An enhanced sensitivity and cleanup strategy for the nontargeted screening and targeted determination of pesticides in tea using modified dispersive solid-phase extraction and cold-induced acetonitrile aqueous two-phase systems coupled with liquid chromatography-high resolution mass spectrometry.

At present, matrix interferences in tea are still a great challenge for analysis of multi-pesticide residues. Herein, a simple sample preparation method was developed based on the modified dispersive solid-phase extraction (DSPE) procedure and cold-induced acetonitrile aqueous two-phase systems (ATPS). In modified DSPE procedure, polyvinylpolypyrrolidone (PVPP) was selected as the matrix dispersive adsorbent to remove polyphenols from the tea with the removal rate of >98.3%. Using cold-induced acetonitrile ATPS, caffeine of the tea extract was sharply reduced by 81.2%, and a 0.798-3.167 of enrichment factor for the representative pesticides was achieved. In liquid chromatography-high resolution mass spectrometry analysis, a full scan/data independent acquisition approach was used for the nontargeted screening and targeted determination of pesticides. In data analysis, an in-house database of pesticides was constructed, and a simple accurate mass calibration method was used to correct the accurate mass variation, which was conducive to reduce the number of false detects.