Analysis of Near 400 Pesticides in Tea via LC–MS/MS: Simple Sample Preparation and APCI to Improve Analyte Coverage

Abstract

As regulatory laboratories search for and implement consolidated methods for multiple matrix and analyte classes, compound lists increase to hundreds or thousands of targets. Multi-instrument approaches are often relied upon to analyze all pesticide targets, with the workload split between liquid chromatography–mass spectrometry (LC–MS) and gas chromatography–mass spectrometry (GC–MS) instrumentation. In this work, a simple solvent extraction approach was coupled with dual source electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) modes on an LC–tandem mass spectrometry (MS/MS) instrument to analyze 395 analytes extracted from black tea (345 compounds via ESI and 50 compounds via APCI, along with the internal standards). Excellent method performance (defined as an accuracy of 70–120% and a precision of <20% at one of two validation levels) was achieved for over 93% of analytes, including compounds normally analyzed by GC–MS, such as trifluralin, chlorfenson, chlormephos, fenchlorphos, etridiazole, and others. This approach can allow the consolidation of a pesticide method to a single instrument or significantly reduce the workload of a complementary GC–MS method.