Monitoring of phenylurea and propanil herbicides in river water by solid-phase-extraction high performance liquid chromatography with photoinduced-fluorimetric detection

The separation and determination of five herbicides, including propanil and the phenylureas diuron, isoproturon, linuron and neburon, has been performed by an HPLC method, using photochemically-induced fluorescence detection. The non-fluorescent herbicides were transformed into fluorescent compounds by post-column photochemical reaction. A 60:40 (v/v) acetonitrile-buffer solution of potassium phosphate dibasic (pH 7, 0.01 M) was used for the chromatographic elution to separate propanil, linuron and neburon. The overlapping of isoproturon and diuron peaks, in the selected conditions, was resolved by changing the initial movil phase composition to 50:50 (v/v) methanol-buffer solution of potassium phosphate dibasic (pH 7, 0.01 M). The procedure was applied with satisfactory results to the analysis of these herbicides in Guadiana river water samples (Badajoz, Spain), allowing the detection of herbicide residues in the order of mug l(-1), by using a solid-phase extraction (SPE) pre-concentration step.     

Use of on-line liquid chromatography-nuclear magnetic resonance spectroscopy for the rapid investigation of flavonoids from Sorocea bomplandii

A HPLC method, using photochemically-induced fluorescence detection, is described for the separation and determination of four phenylurea herbicides including diuron, isoproturon, linuron and neburon. A post-column photoreactor, consisting of a reactor knitted around a 4 W xenon lamp, has been included between the column and the detector, in order to transform the non-fluorescent herbicides into fluorophors. The influence of mobile phase composition, flow-rate, pH, and buffer concentration has been studied. An acetonitrile–buffer solution of potassium phosphate dibasic of pH 7 and 0.01 M concentration (60:40, v/v), was selected as optimum. For the fluorimetric detection, optimal excitation/emission wavelengths 324/403, 301/433, 335/411 and 326/385 nm were selected for the determination of diuron, isoproturon, linuron and neburon, respectively. The detection limits ranged between 0.07 and 0.46 μg/ml, according to the compound.     

Multiresidue Analysis of Phenylurea Herbicides in Environmental and Drinking Water by Capillary Electrophoresis

The present paper describes the application of capillary electrophoresis in the micellar mode to the separation and quantitative determination of five phenylurea herbicides, viz. monuron, linuron, diuron, isoproturon, and monolinuron, in water samples. Using uncoated fused silica capillary and phosphate-borate buffer (pH 7.0) containing SDS, the five pesticides are resolved in less than 15 min and quantitatively determined by an ultraviolet detector at 244 nm. Method optimization and validation parameters are presented. Good linearity and repeatability were observed for all the compounds studied (correlation coefficients 0.999). The feasibility of the method developed was tested by simultaneous determination of these herbicides in environmental and drinking water samples at the minimum residue levels (MRLs) (0.1 μg/L) after solid-phase extraction (SPE) preconcentration procedure.     

液相微萃取／高效液相色谱法测定环境水样中的痕量苯脲类除草剂

建立了液相微萃取／高效液相色谱联用(LPME／HPLC)技术同时测定环境水中痕量异丙隆、秀谷隆和灭草隆除草剂的分析方法.考察了不同萃取条件及测定条件对检测结果的影响.优化后的萃取条件为:6μL正辛醇作萃取剂,液滴体积3μL,搅拌速度450 r/min,萃取30 min.结果表明,在优化条件下,3种除草剂的质量浓度在0....     

High-performance liquid chromatography column switching applied to the trace determination of herbicides in environmental and drinking water samples

A selective and sensitive coupled-column high-performance liquid chromatographic method is developed for the simultaneous determination of 5 phenylurea herbicides (monuron, linuron, isoproturon, monolinuron, and diuron) in environmental and drinking water samples. Sample clean-up is performed automatically by means of a column switching technique. Using 2 octadecyl silica columns connected via two programmable 6-port valves and ultraviolet detection at 244 nm, the aforementioned compounds can be determined at the low concentration levels required for pesticide residue analysis in water samples. A mobile phase consisting of a mixture of methanol-water (55:45, v/v) is pumped at 1 mL/min. For the 5 phenylureas, high recoveries ranging from 94.9 to 101.6%, good reproducibility with relative standard deviations lower than 5%, and wide linear ranges up to 20 micrograms/L are observed with determination limits of 0.05 microgram/L. The method is successfully applied to the screening of different environmental water samples such as surface, ground, rain, and drinking water.     

Influence of the solvent on the gas chromatographic behaviour of urea herbicides

Summary Degradation products of chlorsulfuron, chlortoluron, diuron, fluometuron, isoproturon, linuron, metabenzthiazuron, metobromuron, and monuron formed in the gas chromatographic injector have been used for identification of the respective herbicides. Mass spectra of the derived compounds were obtained with a quadrupole mass spectrometric detector working in scan mode (20–450 amu). The compounds generated often depended on the solvent used for phenylurea herbicide injection (ethanol, methanol, dichloromethane, and acetonitrile). When methanol and ethanol were used as solvents the major products formed from phenylureas were carbamic acid esters. When acetonitrile or dichloromethane were used the main derivatives were phenylisocyanates. Chlorsulfuron and metabenzthiazuron, however, generated a triazine plus a phenylsulfonamide and a benzothiazolamine, respectively, irrespective of the solvent used. Linuron and diuron behaved similarly and gave degradation products with the same mass spectra. The thermal reactions occurred instantaneously in the injector block and were promoted by the high temperature selected (300°C). Detemination of the compounds derived from urea herbicides, by use of a 30 m BP10 column and a selected ion registering (SIR) program based on two or three ions, can be used for sensitive detection of the presence of urea herbicides in environmental extracts. With standards in methanol instrument detection limits ranged from 0.1 pg for chlorsulfuron (detected as 2-chlorobenzensulfonamide) to 1 pg for monuron and metobromuron (both detected as their carbamic acid methyl esters).RSD were below 9% at the 5 ng L⁻¹ level. The response was linearly dependent on quantily (r>0.9986) in the 5 ng L⁻¹ to 25 μg L⁻¹ range. Unequivocal identification of some phenylurea herbicides was not always possible because some herbicides with similar structures, for example diuron and linuron, gave the same derivative.     

An Investigation of Inclusion Complexes of Cyclodextrins with Phenylurea Herbicides by Photochemically-Induced Fluorescence. Analytical Applications

The effect of -cyclodextrin (-CD) and hydroxypropyl--cyclodextrin (HP--CD) upon the photochemically-induced fluorescence (PIF) properties of four phenylurea herbicides, including linuron, diuron, isoproturon and neburon has been studied. Photochemical conversion of these nonfluorescent herbicides into strongly fluorescent photoproducts was shown to occur in -CD and HP--CD aqueous media. The influence of pH, UV irradiation time and photoproduct stability on the fluorescence intensity was also investigated. In addition, the stoichiometry and formation constants of the complexes formed between herbicides and -cyclodextrin (-CD) or 2-hydroxypropyl--cyclodextrin (HP--CD) were determined. The formation constant values, ranging from 184 ± 40 to 1498 ± 245 M^-1, were calculated by applying the iterative nonlinear regression (NLR) approach to the PIF data. Linear calibrations graphs were established in the interval 1–12 g/mL, for diuron, linuron and neburon. The IUPAC limits of detection ranged between 580 and 700 ng/mL, according to the compound. Application to the analysis of phenylurea herbicides in spiked river water was also described.     

Determination of linuron and related compounds in soil by microwave-assisted solvent extraction and reversed-phase liquid chromatography with UV detection

The combination of microwave-assisted solvent extraction (MASE) and reversed-phase liquid chromatography (RPLC) with UV detection has been investigated for the efficient determination of phenylurea herbicides in soils involving the single-residue method (SRM) approach (linuron) and the multi-residue method (MRM) approach (monuron, monolinuron, isoproturon, metobromuron, diuron and linuron). Critical parameters of MASE, viz, extraction temperature, water content and extraction solvent were varied in order to optimise recoveries of the analytes while simultaneously minimising co-extraction of soil interferences. The optimised extraction procedure was applied to different types of soil with an organic carbon content of 0.4-16.7%. Besides freshly spiked soil samples, method validation included the analysis of samples with aged residues. A comparative study between the applicability of RPLC-UV without and with the use of column switching for the processing of uncleaned extracts, was carried out. For some of the tested analyte/matrix combinations the one-column approach (LC mode) is feasible. In comparison to LC, coupled-column LC (LC-LC mode) provides high selectivity in single-residue analysis (linuron) and, although less pronounced in multi-residue analysis (all six phenylurea herbicides), the clean-up performance of LC-LC improves both time of analysis and sample throughput. In the MRM approach the developed procedure involving MASE and LC-LC-UV provided acceptable recoveries (range, 80-120%) and RSDs (<12%) at levels of 10 microg/kg (n=9) and 50 microg/kg (n=7), respectively, for most analyte/matrix combinations. Recoveries from aged residue samples spiked at a level of 100 microg/kg (n=7) ranged, depending of the analyte/soil type combination, from 41-113% with RSDs ranging from 1-35%. In the SRM approach the developed LC-LC procedure was applied for the determination of linuron in 28 sandy soil samples collected in a field study. Linuron could be determined in soil with a limit of quantitation of 10 microg/kg.     

毛细管电泳-电致化学发光法测定兔血浆中的羟考酮

基于稀土Eu(Ⅲ)掺杂的类普鲁士蓝膜修饰的铂电极为工作电极,建立了测定羟考酮的毛细管电泳-电致化学发光分析方法。考察了检测电位、运行缓冲溶液的酸度及浓度、分离电压、进样条件等对电泳分离效果及检测灵敏度的影响。在最佳的实验条件下,羟考酮可在4 min内得到分离,其ECL强度值与羟考酮的质量浓度在7.0×10-2～7.0μg/mL和7.0～70.0μg/mL范围内呈良好的线性关系,检出限为4.2×10-2μg/mL(3σ),峰高和迁移时间的相对偏差分别为3.6%和0.48%(n=6)。方法用于兔血浆中羟考酮含量的检测,加标回收率在99.7%～101.0%之间。     

Trace analysis of herbicides in wastewaters by a dispersive liquid–liquid microextraction approach and liquid chromatography with quadrupole linear ion trap mass spectrometry: Evaluation of green parameters

An analytical method for determining phenylureas (monuron, isoproturon, diuron, linuron and neburon) and propanil herbicides in wastewater has been developed and validated, and the most significant parameters were compared with the corresponding ones found in the literature, thus showing the method performance. The method involves pre‐concentration by a simple, rapid, sensitive and low environmental toxicity temperature‐controlled ionic liquid dispersive liquid–liquid microextraction procedure. The herbicides were identified and determined by liquid chromatography with a hybrid triple quadrupole linear ion trap mass spectrometer. Data acquisition in selected‐reaction monitoring mode allowed the simultaneous identification and quantification of the analytes using two transitions. The information dependent acquisition scan was performed to carry out the identification of those analytes whose second transition was present at low intensity, also providing extra confirmation for the other analytes. Limits of quantification were in the range 1.0–5.0 ng/L. Good recoveries (95–103%) were obtained for the extraction of the target analytes in wastewater samples. The methodology developed was applied to analyze effluent wastewater samples from a wastewater treatment plant located in an agricultural zone of Almería (Spain) and the results indicated the presence of diuron at mean concentration levels of 73.5 ng/L.     

Application of new high-performance liquid chromatography and solid-phase extraction materials to the analysis of pesticides in human urine

A method for the simultaneous determination of diuron and linuron pesticides in human urine was developed, using both solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) phases made in our own laboratory. These materials were prepared by sorption of polysiloxanes onto a silica surface, followed by immobilization. The HPLC columns were prepared from poly(methyloctylsiloxane), PMOS, immobilized onto silica with microwave radiation while the SPE cartridges where made with poly(methyloctadecylsiloxane), immobilized thermally. Method validation was performed for diuron and linuron for three fortification levels. The recoveries obtained were 85-103%, the inter- and intra-assay precisions were less than 1.6 and 1.8%, respectively. The limits of quantitation and detection for diuron were 2.4 and 8.0 microg/l and for linuron were 5.0 and 12 microg/l, respectively.     

Compliance analysis of phenylurea and related compounds in drinking water by liquid chromatography/electrospray ionization/mass spectrometry coupled with solid-phase extraction

A liquid chromatography/electrospray ionization/mass spectrometry method was reported for the compliance analysis of seven phenylurea compounds and two related herbicides (tebuthiuron and propanil) in drinking water. The volumes of the sample and final extract used in the method were 500 mL and 10 mL, respectively. The obtained method detection limits were less than 0.03 microg/L, and the mean recoveries were 74-128% with a relative standard deviation of 2.6-8.3% for all the studied compounds. The peak-to-peak signal-to-noise ratios ranged from 3.3 for cis-siduron to 34.2 for fluometuron. The accuracy and precision resulting from reagent and drinking water samples fortified at higher concentration levels were similar to these results. Several analytes were detected in the drinking water samples, including tebuthiuron at 0.5 microg/L, propanil at 0.7 microg/L, diuron at 0.1-2.1 microg/L, and linuron at 0.1-0.8 microg/L.     

Development of a rapid, specific fluorescence polarization immunoassay for the herbicide chlorsulfuron

A strategy for design of a derivative of chlorsulfuron, which mimics half of the herbicide molecule, was proposed. The 1-[(2-chloro)phenylsulfonyl]monoamidosuccinic acid was synthesized as a derivative of chlorsulfuron for conjugation to carrier proteins. Rabbits were immunized and the resulting polyclonal antibodies were assessed by the fluorescence polarization technique. The antibodies were highly specific to chlorsulfuron. Cross-reactivity to the structurally similar sulfonylurea and urea herbicides chlorbromuron, amidosulfuron, chlortoluron, isoproturon, diuron and linuron was less than 0.1%. A rapid fluorescence polarization immunoassay (FPIA) for chlorsulfuron detection in water samples was developed and optimized. The detection limit of chlorsulfuron in 50 μl of sample was 10 ng ml⁻¹. Total time for the measurement of 10 samples is 7 min. The proposed FPIA is suitable for rapid testing for pesticide contamination where the highest sensitivity is not critical or in combination with pre-concentration techniques.     

Determination of Maleic Hydrazide in Potato Samples Using Capillary Electrophoresis with Dual Detection (UV‐Electrochemical)

A new method for the separation of a mixture of different herbicides (propham, chlorpropham, asulam, metamitron, linuron, and maleic hydrazide) using MEKC is proposed. A base‐line separation for the mixture of herbicides is achieved in less than six minutes. The detection limits obtained for all the herbicides were lower than 1.0 μM using UV detection. This separation method was used for the determination of maleic hydrazide in potato samples. If a dual (UV‐electrochemical) detection system is employed, chlorpropham can be also detected. The results obtained showed that electrochemical detection was ten folds more sensitive than UV detection for maleic hydrazide. The detection limit of the proposed method for maleic hydrazide employing electrochemical detection was 1.3 μg g^?1, this value is lower than 50 μg g^?1, which is the maximum residue level permitted for this plant growth regulator in potato samples. The results obtained in the work clearly demonstrate the advantage of using electrochemical detection coupled to capillary electrophoresis, using this detection the concentration limits are not compromised by miniaturization and the components required are simple and inexpensive.     

气相色谱-串联质谱检测烟草中15种苯氧羧酸类除草剂残留

建立了气相色谱-串联质谱技术对烟草中15种苯氧羧酸类除草剂农药残留量的分析方法。样品采用乙腈提取、Carbon TPT固相萃取柱净化、三甲基硅烷化重氮甲烷衍生化,采用气相色谱-串联质谱对15种苯氧羧酸类除草剂进行测定,通过保留时间、选择离子及相对丰度定性,外标法定量。结果表明,15种苯氧羧酸类除草剂在20~1 000μg/L浓度范围内均呈良好线性关系,相关系数大于0.992,检出限为0.9~3.3μg/kg,定量下限为3.2~10.8μg/kg。在20,100,200μg/kg 3个加标水平下的平均回收率为71.5%~105.6%,相对标准偏差(RSD)为4.5%~14.9%。该方法简便、快速、灵敏,适用于烟草中15种苯氧羧酸类除草剂的同时检测。     

毛细管电泳-电致化学发光法测定土壤中的多抗霉素B

以稀土铕离子(Ⅲ)掺杂的类普鲁士蓝膜(Eu-PB)修饰铂电极为工作电极,采用毛细管电泳-电致化学发光法(CE-ECL)对土壤中的多抗霉素B进行检测.分别对毛细管电泳分离条件和电致化学发光检测条件进行优化,并探讨了体系产生电致化学发光的机理.在优化实验条件下,多抗霉素B可在4 min内得到分离,其ECL强度值与多抗霉素B...     

固相萃取-毛细管电泳法测定兔血清中的山莨菪碱对映体

建立一种可用于定量的毛细管电泳法分离山莨菪碱对映体. 系统研究了三种手性选择剂: 羟丙基-β-环糊精 (HP-β-CD), 甲基-β-环糊精 (Me-β-CD), 羧甲基-β-环糊精(CM-β-CD) 及其浓度、缓冲溶液浓度和 pH 对山莨菪碱拆分的影响. 在110 mmol/L Tris-H3PO4缓冲液中加入20.0 mg/mL HP-β-CD和5.0 mg/mL CM-β-CD (pH 4.0)条件下, 山莨菪碱的4个对映体达到基线分离. 血清样品通过固相萃取预处理和浓缩, 对映体的固相萃取回收率在82.9%～90.7%, 相对标准偏差RSD%均小于7 %. 山莨菪碱的4个对映体血标准溶液浓度与电泳峰面积在77.86～0.39 μg/mL范围内呈良好的线性, r≥0.999, 检出限(S/N＝3)为0.08 μg/mL. 平均日间和日内精密度(RSD% )分别小于6.1% 和4.8%, 方法回收率为97.4% 和105.4%. 建立的方法准确、可靠, 应用于监测兔连续3 d口服75 mg 山莨菪碱后血清中山莨菪碱的血药浓度, 结果满意.     

Gas chromatographic behaviour of urea herbicides

Summary Gas chromatographic conditions for determining eight phenylurea (chlortoluron, diuron, fluometuron, isoproturon, linuron, metabenzthiazuron, metobromuron and monuron) and one sulfonylurea (chlorsulfuron) herbicides were assessed. Degradation products of the herbicides formed in the injector were used for identification. Most phenylureas formed their respective carbamic acid methyl esters, metabenzthiazuron formed an aminobenzothiazol and chlorsulfuron formed an aminotriazine plus a phenylsulfonamide. On-column injection of standards using a BP10 capillary column was evaluated to identify the chromatographic behaviour. Detection limits ranged from 0.05 ng for chlorsulfuron to 3 ng for monuron with the NPD and, from 0.01 ng for chlorsulfuron to 5 ng for metabenzthiazuron with the ECD. The RSDs (n=4) were lower than 4% at the 12–25 ng level. The method was applied to the analysis of surface waters extracted with C18 Empore disks with recoveries higher than 85%. Each herbicide could be determined in water down to 0.1 μg·L⁻¹. Chlortoluron was found (11.4 μg·L⁻¹) in a water sample and its presence was confimed by gas chromatography-mass spectrometry.     

二元环糊精体系对柴胡中柴胡皂苷a与柴胡皂苷d的毛细管电泳分离测定

以磺丁基-B-环糊精(SBE-β-CD)和β-环糊精(β-CD)组成二元手性选择体系,用毛细管电泳法对柴胡中的柴胡皂苷a及柴胡皂苷d进行分离测定.考察了缓冲液的组成和浓度、手性选择剂的组成和浓度、进样方式及样品介质等对灵敏度和分离度的影响.结果表明:采用熔融石英毛细管柱(60 cm×50 μm i.d,有效长度为53 ...     

超高效液相色谱-串联质谱法分析鸡蛋中利巴韦林及其代谢物残留

建立了超高效液相色谱-串联质谱法同时快速测定鸡蛋中利巴韦林及其两种主要代谢物 TCONH2和RTCOOH 的分析检测方法。样品采用乙腈-水(9∶1, V/ V)提取,乙腈饱和正己烷除脂,C18结合 GCB 进行固相分散萃取除杂,Agilent ZORBAX SB-Aq 色谱柱(100 mm ×3.0 mm,1.8μm)分离,超高效液相色谱-串联质谱测定。结果表明：利巴韦林、TCONH2和 RTCOOH 分别在2.0~200μg/ L,0.5~200μg/ L,5.0~200μg/ L 浓度范围内,线性良好,相关系数 R2>0.99,检出限分别为0.54,0.09和1.54μg/ L,定量限分别为1.79,0.31和5.13μg/ L。在5.0,10.0和50.0μg/ L 加标水平下,利巴韦林和 RTCOOH 回收率分别为96.1%~99.6%和42.9%~58.3%;在0.5,2.0和5.0μg/ L 加标水平下,TCONH2的回收率为75.9%~106.7%,相对标准偏差均为4.2%~12.7%。实际样品测定结果表明,本方法操作简单、快速、准确,能够满足鸡蛋中利巴韦林及其两种主要代谢物的分析检测。