Determination of pesticide residues by GC-MS using analyte protectants to counteract the matrix effect.

An analytical method was developed to determine pesticides of various chemical classes in soil, juice and honey using analyte protectants to counteract the enhancement of the chromatographic response produced by the presence of matrix components (matrix effect). This effect was more pronounced for soil and honey samples than for juice samples; regarding the pesticide chemical class, organochlorine pesticides were less affected by the presence of matrix components than triazines and organophosphorus pesticides. Several analyte protectants (2,3-butanediol, L-gulonic acid gamma-lactone, corn oil and olive oil) were tested for counteracting the observed matrix effect. L-Gulonic acid gamma-lactone was an effective protecting agent for most of the pesticides studied in soil and honey samples, whereas olive oil was very effective for juice samples. The combination of these two protectants was found to be an effective analyte protectant for all compounds in soil and honey samples.     

Pesticide residues analysis in honey using ethyl acetate extraction method: validation and pilot survey in real samples

This paper presents a cost-effective and validated multi residue confirmatory method for the determination of 167 chemically different pesticides and a survey study on Cyprus honey samples. This method uses ethyl acetate for the extraction of pesticides from honey and the determination is performed with liquid chromatography (LC) coupled to mass spectrometry (MS) operating in tandem mode (MS/MS) and with GC–ECD (gas chromatography with electron capture detector) analysis. The LC-MS/MS analytical system is especially important in the analysis of polar and non-volatile pesticides. For the validation of the method, blank honey samples were spiked with 146 pesticides (organophosphorous, carbamates, triazoles, amides, neonicodinoids, strobilurines, phenylureas, bendimidazoles and others) for the LC-MS/MS analysis at three levels: 0.01, 0.05 and 0.1 mg kg^?1 and with 21 pesticides for the GC-ECD analysis at two levels: 0.01 and 0.05 mg kg^?1for organochlorines and 0.05 and 0.2 mg kg^?1for the pyrethroids. As blank sample, a sample of honey which did not contain detectable levels of the analytes sought was used. The validation study was in accordance to the DG SANCO guidelines. The scope of validation included recovery, linearity, limits of quantification and precision. Linearity is demonstrated all along the range of concentration that was investigated with correlation coefficients ≥0.98. Recoveries of the majority of compounds were in the 70%–120% range and were characterised by precision lower or equal to 20%. The validated method was used for a survey of 36 samples of honey produced in different areas of Cyprus and this is the first work on Cypriot honey samples investigating a broad range of pesticides. Only coumaphos was detected at concentrations higher than 0.01 mg kg^?1 in the 58.6% of the honey samples analysed for Coumaphos. The results were evaluated in accordance to the provisions of the Commission Regulation (EU) No 37/2010 on pharmacologically active substances and their classification regarding maximum residue limits (MRLs) in foodstuffs of animal origin. The concentrations of coumaphos in all positive samples were at levels much lower than the MRL.     

Sensitive analytical methods for 22 relevant insecticides of 3 chemical families in honey by GC-MS/MS and LC-MS/MS

Several methods for analyzing pesticides in honey have been developed. However, they do not always reach the sufficiently low limits of quantification (LOQ) needed to quantify pesticides toxic to honey bees at low doses. To properly evaluate the toxicity of pesticides, LOQ have to reach at least 1 ng/g. In this context, we developed extraction and analytical methods for the simultaneous detection of 22 relevant insecticides belonging to three chemical families (neonicotinoids, pyrethroids, and pyrazoles) in honey. The insecticides were extracted with the QuEChERS method that consists in an extraction and a purification with mixtures of salts adapted to the matrix and the substances to be extracted. Analyses were performed by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) for the pyrazoles and the pyrethroids and by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) for the neonicotinoids and ethiprole. Calibration curves were built from various honey types fortified at different concentrations. Linear responses were obtained between 0.2 and 5 ng/g. Limits of detection (LOD) ranged between 0.07 and 0.2 ng/g, and LOQ ranged between 0.2 and 0.5 ng/g. The mean extraction yields ranged between 63 % and 139 % with RSD <25 %. A complete validation of the methods also examined recovery rates and specificity. These methods were applied to 90 honey samples collected during a 2009–2010 field study in two apiaries placed in different anthropic contexts.

Multiresidue determination of pesticides in honey by matrix solid-phase dispersion and gas chromatography with electron-capture detection

A multiresidue method was developed for the determination of 15 pesticides (organochlorines, organophosphorus compounds, pyrethroids, and other acaricides) in various commercial honeys (eucalyptus, lavender, orange, rosemary, and multifloral). The analytical procedure is based on the matrix solid-phase dispersion of honey in a mixture of Florisil and anhydrous sodium sulfate; the mixture is placed in small plastic columns and extracted with hexane-ethyl acetate (90 + 10, v/v). The pesticide residues are determined by capillary gas chromatography with electron-capture detection. Recoveries with the method at concentrations between 0.15 and 1.5 microg/g ranged from 80 to 113%, and relative standard deviations were <10% for all the pesticides studied. The pesticide detection limits were within the range 0.5-5 microg/kg for organochlorines, around 3 microg/kg for the chlorinated organophosphorus pesticides studied, near 15 microg/kg for fluvalinate, and about 3 microg/kg for the other pyrethroids.     

Development and validation of a multi-residue method for pesticide determination in honey using on-column liquid-liquid extraction and liquid chromatography-tandem mass spectrometry

We report on the development and validation under ISO 17025 criteria of a multi-residue confirmatory method to identify and quantify 17 widely chemically different pesticides (insecticides: Carbofuran, Methiocarb, Pirimicarb, Dimethoate, Fipronil, Imidacloprid; herbicides: Amidosulfuron, Rimsulfuron, Atrazine, Simazine, Chloroturon, Linuron, Isoxaflutole, Metosulam; fungicides: Diethofencarb) and 2 metabolites (Methiocarb sulfoxide and 2-Hydroxytertbutylazine) in honey. This method is based on an on-column liquid-liquid extraction (OCLLE) using diatomaceous earth as inert solid support and liquid chromatography (LC) coupled to mass spectrometry (MS) operating in tandem mode (MS/MS). Method specificity is ensured by checking retention time and theoretical ratio between two transitions from a single precursor ion. Linearity is demonstrated all along the range of concentration that was investigated, from 0.1 to 20 ng g(-1) raw honey, with correlation coefficients ranging from 0.921 to 0.999, depending on chemicals. Recovery rates obtained on home-made quality control samples are between 71 and 90%, well above the range defined by the EC/657/2002 document, but in the range we had fixed to ensure proper quantification, as levels found in real samples could not be corrected for recovery rates. Reproducibility is found to be between 8 and 27%. Calculated CCalpha and CCbeta (0.0002-0.943 ng g(-1) for CCalpha, and 0.0002-1.232 ng g(-1) for CCbeta) show the good sensitivity attained by this multi-residue analytical method. The robustness of the method has been tested in analyzing more than 100 raw honey samples collected from different areas in Belgium, as well as some wax and bee samples, with a slightly adapted procedure.     

Simultaneous determination of tryptophan, kynurenine, kynurenic and xanthurenic acids in honey by liquid chromatography with diode array, fluorescence and tandem mass spectrometry detection

A liquid chromatography method using diode array-fluorescence detection and atmospheric pressure chemical ionization mass spectrometry (LC-DAD-FLD and LC–APCI-MS/MS) was developed to quantify the levels of tryptophan (TRP), kynurenine (KYN), kynurenic (KYNA) and xanthurenic (XA) acids in honey. This procedure involved isolating the compounds of interest via solid-phase extraction (SPE) with mixed-mode polymeric cartridges. Chromatographic separation of the analytes was performed in isocratic mode on a Synergi 4μ Hydro-RP 80Å (150 × 4.60 mm i.d.) analytical column at 30 °C. The mobile phase of 20 mM ammonium formate (pH 4) and methanol was passed at a flow rate of 0.5 mL/min. In replicate sets of spiked honey samples, the average analyte recoveries ranged from 60 to 98% for TRP, 55 to 120% for KYN, 65 to 106.5 for KYNA and 56 to 114% for XA. Detection limits ranged from 4 to 36 μg/kg for LC-DAD-FLD to 0.2 and 1.0 μg/kg for LC–APCI-MS/MS. A strong matrix effect was found when MS/MS was employed, necessitating calibration using the standard addition method on matrix-matched standards for each honey type. The method was used to quantify each of the compounds of interest in 17 honey samples of distinct botanical origins.     

A multiresidue method using ion-trap gas chromatography–tandem mass spectrometry with or without derivatisation with pentafluorobenzylbromide for the analysis of pesticides in the atmosphere

A multiresidue method using gas chromatography coupled to ion-trap tandem mass spectrometry (MS/MS) was developed for the analysis of 27 pesticides, commonly used in Alsace, in atmospheric samples (particle and gas phases). As pesticides are expected to be present at very low concentrations and in a complex matrix, the analytical method used was both highly selective and sensitive. These two properties were obtained by associating chromatography with ion-trap MS/MS. To develop this method, analysis of electron impact in single MS was first conducted to choose the parent ions of the pesticides studied. Among the 27 pesticides analysed, seven of them require a derivatisation step. This was the case of some ureas (chlorotoluron, diuron and isoproturon), phenoxy acids (2,4-dichlorophenoxyacetic acid, 4-chloro-2-methylphenoxyacetic acid and mecoprop) and of bromoxynil. The derivatisation was performed with success with pentafluorobenzylbromide. Then, a MS/MS method was optimised by parameters such as the radio frequency storage level and the collision-induced dissociation excitation voltage. Finally, a last step enabled the development of two calibrating programs based on the quantification of daughter ions for the 20 pesticides analysed directly (run 1) and for the seven pesticides which needed derivatisation (run 2). With this analytical procedure, the detection limits varied between 2.5 and 1,250 pg m^–3 depending on the compounds studied. This method was tested with success for atmospheric samples collected in Strasbourg (France) during intensive pesticide treatment in 2002.     

Analytical methods used in the United Kingdom Wildlife Incident Investigation Scheme for the detection of animal poisoning by pesticides

The United Kingdom Wildlife Incident Investigation Scheme (WIIS) investigates cases of suspected poisoning of wildlife, honey bees, and companion animals by pesticides. Together with field inquiries and veterinary post-mortem examinations, the analytical procedures presented here provide a comprehensive approach to the investigation of these cases. The paper covers selection of animal tissues for analysis and methods suitable for the analysis of honey bees and for various types of bait. Seven multiresidue methods cover around 130 pesticides, and methods are also described for a further 8 compounds. These methods are currently used on samples submitted to the Scheme in England and Wales.     

高效液相色谱-串联质谱法测定蜂蜜中9种农药残留

建立了同时测定蜂蜜中9种苯并咪唑类和新烟碱类农药的全自动固相萃取-高效液相色谱-串联质谱检测方法。蜂蜜样品用磷酸盐缓冲液（pH=7.8）溶解，超声提取，经亲水亲脂平衡（hydrophilic-lipophilic balance，HLB）固相萃取小柱净化，氮吹浓缩，定容，过滤膜后进行高效液相色谱-串联质谱分析，采用多反应监测（MRM）模式测定，以内标法定量。结果表明，在0.002~0.05 mg/L范围内9种农药呈现出较好的线性关系（相关系数r² ≥ 0.99），检出限和定量限分别为0.1~1.0 μg/kg和0.3~2.0 μg/kg。对阴性蜂蜜，在5.0、10.0、20.0 μg/kg 3个水平下分别进行加标回收试验，测出9种农药的平均回收率在78.2%~101.2%之间，相对标准偏差为1.3%~14.3%（n=6）。该方法可适用于大批量蜂蜜样品的快速准确测定。     

Analysis of Polyphenols in Honey: Extraction,Separation and Quantification Procedures

Polyphenols are secondary plant metabolites playing a major role as potentially functional components. They can also be used for honey authentication. This review gathers the recent literature references about honey extraction procedures, as well as instrumental analysis of phenolic compounds found in honey. Liquid-Liquid extraction is widely used for both extraction and purification purposes, with adequate recovery percentages. However, the use of high solvent volumes is a major disadvantage. More environmentally friendly methods include accelerated solvent extraction, and dispersive and inverse dispersive liquid-liquid microextraction. Solid phase extraction is the most common method for honey polyphenols’ isolation. Polyphenol isolation by a combination of liquid-liquid and solid phase extraction allows good recoveries for a variety of different compounds. High-performance liquid chromatography with ultraviolet or mass spectrometry detectors is by far, the most commonly employed instrumental procedure to separate and quantify polyphenols in honey although capillary electrophoresis has been also successfully used for these purposes. The use of new sorbents, the optimization of current procedures and the development of other simple and rapid analytical techniques are challenges for future analysis of polyphenols found in honey.     

气相色谱-质谱法分析蜂蜜中的多种农药残留

开展了蜂蜜中23种农药残留的气相色谱-电子轰击离子源质谱(GC-EI/MS)分析方法的研究,并对其中3种农药的EI/MS碎片离子的断裂机理与结构进行了初步解析。探讨了蜂蜜试样前处理条件的优化与选择。将蜂蜜试样用乙酸乙酯提取剂超声提取、Florisil硅藻土色谱柱净化和正己烷-乙酸乙酯(体积比为7∶3)混合洗脱剂洗脱后,以PCB103为内标物,采用选择离子监测(SIM)方式下的GC-EI/MS分析。当试样的加标浓度为50,100和200 μg/kg时,加标回收率为82%～120%,相对标准偏差小于11.0%。23种农药的检测限都小于10.0 μg/kg,线性范围为10～500 μg/kg,相关系数都大于0.995。此分析方法已成功地应用于蜂蜜中23种痕量农药残留的分析。     

Influence of matrix on suitability of four methods for organochlorine pesticide analysis in waters

The monitoring of organochlorine pesticides has raised a great concern in the last years due to their toxicity (some of them are carcinogenic and endocrine disruptor compounds) and persistence. European Directive 2008/105/EC establishes very restrictive levels for organochlorine pesticides in surface waters. Therefore, simple, fast, highly sensitive and low cost analytical methods are required to detect and quantify these pollutants in water. In the present work, four procedures for extraction and determination are proposed and compared for the analysis of 28 organochlorine pesticides in tap, surface and sea waters. The suitability of each method of analysis was evaluated for each kind of water. The extraction methods proposed were: two solid-phase extraction methods using C₁₈ laminar disk and Oasis HLB cartridges, a solid-phase microextraction procedure using a polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre, and a micro liquid–liquid extraction procedure using ethyl acetate as solvent. Determination of pesticides was performed by large volume on-column injector-gas chromatography-electron capture detection (LVOCI-GC-ECD), splitless-GC-ECD and GC-MS (mass spectrometry). All methods present a good sensitivity with method detection limits lower than 10?ng?L^?1, good accuracy with recoveries between 75 and 120% (with some exceptions) and good precision (relative standard deviations <15%), according to the Commission Decision 2002/657/EC criteria. The advantages and disadvantages of each method are discussed in terms of the green chemistry principles, the figures of merit and the matrix effect. This work tries to be a useful guidance for routine and control analysis laboratories.     

Determination of Neonicotinoids in Honey Samples Originated from Poland and Other World Countries

A method development for determination of neonicotinoid residues in honey samples was developed. The proposed methodology consisted in QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe). That was used for sample preparation and UHPLC/UV (ultra-performance liquid chromatography with ultraviolet detection) utilized for chromatographic analysis. The developed method proved to be sensitive, with LOD (Limit of detection) value in the range of 60.80 to 80.98 ng/g hence LOQ (Limit of quantification) value was in the range of 184.26 to 245.40 ng/g. The method has tested on Polish honey and applied to honey from various countries (Bulgaria, Czech Republic, France, Greece, Italy, Portugal, Romania, Australia, Brazil, Cameroon, Russia, USA and Turkey). Several honey types were tested, while physicochemical properties of all honeys and were investigated. The methodology for general characterization of pollen grains originated from selected plants, to confirm the type of honey was also presented. There was a total lack of the mentioned neonicotinoids in sunflower honey. Except of this, only two samples of rapeseed and two samples of acacia honey (from Poland and Romania) were neonicotinoids free. In 19 samples the targeted pesticides were detected above LOQ. In all other investigated samples, the neonicotinoids were found at least at the LOD or LOQ level.     

Headspace single-drop microextraction of common pesticide contaminants in honey–method development and comparison with other extraction methods

In the present study the main factors that may influence the headspace single-drop microextraction (HS-SDME) of common pesticide contaminants (diazinon, lindane, chlorpyrifos ethyl, p,p′-DDE, and endosulfan) that may occur in honey were determined and an analytical protocol was further developed by the use of a multivariate optimization. The HS-SDME analytical method developed and two more analytical protocols for the determination of pesticides in honey: (i) by direct SDME (D-SDME), and (ii) by liquid–liquid extraction (LLE), were further validated for the determination of target analytes. The three methods were also applied in the same real honey samples and results were further discussed. By D-SDME, LODs ranged from 0.04?µg?kg^?1 for β-endosulfan to 2.40?µg?kg^?1 for diazinon and repeatability expressed as %RSD from 3 for lindane to 15 for diazinon and chlorpyrifos methyl; by HS-SDME, LODs ranged from 0.07?µg?kg^?1 for p,p′-DDE to 12.54?µg?kg^?1 for chlorpyrifos methyl and repeatability expressed as %RSD from 11 for chlorpyrifos methyl to 19 for p,p′-DDE; by LLE, LODs ranged from 0.09?µg?kg^?1 for β-endosulfan to 19.31?µg?kg^?1 for diazinon and repeatability expressed as %RSD from 6 for p,p′-DDE to 11 for lindane. For all target pesticides but p,p′-DDE that could not be recovered by D-SDME method tested. The proposed HS-SDME optimized in this study was shown to be the method of choice for the determination of diazinon in honey whereas the most favourable analytical characteristics from the comparative study performed were achieved by D-SDME.     

气相色谱-串联质谱法快速筛查测定中药材中144种农药残留

利用气相色谱-串联质谱(GC-MS/MS)检测技术,采用QuEChERS法作为样品前处理方法,建立了能应用于11种中药材中144种农药残留的检测方法。探究了样品前处理过程中提取溶剂、缓冲盐体系、净化剂组成和用量对样品提取、净化等方面的影响,最终确定了用乙腈提取,甲苯复溶,以混合净化剂净化,过有机膜后经GC-MS/MS测定,外标法定量。144种农药在10~2000 μg/kg之间线性关系良好,相关系数(r²)>0.983;除乙酰甲胺磷、灭虫威、西玛津、克菌丹、异狄氏剂、异菌脲外,其余农药的定量限(LOQ)均低于20 μg/kg;在20、50、200 μg/kg的添加水平下,除乙酰甲胺磷、艾氏剂和双甲脒回收率偏低外,其余141种农药的平均回收率在74.3%~111.8%之间,相对标准偏差(RSD)为0.5%~14.6%。与已有的标准方法对比,此方法不仅检测结果一致,而且高效、快速,准确性好,灵敏度高,适用于中药材中144种农药残留的快速筛查与定量分析。     

Analysis of insecticides in honey by liquid chromatography-ion trap-mass spectrometry: comparison of different extraction procedures

The feasibility of different extraction procedures was tested and compared for the determination of 12 organophosphorus and carbamates insecticides in honey samples. In this sense, once the samples were pre-treated - essentially dissolved in hot water by stirring - and before they could be analyzed by liquid chromatography-ion trap-second stage mass spectrometry (LC-MS(2)), four different approaches were studied for the extraction step: QuEChERS, solid-phase extraction (SPE), pressurized liquid extraction (PLE) and solid-phase microextraction (SPME). The main aim of this work was to maximise the sensitivity of pesticides and to minimise the presence of interfering compounds in the extract. All pesticides were linear in the range from CC(β) to 1000× CC(β) for the four extraction methods (three orders of magnitude). Detection capabilities (CC(β)) were 0.024-1.155 mg kg(-1) with QuEChERS, 0.010-0.646 mg kg(-1) with SPE, 0.007-0.595 mg kg(-1) with PLE, and 0.001-0.060 mg kg(-1) with SPME. All the target compounds could be recovered by any of the methods, at a CC(β) fortification level ranged from 28 to 90% for the SPME. In comparison, the PLE method was the most efficient extraction method with recoveries from 82 to 104%. It was followed by the QuEChERS method with recoveries between 78 and 101% and the SPE method with recoveries between 72 and 100%. The repeatability expressed as relative standard deviation (RSDs) was below 20% for all the pesticides by any of the tested extraction methods. Results obtained applying the four extraction techniques to real honey samples are analogous.     

Protocols for optimizing MS/MS parameters with an ion-trap GC-MS instrument

The product ion spectrum allows us to achieve very selective detection of pesticides and to eliminate the ambiguities caused by more conventional analytical approaches. Owing to the enhanced capabilities of GC/MS/MS for multiresidue pesticides, the development of a GC/MS/MS pesticides library will be useful. The aim of this study was to develop a sensitive and specific analytical method for the identification and quantification of compounds without the need of a time-consuming procedure. Two methods were studied in order to optimize the nonresonant conditions of dissociation of five pesticides (deltamethrin, metalaxyl, myclobutanil, procymidone, pirimicarb). The first permits a systematic investigation of the influence of the qz trapping parameter on sensitivity in precursor ion detection and on the efficiency of collision-induced dissociation (CID). The second is more suited for analytical laboratories and less time-consuming and allows us to reach similar results: the experiments were conducted step by step at a constant stability parameter.     

Determination of Polychlorinated Biphenyls and Chlorinated Pesticides in Environmental Biological Samples Using Focused Microwave-assisted Extraction

Abstract

Organochlorine compounds such as polychlorinated biphenyls (PCBs) and chlorinated pesticides have been analysed in environmental biological samples using focused microwave-assisted extraction (FMW). The analytical procedure is presented and the results for two Standard Reference Materials, a cod liver oil and a freeze-dried mussel tissue, are reported. The average recoveries for the sum of the PCBs are between 93% and 106%, and for the sum of the chlorinated pesticides are between 109 to 115% for all the certified compounds analysed. The developped analytical procedure is highly reproducible with an average standard deviation of 8% for the sum of the PCBs and 9.7% for the sum of the chlorinated pesticides in the two matrices.     

Study of the effects of operational parameters on multiresidue pesticide analysis by LC-MS/MS

In this paper, the influence of several operational parameters on a well established multiresidue LC-MS/MS method has been studied in relation to the analysis of 150 pesticides commonly present in vegetable samples. The operational parameters investigated are: (i) the influence of different modifiers (0.1% formic acid; 5 mM ammonium formiate; 5 mM ammonium acetate in aqueous phase) - both on the retention time and on the analytical response of the studied compounds; (ii) the effect of the analytical column's temperature on the retention time and on the analytical response of the pesticides investigated; (iii) the effects of co-elution in mixture containing 150 pesticides and, additionally, (iv) the carrying out of a study about the common transitions obtained by LC-MS/MS. Various common transitions were found among the 150 pesticides, but there were only two problematic cases, the pairs diuron-fluometuron and prometryn-terbutryn, which have common scanned transitions and have very close retention times. The use of ammonium salts as modifier instead of formic acid reports enhancement or suppression of the response depending on the pesticides. No great influence on the retention time or on the response of the pesticides and commodities studied was observed with relation to the column temperature. Two different columns: an HPLC (5 μm particle size) and an UHPLC analytical column (1.8 μm particle size) have been used. As was expected, shorter run times and lower peak width was achieved with the UHPLC column.In this paper, the effect of the compounds on each other in the MS analysis when the number of co-eluting compounds is quite high is also described. Mainly small suppression or enhancement co-elution effect was observed, but some particular pesticides presented high sensitivity (>±60% effect) when they elute together with others. This is an important factor and it has to be taken into account when performing multiresidue pesticide analysis.     

Gas chromatographic-mass spectrometric method for the qualitative and quantitative determination of disaccharides and trisaccharides in honey

An improved method has been developed to identify and quantify honey disaccharides and trisaccharides by gas chromatography and mass spectrometry. The procedure, based on mass spectral and retention data ("retention time windows") determined on two capillary columns with different stationary phases allowed the identification and quantitation in honey of 16 disaccharides and 9 trisaccharides, some of which were not previously identified by GC. The reliability of the analytical results was considerably improved by the use of this procedure: several unidentified disaccharides and trisaccharides were detected, and their presence was taken into account in the quantification.