Determination of matrix effects occurred during the analysis of organochlorine pesticides in agricultural products using GC-ECD

Matrix effects observed during the multiresidue analysis of seven organochlorine pesticides in six different agricultural products with GC-ECD were assessed. The presence of matrix coextractives, a major cause of observed matrix effects, directly and/or indirectly influenced the chromatographic responses of some pesticides. Two types of external calibrations, solvent calibration (SC) and matrixmatched calibration (MC), were used to assess matrix effects. Greater matrix effects were observed at the lower concentrations of each pesticide. The extent of matrix effects varied unpredictably with matrix type. Among the analyzed pesticides, iprodione, cyhalothrin, and cypermethrin exhibited greater matrix effects (>150%) for almost all matrices. The pesticide recovery rates obtained with MC were not statistically different from a 100% recovery rate in most samples, which indicates that MC may diminish the overestimates occurred due to matrix effects in GC analysis.     

Validation study on a method for multiresidue analysis of pesticides in vegetables and fruits with supercritical fluid extraction

Supercritical fluid extraction (SFE) was applied to extraction of pesticides from vegetables and fruits. Residues were extracted from homogenized samples mixed with water-absorbent polymer with supercritical carbon dioxide in a stainless steel tube, followed by elution with acetone. Co-extractives were removed by means of mini-column clean-up. Measurement was performed by GC-MS/MS. Calibration was achieved by preparing matrix-matched calibration standards to counteract matrix effects. With the Japanese method validation guideline as a reference, the method was assessed in 5 agricultural products spiked with 334 pesticides at 0.01 and 0.1 μg/g. Compounds at each level were extracted from 2 samples on 5 separate days. The trueness of the method for 189 pesticides in all samples was 70-120%, and the repeatability and within-run reproducibility were also consistent with the guideline. The trueness of the method for the other 71 pesticides was in the range of 50-70%, though the repeatability and within-run reproducibility were satisfactory. This method is available as a multiresidue analysis method for vegetables and fruits.     

不同基质效应对蔬菜中有机磷农药残留检测的影响

目的探讨不同蔬菜基质对有机磷农药测定的影响以及不同有机磷农药在不同质量浓度水平下产生的基质效应。方法以茄子、豇豆、番茄、黄瓜4种蔬菜为试样,采用气相色谱-火焰光度检测器检测并对峰面积响应值进行比较,分析4种蔬菜基质对8种有机磷农药在0.05、0.1、1.0 mg/L 3个质量浓度水平下产生的基质效应。结果 4种蔬菜对8种有机磷农药的测定均存在不同程度的基质增强或基质减弱效应,其基质效应为0.755~2.442。基质效应的强弱与有机磷农药及蔬菜的种类有关,与有机磷农药的浓度没有明显的关联性。结论在蔬菜有机磷农药残留检测中,建议采用基质配制的标准品进行定量检测,从而保证检测结果的准确性。     

气相色谱-串联质谱法测定5种植物源性食品中氯肽酸和草芽畏残留量

摘 要: 目的 建立气相色谱-串联质谱法测定水果、蔬菜、茶叶、粮谷及花生油等植物源食品中氯肽酸和草芽畏两种农药残留的分析方法。方法 针对非油基质样品, 选取柚子、生菜、茶叶及小麦粉样品, 经2%甲酸乙腈溶液提取, 三甲基硅烷化试剂衍生, MAS-Q盐包吸附色素等杂质, 再经HLB柱净化的前处理方法; 针对含油基质, 选取花生油样品, 经甲醇提取, 三甲基硅烷化试剂衍生, 再经HLB柱净化。净化后样品用气相色谱-串联质谱仪进行检测。结果 为消除基质效应影响,补偿前处理提取过程中的损失,采用过程标准校正法, 两种农药在不同基质样品中呈现良好的线性关系, 相关系数均大于0.99。在0.01、0.02、0.05 mg/kg加标水平下, 两种农药在不同基质中的回收率均在93.6%~113.6%之间, 相对标准偏差在0.9%~9.8%之间 (n=6)。结论 该方法灵敏度高, 选择性好, 在水果、蔬菜、粮谷、乃至茶叶、花生油等复杂基质中, 氯酞酸和草芽畏的定量限均可达到0.01 mg/kg, 满足GB 2763-2021《食品安全国家标准 食品中农药最大残留限量》临时限量的要求。     

Determination of trichothecenes in cereals and cereal-based products by liquid chromatography-tandem mass spectrometry

A sensitive, accurate and precise method for the simultaneous determination of nivalenol (NIV), deoxynivalenol (DON), T-2 toxin (T-2) and HT-2 toxin (HT-2) in different food matrices, including wheat, maize, barley, cereal-based infant foods, snacks, biscuits and wafers, has been developed. The method, using liquid chromatography coupled with atmospheric pressure chemical ionization triple quadrupole mass spectrometry (LC-APCI-MS/MS), allowed unambiguous identification of the selected trichothecenes at low µg per kg levels in such complex food matrices. A clean-up procedure, based on reversed phase SPE Oasis® HLB columns, was used, allowing good recoveries for all studied trichothecenes. In particular, NIV recoveries significantly improved compared to those obtained by using Mycosep® #227 columns for clean-up of the extracts. Limits of detection in the various investigated matrices ranged 2.5-4.0 µg kg^-1 for NIV, 2.8-5.3 µg kg^-1 for DON, 0.4-1.7 µg kg^-1 for HT-2 and 0.4-1.0 µg kg^-1 for T-2. Mean recovery values, obtained from cereals and cereal products spiked with NIV, DON, HT-2 and T-2 toxins at levels from 10 to 1000 µg kg^-1, ranged from 72 to 110% with mean relative standard deviation lower than 10%. A systematic investigation of matrix effects in different cereals and cereal products was also carried out by statistically comparing the slopes of standard calibration curve with matrix-matched calibration curve for each of the four toxins and the eight matrices tested. For seven of the eight matrices tested, statistically significant matrix effects were observed, indicating that, for accurate quantitative analysis, matrix-matched calibration was necessary. The method was applied to the analysis of 57 samples of ground wheat originated from South Italy and nine cereal food samples collected from retail markets.     

QuEChERS-气相色谱-质谱法测定土豆中109种农药残留

建立土豆中109种农药残留的气相色谱-质谱(GC-MS)检测方法。方法 土豆样品以乙腈提取后,经N-丙基乙二胺(PSA)分散固相萃取净化(d-SPE),采用电子轰击电离源(EI)和负化学电离源(NCI)两种电离模式进行GC-MS测定。结果 各农药的定量限在0.001～0.010 mg/kg之间,对空白土豆样品的平均加标回收率为72.7%～118.7%,RSD在1.1%～17.3%之间。在EI模式下,土豆基质对绝大多数农药具有明显的基质效应,因此采用基质匹配标准曲线进行定量分析。应用此方法对欧盟农药残留参比实验室组织的国际比对考核的土豆样品进行定性筛查和定量测定,共检测出13种农药残留,含量范围在0.002～1.669 mg/kg之间,所提交的测定结果的Z评分值在-1.00～1.00之间。结论 本方法简便快速、准确、灵敏度高,适用于农产品中农药多残留的分析。     

Determination of trichothecenes in cereals and cereal-based products by liquid chromatography–tandem mass spectrometry

A sensitive, accurate and precise method for the simultaneous determination of nivalenol (NIV), deoxynivalenol (DON), T-2 toxin (T-2) and HT-2 toxin (HT-2) in different food matrices, including wheat, maize, barley, cereal-based infant foods, snacks, biscuits and wafers, has been developed. The method, using liquid chromatography coupled with atmospheric pressure chemical ionization triple quadrupole mass spectrometry (LC–APCI–MS/MS), allowed unambiguous identification of the selected trichothecenes at low µg per kg levels in such complex food matrices. A clean-up procedure, based on reversed phase SPE Oasis® HLB columns, was used, allowing good recoveries for all studied trichothecenes. In particular, NIV recoveries significantly improved compared to those obtained by using Mycosep® #227 columns for clean-up of the extracts. Limits of detection in the various investigated matrices ranged 2.5–4.0 µg kg^?1 for NIV, 2.8–5.3 µg kg^?1 for DON, 0.4–1.7 µg kg^?1 for HT-2 and 0.4–1.0 µg kg^?1 for T-2. Mean recovery values, obtained from cereals and cereal products spiked with NIV, DON, HT-2 and T-2 toxins at levels from 10 to 1000 µg kg^?1, ranged from 72 to 110% with mean relative standard deviation lower than 10%. A systematic investigation of matrix effects in different cereals and cereal products was also carried out by statistically comparing the slopes of standard calibration curve with matrix-matched calibration curve for each of the four toxins and the eight matrices tested. For seven of the eight matrices tested, statistically significant matrix effects were observed, indicating that, for accurate quantitative analysis, matrix-matched calibration was necessary. The method was applied to the analysis of 57 samples of ground wheat originated from South Italy and nine cereal food samples collected from retail markets.     

Non-targeted screening of pesticides for food analysis using liquid chromatography high-resolution mass spectrometry-a review

ABSTRACT

Targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a robust and reliable tool in quantitative analysis of pesticide residues in food samples. However, these methods have been only targeted to a predefined set of pesticides. Many other unexpected pesticides and/or their (bio)transformation products present in food matrices that may be harmful to consumers need to be discovered for food safety monitoring purpose. Therefore, non-targeted screening approaches using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) have gained much attention in food monitoring recently. However, the development and implementation of non-targeted screening of potential pesticides and their (bio)transformation products in food samples are particularly challenging due to the inherent sample complexity and large quantity of MS data. To provide guidance on how to use non-targeted screening approaches for pesticide screening, three different aspects, namely, sample preparation, data acquisition and data processing, encompassed in the workflow of non-targeted screening approaches have been discussed, and current strategies, advances and challenges regarding these three aspects are reviewed. In addition, the recent application of non-targeted screening analysis of pesticide residues and their (bio)transformation products in food samples has been overviewed in this paper.     

Screening of Over 600 Pesticides,Veterinary Drugs,Food-Packaging Contaminants,Mycotoxins, and Other Chemicals in Food by Ultra-High Performance Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry (UHPLC-QTOFMS)

In this article, an accurate mass multiresidue screening method has been developed for the determination of over 630 multiclass food contaminants in different matrices using ultra-high performance liquid chromatography/(quadrupole)-time-of-flight mass spectrometry. The compounds included in the study were 426 pesticides, 117 veterinary drugs, 42 food-packaging contaminants, 21 mycotoxins, 10 perfluorinated compounds, 9 nitrosamines, and 5 sweeteners. The separation was carried out by liquid chromatography using a C₁₈ column (50 mm × 2.1 mm, 1.8 μm particle size). The identification of the targeted species was accomplished using accurate masses of the targeted ions (protonated or deprotonated molecule) along with retention time data and characteristic fragment ion for reliable identification, using specific software for automated data mining and exploitation. The performance of the screening method was validated in terms of linearity, matrix effect, and limits of quantification for three representative food matrices (tomato, orange, and baby food) using a generic sample treatment based on liquid partitioning with acetonitrile (QuEChERS). The overall method performance was satisfactory with limits of quantification lower than 10 μg kg ^?1 for the 44 % of studied compounds. In some cases (ca. 10–15 % of the pesticides depending on the matrix tested, maximum residue levels were not fulfilled). In orange, 15 % of the compounds displayed LOQs above the maximum residue levels (MRLs) set for the studied pesticides, which can be partially attributed to matrix effects. Moderate signal suppression was observed in the three matrices tested in most cases, being orange the matrix which produced the highest matrix effect and baby food the lowest one.     

Multiresidue analysis of pesticides in tea by supercritical fluid extraction (SFE) and GC-MS

A multiresidue analysis of pesticides in tea using supercritical fluid extraction (SFE) and GC-MS was developed. The preprocessing using SFE shortened the total analysis time. The SFE extract contained less matrices than the extract obtained with organic solvents. However, these matrices disturbed instrumental analysis. So, the extract was cleaned up with ENVI?-Carb/NH2 and InertSep? SI cartridge. A recovery test was carried out for 245 pesticides spiked in samples at the level of 0.1 μg/g. Recovery rates of 178 pesticides ranged from 70 to 120%, the relative standard deviations (RSDs) were less than 15%, and quantitation limits were between 0.01 and 0.05 μg/g. Based on these results, this method is considered to be useful for multiresidue analysis of pesticides in tea samples.     

Application of an HPLC–MS/MS method for mycotoxin analysis in commercial baby foods

This article describes the validation of an analytical method for the detection of 21 mycotoxins in baby food. The analytical method is based on the simultaneous extraction of selected mycotoxins by matrix solid-phase dispersion (MSPD) followed by liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) using a hybrid triple quadrupole-linear ion trap mass spectrometer (QTRAP®). Information Dependent Acquisition (IDA), an extra confirmation tool for samples that contain the selected mycotoxins, was used. The matrix effects were evaluated, and the corrections for the matrix effects were performed using two calibration approaches: external matrix-matched calibration and internal standard calibration. Matrix-matched calibration was ultimately used for accurate quantification, and the recoveries obtained were generally higher than 70%. The analytical method was applied to the analysis of 35 samples of commercial baby foods. No sample exceeded the maximum limit (ML) fixed by the European Union for these mycotoxins in baby food. However, this survey highlighted the occurrence of mycotoxins in cereal-based infant foods.     

Rapid screening for pesticides using automated online sample preparation with a high-resolution benchtop Orbitrap mass spectrometer

For pesticide analysis in food products a common approach is to develop a fast multi-residue method that is capable of identifying and quantifying a large number of analytes in various matrices. This study demonstrates rapid screening and accurate mass confirmation of 116 pesticides in oranges and hazelnuts using an automated online sample preparation method with turbulent-flow chromatography technology coupled to a high-resolution benchtop Orbitrap? mass spectrometer. The limits of quantification (LOQs) for the majority of analytes are well below the maximum residue limit (MRL) set by the European Union and the Japanese government. The recoveries were in the range of 70-120% for over 75% of analytes in both matrices. The present methodology is suitable for routine pesticides analysis in food safety laboratories.     

A multi-residue method for the determination of 90 pesticides in matrices with a high water content by LC-MS/MS without clean-up

A method using QuEChERS extraction and LC-MS/MS in electrospray positive ionisation mode was developed and validated for the analysis of 90 pesticides in a high water content matrix (tomato) in a single chromatographic run. To assess the intra-laboratory reproducibility of the method, validation was conducted on four different days by two different analysts. The validation data was treated using a spreadsheet developed in-house, which sets the most appropriate model for linear fit by determining whether the residuals of the calibration curves are homocedastic or heterocedastic. A statistical test for the significance of regression was also carried out. Calibration was always matrix-matched and the curves were obtained over the range 0.0075-0.10 or 0.020-0.125 mg kg(-1). Identification of analytes was based on retention times and MRM ratios. Recoveries were assessed at four different levels for each analyte and were between 73 and 106%, with relative standard deviations under reproducibility conditions of <20%. The measurement uncertainties of the method for each pesticide analysed were below 50%. Previous validation of the same method, applied to papaya samples and satisfactory results obtained in various proficiency tests with different high water content matrices, demonstrated the applicability of the method to these classes of commodities, without clean-up. The validated method will be applied routinely in the pesticide residues monitoring programme that constitutes the National Residue and Contaminant Control Plan of Brazil.     

Collaborative Study of a T-nos Real-Time PCR Method for Screening of Genetically Modified Organisms in Food Products

In the EU the presence of genetically modified organisms (GMO) in food is controlled by the Member States official laboratories within their national inspection and monitoring programs. The most frequently used approach to detect the presence of GMO material in different food matrices is the PCR-based screening for the CaMV 35S promoter and the nos terminator (T-nos) DNA sequence from Agrobacterium tumefaciens. A real-time PCR method for detection of T-nos and its validation in a collaborative trial study is described in this paper. The PCR system amplifies a 84 bp fragment and showed to be sensitive to detect at least 5 copies of the T-nos DNA sequence. The assay was adapted for use in real-time PCR instruments using plastic reaction vials and glass capillaries, respectively. A total of 24 laboratories participated in the study and each laboratory received 18 DNA blind samples prepared from GMO certified reference materials (0.1 % and 0.5 % NK601 maize) and from a non-GM maize flour. All samples containing NK603 maize DNA were correctly classified as T-nos positive by the participating laboratories. For the blank samples (0 % GMO) only three false-positive results were reported. A detailed evaluation of the results of the collaborative trial study is described. Received: March 19, 2007     

Collaborative Study of a T-nos Real-Time PCR Method for Screening of Genetically Modified Organisms in Food Products

In the EU the presence of genetically modified organisms (GMO) in food is controlled by the Member States official laboratories within their national inspection and monitoring programs. The most frequently used approach to detect the presence of GMO material in different food matrices is the PCR-based screening for the CaMV 35S promoter and the nos terminator (T-nos) DNA sequence from Agrobacterium tumefaciens. A real-time PCR method for detection of T-nos and its validation in a collaborative trial study is described in this paper. The PCR system amplifies a 84 bp fragment and showed to be sensitive to detect at least 5 copies of the T-nos DNA sequence. The assay was adapted for use in real-time PCR instruments using plastic reaction vials and glass capillaries, respectively. A total of 24 laboratories participated in the study and each laboratory received 18 DNA blind samples prepared from GMO certified reference materials (0.1 % and 0.5 % NK601 maize) and from a non-GM maize flour. All samples containing NK603 maize DNA were correctly classified as T-nos positive by the participating laboratories. For the blank samples (0 % GMO) only three false-positive results were reported. A detailed evaluation of the results of the collaborative trial study is described.     

Validation of an alternative method for the identification of 2-dodecylcyclebutanone (2-DCB) of irradiated meats by solid-phase microextraction (SPME) gas chromatography–mass spectrometry (GC-MS)

A rapid and simple procedure to detect irradiated food containing fat is proposed. This method is based on HS-SPME coupled with GC-MS to determine the presence of a radiolytic product in irradiated meats: 2-dodecylcyclobutanone (2-DCB) and is proposed as an alternative to EN 1785:2003, which is a long and complex procedure. The qualitative confirmation method is validated on different type of meats: chicken, turkey, duck, beef, pork on both nonirradiated and irradiated samples at different dose levels (0.05, 0.12, 0.5, 1.0 and 3.0 kGy) with a biological X-ray irradiator. The validation parameters investigated are selectivity, minimum dose level (MDL), limit of detection (LOD), sensitivity and specificity. The MDL and LOD values were 0.5 kGy and 5.0 ng mL⁻¹, respectively, for all matrices. No false positives or false negatives occurred, and 100% of samples were correctly identified. The results show that HS-SPME GC-MS is suitable for routine analysis.     

凝胶渗透色谱净化系统与气相色谱-串联质谱法检测5种食品中14种有机磷和7种拟除虫菊酯类农药残留

建立GPC与GC-MS/MS测定5种食品中14种有机磷和7种拟除虫菊酯类农药残留的方法,初步分析GPC净化技术及MS/MS分析技术在食品农药多残留分析的优势。方法 用GPC作为样品前处理方法,处理韭菜、大白菜、辣椒、猪肉、鱼肉五种食品,用 GC-MS/MS检测并进行定性、定量分析。结果 GPC与GC-MS-MS检测食品中14种有机磷和7种拟除虫菊酯类农药方法的线性相关系数r＞0.995,定量限为0.002～0.034 mg/kg,对韭菜、猪肉样品按0.05、0.10、0.20 mg/kg三组水平加标测试,方法精密度RSD%为2.9～10.2%,回收率为78.6～108.3%。结论 本方法检测样品范围广、灵敏度高、定性可靠、定量准确,适合多种类食品中农药多残留分析。     

Improvement and Validation of Phytate Determination in Edible Seeds and Derived Products,as Mineral Complexing Activity

The analysis of phytates, as antinutrients that naturally occur in edible seeds, is important due to its interaction with certain minerals (Ca, Mg, Zn, Fe) essential for health, especially for children or other groups at risk of deficiency diseases. Although several analytical methods for phytates use complex techniques, complexometric methods are recently applied since they provide the knowledge of real mineral complexing activity of different phytates in foods, which is of great relevance for nutritional studies. A reliable method for phytate quantification in terms of cation binding activity has been optimized, based on previous complexometric methods, with the improvement of quantification through calibration with standards instead of estimation through equations. The methodology was optimized for different matrices of seeds and seed-derived food products, including infant foods, and it was validated according to AOAC standards to assess reliability. Due to the presence of different phytate forms in foods, and the different ability of complexation of each one, the expression of results of phytates as phytic acid equivalents (PAE) is proposed. With this methodology, phytates were found in all the samples analyzed, showing a higher amount in seeds (4029 mg PAE/100 g in dehulled hemp seed) than in infant foods (231 mg PAE/100 g in rice formula). From the validation protocol, the method showed good linearity, accuracy, and precision for food samples over 80 mg PAE/100 g, not requiring high-cost equipment, and providing high reliability and practical applicability for routine laboratories, with the purpose of monitoring of food quality.     

Determination of low-level pesticide residues in agricultural products by ion-trap GC/MS/MS

The objective of this study was to elucidate the utility of ion-trap GC/MS/MS for the analysis of pesticides in extracted matrices from various agricultural products. Identification and quantitative analysis of pesticides in matrices were performed by quadrupole GC/MS and ion-trap GC/MS/MS. Chlorpyrifos was added to the matrix of spinach, soybean in the pod or corn, and aldrin, dieldrin, endrin, alpha-BHC, beta-BHC, gamma-BHC, delta-BHC, p,p'-DDD, p,p'-DDE, o,p'-DDT and p,p'-DDT were added to each matrix of green tea, black tea or oolong tea. Although most of the pesticides in the matrix could not be determined by quadrupole GC/MS-Scan analysis at 0.1 microgram/mL, every pesticide was identified from the mass spectrum using ion-trap GC/MS/MS at the same concentration. The quantitation limit of every pesticide in each matrix by ion-trap GC/MS/MS analysis was higher than that by GC/MS-SIM analysis. The calibration curves obtained by GC/MS/MS were linear in the range of 0.01-0.25 microgram/mL of each pesticide. The recoveries of each pesticide from four kinds of samples spiked at the levels of 0.01 ppm to 0.02 ppm in extracts were 61.2-138.3% with SD values in the range from 1.2 to 15.4%. This study revealed that ion-trap GC/MS/MS was useful for the identification and quantitative analysis of low-level pesticides residues in matrices of agricultural products.     

Methods for determining pesticides and polychlorinated biphenyls in food samples--problems and challenges

Determination of residual amounts of pesticides and polychlorinated biphenyls (PCBs) in food samples requires the use of specific techniques regarding sample preparation as well as instrumental analysis which should be characterized by a very low detection limit. A problem associated with the use of pesticides and PCBs is the need for controlling their residues in the environment, particularly in food, as these chemicals show a propensity to accumulate. The analysis of food samples for the presence of pesticides and PCBs brings on many difficulties because of the specificity of sample preparation consisting of multistep purification procedures of samples that contain trace amounts of an analyte. Concentration determinations of pollutants that easily dissolve in complex matrices, particularly in the presence of a large apportionment of interfering substances, pose a big challenge. Therefore, the basic step in food analysis for the presence of pesticides and PCBs is sample preparation which mainly consists of analyte enrichment and the removal of interfering substances. But all steps of the analytical procedure that include sample collection and preparation, extraction of analytes from matrix, extract purification, and final determination, are very significant; their precision and correct application have a decisive effect on the final result.