Multiresidue analysis of pesticides in vegetables and fruits by gas chromatography/mass spectrometry after gel permeation chromatography and graphitized carbon column cleanup

A multiresidue method for pesticides that enables quantitative, sequential analysis of a large number of vegetable and fruit samples by gas chromatography/mass spectrometry has been developed. First, 89 important target compounds were selected for monitoring, and then the appropriate internal standards for these pesticides, 14 stable isotopically labeled pesticides (surrogates), were used. The sample was extracted with acetonitrile, and the extract was cleaned up by a salting-out step followed by redissolution in ethyl acetate. Coextractives were removed automatically by gel permeation chromatography with a graphitized carbon column, and then by use of a tandem silica-gel/PSA cartridge column. Recoveries of 82 of the 89 pesticides from fortified spinach, tomato, apple, and strawberry were within a range from 70 to 120%, and the relative standard deviation values of 80 of the 89 pesticides were <5%. The method was applied to 188 commercial vegetable and fruit samples to demonstrate its use in routine analysis.     

Multi-residue determination of organochlorine pesticides in vegetables in Kirklareli,Turkey by gas chromatography–mass spectrometry

The aim of this study was to investigate the level of organochlorine pesticides use for treatment of tomatoes, eggplants and cucumbers in Kirklareli, Turkey. Eighteen organochlorine pesticides were identified in vegetable samples using microwave or Soxhlet extraction, and results were obtained by gas chromatography–mass spectrometry. The optimized conditions were 1 mL/min for flow rate in the mobile phase, 1 μL for injection volume and 70 V for fragmentation potential. The analytical parameters show that the microwave oven extraction procedure provided the best results when compared to the Soxhlet extraction procedure. Samples were prepared for analysis with hexane?dichlormethane (1: 1, v/v, 40 mL) using a solid-phase extraction method. The limits of detection and quantitation for the eighteen analytes were between 0.02–0.26 and 0.06–0.87 μg/L, respectively, and the relative standard deviations of the migration time ranged from 2.4 to 8.9%. The recoveries of surrogate spiked in vegetable samples ranged from 70 to 116%, respectively. The obtained concentrations of pesticides in all vegetables studied were proved in the range of ND–123 μg/kg. The organochlorine pesticide sum was below the legal limit, except for Endrin and Methoxychlor, which requires a further elucidation of the organochlorine pesticides pollution sources in the region. These studies on accumulation of organochlorine pesticides were necessary for accomplishing a comprehensive ecological risk assessment.     

Determination of carbamate residues in fruits and vegetables by matrix solid-phase dispersion and liquid chromatography-mass spectrometry

Thirteen carbamates were analysed in orange, grape, onion and tomatoes by matrix solid-phase dispersion (MSPD) followed by liquid chromatography-mass spectrometry (LC-MS). Electrospray (ES) and atmospheric pressure chemical ionisation (APCI) were compared and both gave similar results in terms of sensitivity and structural information because at 20 V fragmentor voltages the fragmentation is minimal. The efficiency of different solid-phases (C18, C8, cyano, amine and phenyl) for the MSPD was compared. Mean recoveries using C8 varied from 64 to 106% with relative standard deviations of 5-15% in the concentration range of 0.01-10 mg kg(-1). Matrix constituents did not interfere significantly with the ionisation process of carbamates. The limits of detection were typically in the 0.001-0.01 mg kg(-1) range, which were between 10 and 100 times lower than the maximum residue levels (MRLs) established by the European Union (EU). The method was applied to residue detection in fruit and vegetable samples taken from Valencian markets, in which carbamates were detected at low concentrations.     

高效液相色谱法同时测定蔬菜水果中的12种农药残留

建立了同时测定蔬菜水果中12种农药残留的反相高效液相色谱分析方法。将样品捣碎,用乙酸乙酯超声提取,经Florisil固相萃取柱净化、正己烷-二氯甲烷(体积比为1∶1)洗脱、氮气吹干、甲醇溶解并定容后,采用高效液相色谱柱分离、紫外检测,以外标法定量。结果表明：12种农药标准曲线的线性相关系数范围为0.9985~0.9999;检测限为0.14~2.65 ng;在水果中的平均加标回收率为62.2%~118.2%,相对标准偏差(RSD)为0.56%~11.8%;在蔬菜中的平均加标回收率为52.1%~124.6%,RSD为0.89%~18.4%。用所建立的方法成功地测定了白菜、莲白、黄瓜、苹果、梨等40份样品中的农药残留。方法具有快速、简便、准确、灵敏、重现性较好的特点,适合于蔬菜水果样品中多种微量农药残留的测定。     

Ultra-performance liquid chromatography for the determination of pesticide residues in foods by tandem quadrupole mass spectrometry with polarity switching

An ultra-performance liquid chromatographic (UPLC) electrospray ionisation tandem quadrupole mass spectrometric method has been developed for the determination of 52 pesticides in cereal-based baby foods, oranges and potatoes. The fast polarity switching capability of the mass spectrometer used enabled the determination of 44 of the compounds in the positive ionisation mode and 8 of the compounds in the negative ionisation mode in a single run. Prior to analysis, co-extractives were removed from acetonitrile extracts using dispersive solid-phase extraction with primary secondary amine (50 mg). The UPLC method separates all of the pesticides, resolves structural isomers (e.g. butocarboxim sulfoxide and aldicarb sulfoxide) and has a short (7 min) cycle time. Extracts spiked with pesticides at 0.10 and 0.01 mg kg(-1) yielded average recoveries in the range of 66-124% with relative standard deviations less than 19% for the majority of the analytes.     

分散固相萃取-气相色谱-三重四极杆质谱分析蔬菜中112种农药残留

评价了分析过程中不同条件下使用分散固相萃取(D-SPE)材料净化对农残分析定量结果可靠性的影响,表明通过条件优化,可明显减小定量误差,并取得满意的回收率。建立了蔬菜中112种农药的多反应监测-气相色谱-串联质谱(GC-MS/MS)检测方法。在pH 5～7范围内,样品经乙腈-甲苯(8:1, v/v)匀浆提取,每5 mL提取液加入0.8 g无水硫酸镁、0.05 g石墨化炭黑(GCB)、0.1 g乙二胺-N-丙基甲硅烷(PSA)、0.05 g C18粉末,分散固相萃取法净化,采用气相色谱-三重串联四极杆质谱(GC-QQQ-MS/MS)在多反应监测模式(MRM)下进行测定,内标法定量。分别对韭菜、黄瓜、紫甘蓝进行3个水平的加标回收试验(20、50、200 μg/kg),其回收率范围为53.1%～138.7%,其中86种农药的3个加标水平的回收率范围均为65.0%～120.0%,方法的相对标准偏差(RSD)小于12%,方法的定量限(LOQ)范围为1.6～13.4 μg/kg。对从市场采集的蔬菜样品进行了测定,检出了三唑磷、甲氰菊酯等农药残留。该方法样品前处理简单快速,灵敏度、准确度和精密度均符合农药多残留检测技术的要求,适用于蔬菜中112种农药残留的快速筛查测定。     

Simultaneous multi-residue pesticide analysis in soil samples with ultra-high-performance liquid chromatography–tandem mass spectrometry using QuEChERS and pressurised liquid extraction methods

To assess soil contamination, it is important to be able to measure different classes of pesticides simultaneously. For this reason we developed a sensitive ultra-high-performance liquid chromatography–tandem mass spectrometry method for the simultaneous analysis of 25 pesticides in soil samples. Multi-class pesticides (triazines, phenylureas, phenoxy acid pesticides etc.) were analysed using a single mass spectrometry method with a fast polarity switching option, allowing the analysis of 19 compounds in the positive ionisation mode and six compounds in the negative ionisation mode. Extraction of pesticides from soil samples was performed employing a pressurised liquid extraction (PLE) and a quick, easy, cheap, effective, rugged and safe (QuEChERS) procedure, recently developed for the extraction of multi-residue pesticides from food matrices. The extraction efficiency, performance and recoveries of these two procedures were evaluated and compared. In addition, we studied the effect of matrix on signal suppression or enhancement. Isotope-labelled internal standards (ILIS) were used to compensate the suppression or enhancement of signal intensities in the extracted samples. The method was validated using reference soil material (EUROSOIL 7) spiked with 50 μg/kg of each pesticide. The average recovery by PLE varied between 65.1% and 122.2% with RSDs of 1.7–23.4%. QuEChERS provided better recoveries for most of the pesticides, the extraction recovery ranging from 79.4% to 113.3% with RSDs of 1.0–12.2%. Limits of quantification for all target compounds were within a range of 0.1–2.9 µg/kg.     

Analysis of artemisinin by a packed-column supercritical fluid chromatography-atmospheric pressure chemical ionisation mass spectrometry technique

A packed-column supercritical fluid chromatography-atmospheric pressure chemical ionisation mass spectrometry method was studied for the determination of artemisinin from Artemisia annua L. extracts. The technique does not require any kind of derivatisation prior to the analysis. All samples were simply dissolved in methanol and injected into the mobile phase. Detection was achieved by using mass spectrometry with atmospheric pressure chemical ionisation. The ionisation technique is relatively soft and provides protonated molecular ion and informative structural fragmentation for the compound. Benzophenone was used as a chromatographic standard for the determination of the analytical reproducibility. The supercritical carbon dioxide mobile phase used in the system was modified by 10% methanol. The average absolute retention time was 3.54 min with a standard deviation of 0.017 min and a relative standard deviation of 0.4% with respect to benzophenone for the procedure. The correlation coefficient was 0.998 and detection limit 370 pg on column.     

Multicomponent determination of pesticides in vegetables by gas chromatography with mass spectrometric detection and multivariate calibration

Three multivariate calibration methods, partial least squares (PLS-1 and PLS-2) and principal component regression (PCR), were applied for the first time to the simultaneous determination of a mixture of six pesticides in vegetables samples by gas chromatography with mass spectrometric detection (GC-MS). PLS-1 method showed better prediction ability than PLS-2 and PCR methods. The GC-MS chromatograms obtained of vegetable samples spiked with the target pesticides were used to build the calibration matrix. The PLS-1 models were evaluated by predicting the concentrations of independent test samples. Also, the proposed models were successfully applied for the determination of these pesticides in vegetable samples after an extraction step with dichloromethane. By using the first derivative signals in PLS-1 models, simultaneous determination of the compounds was not improved.     

Multi-residue method for the analysis of 101 pesticides and their degradates in food and water samples by liquid chromatography/time-of-flight mass spectrometry

A comprehensive multi-residue method for the chromatographic separation and accurate mass identification of 101 pesticides and their degradation products using liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS) is reported here. Several classes of compounds belonging to different chemical families (triazines, organophosphorous, carbamates, phenylureas, neonicotinoids, etc.) were carefully chosen to cover a wide range of applications in the environmental field. Excellent chromatographic separation was achieved by the use of narrow accurate mass windows (0.05 Da) in a 30 min interval. Accurate mass measurements were always below 2 ppm error for all the pesticides studied. A table compiling the accurate masses for 101 compounds together with the accurate mass of several fragment ions is included. At least the accurate mass for one main fragment ion for each pesticide was obtained to achieve the minimum of identification points according to the 2002/657/EC European Decision, thus fulfilling the EU point system requirement for identification of contaminants in samples. The method was validated with vegetable samples. Calibration curves were linear and covered two orders of magnitude (from 5 to 500 microg/L) for most of the compounds studied. Instrument detection limits (LODs) ranged from 0.04 to 150 microg/kg in green-pepper samples. The methodology was successfully applied to the analysis of vegetable and water samples containing pesticides and their degradation products. This paper serves as a guide for those working in the analytical field of pesticides, as well as a powerful tool for finding non-targets and unknowns in environmental samples that have not been previously included in any of the routine target multi-residue methods.     

Determination of pesticides in soil samples by supercritical fluid chromatography-atmospheric pressure chemical ionisation mass spectrometric detection

This paper presents an analytical technique for the determination of pesticides in soil by packed-column supercritical fluid chromatography interfaced with atmospheric pressure chemical ionisation mass spectrometry (pSFC-APCI-MS). The technique provides a versatile method for the detection and quantification of pesticides belonging to three different commonly used classes, triazines (ametryne, atrazine), carbamates (carbofuran) and sulfonylureas (chlorsulfuron, metsulfuron methyl and benzsulfuron methyl). The APCI mass spectra for all the pesticides studied consisted of protonated molecule ions as the most abundant ion at low cone voltages, except for metsulfuron methyl and benzsulfuron methyl, which gave a fragment ion as the most abundant ion with the protonated molecule ion at low intensity. Increasing the cone voltage provided informative fragmentation patterns for all species. The technique shows good linearity over the concentration range of 0.1-50 micrograms ml-1, with r2 values as follows: atrazine 0.997, ametryne 0.995, carbofuran 0.999, benzsulfuron methyl 0.999, chlorsulfuron 0.995 and metsulfuron methyl 0.997. The detection limits in the selected ion mode were atrazine 201, ametryne 144 and carbofuran 385 pg, which were calculated by using the standard solution, and benzsulfuron methyl 2.045, chlorsulfuron 1.435 and metsulfuron methyl 2.414 ng, which were determined by using spiked soil samples. The pSFC-MS system was shown to have a high degree of reproducibility. The technique was then applied to the determination of the above pesticides in soil samples. The results obtained show that there is no matrix effect from the soil and that the detection limits for all pesticides in soil were similar to those found for the standard solutions.     

Multi-residue method for rapid screening and confirmation of pesticides in crude extracts of fruits and vegetables using isocratic liquid chromatography with electrospray tandem mass spectrometry

A LC-MS-MS method capable of the quantitative determination of a range of pesticide residues present in crude extracts from a variety of fruit and vegetables has been developed. Isocratic LC conditions have been used in conjunction with electrospray ionisation tandem mass spectrometry to detect and identify up to 38 pesticides presented as various mixtures in different matrices. The utility of the method is demonstrated by the analysis of crude extracts, with no sample clean up, from grape, kiwi fruit, strawberry, spinach, lemon, peach and nectarine. Mean recoveries ranging from 63 to 96% with relative standard deviations < 20% were obtained for 30 of the 38 pesticides following analysis of organic produce fortified at concentrations between 0.01 and 0.8 mg/kg. Detected residues were quantified from interpolation against calibration data generated using matrix-matched standards that covered analyte concentration ranges between 0.005 and 0.8 microg/ml. Conditions suitable for the qualitative and quantitative confirmation of residues detected in samples are specified.     

Application of fabric phase sorptive extraction with gas chromatography and mass spectrometry for the determination of organophosphorus pesticides in selected vegetable samples

In the present work, a high‐efficiency and solvent minimized microextraction technique, fabric phase sorptive extraction followed by gas chromatography and mass spectrometry analysis is proposed for the rapid determination of four organophosphorus pesticides (terbufos, malathion, chlorpyrifos, and triazofos) in vegetable samples including beans, tomato, brinjal, and cabbage. Fabric phase sorptive extraction combines the beneficial features of sol‐gel derived microextraction sorbents with the rich surface chemistry of cellulose fabric substrate, which collectively form a highly efficient microextraction system. Fabric phase sorptive extraction membrane, when immersed directly into the sample matrix, may extract target analytes even when high percentage of matrix interferents are present. The technique also greatly simplifies sample preparation workflow. Most important fabric phase sorptive extraction parameters were investigated and optimized. The developed method displayed good linearity over the concentration range 0.5–500 ng/g. Under optimum experimental conditions, the limits of detection were found in the range of 0.033 to 0.136 ng/g. The relative standard deviations for the extraction of organophosphorus pesticides were < 5%. Subsequently, the new method was applied to beans, tomato, brinjal, and cabbage samples. The results from the real sample analysis indicate that the method is green, rapid, and economically feasible for the determination of organophosphorus pesticides in vegetable samples.     

Determination of traces of five antifouling agents in water by gas chromatography with positive/negative chemical ionisation and tandem mass spectrometric detection.

A highly selective and sensitive gas chromatography-mass spectrometry methodology has been developed for the determination of five antifouling compounds, currently licensed for use in marine antifouling paints. The procedure uses an ion trap mass spectrometer provided with an external ion source that allows the combined use, in the same analysis, of positive (PCI) and negative (NCI) chemical ionisation and tandem mass spectrometric fragmentation (MS-MS). Ionisation and fragmentation processes were optimised individually for each compound, thus, permitting maximum sensitivity and selectivity to be obtained. A complete validation study, including those aspects that affect both correct quantification and unequivocal confirmation, demonstrated the good performance of the proposed method. Detection limits obtained were lower than 0.005 microg l(-1), except for Irgarol 1051 (0.050 microg l(-1)). The method was applied to real seawater samples from different     

纳米SiO2膜新型萃取头固相微萃取测定蔬菜中5种农药残留量的研究

建立了以纳米SiO2膜为萃取头涂层的固相微萃取(SPME)-气相色谱(GC)联用测定蔬菜中5种农药残留 (p,p′-DDD, p,p′-DDE, o,p′-DDT, p,p′-DDT, 联苯菊酯)的新方法. 探讨并优化了萃取时间、萃取温度和转子转速等参数.     

Determination of pesticides originating from golf courses by solid-phase extraction and liquid chromatography-tandem mass spectrometry

A multi-residue method using liquid chromatography coupled to triple quadrupole tandem mass spectrometry (LC-MS/MS), associated with solid-phase extraction (SPE), was developed for the determination of 21 pesticides in water samples. The compounds investigated are used for the maintenance of golf courses and ordinarily measured by gas chromatography-mass spectrometry (GC-MS). Electrospray ionisation (ESI) was applied to all compounds, and LC and MS conditions were optimised to measure them under SRM mode. This method showed excellent linearity ranges for all pesticides, with correlation coefficients greater than 0.996. Two kinds of extraction cartridges, namely, styrene divinylbenzene polymer (Sep-Pak PS-2) and divinylbenzene-N-vinylpyrrolidone copolymer (Oasis HLB), were tested and the extraction conditions were optimised. All the pesticides were determined using acetonitrile and ethyl acetate as eluents in both cartridges, and good recoveries (>77%) and repeatability with low relative standard deviations (RSDs, <12%) were achieved from ultra-pure water. In addition, satisfactory recoveries (>76%) and low intra-day and inter-day RSDs (<15%) of all pesticides were also obtained with the Sep-Pak PS-2 cartridge when using river water. The method limits of detection (LODs) ranged between 0.068 (diazinon) and 3.9 (triclopyrbutoxyethyl)?ng?L^?1. The analytical method was successfully applied for the determination of pesticides in surface river water.     

有机氯农药残留检测的快速样品前处理效果研究

应用快速样品前处理技术（QuEChERS）与《NY/ T 761-2008 蔬菜和水果中有机磷、有机氯、拟除虫菊酯和氨基甲酸酯类农药多残留的测定法》（NY/ T 761-2008）的前处理方法处理农产品样本,采用气相色谱检测多种农产品中有机氯农药残留量. 分析了 QuEChERS 法前处理用于有机氯农残检测的效果. 结果表明：QuEChERS 法前处理测定18 种有机氯农药残留加标回收率在72. 1% ~ 123. 9%之间,RSD 在0. 5% ~ 19. 1%之间,有72. 2%的农药检出限大于等于 NY/ T 761-2008 方法,只有27. 8%略低于 NY/ T 761-2008 方法,对多种蔬菜水果的测试均符合多农残检测方法要求,结果准确可靠. QuEChERS 法前处理消耗的有机溶剂少、处理速度快、选择性强、回收率高、精密度高、实用性强、安全性更高. 检测有机氯农残时,可在-般情况下替代 NY/ T 761-2008 的前处理方法.     

气相色谱双柱法和气相色谱-质谱法在蔬菜农药多残留检测中的应用

在各种蔬菜的多种残留农药的检测中,蔬菜的基体常对农药的检测带来严重干扰。试样的预处理选用了较为简单的乙腈萃取法,以避免造成农药的损失。有机含磷农药的GC检测采用FPD检测器,而有机含氯农药及菊酯类农药用GC-ECD检测器,为了使被测农药能与干扰物质达到更好的分离,采用了具有不同极性的两个色谱柱。尽管如此,有时仍可能获得假结果（例如假阳性结果等）。为此进一步采用GC与MS联用的检测措施,使上述问题得以澄清。按所提出的方法,使多种共存的农药的检测,在准确性及可靠性方面得到很大提高。     

Monitoring multi-class pesticide residues in fresh fruits and vegetables by liquid chromatography with tandem mass spectrometry

A new analytical method was developed using liquid chromatography with tandem mass spectrometry for the routine analysis of 31 multi-class pesticide residues and applied to approximately 50 fresh fruit and vegetable samples (green bean, cucumber, pepper, tomato, eggplant, watermelon, melon and zucchini). Extraction of the pesticides with ethyl acetate was carried out. The optimal ionisation conditions were selected for each pesticide in the same run. The procedure was validated and the values of some merit figures, such as recovery, precision, linear range, detection limit and quantification limit for each pesticide were calculated together with its calculated expanded uncertainty (U). The average recoveries in cucumber obtained for each pesticide ranged between 74 and 105% at two different fortification levels (n = 10 each) that ranged between 9 and 250 ng g(-1) (depending on the pesticide). The uncertainty associated to the analytical method was lower than 23% for all compounds tested. The calculated limits of detection and quantitation were typically <1 ng g(-1) that were much lower than the maximum residue levels established by European legislation.     

气相色谱-负化学电离质谱法测定食用植物油中5种酰基吡唑类农药残留

建立了气相色谱-负化学电离质谱联用技术测定食用植物油中5种酰基吡唑类农药（呋吡菌胺、吡噻菌胺、氟唑菌苯胺、吡唑特、苄草唑）残留量的检测方法。样品经乙腈冷冻提取，分散固相萃取技术（QuEChERS）净化，采用基质校正曲线外标法定量。在20~1000 μg/L范围内，所有目标物的峰面积与其质量浓度均呈现良好的线性关系，定量限均低于2 μg/kg，能满足国内外的限量要求。在0.01、0.02、0.05 mg/kg 3个添加水平下，所有农药的平均回收率均处于82.7%~112.4%之间，相对标准偏差≤ 12.3%。该法准确度较高，精密度较好，灵敏度高，可用于食用植物油中酰基吡唑类农药残留量的测定。