ICAR-Central Tobacco Research Institute, Rajahmundry, India, 533105.
ICAR-National Institute of Natural Fibre Engineering and Technology, Kolkata, India, 700040.
J AOAC Int. 2020 Jan 1;103(1):55-61. doi: 10.5740/jaoacint.19-0204.
False detection of pesticides in agricultural produce may raise serious questions regarding both consumer safety and trade. High levels of delta-hexachlorocyclohexane (δ-HCH; 11.7-22.3 mg/kg) were detected in some tobacco samples in a retention time-based GC analysis. Hence, the selection of an appropriate analytical method is an uncompromisable necessity.
This research work aimed to elucidate false detection of pesticides along with identification of coeluting tobacco matrix compounds to understand the dynamics of false detection with an increase in the number of analyzed pesticides and to screen suitable analytical methods.
Initially, retention time-based GC analysis was performed for monitoring of 10 pesticide residues in tobacco leaf matrix, followed by GC-MS/selected-ion monitoring (SIM) analysis. Then, the total number of pesticides to be analyzed was increased to 47, and residue analysis was performed by involving GC-MS/SIM and multidimensional (MD) GC-MS.
A false-positive detection of δ-HCH due to a coeluting tobacco aroma compound, neophytadiene, during residue analysis of 10 pesticides in tobacco (Nicotiana tabacum L.) leaf was observed. This problem was resolved by employing the unique quantifier and qualifier ions in SIM mode. However, with 47 pesticides, neophytadiene completely masked the signal of δ-HCH, which resulted in an impure spectrum of δ-HCH (<30% similarity match) even after application of selective quantifier and qualifier ions. Finally, MDGC-MS analysis could resolve it by chromatographic separation of the said analyte from the coeluting matrix compound.
The findings of this work offer the potential to minimize false reporting of target pesticides to comply with consumer safety and trade standards.
The study identifies various tobacco matrix compounds coeluting with pesticides during multiresidue analysis. Neophytadiene, a tobacco aroma compound, resulted in false-positive detection of δ-HCH. The MDGC-MS could be effectively used as a confirmatory analysis tool for reliable detection of pesticide residue in tobacco leaf matrix.
农产品中农药的假检测可能会引发消费者安全和贸易方面的严重问题。在基于保留时间的 GC 分析中，一些烟草样品中检测到高水平的δ-六氯环己烷（δ-HCH；11.7-22.3mg/kg）。因此，选择适当的分析方法是不可妥协的必要条件。
本研究旨在阐明农药的假检测，并鉴定共洗脱的烟草基质化合物，以了解随着分析农药数量的增加，假检测的动态，并筛选合适的分析方法。
最初，进行基于保留时间的 GC 分析，以监测烟草叶基质中的 10 种农药残留，然后进行 GC-MS/选择离子监测（SIM）分析。然后，将待分析的农药总数增加到 47 种，并通过 GC-MS/SIM 和多维（MD）GC-MS 进行残留分析。
在对烟草（Nicotiana tabacum L.）叶中的 10 种农药进行残留分析时，由于共洗脱的烟草香气化合物新植二烯，观察到δ-HCH 的假阳性检测。通过在 SIM 模式下使用独特的定量和定性离子，解决了这个问题。然而，对于 47 种农药，新植二烯完全掩盖了δ-HCH 的信号，即使应用了选择性定量和定性离子，δ-HCH 的光谱也不纯净（<30%相似度匹配）。最后，MDGC-MS 分析通过将所述分析物与共洗脱的基质化合物进行色谱分离，能够解决这个问题。
这项工作的结果提供了减少目标农药误报以符合消费者安全和贸易标准的潜力。
本研究鉴定了在多残留分析中与农药共洗脱的各种烟草基质化合物。烟草香气化合物新植二烯导致δ-HCH 的假阳性检测。MDGC-MS 可有效用作可靠检测烟草叶基质中农药残留的确认分析工具。
