Evaluation of different sample treatments for determining pesticide residues in fat vegetable matrices like avocado by low-pressure gas chromatography-tandem mass spectrometry

A multi-residue method has been developed for determining 65 pesticide residues in greasy vegetable matrices such as avocado. Conventional organic solvent extraction assisted by a high-speed homogenizer was compared to pressurized liquid extraction (PLE) as extraction techniques. Following this, the lipophilic extract was purified using gel permeation chromatography (GPC). Alternative clean-up methods were also evaluated, as solid-phase extraction cartridges individually used and downstream coupled, but less effective lipophilic separation was archived. The pesticide residue determination was carried out using low-pressure gas chromatography coupled to tandem mass spectrometry (LP-GC-MS-MS), showing the applicability of this type of GC columns for the analysis of fat vegetable matrices. The proposed methodology was validated in avocado matrix. The recoveries were in the range 70-110%, with RSD values lower than 19%, at 12 and 50 microg/kg spiking levels. The limits of quantitation (LOQs) were in the range 0.04-8.33 microg/kg and the limits of detection (LODs) were between 0.01 and 2.50 microg/kg. All of them were lower than the maximum residue levels (MRLs) set by the European Union (EU) in avocado. The proposed method was evaluated analyzing pesticide residues in real avocado samples.     

Application of hollow fiber supported liquid membrane extraction to the simultaneous determination of pesticide residues in vegetables by liquid chromatography/mass spectrometry

A new analytical procedure using a hollow fiber supported liquid membrane (HFSLM) has been developed for the simultaneous determination of pesticide residues in vegetables by liquid chromatography (LC) coupled with electrospray mass spectrometry (MS). The extraction technique requires minimal sample preparation and solvent consumption. Optimum extraction conditions have been evaluated with respect to sample pH, ionic strength, liquid membrane composition, extraction time, stirring rate and acceptor composition. The extraction method has been validated for matrices such as cucumber, tomato and pepper, indicating that cucumber can be selected as representative matrix for routine analysis of these food commodities. Linear ranges of pesticides in vegetable samples were 10 to 200 microg/kg, and the repeatability of the method was less than 20% for the lowest calibration point. The limits of detection ranged from 0.06 to 2.7 microg/kg and the limits of quantification from 0.2 to 9.0 microg/kg, which were low enough to determine the pesticide residues at concentrations below or equal to the maximum residue levels (MRLs) specified by European Union. The method was finally applied to the determination of more than 20 pesticides in market vegetable samples and the concentrations found in these samples were always lower than the MRLs. This new approach can be considered as a powerful alternative to the traditional extraction techniques.     

Simultaneous determination of carbamate and organophosphorus pesticides in fruits and vegetables by liquid chromatography-mass spectrometry

A liquid chromatography-mass spectrometry (LC-MS) method was established for the purpose of simultaneous determination of carbamate and organophosphorus (OPPs) pesticides in fruits and vegetables. Samples were extracted with acetonitrile; and then prepared by dispersive solid-phase extraction (dispersive-SPE) with primary secondary amine (PSA) as the sorbent. Four common representative samples (tomato, apple, carrot, and cabbage) were selected from the supermarket to investigate the effect of different matrices on pesticides recoveries and assay precision after spiking samples with 0.05 mg/kg. Matrix composition did not interfere significantly with the determination of the pesticides. The obtained recoveries were, with a few exceptions, in the range of 70-110% with RSDs less than 8%. It was applied to pesticide residue monitoring in vegetables and fruits from local markets.     

A new multi-residue method for analysis of pesticide residues in fruit and vegetables using liquid chromatography with tandem mass spectrometric detection

A new multi-residue method for determination of pesticide residues in a wide variety of fruit and vegetables, using the National Food Administration (NFA) ethyl acetate extraction and determination by means of LC-MS/MS, is presented. The method includes pesticides normally detected by LC-UV or LC-fluorescence such as benzimidazoles, carbamates, N-methylcarbamates and organophosphorus compounds with an oxidisable sulphide group as well. After extraction with ethyl acetate, the extract is concentrated and an aliquot of the extract is evaporated to dryness and redissolved in methanol before injection on LC-MS/MS. The method has been validated for 57 different pesticides and metabolites. Representative species from different commodity groups were chosen as matrices in order to study the influence from different matrices on recoveries. The fortification levels studied were 0.01-0.5 mg kg(-1). Matrix effects were tested for all matrices by means of standard addition to blank extracts. The matrix effect, expressed as signal in solvent compared to signal in matrix, was in general found to be small. The obtained recoveries are, with a few exceptions, in the range 70-100%. The proposed method is quick and straightforward and no additional clean-up steps are needed. The method can be used for the analysis of all 57 pesticides in one single determination step at 0.01 mg kg(-1).     

Application of single-drop microextraction coupled with gas chromatography for the determination of multiclass pesticides in vegetables with nitrogen phosphorus and electron capture detection

In the present work the single-drop microextraction (SDME) technique coupled with GC-NPD and GC-ECD was evaluated for the determination of multi-class pesticides in vegetables. The donor sample solution preparation was optimized by testing different mixtures of solvents and dilutions with water. The SDME procedure was optimized by controlling drop organic solvent, drop volume, agitation, and exposure time. The optimum sample preparation was achieved with the use of a mixture of acetone/H(2)O (10/90, v/v) in donor sample solution preparation and the consequent SDME using a toluene drop under mild stirring for 25min. The efficiency of the extraction process was studied in fortified tomato and courgette samples and matrix effects were further estimated. The proposed method showed good linearity, limits of detection at the sub-microgkg(-1) level and high precision (RSD <15%) and was applied with success in real vegetable samples showing that SDME can be a promising way for sample preparation in pesticide residue analysis.     

Comprehensive multi-residue method for the target analysis of pesticides in crops using liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS) multi-residue method for the simultaneous target analysis of a wide range of pesticides and metabolites in fruit, vegetables and cereals has been developed. Gradient elution has been used in conjunction with positive mode electrospray ionization tandem mass spectrometry to detect up to 171 pesticides and/or metabolites in different crop matrices using a single chromatographic run. Pesticide residues were extracted/partitioned from the samples with acetone/dichloromethane/light petroleum. The analytical performance was demonstrated by the analysis of extracts from lettuce, orange, apple, cabbage, grape and wheat flour, spiked at three concentration levels ranging from 0.01 to 0.10 mg/kg for each pesticide and/or metabolite. In general, recoveries ranging from 70 to 110%, with relative standard deviations better than 15%, were obtained. The recovery and repeatability data are in good accordance with EU guidelines for pesticide residue analysis. The limit of quantification for all targeted pesticides and metabolites tested was 0.01 mg/kg. The selectivity and robustness of the LC-MS/MS method was demonstrated by a 1-year comparison of its analytical results with those obtained from our validated GC and LC multi-residue methods applied to more than 3500 routine samples. The validated LC-MS/MS method has been implemented in our analytical scheme since 2004, replacing four of the conventional detection methods, i.e. GC-flame-photometric detection (acephate, methamidophos, etc.), GC-nitrogen-phosphorus detection, LC-UV detection (carbendazim, thiabendazole, imazalil and prochloraz) and LC-fluorescence detection (N-methylcarbamate pesticides). During a 3-year period, the LC-MS/MS method has been applied to the analyses of more than 12,000 samples.     

食品中邻苯二甲酸酯类化合物的分析方法研究进展

邻苯二甲酸酯是应用最广泛的增塑剂,具有生殖、发育毒性及致癌性,是近年来食品污染的一个重要来源。该类化合物种类多、同系物和同分异构体性质接近、在基体中含量范围宽,高效样品前处理、高选择性分离和高灵敏检测、降低本底干扰等技术是食品中邻苯二甲酸酯类化合物准确测定面临的挑战。本文综述了液液萃取、液液微萃取、固相萃取、固相微萃取、基质固相萃取等传统及新型的提取与净化技术在食品样品分析中的应用,比较分析了气相色谱、液相色谱、串联质谱、高分辨质谱以及酶联免疫、离子迁移谱等快速检测技术的特点,并展望了发展趋势。     

A review of sample preparation methods for the pesticide residue analysis in foods

The pesticide residues in foods have received increasing attention as one of the most important food safety issues. Therefore, more strict regulations on the maximum residue limits (MRLs) for pesticides in foods have been established in many countries and health organizations, based on the sensitive and reliable analysis methods of pesticide residues. However, the analysis of pesticide residues is a continuing challenge mainly because of the small quantities of analytes as well as the large amounts of interfering substances which can be co-extracted with them, often leading to experimental errors and damage to the analytical instruments. Thus, extensive sample preparation is often required for the pesticide residue analysis for the effective extraction of the analytes and removal of the interferences. This paper focuses on reviewing the recent development in the sample preparation methods for the pesticide residue analysis in foods since 2006. The methods include: liquid-liquid extraction (LLE), supercritical-fluid extraction (SFE), pressurized-liquid extraction (PLE), microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), gel permeation chromatography (GPC), solid-phase extraction (SPE), molecularly imprinted polymers (MIPs), matrix solid-phase dispersion (MSPD), solid-phase micro-extraction (SPME), QuEChERS, cloud point extraction (CPE) and liquid phase micro-extraction (LPME), etc. Particularly their advantages, disadvantages and future perspectives will be discussed.     

Analysis of organic micropollutants in the lipid fraction of foodstuffs.

An overview is given of current techniques for the analysis of organic micropollutants that accumulate in the fatty fraction of foodstuffs, such as pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, polychlorinated dibenzodioxins and polychlorinated dibenzofurans. Isolation and clean-up are considered to be of great importance in the field of residue analysis. In general, problems are related to the low levels of the individual compounds at which they usually occur and the complexity of extraction and clean-up procedures for isolating and separating analytes from matrix components and other contaminants. Therefore, special attention is focused on sample pretreatment and on coupled chromatographic techniques, showing developments towards multi-residue methods, miniaturization and automation of analytical procedures. Coupling of chromatographic techniques with spectroscopic techniques is also considered as an important tool for identification and confirmation purposes.     

高效液相色谱-串联质谱法快速测定6类食品中增效醚的残留

建立了水果、蔬菜、粮谷、油料、动植物脂类、动物源性食品等6类食品中增效醚残留量快速测定的液相色谱-质谱/质谱(LC-MS/MS)方法。样品盐析并除水后,用三氯甲烷提取,氟罗里硅土填料固相萃取柱净化,丙酮-三氯甲烷混合溶剂洗脱,以乙腈-0.1%甲酸为流动相,在Zobax SB C18液相色谱柱完成分离,并于电喷雾正离子多反应监测模式下质谱测定。考察了提取溶剂、净化方法、柱容量、仪器条件、基质效应对分析结果的影响。增效醚质量浓度在0.5～100μg/L范围内,线性相关系数(r)为0.9976,方法定量限(LOQ)为10μg/kg。17种食品基质添加LOQ、低MRL、2倍MRL、高MRL 4个不同浓度水平时,回收率在80.3%～96.3%之间,相对标准偏差为2.7%～14%,方法可以满足多种食品基质中增效醚残留量的定性和定量检测要求。     

Multi-residue screening of pesticides in vegetables,fruits and baby food by stir bar sorptive extraction-thermal desorption-capillary gas chromatography-mass spectrometry

The performance of stir bar sorptive extraction (SBSE) for the enrichment of pesticides from vegetables, fruits and baby food samples is discussed. After extraction with methanol, an aliquot is diluted with water and SBSE is performed for 60 min. By applying a new thermal desorption unit (TDU), fully automated and unattended desorption of 98 stir bars is feasible, making SBSE very cost-effective. The presence of pesticide residues is elucidated with the retention time locked gas chromatography–mass spectroscopy method (RTL-capillary GC–MS). With SBSE–RTL-capillary GC–MS operated in the scan mode, more than 300 pesticides can be monitored in vegetables, fruits and baby food. The multi-residue method (MRM) described provides detectabilities from the mg/kg (ppm) to the sub-μg/kg (ppb) level, thereby complying with the maximum residue levels (MRLs) set by regulatory organizations for pesticides in different matrices. Several examples, i.e. pesticide residues in lettuce, pears, grapes and baby food, illustrate the potential of SBSE–RTL-capillary GC–MS.     

Analysis of pesticide residues in fruit and vegetables with ethyl acetate extraction using gas and liquid chromatography with tandem mass spectrometric detection

A multiresidue method based on extraction with ethyl acetate has been used at the Swedish National Food Administration since 1989 to monitor pesticide residues in fruit and vegetables. The method has been continuously adjusted, resulting in simple and quick analyses of pesticide residues. To recover basic pesticides, the addition of an alkali is necessary. The addition of sodium hydrogen carbonate has been shown to recover all pesticides effectively without any degradation. The liquid chromatography (LC) with tandem mass spectrometry (MS/MS) technique has made it possible to analyse more polar pesticides and to replace many single methods. The latest development in the multiresidue method, comprising the use of gas chromatography (GC) with MS/MS, has further improved the analysis by replacing the conventional GC detectors. The need for cleanup has been reduced or eliminated entirely. Consequently, the method has been simplified in a way that makes it possible to recover all included analytes in many different matrices in one single extraction and to detect them either with GC-MS/MS or with LC-MS/MS.     

Novel analytical methods for the determination of steroid hormones in edible matrices

This paper reviews recently published multi-residue chromatographic methods for the determination of steroid hormones in edible matrices. After a brief introduction on steroid hormones and their use in animal fattening, the most relevant EU legislation regarding the residue control of these substances is presented. An overview of multi-residue analytical methods, covering sample extraction and purification as well as chromatographic separation and different detection methods, being in use for the determination of steroid hormones (estrogens, gestagens and androgens), is provided to illustrate common trends and method variability. Emphasis was laid on edible matrices and more specifically on meat, liver, kidney, fat and milk. Additionally, the possibilities of novel analytical approaches are discussed. The review also covers specific attention on the determination of natural steroids. Finally, the analytical possibilities for phytosterols, naturally occurring steroid analogues of vegetable origin and a specific group of steroid hormones with a hemi-endogenous status are highlighted.     

超高效液相色谱-串联质谱法快速检测蔬菜中248种农药残留

采用超高效液相色谱-串联质谱（UHPLC-MS/MS）技术建立了快速检测蔬菜中248种农药残留的分析方法。蔬菜样品采用乙腈提取,盐析后无需净化,缩短了样品前处理的时间。采用正负离子多反应监测（MRM）模式对蔬菜中248种农药残留进行定性和定量分析。245种农药在各自的线性范围内线性关系良好（r>0.99）。除丁硫克百威、灭蝇胺、苯磺隆和二氯喹啉酸4种农药外,其余244种农药在3个添加水平下的平均回收率范围为63.0%～126.4%,相对标准偏差（RSD）范围为0.5%～26.7%,方法的定量限为0.001～0.030 mg/kg。该方法具有简单、快速、灵敏度高、准确度高等优点,适合蔬菜样品中农药多残留的快速检测分析。     

Application of gas chromatography/tandem quadrupole mass spectrometry to the multi-residue analysis of pesticides in green leafy vegetables

A new, sensitive and specific method has been developed for the simultaneous determination of 129 pesticides in lettuce and other green leafy vegetables. The samples were extracted with acetonitrile and co-extractives such as fatty acids and pigments were removed using dispersive solid-phase extraction (dispersive-SPE) with primary secondary amine (PSA) and graphitized carbon black (GCB). All pesticides were analyzed in a single injection gas chromatography/tandem quadrupole mass spectrometry (GC/MS/MS) acquisition method. Two multiple reaction monitoring (MRM) transitions of precursor ions fragmenting into product ions were recorded for the targeted pesticides, thus fulfilling the EU identification points system criteria for the identification of contaminants (2002/657/EC). Calibration curves were determined using matrix-matched standards, and exhibited excellent linearity at two orders of magnitude from 0.005 to 0.5 mg/kg for almost all the pesticides studied (R(2) > or = 0.99). The analytical performance was demonstrated by the analysis of lettuce samples spiked at five concentration levels ranging from 0.005 to 0.5 mg/kg for each pesticide. The recovery and repeatability results satisfied SANCO/2007/3131 criteria (i.e. average recoveries were in the range 70-120% with RSDs < or =20%) for 114 of the 129 pesticides at the 0.005 mg/kg spiking level, and for almost all pesticides at the higher spiking levels. The methodology was applied successfully to identify and quantify pesticide residues in leafy vegetable samples such as lettuce, cabbage and leek.     

QuEChERS-液相色谱-串联质谱法同时测定果蔬中16种农药残留

建立了果蔬中吡虫啉、咪鲜胺、苯醚甲环唑、嘧菌酯、噻虫嗪等16种常见农药多残留的液相色谱-串联质谱(LC-MS/MS)分析方法。以乙腈为提取剂,样品经高速匀浆方法提取后,提取液采用液-液萃取静置分层,取上清液进行净化处理。比较了石墨化碳-氨基复合固相萃取与QuEChERS两种不同净化技术的净化效果,最终确定采用QuEChERS方法为净化手段。即提取液经装有150 mg N-丙基乙二胺(PSA)填料、900 mg无水硫酸镁的净化管净化,除去样品中大部分的色素及有机酸等干扰基质,再经LC-MS/MS分析,有效地降低了样品中的复杂基质所带来的背景干扰。加标水平为5、10、20 μg/kg时,16种农药的平均回收率为75%~111%,相对标准偏差小于16%。16种农药的检出限为0.2~5 μg/kg。采用LC-MS/MS定性分析、基质匹配标准曲线法定量分析,线性关系和回收率结果均令人满意。实验证明,建立的QuEChERS净化与LC-MS/MS相结合的检测方法具有快速、准确、灵敏度高等优点,能够准确测定果蔬中16种农药残留。     

Determination of pesticide transformation products: A review of extraction and detection methods

Pesticides are widely applied and they can produce a variety of transformation products (TPs), through different pathways and mechanisms. Nowadays there is a growing interest related to the determination of pesticide TPs in several matrices (environmental, food and biological samples), due to these compounds can be more toxic and persistent than parent compounds, and some of them can be used as markers of exposure to different pesticides. Although solid-phase extraction (SPE) is mainly used for the extraction of TPs, alternative techniques such as solid-phase microextraction (SPME) and liquid-phase extraction (LPE) can be used. These TPs are mainly determined by liquid chromatography (LC) due to the recent developments in this technique, especially when it is coupled to mass spectrometry (MS) detectors, allowing the determination of known and/or unknown TPs. Furthermore, MS is a very valuable tool for the structural elucidation of unknown TPs. This review discusses all phases of analytical procedure, including sample treatment and analysis, indicating the main problems related to the extraction of TPs from several matrices due to their high polarity, as well as the different alternatives found for the simultaneous determination of parent compounds and TPs, using chromatographic techniques coupled to MS detection.     

A Rapid Method for the Determination of Organochlorine, Pyrethroid Pesticides and Polychlorobiphenyls in Fatty Foods Using GC with Electron Capture Detection

A new, single-step extraction and purification method was developed for the separation of 26 organochlorine pesticides (OCPs), three pyrethroid pesticides (PPs) and six polychlorinated biphenyls (PCBs) from fatty foods of either animal or vegetable origin. The method includes homogenisation of extracted fat and diatomaceous earth. Separation was achieved using a mini Pasteur pipette where a matrix solid-phase dispersion extraction was carried out with only 5 mL of dimethyl sulphoxide as an eluting solvent. A Pasteur pipette was joined to a prepacked slurry filled Florisil column, water deactivated to 15% where a liquid–liquid extraction and adsorption chromatography successively took place. The elution of OCPs, PPs and PCBs was performed with n-hexane/diethyl ether. Recoveries for PCBs were from 81 to 86% and for OCPs 68 to 94%, except for β-HCH, which gave lower, more variable recoveries. Excellent recoveries were obtained for pyrethroid pesticides, mostly more than 80%. The method was applied to 509 fatty samples for monitoring of these compounds. GC, with two columns connected to two electron capture detectors (ECD), was used.     

Chromatographic determination of pesticides in soil: Current trends in analysis and sample preparation

Soil is a primary sink and reservoir for pesticides pollution and one of the priority objects in terms of pesticides safety guidelines. Pesticides’ analysis in soil is a field of research which is in constant development facing numerous challenges such as the increasing amount and variety of analytes and their combinations, as well as the increasing demand for faster, simpler, more accurate and multiresidue analysis. This review provides the summary of studies on pesticides analysis in soil based on chromatography-coupled methods published between 2015 and 2022. We discuss the shift toward faster, greener, and simpler alternatives to conventional techniques, application of sample preparation and detection methods to targeted and untargeted pesticide analysis, as well as the developments in stereoselective determination of chiral pesticides. The sample preparation methods such as solid-phase extraction, dispersive solid-phase extraction, and derived methods, as well as the recent trends and developments in chromatographic separation of pesticides are covered in this review. For sample preparation, the QuEChERS method is replacing other techniques and has proved to be efficient in both screening and accurate quantification in multiresidue analysis. Shift towards minimal sample preparation is supported by a wider application of highly sensitive and selective separation and detection systems such as LC-MS/MS. The features of different methods of sample preparation and detection are discussed with focus on optimal parameters, advantages, and drawbacks. The optimal parameters of sample preparation methods were summarized based on respective publications, which makes the review a useful tool for method development and further investigations.     

Selection of SPE cartridge for automated solid-phase extraction of pesticides from water followed by liquid chromatography-tandem mass spectrometry

In environmental analyses there is an ever-increasing need to develop simple and sensitive multi-residue methods. In many agricultural regions, there is particular concern of the potential for pesticides to enter rivers and other waterways. This study reports on the development and validation of a multi-residue method of analysis for 30 pesticides in water samples using solid-phase extraction (SPE) followed by LC-MS/MS. The electrospray and MS/MS parameters were optimised for each pesticide, including capillary voltage, collision-induced dissociation voltage, and selection of a precursor ion and two product ions. A variety of SPE sorbents were tested for sample pre-concentration, including numerous polymeric based phases. Bond Elut PPL and Oasis HLB were the only phases capable of retaining the majority of the target analyte classes in a single method. An off-line pre-concentration method using a Gilson Aspec system was optimised using the Bond Elut PPL cartridges, with a concentration factor of 25 producing limits of quantitation in the order of 6–100 ng/L. Excellent linearity (r ² > 0.9), precision (<20%) and recovery (>60%) was obtained for nearly all of the analytes, covering a wide variety of chemical and physical properties. This is the first study to fully validate Bond Elut PPL cartridges for use in multi-residue pesticide analysis.