基质干扰是造成茶叶中农药残留快速检测假阳性结果的最主要原因。囿于咖啡碱等基质成分的理化性质,这些基质成分的高效去除一直是茶样前处理方法开发中的难题。基于基质成分的分子结构特征,在常规茶样前处理方法的基础上,引入酸溶液和聚乙烯聚吡咯烷酮吸附剂,开发了一种高效、高选择性的茶样前处理方法,茶多酚、咖啡碱、氨基酸等基质成分去除率达到99.99%以上,显著降低了茶样检测的基质效应。利用本方法,实现了茶叶中克百威和灭多威的残留检测,检出限分别达到0.57 mg·kg-1和0.20 mg·kg-1。
The false-positive results encountered in the rapid detection of pesticide residues in tea samples are primarily caused by matrix interference. However, limited by the physical and chemical properties of tea matrix components (e.g., caffeine), the development of pretreatments suffers major dilemmas in matrix removal effectiveness. In current work, a novel pretreatment method for tea samples was proposed by developing specific removal procedures based on the molecular structure characteristics of the main matrix components. On the basis of conventional pretreatment for tea samples, the novel method introduced acid solutions and polyvinylpolypyrrolidone adsorbents, which reduced the matrix effect of tea sample detection significantly with a high matrix removal rate of more than 99.99%. Under the assistance of the current pretreatment, the rapid detection of methomyl and carbofuran residues in tea samples was successfully achieved accurately. The limits of detection for carbofuran and methomyl in tea were 0.57 mg·kg-1 and 0.20 mg·kg-1, respectively.
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