Matrix effects (MEs) can adversely affect quantification in pesticide residue analysis using GC. Analyte protectants (APs) can effectively interact with and mask active sites in the GC system, and are added individually or in combination to sample extracts and calibration solutions to minimize errors related to MEs. Unfortunately, APs cannot sufficiently compensate for MEs in all cases. Plant extracts, containing a broad range of natural compounds with AP properties, can also be used for this purpose. In this study, the applicability of cucumber extract as a natural AP mixture was investigated both alone and in combination with traditional APs. Extracts of two selected difficult matrices (onion and garlic) were prepared according to the citrate-buffered QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure. ME values of 40 representative GC-amenable pesticides were compared when calibrating against standards in pure solvent and in cucumber extract, with and without the addition of APs. Using a GC system with a contaminated inlet liner, the use of a cucumber-based calibration solution decreased MEs remarkably. The combination of APs with cucumber raw extract further decreased MEs, resulting in more than 85% of the tested pesticides showing ≤ 10% ME in onion and ≤ 20% ME in garlic. These results demonstrate that the preparation of calibration standards based on cucumber extracts (with or without the addition of APs) is a very useful and practical approach to compensate for MEs in pesticide residue analysis using QuEChERS and GC-MS/MS. The use of various internal standards is furthermore critically discussed.

基质效应（MEs）会对使用GC的农药残留分析中的定量产生不利影响。分析保护剂（AP）可以有效地与GC系统中的活性部位相互作用并掩盖其活性位点，并且可以单独或组合添加到样品提取物和校准溶液中，以最大程度地减少与ME相关的误差。不幸的是，AP无法在所有情况下充分补偿ME。含有多种具有AP特性的天然化合物的植物提取物也可用于此目的。在这项研究中，黄瓜提取物作为天然AP混合物的适用性被单独或与传统AP结合使用进行了研究。根据柠檬酸盐缓冲的QuEChERS（快速，简便，便宜，有效，坚固和安全）的程序，制备了两种选定的困难基质（洋葱和大蒜）的提取物。在添加和不添加AP的情况下，对纯溶剂和黄瓜提取物中的标准品进行校正时，比较了40种代表性的适合GC的农药的ME值。使用带有污染的进样口衬套的GC系统，使用基于黄瓜的校准溶液可显着降低MEs。AP与黄瓜粗提物的组合进一步降低了ME，导致超过85％的受测试农药的洋葱中ME≤10％，大蒜中ME≤20％。这些结果表明，基于黄瓜提取物（添加或不添加AP）的校准标准品的制备是补偿QuEChERS和GC-MS / MS分析农药残留中的ME的非常有用和实用的方法。此外，还对各种内部标准的使用进行了严格的讨论。