Comparison of a non-aqueous capillary electrophoresis method with high performance liquid chromatography for the determination of herbicides and metabolites in water samples

A method of capillary electrophoresis (CE) for the determination of triazine herbicides and some of their main metabolites in water samples has been developed. The proposed CE method includes an off-line solid-phase extraction (SPE) procedure with LiChrolut EN sorbent coupled to a non-aqueous capillary electrophoresis (NACE) separation with UV detection. The target compounds were the chloro-s-triazines simazine, atrazine, propazine; the methyltio-s-triazines ametryn and prometryn and three main derivatives from the atrazine degradation products; namely, deethylatrazine, deethylhydroxyatrazine and deisopropylhydroxyatrazine. The analytical characteristics of the CE method are reported. The repeatability of the method was studied considering the different steps of the method separately in order to determine the contributions of each step to the total variability of the method. The NACE-UV results are compared with those obtained with a high performance liquid chromatography with UV detection (HPLC-UV) method. The same off-line SPE procedure was applied to both techniques. The results obtained show that both methods afford the same results in the analysis of surface and drinking water samples, with a level of significance regarding the F- and t-tests greater than 0.05 in all the cases. The detection limits in surface water samples were in the 0.04-0.32 microg l(-1) and 0.11-1.2 microg l(-1) ranges for the NACE-UV and HPLC-UV methods, respectively. The recoveries (spiked/found) were significantly 100% in all cases.     

Trace-level determination of triazines and several degradation products in environmental waters by disk solid-phase extraction and micellar electrokinetic chromatography

An analytical method combining disk solid-phase extraction with micellar electrokinetic chromatography has been developed for the determination of atrazine, simazine, hydroxyatrazine, deisopropylatrazine, deethylatrazine, propazine and prometryn in water samples. The influence of the buffer and sodium dodecyl sulfate (SDS) concentration, pH and organic modifier on the separation has been studied. Baseline separation of the seven triazines was achieved under the following conditions: 10 mM borate buffer, 60 mM SDS, 20% methanol and pH 9.2. C18-bonded silica and poly(styrene-divinylbenzene) (PS-DVB) disks were evaluated for solid-phase extraction of the selected pesticides (11 of water sample). Using two PS-DVB disks, quantitative recoveries were obtained for all pesticides tested. The method was successfully applied for the determination of the seven triazines in drinking and well water at the 0.1 microg l(-1) and 0.5 microg l(-1) concentration levels, respectively. The detection limits for these analytes using the proposed analytical method were within the 0.02-0.06 microg l(-1) range in drinking water and the 0.06-0.30 microg l(-1) range in well water.     

Pesticide levels in ground and surface waters of Primavera do Leste Region, Mato Grosso, Brazil

Residues of the herbicides simazine, metribuzin, metolachlor, trifluralin, atrazine, and two metabolites of atrazine, deisopropylatrazine (DIA) and deethylatrazine (DEA), are surveyed in the surface and groundwater of the Primavera do Leste region, Mato Grosso, Brazil during September and December 1998 and April 1999. Different water source sampling stations of groundwater (irrigation water well, drinking water well, and water hole) and surface water (dam and river) are set up based on agricultural land use. A solid-phase extraction procedure followed by gas chromatography-nitrogen-phosphorus detection is used for the determination of these compounds. All compounds are detected at least once in water samples. A temporal trend of pesticide contamination is observed, with the highest contamination frequency occurring in December during the main application season. Metribuzin shows the highest individual detection frequencies throughout the monitoring period, followed by metolachlor, simazine, and DEA. The maximum mean concentrations of pesticides in this study are in the range from 0.14 to 1.7 microg/L. We deduct that the contamination of water resources is predominantly caused by non-point pollution of pesticides used in intensive cash-crop cultures of the Cerrado area. Therefore, a continuous monitoring of pesticide concentrations in water resources of this tropical region is necessary to detect the longer term contamination trends and developing health risks.     

Preservation and analytical procedures for the analysis of chloro-s-triazines and their chlorodegradate products in drinking waters using direct injection liquid chromatography tandem mass spectrometry

A direct injection, liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for the analysis of the chloro-s-triazine herbicides and their degradates in finished drinking water. The target compounds in the method were selected based on their inclusion in a common mechanism group (CMG) because of their ability to induce a similar toxic effect through a common mechanism of toxicity. The target list includes the chloro-s-triazines (atrazine, simazine, cyanazine, and propazine) and their dealkylated degradates (desethylatrazine, desisopropylatrazine, and diaminochlorotriazine). Potential matrix effects are minimized by the use of individual isotopically enriched internal standards. Analyte stability in finished chlorinated drinking water samples is ensured through careful selection of proper dechlorinating and antimicrobial reagents and through buffering sample pH. In the absence of proper dechlorination, the target analytes were found to degrade over a short period of time, even under refrigerated storage conditions. The final method has adequate sensitivity to accurately detect all target analytes at or below 0.1 microg/L and displays sufficient precision and robustness to warrant publication as EPA Method 536.     

Monitoring of priority pesticides and other organic pollutants in river water from portugal by gas chromatography-mass spectrometry and liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS) were optimized and applied for the trace-level determination of 42 priority pesticides and 33 priority organic pollutants from European Union Directive EC 76/464. First, off-line solid-phase extraction of 200 ml of river water using an OASIS solid-phase extraction cartridge, followed by GC-MS was used. Next, selected samples that were positive to GC-MS were analyzed by LC-APCI-MS in order to detect further polar byproducts or to improve the determination of previously detected polar analytes. The transformation products of triazine pesticides like deethylatrazine (DEA) and deisopropylatrazine (DIA) and compounds such as diuron and several chlorophenols were positively identified by LC-APCI-MS. The present methodology has also been used for searching for new analytes not included in the EC 76/464 list, like Irgarol, DEA and DIA. In addition it was applied to target pollutants in 43 river water samples from Portugal during a pilot survey from April to July 1999. Atrazine followed by simazine and 2,4,6-trichlorophenol were the most ubiquitous compounds detected in this area. The levels detected of the different compounds were in the range of: 0.01-2.73 microg/l, 0.05-0.74 microg/l, 0.02-1.65 microg/l, 0.02-5.43 microg/l, 0.01-0.40 microg/l, 0.01-0.26 microg/l, 0.02-0.61 microg/l, 0.01-3.90 microg/l, 0.01-1.24 microg/l, 0.02-2.3 microg/l, 0.01-0.13 microg/l and 0.01-0.5 microg/l for atrazine, simazine, terbuthylazine, alachlor, metolachlor, Irgarol, propanil; tributhylphosphate, diuron, 2,4,6-trichlorophenol, deisopropylatrazine and deethylatrazine, respectively.     

尿中莠去津去烃基代谢物的特丁二甲硅烷基衍生化/气相色谱-质谱联用分析法

建立了尿中除草剂莠去津(ATRZ)代谢物去乙基莠去津(DEA)、去异丙基莠去津(DIA)及去乙基去异丙基莠去津(DDA)的分析方法.尿样加入内标2-氨基-4-甲氧基-6-甲基-1,3,5-三氮嗪(AMMT),碱化后用高极性GDX501大孔树脂吸附、乙酸乙酯洗脱进行固相萃取,萃取物在乙腈溶剂中用N-甲基-N-特丁二甲硅烷...     

Determination of atrazine, deethylatrazine and simazine in water at parts-per-trillion levels using solid-phase extraction and gas chromatography/ion trap mass spectrometry

Methods for trace analysis of atrazine and simazine in water have been developed by using stable-isotope dilution with detection by gas chromatography/mass spectrometry. D(5)-Atrazine was used as the internal standard for the determination of atrazine and deethylatrazine, while (13)C(3)-simazine was used for simazine analysis. Water samples were fortified with known amounts of the internal standards and submitted to solid-phase extraction with a C(18) bonded-silica cartridge. A gas chromatograph coupled with an ion-trap mass spectrometer was used to analyze the water sample extracts. Method detection limits were 38 parts-per-trillion (ppt) for atrazine and deethylatrazine and 75 ppt for simazine. The accuracy of the method, represented by relative analytical errors, was less than 15%, and the method precision was less than 5% (relative standard deviation, n = 9). The method was successfully applied to analyze surface water samples collected from a reservoir and a river at ppt levels.     

Gas chromatography/ion trap mass spectrometry applied for the analysis of triazine herbicides in environmental waters by an isotope dilution technique

A gas chromatography/ion trap mass spectrometry method was developed for the analysis of simazine, atrazine, cyanazine, as well as the degradation products of atrazine, such as deethylatrazine and deisopropylatrazine in environmental water samples. Isotope dilution technique was applied for the quantitative analysis of atrazine in water at low ng/l levels. One liter of water sample spiked with stable isotope internal standard atrazine-d₅ was extracted with a C₁₈ solid-phase extraction cartridge. The analysis was performed on an ion trap mass spectrometer operated in MS/MS method. The extraction recoveries were in the range of 83-94% for the triazine herbicides in water at the concentrations of 24, 200, and 1000 ng/l, while poor recoveries were obtained for the degradation products of atrazine. The relative standard deviation (R.S.D.) were within the range of 3.2-16.1%. The detection limits of the method were between 0.75 and 12 ng/l when 1 l of water was analyzed. The method was successfully applied to analyze environmental water samples collected from a reservoir and a river in Hong Kong for atrazine detected at concentrations between 3.4 and 26 ng/l.     

Development of a highly sensitive enzyme-immunoassay for the determination of triazine herbicides

A monoclonal antibody (Mab) with extraordinary sensitivity and high class selectivity to triazine herbicides is described. With an enzyme-linked immunosorbent assay (ELISA) using Mab 4A54 IC₅₀ values for terbuthylazine, atrazine, propazine and simazine below 0.1 μg/L (the EU maximum admissible concentration for individual pesticides) have been obtained. Detection limits of 0.004 μg/L for terbuthylazine, 0.006 μg/L for atrazine, 0.003 μg/L for propazine, 0.01 μg/L for simazine and 0.05 μg/L for deethylterbuthylazine could be achieved. Therefore, Mab 4A54 allows a sum screening of these five triazines in a relevant concentration range. To our knowledge, this is the most sensitive antibody to terbuthylazine at all and also the most sensitive Mab to all these four triazines. Another monoclonal antibody resulting from the same immunization, clone 4A118, exhibits best sensitivity for propazine (detection limit: 0.02 μg/L) at lower cross-reactivity to terbuthylazine and atrazine compared to clone 4A54. Affinity constants of both Mabs towards several triazines have been calculated. The application of both Mabs for the analysis of triazines in water samples of different origin has been tested and their resistance towards humic acid influence could be shown. A good correlation of the analysis of water samples with GC and ELISA was observed.     

Development of a highly sensitive enzyme-immunoassay for the determination of triazine herbicides

A monoclonal antibody (Mab) with extraordinary sensitivity and high class selectivity to triazine herbicides is described. With an enzyme-linked immunosorbent assay (ELISA) using Mab 4A54 IC₅₀ values for terbuthylazine, atrazine, propazine and simazine below 0.1 μg/L (the EU maximum admissible concentration for individual pesticides) have been obtained. Detection limits of 0.004 μg/L for terbuthylazine, 0.006 μg/L for atrazine, 0.003 μg/L for propazine, 0.01 μg/L for simazine and 0.05 μg/L for deethylterbuthylazine could be achieved. Therefore, Mab 4A54 allows a sum screening of these five triazines in a relevant concentration range. To our knowledge, this is the most sensitive antibody to terbuthylazine at all and also the most sensitive Mab to all these four triazines. Another monoclonal antibody resulting from the same immunization, clone 4A118, exhibits best sensitivity for propazine (detection limit: 0.02 μg/L) at lower cross-reactivity to terbuthylazine and atrazine compared to clone 4A54. Affinity constants of both Mabs towards several triazines have been calculated. The application of both Mabs for the analysis of triazines in water samples of different origin has been tested and their resistance towards humic acid influence could be shown. A good correlation of the analysis of water samples with GC and ELISA was observed. Received: 17 February 1997 / Revised: 1 April 1997 / Accepted: 3 April 1997     

Development of a sequential injection chromatography (SIC) method for determination of simazine,atrazine, and propazine

This paper describes the development of a sequential injection chromatography (SIC) procedure for separation and quantification of the herbicides simazine, atrazine, and propazine exploring the low backpressure of a 2.5 cm long monolithic C₁₈ column. The separation of the three compounds was achieved in less than 90 s with resolution >1.5 using a mobile phase composed by ACN/1.25 mmol/L acetate buffer (pH 4.5) at the volumetric ratio of 35:65 and flow rate of 40 μL/s. Detection was made at 223 nm using a flow cell with 40 mm of optical path length. The LOD was 10 μg/L for the three triazines and the quantification limits were of 30 μg/L for simazine and propazine and 40 μg/L for atrazine. The sampling frequency is 27 samples per hour, consuming 1.1 mL of ACN per analysis. The proposed methodology was applied to spiked water samples and no statistically significant differences were observed in comparison to a conventional HPLC–UV method. The major metabolites of atrazine and other herbicides did not interfere in the analysis, being eluted from the column either together with the unretained peak, or at retention times well‐resolved from the studied compounds.     

Determination of herbicides by solid phase extraction gas chromatography-mass spectrometry in drinking waters

A solid phase extraction (SPE) method has been optimized for the gas chromatography-mass spectrometry (GC-MS) simultaneous determination of herbicides belonging to the following different families: carbamate (molinate), atrazines (atrazine, propazine, simazine, ametryne, cyanazine, terbutylazine, deethylterbutylazine, deethylatrazine), dinitroaniline (trifluralin, pendimethalin), chloroacetamide (alachlor, metolachlor). Different solid substrates have been compared (C18, cyano, styrene-divinylbenzene, phenyl, graphitic carbon). The type of conditioning and elution solvent, its volume, and the sample flow rate have been considered as variables affecting the recovery yields of the herbicides.The optimized experimental conditions are C18 phase conditioned with 3 mL acetone, loaded with 1 L water sample at 5 mL min⁻¹, and eluted with 3 mL acetone. Good recoveries (included between 79% and 99%) and R.S.D. (included between 2% and 12%) have been obtained for all analytes, except for deethylatrazine whose recovery was 46 ± 7%. The recovery of deethylatrazine increases up to 94 ± 17% if a non-porous graphitic carbon is coupled to the C18 phase, keeping the other parameters constant as optimized. The optimized method has been successfully checked for the identification and quantitation of the selected herbicides in raw and drinking water samples, with quantitation limits as low as 0.01 μg L⁻¹, fully in agreement with the current legislation. The method is easily routinable. After development, the method is currently routinely applied for the analysis of herbicides in waters and, up today, more than one thousand samples have been analysed at the “Laboratorio della Società Metropolitana Acque di Torino” (Laboratory of the Municipal Waterworks of Turin) in charge of the control of drinking water quality in Torino.     

Book Reviews

A gas chromatography/ion trap mass spectrometry method was used for the trace analysis of atrazine and its deethylated degradation product deethylatrazine in environmental water and sediment samples. The isotope dilution technique was applied for the quantitative analysis of atrazine at parts-per-trillion levels. Water samples were pre-concentrated by solid-phase extraction using a C18 cartridge while the sediment samples were extracted by sonication with methanol. The concentrated extracts were analysed by a GC/ion trap MS operated in the MS/MS method. The extraction recoveries for the analytes were better than 83% when 1 L of water or 10 g of sediment was analysed. The method detection limits were 0.75 ng/L and 0.13 ng/g for atrazine and deethylatrazine detected in water and sediment, respectively. The precisions of the method represented by the relative standard deviation were in the range of 3.2-16.1%. The method was successfully applied to analyse surface water and sediment samples collected from Beijing Guanting reservoir. Trace levels of atrazine at 35.9-217.3 ng/L and 2.4-8.4 ng/g were detected in the water and sediment samples, respectively. The levels of deethylatrazine were five to 20 times lower that those of atrazine.     

固相萃取-高效液相色谱法测定环境水样中的三嗪类化合物

建立了固相萃取-高效液相色谱法(SPE-HPLC)测定地表水中三嗪类化合物的方法。考察了4种不同固相萃取柱对三嗪类化合物的吸附效果,最终选择ENVI-18固相萃取柱用于萃取地表水中的三嗪类化合物;系统研究了环境水样中三嗪类化合物的最佳固相萃取条件,选择洗脱溶剂为甲醇,洗脱溶剂用量5 mL,水样在萃取前不需要添加甲醇,不调节pH值。测定了方法的检测限,结果表明,扑草净、莠去津、西玛津、脱乙基莠去津、羟基化莠去津和脱异丙基莠去津的最低检测限依次为0.14 μg/L,0.12 μg/L,0.08 μg/L,0.08 μg/L,0.10 μg/L和0.18 μg/L。将该法应用于实际环境水样的分析测定,结果表明某湖水中扑草净的含量为（9.33±0.27） μg/L,某江水中莠去津和扑草净的含量分别为（5.28±0.43） μg/L和（7.12±0.54） μg/L。     

Factors affecting multiresidue determination of priority herbicides when using solid-phase microextraction

A solid-phase microextraction (SPME) procedure was developed for the determination of 10 selected organonitrogen herbicides (s-ethyl dibropylthiocarbamate [EPTC], molinate, propachlor, trifluralin, simazine, atrazine, propazine, terbuthylazine, alachlor, and prometryn) and was tested with various natural waters. Gas chromatography coupled with flame thermionic and mass spectrometric detection was used for quantitation. For this purpose, polydimethylsiloxane and polyacrylate fibers were used and the factors affecting the SPME process such as pH, ionic strength, methanol content, memory effect, stirring rate, and adsorption-time profile were investigated and optimized. By using spiked liquid chromatography water, optimal factors were determined to be 25% salt, <0.5% methanol, stirring rate of 960 rpm, pH 4, and an equilibrium time of 30 min. These conditions were used in further studies of the fibers and in analysis of natural water samples. The method was applied to spiked natural waters such as ground water, sea water, lake water, and river water at a concentration range of 0.5-10 microg/L. Limits of detection ranged from 5 to 90 ng/L, and precision ranged from 5 to 15% (as relative standard deviation), depending on the pesticide, fiber, and detector used. The recoveries of herbicides were 70.2-118.4%, and the average r2 values of the calibration curves were >0.99 for all analytes. The results demonstrate the suitability of the SPME method to determine these organonitrogen herbicides in various natural waters. River water samples originating from the Epirus region (Northwestern Greece) were analyzed to verify the performance of the optimized method by comparing the results obtained by SPME with those obtained by using conventional solid-phase extraction of the selected herbicides.     

Development of Polarization Fluoroimmunoassay for the Detection of s-Triazine Herbicides

Abstract

A rapid, non-isotopic polarization fluoroimmunoassay (PFIA) for the monitoring of the simazine (striazine herbicide) level in water was developed. Polyclonal antiserum was raised in rabbits by immunization with simazine – Keyhole Limpet Haemocyanin conjugate. Sensitivity of the PFIA with the use of heterologous tracer with the shortest bridge between antigen and fluorescein proved to be the highest. All analytical criteria for PFIA were satisfied. The detection limit of simazine (3 ng/ml in 50 μl of sample) was comparable to that for liquid or gas chromatography method. The detection limit of ELISA using the same antiserum and conjugate derivative of atrazine with horseradish peroxidase was 0.1 ng/mL of simazine. The cross-reactivity for PFIA with widely used s-triazine herbicides: atrazine, propazine, terbuthylazine was 100%, 32% and 20%, respectively. The cross-reactivity for PFIA with some metabolites of s-triazines and other herbicides was negligible.     

Improving the Detectability of Sequential Injection Chromatography (SIC): Determination of Triazines by Exploiting Liquid Core Waveguide (LCW) Detection

Coupling a liquid core waveguide cell to a sequential injection chromatograph improved the detection limits for determination of triazine herbicides without compromising peak resolution. Separation of simazine, atrazine, and propazine was achieved in water samples by a 25 mm long C₁₈ monolithic column. Detection was made at 238 nm using a type II LCW (silica capillary coated with Teflon® AF2400) cell with 100 cm of optical path length. Detection limits for simazine, atrazine, and propazine were 2.3, 1.9, and 4.5 µg L^?1, respectively. Reduced analysis time and low solvent consumption are other remarkable features of the proposed method.     

Confirmation of chlorotriazine pesticides,their degradation products and organophosphorus pesticides in soil samples using gas chromatography-mass spectrometry with electron impact and positive- and negative-ion chemical ionization

Gas chromatography-mass spectrometry (GC-MS) with electron impact (EI), positive-ion chemical ionization (PCI) and negative-ion chemical ionization (NCI) were applied as confirmatory techniques for residue analysis of chlorotriazine pesticides, their degradation products and organophosphorus pesticides in soil samples. Clean-up was effected using a Florisil column with subsequent analysis by GC with a nitrogen-phosphorus detector. GC-MS with the EI mode of operation is the common mode of confirmation for all the pesticides. Further confirmation by either GC-MS with PCI and NCI for chlorotriazines and organophosphorus pesticides, respectively, is recommended. The method was applied to the determination of residue levels of atrazine, deethylatrazine, deisopropylatrazine, simazine, fenitrothion and tetrachlorvinphos in several soil samples at levels from 5 ng g^?1 to 9 μg g^?1.     

气相色谱法分析尿液样品中的阿特拉津及其代谢物

建立了尿液样品中阿特拉津(ATZ)及其代谢物脱乙基阿特拉津(DEA)、脱异丙基阿特拉津(DIA)、脱乙基脱异丙基阿特拉津(DEDIA)的气相色谱分析方法。样品经乙酸乙酯萃取、硫酸钠脱水、弗罗里硅土净化、浓缩后用气相色谱-电子俘获检测器分析。对样品萃取时的pH值等条件进行了优化,获得了较好的回收率。方法的检出限分别为DEDIA 0.0025 mg/L,DEA、DIA、ATZ 0.005 mg/L。4种化合物在进样量为0.2~8 ng时与其峰面积呈良好的线性关系。利用该方法对阿特拉津生产厂工人的尿液样品进行了分析,尿液中4种化合物的质量浓度为：DEDIA 0.003～0.301 mg/L,DEA 0.005～0.011 mg/L,DIA 0.006～0.276 mg/L,ATZ 0.005～0.012 mg/L。     

Immunochemical array for the identification of cross-reacting analytes

A method for the identification and quantification of cross-reacting analytes using competitive immunochemical assays is described. The method uses information both of antibodies with and without significant inhibition caused by a sample. Maximum concentrations of all possible analytes were estimated for all antibodies not showing a significant inhibition. These maximum concentrations could be used to exclude certain analytes from the further identification process. A minimum variance method was used for the identification of analytes from the data given by antibodies showing significant inhibition. All samples were measured in a parallel affinity sensor array (PASA). The PASA system allows the parallel performance of numerous individual immunochemical assays. Triazines were used as a model substance class. Samples containing either atrazine, terbuthylazine, simazine or deethylatrazine at different concentration levels were generated and analyzed in the PASA system. 11 out of 13 samples were correctly identified, 2 samples could not be identified without doubt, no wrong identification was observed. Samples of atrazine, terbuthylazine and simazine at a concentration level of 0.1 μg/L, the EU maximum admissible concentration for individual pesticides, and of deethylatrazine at 0.3 μg/L could be quantified. Received: 25 September 1998 / Revised: 30 November 1998 / Accepted: 5 December 1998