Canadian Food Inspection Agency, Calgary Laboratory, 3650-36th Street N.W., Calgary, Alberta T2L 2L1, Canada.
J Agric Food Chem. 2014 Jan 29;62(4):966-83. doi: 10.1021/jf404123h. Epub 2014 Jan 15.
This paper presents a study on pesticide residue transfer rates (%) from dried tea leaves to brewed tea. In the study, a brewing procedure simulated the preparation of a hot tea drink as in routine. After brewing, pesticide residues were extracted from brewed tea using a method known as QuEChERS (quick, easy, cheap, effective, rugged, and safe). An UHPLC/ESI-MS/MS method was developed and validated to identify and quantify up to 172 pesticides in both tea leaves and brewed tea samples. Quantification was achieved using matrix-matched standard calibration curves with isotopically labeled standards or a chemical analogue as internal standards, and the calibration curves consisted of six points (0.4, 2.0, 8.0, 16.0, 24.0, and 40.0 μg/L equivalent in sample). The method was validated at four concentration levels (4.0, 12, 20.0, and 32.0 μg/L equivalent in sample) using five different brewed tea matrices on two separate days per matrix. Method performance parameters included overall recovery, intermediate precision, and measurement uncertainty, which were evaluated according to a nested experimental design. Approximately, 95% of the pesticides studied had recoveries between 81 and 110%, intermediate precision ≤20%, and measurement uncertainty ≤40%. From a pilot study of 44 incurred tea samples, pesticide residues were examined for their ability to transfer from dried tea leaves to brewed tea. Each sample, both tea leaves and brewed tea, was analyzed in duplicate. Pesticides were found to have different transfer rates (%). For example, imidacloprid, methomyl, and carbendazim had transfer rates of 84.9, 83.4, and 92.4%, respectively.
本文研究了干茶叶到冲泡茶中农药残留转移率（%）。在研究中，模拟了常规热茶饮料的制备方法进行冲泡。冲泡后，采用 QuEChERS（快速、简便、廉价、有效、坚固、安全）方法从冲泡茶中提取农药残留。建立并验证了 UHPLC/ESI-MS/MS 方法，用于鉴定和定量分析茶叶和冲泡茶样品中多达 172 种农药。采用基质匹配标准校准曲线，使用同位素标记标准品或化学类似物作为内标进行定量，校准曲线由 6 个点（样品中 0.4、2.0、8.0、16.0、24.0 和 40.0μg/L 等效物）组成。该方法在 4 个浓度水平（样品中 4.0、12、20.0 和 32.0μg/L 等效物）下进行验证，使用两种不同的冲泡茶基质，每个基质在两天内进行五次测定。方法性能参数包括总回收率、中间精密度和测量不确定度，根据嵌套实验设计进行评估。研究的大约 95%的农药回收率在 81%至 110%之间，中间精密度≤20%，测量不确定度≤40%。在 44 个实际茶叶样品的初步研究中，研究了农药残留从干茶叶转移到冲泡茶的能力。每个样品（茶叶和冲泡茶）均进行了两次重复分析。结果发现，农药具有不同的转移率（%）。例如，吡虫啉、灭多威和多菌灵的转移率分别为 84.9%、83.4%和 92.4%。
