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1.
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
2.
Summary A method is reported for the determination of dibutyltin (DBT), diphenyltin (DPhT), tributyltin (TBT), and triphenyltin (TPhT)
species at the nanogram per litre concentration level in natural water samples. Analytes were isolated from samples by solid-phase
extraction and analysed both off-line and on-line by reversed-phase high-performance liquid chromatography with post-column
derivatization and fluorimetric detection. Several SPE cartridges and eluents were evaluated; C18 enrichment and elution with a mixture of methanol, acetic acid, and water was found most suitable. Preconcentration factors
up to 250 can be achieved when a 500-mL sample is processed. Detection limits, recovery rates, and the precision of the whole
process have been determined. The method has been applied to the determination of organotin species in spiked natural water
samples collected on the NW Mediterranean coast. Recovery rates range from 75 to 110% and detection limits are at the low
ng L−1 level (1–3 ng Sn L−1 for DPhT, DBT, and PhT and 40 ng Sn L−1 for TBT when 250 mL spiked sea water is processed.) 相似文献
3.
J. L. Bernal M. J. Nozal L. Toribio M. L. Serna F. Borrull R. M. Marcé E. Pocurull 《Chromatographia》1997,46(5-6):295-300
Summary The eleven Environmental Protection Agency (EPA) priority phenolic compounds have been determined by solid-phase extraction
(SPE) coupled on-line to supercritical-fluid chromatography (SFC) with diodearray detection. The variables affecting chromatographic
separation were optimized and the analytes were separated at 40 °C in two diol columns connected in series; a gradient of
methanol, as modifier, and CO2 was used as mobile phase. Under these conditions, all the compounds studied were separated to baseline in less than 13 min.
PLRP-S and LiChrolut EN were tested as sorbents in a 10×3 mm i.d. laboratory-packed precolumn for solid-phase extraction.
An ion-pair reagent, tetrabutylammonium bromide (TBA), was used in the extraction process to increase break-through volumes.
The performance of the method was checked with tap and river waters and the pre-concentration of 20 mL of sample in a PLRP-S
pre-column enabled phenolic compounds to be determined at low μg L−1 levels with limits of detection ranging between 0.4 and 2 μg L−1. The repeatability and reproducibility between days (n=3) for real samples spiked at 10 μg L−1 were lower than 10%. 相似文献
4.
Th. Hankemeier J. Rozenbrand M. Abhadur J. J. Vreuls U. A. Th. Brinkman 《Chromatographia》1998,48(3-4):273-283
Summary A procedure is described for the (non-target) screening of hetero-atom-containing compounds in tap and waste water by correlating
data obtained by gas chromatography (GC) using atomic emission (AED) and mass selective (MS) detection. Solid-phase extraction
(SPE) was coupled on-line to both GC systems to enable the determination of microcontaminants at the 0.02–1 μg L−1 level in 7–50 mL of aqueous sample. The screening was limited to compounds present in at least one heteroatom-selective GC-AED
trace above a predetermined concentration level. These compounds were identified by their partial formulae (AED) and the corresponding
mass spectra, which were obtained from the GC-MS chromatogram via the retention index concept. The potential of the approach
was demonstrated by the identification of target compounds as well as all unknowns present in tap and waste water above the
predetermined threshold of 0.05 μg L−1 (tap water) or 0.5 μg L−1 (waste water). 相似文献
5.
Montesdeoca-Esponda S Sosa-Ferrera Z Santana-Rodríguez JJ 《Analytical and bioanalytical chemistry》2012,403(3):867-876
Benzotriazoles are a group of UV absorbing compounds considered emerging contaminants that are used in different personal
care products, and therefore, it is of high interest to develop sensitive and fast methods for investigating their presence
in the environment. In this work, we present the development and application of a novel method based on on-line solid-phase
extraction coupled to ultra-performance liquid chromatography with tandem mass spectrometry detection (SPE-UPLC-MS/MS) for
the determination of seven benzotriazole UV stabilizers (BUVSs) in coastal marine and wastewater samples. This process is
compared with a conventional off-line SPE procedure followed by UPLC-MS/MS. The parameters affecting the performance of the
sample preparation and determination processes were evaluated. The results indicate that the on-line procedure provides for
better sensitivity and reproducibility and is faster and easier than the off-line procedure. The detection limits and quantification
limits achieved were in the range of 0.6–4.1 ng∙L−1 and 2.1–14 ng∙L−1 and relative standard deviation between 6.2 and 10 %. The developed method was applied to coastal marine and wastewater samples
from Gran Canaria Island (Spain). All of the BUVSs studied were detected in the samples from wastewater treatment plants and
two were found in the seawater samples (UV P in the range of 2.8–4.4 ng∙L−1 and UV 360 between 3.6 and 5.2 ng∙L−1). 相似文献
6.
Alaa S. Amin 《Chemical Papers》2009,63(6):625-634
A simple, selective, highly sensitive and accurate procedure for the determination of trace amounts of copper has been developed
based on solid-phase spectrophotometry. Copper reacts with 5-(2-benzothiazolylazo)-8-hydroxyquinoline (BTAHQ) to give a complex
with high molar absorptivity (3.17 × 107 L mol−1 cm−1, 3.07 × 108 L mol−1 cm−1, 1.22 × 109 L mol−1 cm−1, and 1.80 × 109 L mol−1 cm−1), fixed on a Dowex 1-X8 type anion-exchange resin for 10 mL, 100 mL, 500 mL, and 1000 mL, respectively. The absorbance at
667 nm and 800 nm packed in a 1.0 mm cell was measured directly. Calibration is linear over the range 0.2–3.7 μg L−1 with RSD of < 1.28 % (n = 10). The detection and quantification limits of the 500 mL sample method are 79 ng L−1 and 260 ng L−1 when using 60 mg of Dowex 1-X8. For a 1000 mL sample, the detection and quantification limits are 67 ng L−1 and 220 ng L−1 using 60 mg of the exchanger. Increasing the sample volume can enhance the sensitivity. The proposed method was applied to
the determination of copper in different environmental water samples (tap, pit, spring, and river), food products (rice, corn
flour, and tea), and mushrooms, using the standard addition technique. 相似文献
7.
K. K. Verma A. J. H. Louter A. Jain E. Pocurull J. J. Vreuls U. A. Th. Brinkman 《Chromatographia》1997,44(7-8):372-380
Summary On-line solid-phase extraction-gas chromatographyion-trap tandem mass spectrometry (SPE-GC-MS/MS) has been used for the trace-level
determination of polar and apolar pesticides. The SPE-GC interface, an Autoloop 2000, was operated at an injection temperature
of 90°C which permitted the determination of thermolabile pesticides such as carbofuran and carbaryl. Rectilinear calibration
curves were obtained for the analytes tested over a range of 0.1–500 ng L−1, using a sample volume of 10–100 mL for enrichment on an SPE cartridge packed with styrene-divinylbenzene copolymer. The
detection limits for the pesticides were in the 0.01–4 ng L−1 range. For a number of pesticides acceptable tandem mass spectra were obtained at levels as low as 0.1 ng L−1 level in real-life water samples.
As a demonstration of the applicability of this technique for inorganic anions, bromide and nitrite were converted into 4-bromoacetanilide
and 2-phenylphenol, respectively. The reaction products were pooled and subjected to simultaneous analysis by the present
method using full-scan mass spectrometric detection. The detection limits were 0.3 and 2 ng L−1, respectively. 相似文献
8.
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
9.
Perreau F Bados P Kerhoas L Nélieu S Einhorn J 《Analytical and bioanalytical chemistry》2007,388(5-6):1265-1273
Two alternatives for the rapid simultaneous quantification of six sulfonylurea herbicides and five of their main degradation
products in natural water are proposed. For concentration, the compounds were extracted on a polystyrene–divinylbenzene solid
phase under pH and elution conditions that suppressed any hydrolysis. The eluates were analysed by liquid chromatography coupled
to electrospray tandem mass spectrometry within 20 min. The whole method was validated and shown to give no hydrolysis artefacts.
The application of off-line and on-line SPE of sulfonylureas enabled the 0.1 μg L−1 and 1 ng L−1 LOQ levels to be reached, respectively. The on-line SPE–LC–MS–MS method allowed the accurate quantitation of all sulfonylureas
and three degradation products at 0.1 μg L−1 or below in natural water, with an average repeatability of 8%. 相似文献
10.
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
11.
A method based on on-line solid-phase extraction (SPE) coupling to high-performance liquid chromatography (HPLC) for the determination of estrogens has been developed. This method can continuously perform extraction of estrone, estradiol, estriol and diethylstilbestrol from aqueous samples without any other pretreatment, which can then be analyzed by HPLC with a UV detector at 230 nm. A pre-concentration column was adapted with methanol/water for chromatographic separation and two kinds of sorbents were involved, which are octadecyl-bonded silica and cigarette filter. The condition of pH of samples, sample loading flow rate and desorption time were all optimized, and the performances of both two sorbents were satisfactory. The on-line SPE system requires very low maintenance and just involved a switching-valve-filter system and a flow-inject pump, and the operation of the whole SPE-HPLC instrumentation is quite simple. The detection limits for pre-concentrating 50 mL of standard solution using cigarette filter as sorbent ranged from 0.98 to 78.1 ng L−1. The enhancement factors were in the range of 197-326. The recoveries of estrogens spiked in real water samples ranged from 85 to 112%. The precisions for nine replicate measurements of a standard mixture (5.0 μg L−1) were in the range of 1.0-3.4%. 相似文献
12.
Preconcentration Systems Using Polyurethane Foam/Me-BDBD for Determination of Copper in Food Samples
Valfredo Azevedo Lemos Daniel Rodrigues Vieira Cleber Galvão Novaes Marcelo Eça Rocha Moacy Selis Santos Regina Terumi Yamaki 《Mikrochimica acta》2006,153(3-4):193-201
A new reagent, 6-[2′-(6′-methyl-benzothiazolylazo)]-1,2-dihydroxy-3,5-benzenedisulfonic acid (Me-BDBD), was synthesised and
used in on-line and off-line systems for copper preconcentration by solid-phase extraction. Spectrophotometry and Flame Atomic
Absorption Spectrometry (FAAS) were the detection techniques. Polyurethane foam loaded with Me-BDBD packed in a minicolumn
was used as sorbent in both systems. The spectral characteristics of Me-BDBD were investigated. The optimum pH values for
maximum sorption of the metal are between 7.0 and 8.5. Copper was desorbed with 0.05 and 0.50 mol L−1 hydrochloric acid solutions, for on-line and off-line systems, respectively. The effects of several foreign substances on
the adsorption of copper are reported. The enrichment factors obtained were 7 (on-line) and 26 (off-line) for the systems.
The proposed procedures allowed the determination of copper with detection limits of 3.4 and 1.4 μg L−1 (0.85 and 0.35 μg per gram of sample) for on-line and off-line systems, respectively. The precision of the procedures was
also calculated: 3.2 (on-line) and 1.9% (off-line). The validation of the procedures was carried out by analysis of certified
reference material. The copper contents in corn and rice flour and black tea samples were determined by applying the proposed
procedures. 相似文献
13.
The environmental analysis of estrogens and progestogens at physiologically active concentrations (low ng/l range) requires the use of very sensitive and selective methods, which, in most cases, make necessary an extraction/purification step. In this study, various procedures for the determination of several estrogens (estriol, estradiol, ethynyl estradiol, estrone, and diethylstilbestrol) and progestogens (progesterone, norethindrone, and levonorgestrel) in environmental matrices, including water and river sediment, are described. In all procedures, final analysis of the target compounds is performed by reversed-phase liquid chromatography-diode array detection-mass spectrometry, whereas sample preparation always includes a solid-phase extraction (SPE) step. For this SPE step. various types of sorbents, protocols, and devices have been used, and their respective advantages and disadvantages are discussed. For the off-line SPE of estrogens and progestogens from water samples, a syringe type cartridge LiChrolut RP-18 (500 mg) was selected out of two other sorbents--LiChrolut EN (200 mg) and Isolut ENV (500 mg)--for use with the automated sample preparation instrument ASPEC XL. For the on-line SPE and analysis of water samples the 10 mm x 2 mm I.D. HySphere-Resin-GP cartridge, was preferred to the C18 Baker, the PLRP-S, and the Oasis HLB. for use with the Prospekt system. A completely manual protocol based on the use of Sep-Pak C18 Plus cartridges was developed for purification of sediment extracts. All procedures were shown to be linear over a wide range of concentration, exhibited satisfactory repeatability and accuracy, and reached limits of detection usually in the low ng/l and ng/g range. Comparatively, the on-line method was shown to be advantageous in terms of automation and general method performance. 相似文献
14.
Solid-Phase Extraction and LC with Fluorescence Detection for Analysis of PAHs in Rainwater 总被引:1,自引:0,他引:1
The efficiency of extraction of polycyclic aromatic hydrocarbons (PAHs) from rainwater by solid-phase extraction (SPE) with
three different types of cartridge, and analysis by high-performance liquid chromatography with fluorescence detection, are
discussed in this paper. Three cartridges were investigated but only one was suitable. After equilibration in a desiccator
for 65–80 h or in ambient air for 90–100 h the SPE cartridges were activated with 5 mL dichloromethane then 5 mL 2-propanol.
The volume of sample passed through the cartridges was 50 mL; after loading of the sample the cartridges were dried under
vacuum for approximately 20 min by application of a pressure of 15 mbar to the SPE manifold. The PAHs were eluted with 5 mL
dichloromethane–hexane, 50:50 (v/v). The flow rate used for conditioning, sample loading, and elution was 2.5 mL min−1, achieved by application of a pressure of 6 mbar. For analysis of PAHs in rainwater, recovery was between 67 and 99%, the
relative standard deviation varied between 2 and 5%, and the detection limits of the method were less than 16.9 ng L−1 for several PAHs. These optimum conditions were used for analysis of rainwater collected between June 2002 and May 2003 at
two sites in Alsace (eastern France) and 17 PAHs were quantitatively determined. Concentrations varied between 1.6 and 968.1 ng L−1. 相似文献
15.
Solid-phase extraction (SPE) followed by derivatization and gas chromatography-atomic emission detection (GC-AED) was evaluated for the determination of five chlorophenols (CPs) in water samples. The derivatization was based on the esterification of phenolic compounds with ferrocenecarboxylic acid. The determination of the derivatized phenols was performed by GC-AED in the iron selective detection mode at 302 nm. The described method was tested on spiked water samples.The overall method gave detection limits of 1.6-3.7 ng L−1 and recoveries of 90.9-104.5% for the examined mono- to trichlorophenols in 10 mL water samples. The CPs extracted from a 10 mL water sample with SPE were concentrated into 100 μL of organic solvent, a preconcentration factor of 100. The method was applied to lake and tap water samples, and CP contents between 6 and 51 ng L−1 in lake water and between below the detection limit and 8 ng L−1 in tap water were found for different CPs. The method is quick, simple and gives excellent recoveries, limits of detection and standard deviations. 相似文献
16.
Summary A method has been developed for the determination of trace levels of 32 pesticides, 19 explosives and 16 polycyclic aromatic
hydrocarbons (PAH) in water in three individual steps. Solid-phase enrichment (SPE) is coupled to high-performance liquid
chromatography (HPLC) with a fully automated system. The organic pollutants are enriched on reusable cartridges packed with
adsorbent materials: pesticides and explosives on a mixed bed of divinylbenzene-ethylvinylbenzene copolymers (LiChrolut EN?) and perfluorinated polyethylene (PolyF?), and polycyclic aromatic hydrocarbons on C18-modified silica (Zorbax? ODS1). Thermally assisted desorption (TAD) has been shown to increase the recovery of analytes significantly. As all enriched
analytes are transferred to the detector, only fifty millilitres of sample is needed for each single on-line analysis, compared
with at least a litre for conventional methods. The separation of the enriched organic analytes is performed on specialized
HPLC columns based on reversed-phase materials. The limits of detection of the system employed were found to be below 100
ng L−1. Use of fluorescence detection for the polycyclic aromatic hydrocarbons resulted in limits of detection in the upper pg L−1 range. Thek values, number of theoretical plates, the recovery rates and the limits of detection of this method for fast screening of
organic pollutants from three fifty-millilitre aqueous samples are described.
Presented at the 21st ISC held in Stuttgart, Germany, 15th–20th September, 1996 相似文献
17.
A method involving solid-phase extraction (SPE) and reversed-phase liquid chromatography–mass spectrometry (LC–MS) has been
developed for determination, in groundwater, of nitrobenzoic acids associated with 2,4,6-trinitrotoluene production. Pre-concentration
on a co-polymer-based SPE cartridge enabled quantitative extraction of the analytes from water. Investigation of negative
ion electrospray and atmospheric-pressure chemical ionization mass spectrometry indicated the sensitivity of APCI was more
than twice that of ESI. An 15N-labeled internal standard was used to achieve more accurate quantitation and mass assignment. Recovery was better than 80%
when 10 mL water was extracted with the SPE cartridge. Combination of SPE with LC–MS analysis resulted in method detection
limits of less than 5 μg L−1. The method has been used for analysis of groundwater samples collected from a site of a former ammunition plant. Contamination
with nitrobenzoic acids was determined at μg L−1 levels. 相似文献
18.
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
19.
Measurement of trace levels of antibiotics in river water using on-line enrichment and triple-quadrupole LC-MS/MS 总被引:1,自引:0,他引:1
This study presents the development of an automated on-line solid phase extraction (SPE)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of 23 antibiotics in environmental water samples. After optimisation of LC-MS/MS conditions, SPE parameters such as sorbent type, sample pH or sample volume were optimised. Antibiotic recoveries ranged from 64% to 98% and compared favourably with those achieved using off-line SPE. Limits of detection were in the range 0.5-13.7 ng L−1.This on-line SPE-LC-MS/MS procedure was applied to the analysis of water samples taken in three rivers within the Seine River basin, near Paris (France). The obtained results revealed the occurrence of 12 antibiotics, including tylosin, erythromycin, tetracycline, amoxicillin, trimethoprim, sulfamethoxazole, oxolinic acid, flumequine, norfloxacin, ciprofloxacin, ofloxacin, and vancomycin (2-1435 ng L−1). 相似文献
20.
D. Bratkowska N. Fontanals F. Borrull P.A.G. Cormack D.C. Sherrington R.M. Marcé 《Journal of chromatography. A》2010,1217(19):3238-3243
Three new hypercrosslinked polymers with hydrophilic character arising from hydroxyl moieties in their skeletons have been prepared in microsphere format and applied to the off-line solid-phase extraction (SPE) of polar compounds from water samples. For sample volumes of 1000 ml, the recoveries of various polar pesticides, such as oxamyl, methomyl, selected phenolic compounds, as well as some pharmaceuticals, were close to 90%. The HXLPP-polar polymer with the best performance characteristics was applied to real samples. Its performance was also compared to commercially available sorbents, such as LiChrolut EN (hydrophobic, hypercrosslinked), Oasis HLB (hydrophilic, macroporous) and Isolute ENV+ (hydrophilic, hypercrosslinked); the new sorbent out-performed the commercially available sorbents. The polymer was applied successfully in off-line SPE of river water samples followed by liquid chromatography and ultraviolet detection, providing a good linear range and detection limits of 0.2 μg l−1 for the majority of the compounds, with the exception of oxamyl, methomyl, guaiacol and salicylic acid where the detection limit was 0.5 μg l−1. 相似文献