Simultaneous determination of selected endocrine disrupters (pesticides,phenols and phthalates) in water by in-field solid-phase extraction (SPE) using the prototype PROFEXS followed by on-line SPE (PROSPEKT) and analysis by liquid chromatography-atmospheric pressure chemical ionisation-mass spectrometry

In this study, a new procedure, based on on-line solid-phase extraction (SPE) and analysis by liquid-chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS), has been developed for the simultaneous, multianalyte determination of 21 selected pesticides, phenols and phthalates in water. SPE was carried out on polymeric PLRP-s cartridges by percolating 20 mL-samples. For sample preconcentration, the performance of a prototype programmable field extraction system (PROFEXS) was evaluated against the commercial laboratory bench Prospekt system used for method development. The Profexs is designed for the automated on-site sampling, SPE preconcentration, and storage of up to 16 samples in SPE cartridges. These cartridges are further eluted and on-line analyzed with the Prospekt coupled to the chromatographic system. In the optimized method, where completely on-line SPE-LC-MS analysis of the samples is carried out with the Prospekt in the laboratory, detection limits lower than 100 ng/L, and satisfactory precision (relative standard deviations <25%) and accuracies (recovery percentages >75%) were obtained for most investigated compounds from the analysis of spiked Milli-Q water. The extraction efficiency achieved with the Profexs was comparable to that of the Prospekt for most compounds and somewhat lower for the most apolar analytes, probably due to adsorption on the pump filters. The completely on-line optimized method was applied to the analysis of surface water, ground water and drinking water from a waterworks in Barcelona. Some pesticides and phenols were found in both surface water and groundwater at ng/L or µg/L levels, but not in the final drinking water. Di(2-ethylhexyl)phthalate (DEHP) was present in all samples investigated, including blanks. To the author's knowledge, this is the first work describing the application of a fully automated on-line SPE-LC-MS method for the simultaneous analysis of pesticides, phenols, and phthalates in water, and the second one that examines the possibilities of the prototype Profexs for automated on-site SPE preconcentration of organic pollutants from water samples.     

On-line coupling of solid-phase extraction to liquid chromatography-tandem mass spectrometry for the determination of macrolide antibiotics in environmental water

An automated on-line solid-phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) system was developed for the determination of macrolide antibiotics including erythromycin (ETM), roxithromycin (RTM), tylosin (TLS) and tilmicosin (TMC) in environmental water samples. A Capcell Pak MF Ph-1 column packed with restricted access material (RAM) was used as SPE column for the concentration of the analytes and clean-up of the sample. One milliliter water sample was injected into the conditioned SPE column and the matrix was washed out with 3 mL high purity water. By rotation of the switching valve, macrolides (MLs) were eluted in the back-flush mode and transferred to the analytical column by the chromatographic mobile phase. The matrix effect was evaluated by the directly injection LC-MS and on-line SPE-LC-MS methods. The limits of detection (LODs) and limits of quantification (LOQs) obtained are in the range of 2-6 and 7-20 ng L⁻¹, respectively, which means that the proposed method is suitable for trace analysis of MLs at low level concentration. The intra- and inter-day precisions are in the range of 2.9-7.2% and 3.3-8.9%, respectively. In the three fortified levels (20, 200 and 2000 ng L⁻¹), recoveries of MLs ranging from 86.5% to 98.3% are obtained.     

Liquid chromatography and tandem mass spectrometry: a powerful approach for the sensitive and rapid multiclass determination of pesticides and transformation products in water

In this paper we will show the results of our research on the direct simultaneous determination of multi-class pesticides and transformation products with different polarities and acid-base properties by applying an on-line trace enrichment coupled to the chromatographic system supplied with electrospray interface (SPE-LC-MS/MS method). The specific chromatographic separation allows the correct determination of almost fifty compounds (37 pesticides and 10 transformation products) using very low sample volume and very little sample handling. Recoveries between 70-120% were obtained for all compounds in drinking and groundwater, meanwhile in surface water 44 compounds were correctly quantified. Relative standard deviations lower than 15% were obtained for all compounds. Even at the lowest concentration level tested (25 ng L(-1)) 40 compounds presented satisfactory recoveries and repeatability. The use of methanol as organic modifier and the increase of injection volume are also studied. The applicability of the developed method to a monitoring programme is demonstrated by applying it to the analysis of hundreds of samples.     

Measurement of trace levels of antibiotics in river water using on-line enrichment and triple-quadrupole LC-MS/MS

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).     

固相萃取-液相色谱-串联质谱法测定海水中软骨藻酸

软骨藻酸(domoic acid, DA)是一种由海洋硅藻产生的生物毒素,具有强烈的神经毒性,近海水环境中的DA严重威胁海洋渔业生物和人类健康,因此对近海水环境中的DA进行有效监测至关重要。该文基于固相萃取-液相色谱-串联质谱联用技术(SPE-LC-MS/MS),建立了适用于海水中痕量、超痕量DA的检测方法。针对近海水生环境中DA浓度相对较高的情况下,采用在线SPE-LC-MS/MS检测模式,可减少前处理过程,提高样品的分析效率。离线SPE结合在线SPE-LC-MS/MS可实现大洋和极地海水中含量更低的DA的检测。通过对在线固相萃取条件和液相色谱、质谱条件的优化,海水样品经过滤和酸化简单处理后直接进样0.6 mL进行在线SPE-LC-MS/MS检测,DA在10.0~500.0 ng/L范围内线性关系良好(线性相关系数R²=0.9992),检出限(LOD)和定量限(LOQ)分别为4.0和10.0 ng/L,并且具有较好的方法回收率(≥81.0%)和精密度(RSD≤4.2%),表明方法可用于近海海水中痕量DA的检测。通过对离线固相萃取柱的选择和酸化条件的优化,80.0 mL海水样品经离线HLB固相萃取柱富集后,进行在线SPE-LC-MS/MS检测,DA在0.3~50.0 ng/L范围内线性关系良好(R²=0.9990),回收率(≥69.2%)和精密度(RSD≤4.4%)较好,LOD和LOQ分别为0.1和0.3 ng/L,说明方法的灵敏度较直接进样法大幅提升,实现了海水中超痕量DA的准确测定。这两种检测方法操作简单,样品用量小,灵敏度高,可满足近海养殖区及远岸海水中DA监测的要求。     

Rapid narrow band elution for on-line SPE using a novel solvent plug injection technique

Determination of trace constituents in biological and environmental samples usually requires a pre-concentration step. While solid-phase extraction (SPE) has been widely used, it is slow, labor intensive and adversely affected by analytical errors from handling. On-line SPE eliminates some of the flaws but often suffers from solvent compatibility problems with the subsequent chromatography separation. In this study, we are presenting a technical solution for overcoming some of these compatibility issues, by utilizing a fully automated, focused SPE sample transfer technique utilizing narrow-band solvent plugs, for seamless hyphenation with high-performance liquid chromatography (HPLC) or flow injection mass spectrometry (MS). A wide range of pharmaceutical compounds was studied in different sample matrices. Short plugs of high elution strength solvent were generated by means of an electrically actuated sample loop and enrichment and transfer steps monitored using on-line SPE-MS. The impact of the solvent plugs on chromatographic separation was studied using hyphenated SPE-LC-MS. By carefully examining elution profiles of solvent plugs of different compositions, optimum conditions for quantitative elution within well-defined volumes were found for all substances. In addition, the highly focused elution bands resulted in excellent retention time and peak area reproducibilities when injected on-line onto HPLC columns. Finally, to demonstrate proof-of-principle, the fully integrated on-line SPE-LC-MS system was applied to the analysis of spiked urine and river water samples.     

Simple and rapid screening procedure for pesticides in water using SPE and HPLC/DAD detection

An HPLC method, using a photodiode array detector (DAD) has been developed for the simultaneous screening of pesticides. A solid phase extraction system (SPE) has been combined, off-line, with the HPLC/DAD to isolate, recover and quantify pesticides from water samples at ppb levels. The pesticides are eluted from a Hypersil C₁₈ column 5 μm applying a solvent elution programme with two steps, isocratic and gradient mode, in reverse phase. Full UV spectra from 200 to 400 nm are recorded on-line during the analysis and may be compared to stored spectra. The method has been applied to the determination of pesticides in real water samples.     

固相萃取-气相色谱-质谱联用同时测定河水和海水中87种农药

采用固相萃取-气相色谱-质谱联用技术,建立了河水和海水中87种农药(24种有机磷、15种有机氯、12种唑类、9种拟除虫菊酯类、5种氨基甲酸酯类、7种酰胺类及15种其他新型农药)的多残留同时分析方法。优化了影响分离效果和灵敏度的仪器参数,考察了固相萃取柱柱型及水样体积、pH、盐度的影响,采用NH2柱优化了净化效果,内标法和替代物法用于数据的质量控制。结果表明: 在最佳条件下,各目标农药的方法检出限为0.1～6.6 ng/L;以实际河水和海水为基底,在5 ng/L和20 ng/L的加标水平下,绝大多数目标农药的回收率为60%～120%,相对标准偏差(n=4)为0.01%～9.7%。该法灵敏、准确,已成功地应用于福建九龙江河口区表层水样中多种类农药的复合污染监测,检出包括5种有机磷类、3种酰胺类、4种唑类、3种氨基甲酸酯类、2种拟除虫菊酯类等农药20种。     

在线固相萃取/液相色谱-线性离子阱质谱法同时检测生物样品中18种氨基甲酸酯类农药

建立了同时测定全血、尿液和肝组织等生物样品中18种氨基甲酸酯类农药的在线固相萃取/液相色谱-线性离子阱质谱(On-line SPE/LC-LIT/MS)分析方法。样品经乙腈处理,稀释和离心后直接进样。经Waters OasisHLB在线SPE柱富集纯化,以BETASIL C18柱为分析柱,甲醇-水(均含0.1%甲酸)为流动相进行梯度洗脱;使用电喷雾电离(ESI)正离子模式测定,扫描方式为选择反应监测(SRM)和连续反应监测(CRM)。18种农药在考察的质量浓度范围内线性关系良好(权重因子1/X),相关系数为0.994 3~0.999 4;在全血和尿液中的检出限为0.1~5 ng/m L,在肝组织中的检出限为0.1~5 ng/g;3个加标水平的回收率为90.2%~114.5%,相对标准偏差(n=4)为0.5%~7.5%。该方法简单准确,灵敏度高,能够满足生物样品中18种氨基甲酸酯类农药的快速分析要求。     

Development and validation of an HPLC-DAD method for the simultaneous determination of most common rice pesticides in paddy water systems

Rice crop is mainly cultivated in large river basins which constitute unique ecosystems and their ecological quality is invaluable. However, the high loads of pesticides used in rice cultivation contribute to the contamination of the water resources in such rice-cultivated regions. To regularly monitor the quality of such water resources there is a need for a rapid and sensitive multi-residue analytical method. This study presents the development and validation of a new analytical method for the simultaneous determination of most rice pesticides including penoxsulam, tricyclazole, propanil and its main metabolite 3,4-dichloroaniline, azoxystrobin, molinate, profoxydim and deltamethrin. A solid-phase extraction (SPE) procedure followed by high performance liquid chromatography (HPLC) with diode array detection (DAD) was used. A C₁₈ RP column operated at 30°C was utilised and the analytes were separated with a mobile phase of acetonitrile/water mixture in a linear gradient. Clean-up of water samples and isolation of pesticides was performed on SPE Bakerbond octadecyl cartridges and an ethyl acetate-dichlomethane mixture (9?:?1 v/v, 2?mL) was used for elution. Method validation was performed by means of intra-day (n?=?5) and inter-day accuracy and precision (n?=?8), sensitivity and linearity. The relative recoveries of the pesticides in paddy water samples were acceptable (80.6–110.2%) and the relative standard deviation (RSD%) ranged from 1.9 to 7.6%. Limits of detection (LOD) and limits of quantification (LOQ) varied from 0.1 to 0.8?ng?mL^?1 and 0.25 to 2.0?ng?mL^?1 respectively, depending on the analyte. The method was subsequently applied for the determination of pesticide residues in paddy and canal water samples. Tricyclazole was the most frequently detected pesticide at the highest concentrations, while herbicides were less frequently detected and at lower concentrations. The method described could be a valuable tool for regular monitoring of surface water systems in rice-cultivated basins.     

Development and validation of a SPE-GC-MS method for the determination of pesticides in surface water

A method for analysis of 20 commonly used pesticides in surface water based on solid-phase extraction and gas chromatography-mass spectrometry was proposed. During method development the key parameters that can affect SPE extraction and determination such as selection of efficient SPE sorbent, pH of water sample, type and volume of elution solvent, breakthrough volume and matrix effects were investigated. The method was validated using spring water spiked with appropriate concentration of pesticides. The obtained correlation coefficients were in range 0.9972–1.000, limits of detection (LOD) were 0.001–0.5?µg?L^?1 and the limits of quantification (LOQ) were 0.005–1?µg?L^?1 depending on a pesticide. Much higher LOD (20?µg?L^?1) and LOQ (50?µg?L^?1) values were obtained for bentazone. The influence of matrix was assessed using real water samples spiked with appropriate concentration of pesticide standards solution. Both signal enhancement and suppression were observed, depending on a pesticide, therefore standard addition method was used for pesticides determination. The developed method was applied on real water samples taken in close vicinity of agricultural fields. Many of the targeted pesticides were found in the samples and the results are presented in this article.     

Simple, rapid solid-phase extraction procedure for the determination of ultra-trace levels of pyrethroids in ground and sea water by liquid chromatography/electrospray ionization mass spectroscopy

A method based on liquid chromatography/mass spectroscopy with electrospray ionization in positive mode (LC/ESI-MS) to determine trace levels of pyrethroids in environmental water samples has been developed. The chromatographic and the MS parameters were optimized to obtain the best sensitivity and selectivity for all pesticides. Solid-phase extraction (SPE) using C18 cartridges was applied for preconcentration of pesticide trace levels (ng/L) in both ground and sea water samples. The preconcentration step was carried out with 800 mL of water sample modified with 200 mL of MeOH to improve the recovery percentages in the SPE procedure. The SPE-LC/ESI-MS methodology was applied to determine pyrethroids in ground and sea water samples spiked at ng/L concentration levels. Recoveries obtained in ground water were satisfactory (between 72 and 110%). However, an enhancement of the signals of all pesticides in the sea water was found due to the negative effect of the salt in the ionization source. To eliminate this effect a simple cleanup step of the SPE cartridge using 200 mL of Milli-Q water was performed. The cleanup removed the matrix effect completely from the marine samples. Thus, the recovery percentages ranged from 80 to 115%. The method was applied to determine ng/L of pyrethroids in both ground and marine water samples with precision values lower than 10%.     

Sensitive determination of Fenamiphos in water samples by flow injection photoinduced chemiluminescence

In this work, a sensitive flow injection chemiluminescence (FI-CL) method for the determination of nematicide Fenamiphos in a rapid and simple way is proposed. Fenamiphos is first photodegraded in basic medium. These photofragments react with Ce(IV) providing the chemiluminescence signal. To the authors’ knowledge, no chemiluminescence method has been described in the literature for the determination of the nematicide Fenamiphos. All physical and chemical parameters in the flow injection chemiluminescence system were optimized in order to obtain the best sensitivity, selectivity and sample throughput. Before the injection of the sample in the FI-CL system, a preconcentration step with solid phase extraction C18 cartridges was performed. By applying solid phase extraction (SPE) to 250?mL of standard (final volume 10?mL), the linear dynamic range was between 3.4 and 60?µg?L^?1, and the detection limit was 1?µg?L^?1. When SPE was applied to 500?mL of standard (final volume 10?mL), the detection limit was 0.5?µg?L^?1. These detection limits are below the emission limit value established by the Spanish Regulations of the Hydraulic Public Domain for pesticides (50?µg?L^?1) and of the same order as the limit established for total pesticides (0.5?µg?L^?1) at European Directive on the quality of water for human consumption. The sample throughput was 126 hour^?1. Intraday and interday coefficients of variation were below 10% in all cases. No interference was registered in presence of usual concentrations of anions, cations and other organophosphorus pesticides. The method was successfully applied to the analysis of environmental water samples, obtaining recoveries between 96 and 107.5%.     

Determination of carbamates at trace levels in water and cucumber by capillary liquid chromatography

A sensitive and reliable method using capillary HPLC with UV-diode array detection (DAD) has been developed and validated for trace determination of carbamate pesticides in cucumber and environmental water samples. The analytes, including carbofuran, carbaryl, methiocarb, promecarb, benthiocarb and fenoxycarb, present legal residue levels regulated by the EU Council Directive 98/83/EC on drinking water and by the Regulation (EC) No. 396/2005 on vegetables. A previous off-line solid-phase extraction (SPE) procedure was required for preconcentration and sample clean-up. The separation was achieved using a C₁₈ column (150?mm?×?0.5?mm I.D, 5?µm particle size) and a mobile phase consisting of ACN?:?water using gradient mode, with a flow rate of 10?µl min^?1. Taking advantages of the characteristics of capillary HPLC, low volume of sample and solvents were required, achieving limits of detection for the studied compounds ranged from 10.0–29.6?ng l^?1 for water samples and 1.8–5.6?µg kg^?1 for cucumber, using UV-detection. Recoveries studies for fortified samples, at three different concentration levels, were carried out obtaining recoveries ranging from 70.0 to 111.1% and relative standard deviations (RSDs) lower than 10.6%.     

On-line separation and preconcentration of trace cadmium in environmental water samples by micro column filled with modified nanometer Si-HAP prior to FAAS determination

A novel method of on-line solid phase extraction (SPE) preconcentration has been established for the determination of cadmium in environmental water samples by flame atomic absorption spectrometry (FAAS). The method is based on the on-line retention of cadmium on a micro column of nanometer Silicon Hydroxyapatite (Si-HAP) modified with 1-phenyl-3-methyl-4-bonzoil-5-pyrazone (PMBP) and subsequent elution with 1.0?M thiourea and determination by FAAS. The effect of various parameters that could affect the performance of the system was investigated. The enrichment factor (EF) for cadmium (II) was 250. The limit of detection (LOD) obtained under optimum conditions was 0.28?µg?L^?1 and the relative standard deviation (RSD) for seven replicates at 100?µg?L^?1 Cd²⁺ concentration level was 1.4%. The method was applied to water samples and standard reference materials. The accuracy was assessed through recovery experiments and comparing the results with the accepted values of standard reference material.     

改性多壁碳纳米管固相萃取-高效液相色谱法测定农产品中痕量残留的4种有机氯农药

对多壁碳纳米管(MWNTs)的表面进行酸氧化处理制备了改性的MWNTs,并建立了以改性MWNTs作为固相萃取(SPE)吸附剂测定农产品中痕量残留的4种有机氯农药(p,p′-DDD、p,p′-DDT、o,p′-DDT、p,p′-DDE)的SPE-高效液相色谱(HPLC)分析方法。考察了氧化处理条件、SPE操作条件和色谱条件等对有机氯农药残留测定的影响,优化了实验条件。在优化实验条件下,4种农药在较宽线性范围内线性良好,相关系数为0.9978～0.9995,检出限为0.050 mg/L;在样品中分别添加0.10、2.0、50 mg/L的4种农药,其加标回收率为78%～104%,相对标准偏差(RSD)为2.7%～7.6%。MWNTs作为SPE填料用于陈皮、西洋参、卷心菜和茶叶等样品的净化效果良好,测定结果准确,灵敏度高,符合农产品中痕量农药残留的分析方法要求,为农产品中此类农药的痕量残留分析提供了有益的参考。     

An On-line Admicellar SPE-HPLC System Using CTAB-Modified Zeolite NaY as Sorbent for Determination of Carbamate Pesticides in Water

Zeolite NaY modified with cetyltrimethylammonium bromide (CTAB) was considered for extraction/preconcentration of carbamate pesticides using an on-line SPE-HPLC system. The simultaneous determination of carbamate pesticides, including aldicarb, carbofuran, carbaryl, isoprocarb, methiocarb and promecarb, was performed by HPLC–UV using a LichroCART RP-18 column with gradient elution of methanol and 0.1 % acetic acid. The sorbent presented admicelles of CTAB on its surfaces and exhibited a sorption capacity of 180–18,600 mg kg⁻¹ sorbent, which could be re-modified for at least five extraction cycles. The quantitative retention of target pesticides on the admicellar sorbent involved hydrophobic and π-cation interaction, while pesticides were eluted from the admicellar SPE column using only 750 μL of methanol. LODs and LOQs of the proposed method were 0.005–140 and 0.02–600 μg L⁻¹, respectively. The analytes were effectively concentrated with the enrichment factors between 5 and 551. The developed on-line admicellar SPE-HPLC system was successfully applied to the determination of carbamate pesticides in ten environmental water samples from different sources. Recoveries of spiked samples at a concentration of 0.1–5 mg L⁻¹ ranged from 77 to 111 %.

     

Advantages and limitations of on-line solid phase extraction coupled to liquid chromatography-mass spectrometry technologies versus biosensors for monitoring of emerging contaminants in water

On-line solid phase extraction (SPE) coupled to liquid chromatography-mass spectrometry (LC-MS) and biosensors are advanced technologies that have found increasing application in the analysis of environmental contaminants although their application to the determination of emerging contaminants (previously unknown or unrecognized pollutants) has been still limited. This review covers the most recent advances occurred in the areas of on-line SPE-LC-MS and biosensors, discusses and compares the main strengths and limitations of the two approaches, and examines their most relevant applications to the analysis of emerging contaminants in environmental waters. So far, the on-line configuration most frequently used has been SPE coupled to liquid chromatography-(tandem) mass spectrometry. Sorbents used for on-line SPE have included both traditional (alkyl-bonded silicas and polymers) and novel (restricted access materials (RAMs), molecularly imprinted synthetic polymers (MIPs), and immobilized receptors or antibodies (immunosorbents) materials. The biosensor technologies most frequently applied have been based on the use of antibodies and, to a lesser extent, enzymes, bacteria, receptors and DNA as recognition elements, and the use of optical and electrochemical transducing elements. Emerging contaminants investigated by means of these two techniques have included pharmaceuticals, endocrine disrupting compounds such as estrogens, alkylphenols and bisphenol A, pesticides transformation products, disinfection by-products, and bacterial toxins and mycotoxins, among others. Both techniques offer advantageous, and frequently comparable, features such as high sensitivity and selectivity, minimum sample manipulation, and automation. Biosensors are, in addition, relatively cheap and fast, which make them ideally suited for routine testing and screening of samples; however, in most cases, they can not compete yet with on-line SPE procedures in terms of accuracy, reproducibility, reliability (confirmation) of results, and capacity for multi-analyte determination.     

Simple and Rapid Determination of Benzoylphenylurea Pesticides in River Water and Vegetables by LC–ESI-MS

Liquid chromatography with electrospray mass spectrometry (LC–ESI-MS) instrumentation equipped with a single quadrupole mass filter has been used to determine several benzoylphenylurea insecticides (diflubenzuron, triflumuron, hexaflumuron, lufenuron and flufenoxuron). Chromatographic and MS parameters were optimised to obtain the best sensitivity and selectivity for all pesticides. Solid-phase extraction (SPE) using C₁₈ cartridges was applied for preconcentration of pesticide trace levels in river water samples. Recoveries of benzoylphenylurea pesticides from spiked river water (0.01 and 0.025 μg L⁻¹) were between 73 and 110% and detection limits were between 3.5 and 7.5 ng L⁻¹. The applicability of the method to the determination of benzoylphenylurea insecticides in spiked cucumber, green beans, tomatoes and aubergines was evaluated. Samples were extracted into dichloromethane without any clean-up step. The limits of detection ranged from 1.0 to 3.2 ng mL⁻¹ (0.68 and 2.13 μg kg⁻¹ in the vegetable samples). Mean recoveries ranged from 79 to 114% at spiking levels of 0.01 and 0.03 mg kg⁻¹. The method was applied to determine traces of benzoylphenylureas in both river water and vegetable samples with precision values lower than 10%. Interferences due to the matrix effect were overcome using matrix-matched standards.     

Analysis of triazolopyrimidine herbicides in soils using field-enhanced sample injection-coelectroosmotic capillary electrophoresis combined with solid-phase extraction

In this work, a combined methodology using off-line solid-phase extraction (SPE), on-line field-enhanced sample injection (FESI) and coelectroosmotic capillary electrophoresis with UV detection (CE-UV) is developed for the trace analysis of five triazolopyrimidine sulfonanilide pesticides (i.e., flumetsulam, florasulam, cloransulam-methyl, diclosulam and metosulam). An adequate background electrolyte (BGE) was obtained for the separation of these pesticides using hexadimethrine bromide (HDB) as electroosmotic flow (EOF) modifier. This BGE consisted of 0.00042% HDB, 11 mM formic acid, 16 mM ammonium carbonate and 2.5 mM alpha-CD solution at pH 7.6. The use of this running buffer together with the FESI preconcentration method provided limits of detection (LODs) in the low microg/L range (i.e., between 13.0 and 31.5 microg/L). The optimized FESI-CE-UV method was combined with off-line SPE using C(18) cartridges and applied to the determination of the selected group of pesticides in soil samples. Recovery percentages ranged between 50 and 84% in these samples with LODs between 18 and 34 microg/kg. This work shows the great possibilities of the combined use of SPE-FESI-CE-UV to improve CE sensitivity allowing the achievement of LODs similar to other analytical techniques as GC or HPLC.