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1.
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
2.
Summary Indirect UV detection in capillary zone electrophoresis (CZE) is frequently used for the determination of inorganic anions
and carboxylic acids. However, there are few reports on direct UV detection of these solutes in real samples. This paper describes
the use of direct UV detection of inorganic anions and organic acids in environmental samples using co-electroosmotic capillary
zone electrophoresis (co-CZE) at 185 nm. The best separation and detection of the solutes was achieved using a fused silica
capillary with an electrolyte containing 25 mM phosphate, 0.5 mM tetradecyltrimethylammonium bromide (TTAB) and 15% acetonitrile
(v/v) at pH 6.0. Four common inorganic anions (Cl−, NO2
−, NO3
− and SO4
2−) and 11 organic acids (oxalic, formic, fumaric, tartaric, malonic, malic, citric, succinic, maleic, acetic, and lactic acid),
were determined simultaneously in 15 min. Linear calibration plots for the test solutes were obtained in the range 0.02–0.5
mM with detection limits ranging from 1–9 μM depending on the analyte. The proposed method was successfully used to determine
inorganic anions and carboxylic acids in soil and plant tissue extracts with direct injection of the sample. 相似文献
3.
Comparison of adsorbents for on-line solid-phase extraction of polycyclic aromatic hydrocarbons before liquid chromatography with UV detection 总被引:1,自引:0,他引:1
Summary On-line solid-phase extraction (SPE) coupled with reversed-phase liquid chromatography and UV detection at 254 nm has been
used for the determination of trace-level polycyclic aromatic hydrocarbons (PAH) in soil extracts. Five commercially available
adsorbents (C8, C18, PLRP-S, PRP-1, and Bond-Elut Env) were evaluated. Results showed that recovery of the PAH decreased with increasing molecular
weight, because of their poorer solubility. Recovery of high-molecular-weight PAH was significantly improved by addition of
10% (v/v) acetonitrile to the sample before loading of the SPE adsorbent. PAH recovery ranged from 64.0 to 108% when a 50
mL sample spiked with 1 μg L−1 was applied to these adsorbents. Determination of PAH was possible with detection limits below 0.05 μg L−1, which corresponds to 0.2 μg kg−1 soil. The method was successfully used to determine PAH in soil extracts. 相似文献
4.
Summary A novel method for the extraction into an aqueous medium of PAHs in soil is described, where sodium dodecyl sulphate (SDS)
is used as micelle former. After optimisation of this step using a multivariate approach, recoveries of the target analytes
from spiked soil ranging between 98.3%–99.7% were obtained when the samples were subjected to extraction with 25 mL of an
aqueous SDS solution (2.9 10−2 mol L−1) while irradiated with focused microwaves at 240 W for 40 min. The overall method involving determination of the extracted
compounds consists of three steps: 1) extraction of the analytes into the aqueous micellar medium assisted by focused microwaves;
2) trapping of the analytes on a C18 cartridge for clean up and preconcentration and; 3) HPLC separation with fluorimetric detection. The method was validated
using the certified reference material CRM 524 and the results found were in agreement with the certified values. 相似文献
5.
A rapid and inexpensive method for simultaneous quantification of terbumeton (TER), and its major potential metabolites (TED;
terbumeton-desethyl, TOH; terbumeton-2-hydroxy and TID; terbumeton-deisopropyl) in soil bulk water (SBW) samples is proposed.
The analytical method involves extraction–concentration from SBW samples using a graphitized carbon black (GCB) cartridge
followed by their separation–detection by reversed-phase high-performance liquid chromatography analysis using a C18 column and a diode array detector. A mobile phase of acetonitrile−0.005 mol L−1 phosphate buffer (pH 7.0) (35:65, v/v) at a flow rate of 0.8 mL min−1 in isocratic elution mode has been used. After optimization of the extraction and separation conditions, this method can be
used for the simultaneous determination of investigated compounds in the range of the international limits of 0.1 μg L−1. For TER the detection limit was 0.009 μg L−1 and it was 0.100, 0.550, and 0.480 μg L−1 for TED, TOH, and TID, respectively. The recoveries of TER, TED, TOH, and TID from SBW samples, measured at three levels of
concentration range, were found to be between 48.0 and 102.0%. The intra-day precision measured by relative standard deviation
(RSD) was always lower than 9.0%. 相似文献
6.
This study investigates an off-line solid phase extraction (SPE) for improving the sensitivity in the capillary electrophoretic
(CE) analysis of four cephalosporins. Two sorbents—LiChrolut-C18 and Oasis HLB—were used in a SPE process to detect cephalosporins in natural waters (tap, river and hospital sewage) and
their performances were compared. By using Oasis HLB sorbent higher recoveries for river water were obtained (94–107% when
500 mL of sample were analyzed). The off-line SPE–CZE method was validated for river water with good detection limits (3 μg L−1) and the linearity ranged between 5 and 200 μg L−1. 相似文献
7.
Qiuhua Wu Chun Wang Zhimei Liu Chunxia Wu Xin Zeng Jialin Wen Zhi Wang 《Journal of chromatography. A》2009,1216(29):5504-5510
Dispersive solid-phase extraction (DSPE) combined with dispersive liquid–liquid microextraction (DLLME) has been developed as a new approach for the extraction of four sulfonylurea herbicides (metsulfuron-methyl, chlorsulfuron, bensulfuron-methyl and chlorimuron-ethyl) in soil prior to high-performance liquid chromatography with diode array detection (HPLC-DAD). In the DSPE-DLLME, sulfonylurea herbicides were first extracted from soil sample into acetone–0.15 mol L−1 NaHCO3 (2:8, v/v). The clean-up of the extract by DSPE was carried out by directly adding C18 sorbent into the extract solution, followed by shaking and filtration. After the pH of the filtrate was adjusted to 2.0 with 2 mol L−1 HCl, 60.0 μL chlorobenzene (as extraction solvent) was added into 5.0 mL of it for DLLME procedure (the acetone contained in the solution also acted as dispersive solvent). Under the optimum conditions, the enrichment factors for the compounds were in the range between 102 and 216. The linearity of the method was in the range from 5.0 to 200 ng g−1 with the correlation coefficients (r) ranging from 0.9967 to 0.9987. The method detection limits were 0.5–1.2 ng g−1. The relative standard deviations varied from 5.2% to 7.2% (n = 5). The relative recoveries of the four sulfonylurea herbicides from soil samples at spiking levels of 6.0, 20.0 and 60.0 ng g−1 were in the range between 76.3% and 92.5%. The proposed method has been successfully applied to the analysis of the four target sulfonylurea herbicides in soil samples, and a satisfactory result was obtained. 相似文献
8.
Summary Clenbuterol has been determined in urine by solidphase extraction on a C18 cartridge, diazotization of the eluate with nitrite, coupling of the diazonium ion with 1-(naphthyl)ethylenediamine, and
separation of the azo dye formed by HPLC with a C18 column and a micellar mobile phase containing 0.1 M sodium dodecyl sulphate, 12%n-butanol and 0.05 M citrate buffer, pH 3. Recoveries higher than 90% were obtained by mixing the samples with a 20% 0.2 M
NaOH before extraction. Limits of detection of 51 and 6.7 ng L−1 were obtained with spectrophotometric and thermal lens spectrometric detection, respectively; respective repeatabilities
were 3.1% (5 μg mL−1) and 5.6% (0.16 μg mL−1). 相似文献
9.
Summary An on-line flow injection-solid-phase extraction-capillary zone electrophoresis (FI-SPE-CZE) method has been developed for
determination of cimetidine in human plasma. Sodium dodecylsulfate (SDS) was used as dynamic chemical modifier for elimination
of capillary contamination by biological macromolecules. FI on-line preconcentration and cleaning of the analyte by means
of a C18 microcolumn was performed automatically and CZE separation was performed consecutively without interruption of the applied
voltage and between-run-washing of the capillary. A detection limit of 8 μgL−1 (3×σ) was achieved at a sample throughput of 12h−1. The approach was successfully used for a pharmacokinetic study of cimetidine. 相似文献
10.
Arsenic-speciation analysis in marine samples was performed by high-pressure liquid chromatography (HPLC) with ICP–MS detection.
Separation of eight arsenic species—AsIII, MMA, DMA, AsV, AB, TMAO, AC and TeMAs+—was achieved on a C18 column with isocratic elution (pH 3.0), under which conditions AsIII and MMA co-eluted. The entire separation was accomplished in 15 min. The HPLC–ICP–MS detection limits for the eight arsenic
species were in the range 0.03–0.23 μg L−1 based on 3σ for the blank response (n=5). The precision was calculated to be 2.4–8.0% (RSD) for the eight species. The method was successfully applied to several
marine samples, e.g. oysters, fish, shrimps, and marine algae. Low-power microwave digestion was employed for extraction of
arsenic from seafood products; ultrasonic extraction was employed for the extraction of arsenic from seaweeds. Separation
of arsenosugars was achieved on an anion-exchange column. Concentrations of arsenosugars 2, 3, and 4 in marine algae were
in the range 0.18–9.59 μg g−1.
This paper was presented at the European Winter Conference 2005 相似文献
11.
Yan Liang Jie Sun Lin Xie An Kang Yuan Xie Wei-Dong Chen Hua Lv Guang-Ji Wang 《Chromatographia》2007,66(3-4):165-170
A sensitive and specific liquid chromatographic method with electrospray ionization mass spectrometry (LC–ESI-MS) has been
developed and validated for identification and quantification of mitiglinide in human urine. A simple liquid–liquid extraction
procedure was followed by separation on a C18 column with gradient elution, and detection using a single-quadrupole mass spectrometer in selected-ion-monitoring (SIM)
mode. The method was tested using six different batches of urine. Linearity was established for the mitiglinide concentrations
in the range 0.005–1.0 μg mL−1, with a coefficient of determination (r) of 0.9998 and good back-calculated accuracy and precision. Intra- and inter-day precision (as RSD, %) was below 10% and
accuracy for mitiglinide ranged from 85 to 115%. The lower limit of quantification was reproducible at 0.002 μg mL−1 for 500 μL urine. The proposed method enables unambiguous identification and quantification of mitiglinide in pre-clinical
and clinical studies. 相似文献
12.
Huang KJ Zhang M Xie WZ Zhang HS Feng YQ Wang H 《Analytical and bioanalytical chemistry》2007,388(4):939-946
A simple, sensitive, selective, and low-cost method is proposed for rapidly determining nitric oxide (NO) in some rat tissues.
Polymer monolith microextraction (PMME) using a poly(methacrylic acid–ethylene glycol dimethacrylate) (MAA-EGDMA) monolithic
column was combined with derivatization of NO using 1,3,5,7-tetramethyl-8-(3′,4′-diaminophenyl)-difluoroboradiaza-s-indacene (TMDABODIPY), and this was used to analyze the derivatives of NO by high-performance liquid chromatography (HPLC)
with fluorescence detection at λ
ex/λ
em = 498/507 nm. The baseline separation of TMDABODIPY and its NO derivative is performed under simple conditions in which a
C18 column is used and eluted with 50 mmol L−1 ethanolamine and methanol. The conditions for the extraction of NO derivatives were optimized. The limit of detection of
NO was 2 × 10−12 mol L−1 (S/N = 3). The linearity range of the method was 9 × 10−11−4.5 × 10−8 mol L−1. The interday and intraday relative standard deviations were less than 5%. The proposed method was successfully applied to
the determination of NO levels in some rat tissue samples including heart, kidney, and liver with recoveries varying from
87.1 to 95.2%. 相似文献
13.
Orrapat Pureesatien Chitchamai Ovatlarnporn Arunporn Itharat Ruedeekorn Wiwattanapatapee 《Chromatographia》2008,67(7-8):551-557
A reversed-phase high-performance liquid chromatographic method has been developed and validated for the determination of
pyridostemin, the major pesticidal alkaloid found in Stemona curtisii. This methodology was applied to the investigation of plant extracts and water dispersible granule formulations. Stability
indicating procedures have also been carried out. The chromatographic separation was on a C18 column with a mixture of acetonitrile–water–triethylamine (30:70:0.12, v/v/v), using UV detection at 300 nm. Validation procedures showed that the method was specific, accurate and precise. The response
was linear over a range of 5–25 μg mL−1 with recoveries in the range of 98.28–102.85%. The RSD for intra- and inter-day precision were <0.72 and <1.29%, respectively.
Extraction of plant material with dichloromethane gave a significantly higher pyridostemin content in the crude extracts when
compared with extractions in methanol. Partial purification of the crude extracts by silica gel column chromatography was
used to concentrate the mixture about fourfold. Degradation behavior of pyridostemin in the partially purified extracts followed
first-order kinetics. The main pathways for its decomposition were base hydrolysis and oxidation. 相似文献
14.
Summary Several extraction, separation and detection methods for heterocyclic amines (HAs) in chicken legs were evaluated by liquid
chromatography. Results showed that the most appropriate extraction method includes the removal of macrosubstances by centrifugation
and subsequent purification using a PRS (propylsulfonic acid silica gel) and a C18 cartridge, and the recovery obtained ranged between 51 and 89 %. For HPLC separation, a binary solvent system consisting
of acetonitrile and 0.05 M ammonium acetate solution (pH 3.6) with gradient elution with flow rate of 1.0 mL min−1 and detection at 258 nm was used to resolve 16 HAs. With fluorescence nine HAs could be detected by employing a programmable
wavelength, and the sensitivity was 100–400 times higher than that by UV detection. The detection limits for UV and fluorescence
detection were 0.02≈0.5 ng and 0.05≈3 pg respectively, with a signal-to-noise ratio 3. The presence of HAs in fried chicken
legs was also determined. 相似文献
15.
A survey of contamination of surface and drinking waters around Lake Maggiore in Northern Italy with polar anthropogenic environmental
pollutants has been conducted. The target analytes were polar herbicides, pharmaceuticals (including antibiotics), steroid
estrogens, perfluorooctanesulfonate (PFOS), perfluoroalkyl carboxylates (including perfluorooctanoate PFOA), nonylphenol and
its carboxylates and ethoxylates (NPEO surfactants), and triclosan, a bactericide used in personal-care products. Analysis
of water samples was performed by solid-phase extraction (SPE) then liquid chromatography–triple-quadrupole (tandem) mass
spectrometry (LC–MS–MS). By extraction of 1-L water samples and concentration of the extract to 100 μL, method detection limits
(MDLs) as low as 0.05–0.1 ng L−1 were achieved for most compounds. Lake-water samples from seven different locations in the Southern part of Lake Maggiore
and eleven samples from different tributary rivers and creeks were investigated. Rain water was also analyzed to investigate
atmospheric input of the contaminants. Compounds regularly detected at very low concentrations in the lake water included:
caffeine (max. concentration 124 ng L−1), the herbicides terbutylazine (7 ng L−1), atrazine (5 ng L−1), simazine (16 ng L−1), diuron (11 ng L−1), and atrazine-desethyl (11 ng L−1), the pharmaceuticals carbamazepine (9 ng L−1), sulfamethoxazole (10 ng L−1), gemfibrozil (1.7 ng L−1), and benzafibrate (1.2 ng L−1), the surfactant metabolite nonylphenol (15 ng L−1), its carboxylates (NPE1C 120 ng L−1, NPE2C 7 ng L−1, NPE3C 15 ng L−1) and ethoxylates (NPE
n
Os, n = 3-17; 300 ng L−1), perfluorinated surfactants (PFOS 9 ng L−1, PFOA 3 ng L−1), and estrone (0.4 ng L−1). Levels of these compounds in drinking water produced from Lake Maggiore were almost identical with those found in the lake
itself, revealing the poor performance of sand filtration and chlorination applied by the local waterworks. 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.
Simultaneous determination of arbutin (ART) and l-ascorbic acid (AA) by HPLC with chemiluminescence detection is proposed for the first time. This method is based on the CL
reaction of acidic potassium permanganate with ART and AA in the presence of formaldehyde as enhancer. The separation was
performed on a C18 column with a 90:10 (v/v) mixture of 0.02 M phosphate buffer and methanol as mobile phase. The effects of several conditions on HPLC resolution and
CL emission were studied systematically. The linear ranges were 0.5–50 and 1–200 μg mL−1 for ART and AA, respectively. The detection limits were 0.2 and 0.3 μg mL−1, respectively. The method was successfully applied to the determination of ART and AA in whitening cosmetics. 相似文献
18.
Summary Two procedures, based on large-volume injection with a programmed-temperature vaporizer (PTV), have been developed for the
determination of several triazine and organophosphorus pesticides. The use of PTV for injection in gas chromatography (GC)
has enabled the introduction of up to 200 μL sample extract into the GC, thus increasing the sensitivity of the method. PTV
injection has been combined off-line with two different microextraction procedures—liquid-liquid partition and solid-phase
extraction.
A simple and rapid off-line liquid-liquid microextraction procedure (5 mL water/1 mL methyltert-butyl ether) was applied to surface water samples spiked at levels between 0.01 and 5μg L−1. Recoveries of the overall procedure were >80% and the precision was better than 15%. Detection limits were <30 ngL−1 from 200-μL injections in GC-NPD analysis of triazines and GC-FPD analysis of organophosphorus pesticides. Off-line automated
solid-phase extraction with C18 cartridges has been applied to water samples (50 mL) spiked at 0.01, 0.1 and 1 μg L−1. The overall procedure was satisfactory (recoveries >80% and coefficients of variation <12%) and the limits of detection
ranged from 1 to 9 ng L−1.
Finally, several surface water samples were anlysed, and triazine herbicides were detected at concentrations of approx. 0.1–0.2
μg L−1. The results were similar to those obtained by conventional solvent extraction then GC-MSD after splitless injection of 2
μL. 相似文献
19.
C. Molins E. A. Hogendoorn H. A. G. Heusinkveld A. C. van Beuzekom P. van Zoonen R. A. Baumann 《Chromatographia》1998,48(5-6):450-456
Summary Recent work demonstrated that the combination of microwave assisted solvent extraction (MASE) and capillary gas chromatography
with selective nitrogen detection (GC-NPD) is a viable approach for the efficient determination of triazine herbicides in
soils. However, for soils with a high organic matter content or the injection of more concentrated extracts to obtain lower
LOD's the performance of gas chromatographic analysis of uncleaned extracts is hampered. This results in both a decrease of
the chromatographic response of analytes and a decrease in the life time of the column due to coextracted matrix substances.
The effect of various types of soils on the chromatographic analysis of triazine herbicides was studied. It appeared that
for the investigated samples with an organic matter content below 5% processing of uncleaned extracts is possible. Samples
with a higher organic matter content required a cleanup step. A rapid procedure on 100 mg silica cartridges has been developed
using solvents compatible with the MASE extracts and the instrumental analysis. Beside the testing with different standard
soils, about 120 samples of an ongoing monitoring program involving three different types of soil (organic matter content:
3–37%) were analysed. The selected compounds atrazine, desethylatrazine, desisopropyl-atrazine and simazine could be assayed
in the various soil types to a level of at least 2 μg kg−1. For soil samples with a high organic matter content (>5%), the rapid cleanup procedure allowed the trace analysis of the
triazines and considerably increased the life time of the capillary column. Recoveries at levels from 2 to 50 μg kg−1 ranged from 70 to 100% with RSDs ranging from 5.1 to 9.5%. Confirmation of positive samples was carried out by gas chromatography
mass spectrometry. 相似文献
20.
Summary A simple and sensitive method has been developed for the liquid chromatographic determination of short-chain aliphatic amines
in water. Analytes are retained in solid-phase extraction (SPE) cartridges, and then derivatized by drawing an aliquot of
the fluorogeneic reagent 9-fluorenylmethyl chloroformate (FMOC) through the cartridges. After a certain reaction time the
derivatives formed are desorbed with acetonitrile. The collected extracts are then chromatographed on a LiChrospher 100 RP18 125 mm×4 mm i.d., 5 μm, column using an acetonitrile-water gradient. The influence of experimental conditions (SPE material,
volume of sample, concentration of FMOC, time of reaction and pH) has been investigated. Optimal results have been obtained
with C18 SPE cartridges using a sample volume of 5.0 mL. For derivatization, 0.25 mL aliquots of 25 mM FMOC have been used, the reaction
time being only 2 min. The method has been applied to the quantification of several aliphatic amines: methylamine, ethylamine,
dimethylamine,n-butylamine,n-pentylamine andn-hexylamine. Under the proposed conditions the percentages of analytes retained plus derivatized were of about 54–107% compared
to those obtained with direct solution derivatization. The method provided good reproducibility, linearity and accuracy within
the 0.050–1.0 mg L−1 concentration range. The limits of detection were in the 0.25–5.0 μg L−1 range. The utility of the described approach has been tested by analysing tap water, river water and industrial waste water. 相似文献