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.     

A review of methodology for the analysis of pyrethrin and pyrethroid residues in food of animal origin

Pyrethrin and pyrethroid pesticides are commonly used in crop protection and animal health, to control pests. As a result, they can potentially transfer into food if good agricultural practice is not followed or even due to accidental contamination. The analysis of these compounds has been widely reported in crops and the environment. However, the analysis of pyrethrin and pyrethroids has not been reported frequently in foods of animal origin, particularly animal tissues. The focus of this review is to report on pyrethrin and pyrethroid analysis including key aspects such as chemistry, choice of target matrix, sample preparation, chemical analysis, legislation and method validation. This review shows that most methodologies for the analysis of these compounds are based on gas chromatography with the trend in recent years to move towards GC-MS or GC-MS/MS based platforms. This review shows that these compounds can also be satisfactorily analysed by LC-MS/MS, which can be advantageous because of shorter chromatographic run times. A wide range of sample preparation procedures have been applied in analytical methods and more complex protocols are required for GC applications, whereas more crudely prepared extracts can be analysed by LC-MS/MS. This review demonstrates that pyrethrin and pyrethroid residues should be included as analytes in multi-class analytical methods for pesticides and veterinary drug residues in animal derived foods.     

Applications of sample preparation techniques in the analysis of pesticides and PCBs in food

Pesticides and polychlorinated biphenyls (PCBs) are found in various parts of the environment in quite small concentrations, but they accumulate and thus become a threat to human health and life. A review is focused on the application of some popular techniques for sample preparation in analysis of these compounds in food. Even with the emergence of advanced techniques of final analysis, complex matrices, such as food, require extensive sample extraction and purification. Traditional sample preparation techniques are time consuming and require large amount of solvents, which are expensive, generate considerable waste, contaminate the sample and can enrich it for analytes. There have been many sample preparation techniques proposed to meet the requirements connected with the multiplicity of food. Optimal sample preparation can reduce analysis time, sources of error, enhance sensitivity and enable unequivocal identification and quantification. Sample extraction and purification techniques are discussed and their most recent applications in food analysis are provided. This review pointed out that sample preparation is the critical step.     

分散固相萃取技术在动物源性食品兽药残留检测中的应用进展

高效的样品前处理是实现准确分析的前提条件。分散固相萃取（DSPE）是一种通过将固体吸附剂分散在液体分析物中,从复杂基质中分离和净化不同的分析物的方法。这种方法具有高效、快速、选择性强、易操作等优点,已经被广泛应用于环境、食品、药物、生物等领域的样品前处理中。本文旨在回顾DSPE方法的设计原理,并综述吸附剂的分散方法、种类、性质,以及在动物源性食品兽药残留检测方面的应用。     

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.     

Methods for the analysis of melamine and related compounds in foods: a review

In recent years, two adulteration incidents concerning the addition of melamine (MEL) and related compounds to dairy products and vegetable proteins have occurred in China. These episodes prompted numerous governmental and private laboratories to develop or implement methods for the analysis of a wide variety of food products for MEL and related compounds, including cyanuric acid, ammeline, and ammelide. Methods have been developed for both screening and quantitation purposes; procedures used in the methods range from sensitive hyphenated chromatographic-mass spectrometric techniques to immunoselective assays. Various issues are encountered during the analysis of MEL and related compounds in food products. These issues include contamination, matrix effects, and analyte instability, and their severity varies according to the method used, and matrices and analytes examined.     

固相萃取-气相色谱法检测金银花中9 种拟除虫菊酯农药残留

采用固相萃取净化,气相色谱电子捕获检测器检测,建立了金银花中9 种拟除虫菊酯农药残留量的检测方法。金银花样品经正己烷涡旋振荡提取、TPH固相萃取柱净化后,用气相色谱检测。9 种拟除虫菊酯农药的线性范围在0.01～0.8 mg/L,平均回收率为82.8%～104.6%,相对标准偏差为3.5%～5.7%,检出限为0.002～0.005 mg/L。该方法灵敏、准确,适用于金银花中9 种拟除虫菊酯类农药残留量分析。     

磁性固相萃取技术在食品真菌毒素分析中的应用

真菌毒素常见于食品和各种粮食作物中，具有致癌性、诱变性、致畸性等危害，严重威胁人类和动物的健康。由于真菌毒素在食品基质中存在种类多、浓度低、极性范围广等特点，因此建立快速高效的食品样品前处理方法对真菌毒素的痕量分析十分重要。磁性固相萃取（magnetic solid-phase extraction，MSPE）是一种基于磁相互作用的样品前处理技术，凭借简单快速、绿色安全、高效经济等特点，已广泛应用于食品样品真菌毒素分析的前处理中。本文介绍了MSPE的萃取过程和磁性纳米材料的制备和修饰，综述了以无机材料（氧化硅基和碳基）、有机材料（印迹型、有机高分子、表面活性剂和有机小分子）和其他材料（离子液体和单克隆抗体）为代表的MSPE吸附剂在食品样品真菌毒素检测中的应用，并对MSPE技术的发展趋势进行了展望。     

分散固相萃取-液相色谱-串联质谱法测定典型小宗作物中6种农药残留

建立生姜、红薯、土豆、荔枝中多菌灵、吡虫啉、涕灭威、三唑酮、乙草胺、苯醚甲环唑的液相色谱-串联质谱检测方法。样品经乙腈溶液提取,50 mg N-丙基乙二胺吸附剂、25 mg十八烷基键合硅胶(C_(18))净化,C_(18)色谱柱分离,0.1%甲酸溶液-甲醇作为流动相进行梯度洗脱,在电喷雾正离子电离模式下,质谱多离子监测模式定量分析,基质标准曲线外标法定量。结果表明,6种农药在10~500μg/L范围内呈良好的线性关系,相关系数(r)均大于0.995。3个加标水平下,6种农药的平均回收率为87.9%~110.3%,相对标准偏差不大于14.6%。该方法简单、快速、灵敏度高,能够满足小宗作物农药残留的监控要求。     

Development of a Sensitive and Accurate Stable Isotope Dilution Assay for the Simultaneous Determination of Free 4-Hydroxy-2-(E)-Nonenal and 4-Hydroxy-2-(E)-Hexenal in Various Food Matrices by Gas Chromatography–Mass Spectrometry

An analytical method suitable for the determination of 4-hydroxy-2-(E)-nonenal (HNE) and 4-hydroxy-2-(E)-hexenal (HHE) in various food matrices was developed and validated. The method involves the use of deuterated HNE and HHE as internal standards, extraction of the analytes from the matrices followed by derivatization and detection with gas chromatography–mass spectrometry. Four different food matrices were chosen as model systems including vegetable oils, unprocessed meat, fried potato crisps, and infant formula and three different extraction techniques suitable for the different matrices were applied including the Quick Easy Cheap Effective Rugged Safe method. The simplicity of the extraction techniques allows the method to be applied for routine analysis of a large amount of samples. The results verify the accuracy and reproducibility of the analytical technique and its ability to provide reliable quantification of both analytes at concentrations as low as 12.8 ng g^?1 in meat samples. Furthermore, a short overview of the levels of HNE and HHE in several products available in the Belgian market is presented.