD 《Analytical and bioanalytical chemistry》2011,401(4):1285-1293
Pyrethroid insecticides widely used in forestry, agricultural, industrial, and residential applications have potential for
human exposure. Short sample preparation time and sensitive, economical high-throughput assays are needed for biomonitoring
studies that analyze a large number of samples. An enzyme-linked immunosorbent assay (ELISA) was used for determining 3-phenoxybenzoic
acid (3-PBA), a general urinary biomarker of exposure to some pyrethroid insecticides. A mixed-mode solid-phase extraction
reduced interferences from acid hydrolyzed urine and gave 110 ± 6% recoveries from spiked samples. The method limit of quantification
was 2 μg/L. Urine samples were collected from forestry workers that harvest pine cone seeds where pyrethroid insecticides
were applied at ten different orchards. At least four samples for each worker were collected in a 1-week period. The 3-PBA
in workers classified as high, low, or no exposure based on job analysis over all sampling days was 6.40 ± 9.60 (n = 200), 5.27 ± 5.39 (n = 52), and 3.56 ± 2.64 ng/mL (n = 34), respectively. Pair-wise comparison of the differences in least squares means of 3-PBA concentrations among groups
only showed a significant difference between high and no exposure. Although this difference was not significant when 3-PBA
excretion was normalized by creatinine excretion, the general trend was still apparent. No significant differences were observed
among days or orchards. This ELISA method using a 96-well plate was performed as a high-throughput tool for analyzing around
300 urine samples measured in triplicate to provide data for workers exposure assessment. 相似文献
13.
A rapid and accurate method for the quantification of cis-abienol in oriental tobacco leaves by normal phase liquid chromatography was developed. Freeze-dried tobacco samples were
sonicated in methylene chloride for 10 min. The supernatant was purified using a silica gel solid phase extraction cartridge.
Ten milliliter of the resulting methylene chloride eluate was collected, then separated on a 250 × 4.6 mm, 5 μm particle-size
CN column with n-hexane: ethyl acetate, 100:2 (v/v) at a flow rate of 1 mL min−1. cis-Abienol was detected by UV absorption at 254 nm. The linear range was from 2.14 × 10−4 to 4.28 × 10−2 mg mL−1 and the correlation coefficient was 1.000. The average recovery was 98.7, 105.2 and 103.1% in five replicated sets of tobacco
samples spiked with 0.2856, 0.7140 and 1.904 mg cis-abienol. The relative standard deviations (RSDs) were 1.04, 0.63 and 1.25%, respectively (n = 5). Limit of detection (S/N = 3) was 21.84 μg g−1 and limit of quantification (S/N = 10) was 72.80 μg g−1. The method was found to be suitable for determination of cis-abienol in oriental tobacco leaves. Furthermore, pure cis-abienol used for method validation was obtained by preparative reversed phase high-performance liquid chromatography. Identification
was performed by UV detection, nuclear magnetic resonance and mass spectrometry. 相似文献
14.
Li Shunxin Qian Shahua Huang Ganquan He Fei 《Fresenius' Journal of Analytical Chemistry》1999,365(5):469-471
A novel method for the separation and preconcentration of Se(IV)/ Se(VI) with algae and determination by graphite furnace
atomic absorption spectrometry (GFAAS) has been developed. The Se(VI) is extracted with algae from the solution containing
Se(IV)/Se(VI) at pH 5.0, and the remaining Se(IV) is then preconcentrated pH 1.0. The detection limits (3σ, n = 11) of 0.16 μg L–1 for Se(IV) and 0.14 μg L–1 for Se(VI) are obtained using 40 mL of solution. At the 2.0 μg L–1 level the relative standard deviation is 2.6% for Se(IV) and 2.3% for Se(VI). The method has been applied to the determination
of Se(IV)/Se(VI) in sediment and water samples. Analytical recoveries of Se(IV) and Se(VI) added to samples are ?97 ± 5% and
102 ± 6% (95% confidence), respectively.
Received: 10 February 1999 / Revised: 21 June 1999 / /Accepted: 22 June 1999 相似文献
15.
Mazzucchelli I Rapetti M Fattore C Franco V Gatti G Perucca E 《Analytical and bioanalytical chemistry》2011,401(3):1013-1021
The development of a simple and rapid high-performance liquid chromatography (HPLC) method for the determination of the new
antiepileptic drug rufinamide (RFN) in human plasma and saliva is reported. Samples (250 μl) are alkalinized with ammonium
hydroxide (pH 9.25) and extracted with dichloromethane using metoclopramide as internal standard. Separation is achieved with
a Spherisorb silica column (250 × 4.6 mm i.d., 5 μm) at 30 °C using as mobile phase a solution of methanol/dichloromethane/n-hexane
10/25/65 (vol/vol/vol) mixed with 6 ml ammonium hydroxide. The instrument used was a Shimadzu LC-10Av chromatograph and flow
rate was 1.5 ml min-1, with a LaChrom L-7400 UV detector set at 230 nm. Calibration curves are linear [r
2 = 0.998 ± 0.002 for plasma (n = 10) and r
2 = 0.999 ± 0.001 for saliva (n = 9)] over the range of 0.25–20.0 μg ml-1, with a limit of quantification at 0.25 μg ml-1. Precision and accuracy are within current acceptability standards. The assay is suitable for pharmacokinetic studies in
humans and for therapeutic drug monitoring. 相似文献
16.
A stability-indicating HPLC assay method was developed for the quantitative determination of tadalafil in bulk samples and
in pharmaceutical dosage forms in the presence of the degradation products. It involved a 250 mm × 4.6 mm, 5 μm C-18 column.
The gradient LC method employs solution A and B as mobile phase. Solution A contains a mixture of buffer (phosphate buffer
and tetra-n-butyl ammonium hydrogen sulfate) pH 2.5: acetonitrile (80:20, v/v) and solution B contains a mixture of water: acetonitrile (20:80, v/v). The flow rate was 1.0 mL min−1 and the detection wavelength was 220 nm. The retention time of tadalafil is about 17 min. Tadalafil was subjected to different
ICH prescribed stress conditions. Degradation was found to occur in hydrolytic and to some extent in oxidative stress conditions,
while the drug was stable to photolytic and thermal stress. The drug was particularly labile under alkaline hydrolytic conditions.
The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. The assay of stress
samples was calculated against a qualified reference standard and the mass balance was close to 99.5%. The developed RP-LC
method was validated with respect to linearity, accuracy, precision and ruggedness. 相似文献
17.
Sánchez-Rodas D Luis Gómez-Ariza J Oliveira V 《Analytical and bioanalytical chemistry》2006,385(7):1172-1177
A rapid extraction procedure has been developed for speciation of arsenic in chicken tissue. Water, methanol–water (1:1),
and methanol–chloroform (1:1) were tested as extraction media. Individual use of an ultrasonic bath, a microwave oven, or
an ultrasonic probe was not sufficient for quantitative recovery of As(III), dimethylarsinate, monomethylarsonate, As(V),
and arsenobetaine in spiked samples of chicken tissue. A new extraction procedure using a methanol–water mixture and a microwave
oven then an ultrasonic probe enabled extraction of the arsenic species in 7 min with efficiencies ranging from 80 to 100%.
HPLC–UV–HG–AFS was used for the determinations. The extraction procedure was 100% efficient when applied to real samples of
chicken tissue. AsB (48±5 μg As kg −1) and one containing-arsenic feed additive, Nitarsone (227±5 μg As kg −1) were detected. 相似文献
18.
Campos-Candel A Llobat-Estellés M Mauri-Aucejo AR 《Analytical and bioanalytical chemistry》2007,387(4):1517-1523
A procedure for the determination of benzene, toluene, ethylbenzene and o-xylene, m-xylene and p-xylene (BTEX) in occupational environments is proposed. These compounds are extracted from activated charcoal using accelerated
solvent extraction. Operational parameters are optimized and quantitative recovery is obtained using acetonitrile as the extraction
solvent and 1-mL extraction cells, a preheat time of 2 min, a temperature of 160 °C, a pressure of 1,500 psi, a static period
of 5 min, a flush volume of 110%, two cycles and a purge time of 90 s. Determination of BTEX compounds is carried out by gas
chromatography using a flame ionization detector. The recoveries, obtained for a confidence level of 95%, are 91 ± 4, 100 ± 3,
104 ± 2, 93 ± 4, 99 ± 2 and 99 ± 2% for benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene, respectively. The detection limits are 0.5 μg for benzene, 0.7 μg for toluene and 1.0 μg for the other compounds.
The proposed procedure has been applied to real samples collected in several workplaces, like a microbiology laboratory, an
analytical chemistry laboratory, a printer’s, a car repair shop and a petrol station. From the results obtained, it can be
concluded that the occupational exposures determined are always acceptable because they are lower than the tenth part of the
recommended exposure limits (VLA-ED and VLA-EC). 相似文献
19.
Solid-phase extraction was used to isolate sulfacetamide, sulfathiazole, sulfapyridine, sulfamerazine, sulfamethoxypyridazine and sulfamethoxazole from honey. The optimized procedure used polymeric Abselut Nexus cartridges and the sulfonamides were separated, in the isocratic mode, on an Inertsil ODS-3 (250 × 4 mm I.D., 5 μm) column, using methanol-0.05 M acetate buffer (pH 3.6) (20:80 v/v) with 1% (v/v) of acetic acid, UV detection at 263 nm and a flow-rate of 1 mL min−1. Caffeine was used as internal standard. Average recoveries of the analytes from spiked honey ranged from 80 to 117% and the detection limits based on a spiked honey extract were 20–25 μg kg−1. 相似文献
20.
A simple reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the simultaneous determination
of the antiepileptic drugs (AEDs) zonisamide (ZNS), primidone (PRI), lamotrigine (LTG), phenobarbital (PB), phenytoin (PHT),
oxcarbazepine (OXC), and carbamazepine (CBZ) and two of their active metabolites, monohydroxycarbamazepine (MHD) and carbamazepine
10,11-epoxide (CBZE) in human plasma. Plasma (100 μL) was pretreated by deproteinization with 300 μL methanol containing 20 μg mL−1 propranolol hydrochloride as internal standard. HPLC was performed on a C8 column (4.6 mm × 250 mm; particle size 5 μm) with methanol–acetonitrile–0.1% trifluoroacetic acid, 235:120:645 (v/v), as mobile phase at a flow rate of 1.5 mL min−1. ZNS, OXC, and CBZ were monitored by UV detection at 235 nm, and PRI, LTG, MHD, PB, PHT, and CBZE by UV detection at 215 nm.
Relationships between response and concentration were linear over the concentration ranges 1–80 μg mL−1 for ZNS, 5–50 μg mL−1 for PRI, 1–25 μg mL−1 for LTG, 1–50 μg mL−1 for MHD, 5–100 μg mL−1 for PB, 1–10 μg mL−1 for CBZE, 0.5–25 μg mL−1 for OXC, 1–50 μg mL−1 for PHT, and 1–25 μg mL−1 for CBZ. Intra-day and inter-day reproducibility were adequate (coefficients of variation were ≤11.6%) and absolute recovery
ranged from 95.2 ± 6.13 to 107.7 ± 7.76% for all the analytes; for the IS recovery was 98.69 ± 1.12%. The method was proved
to be accurate, reproducible, convenient, and suitable for therapeutic monitoring of the nine analytes. 相似文献