Pesticide Multi-Residue Analysis in Tea Using d-SPE Sample Cleanup with Graphene Mixed with Primary Secondary Amine and Graphitized Carbon Black Prior to LC-MS/MS

Graphene is a novel class of carbon nanostructures with ultrahigh specific surface area. Graphene has already been used in many fields and has great promise for use in sorbent materials. In this study, we used graphene mixed with primary secondary amine (PSA) and graphitized carbon black (GCB) as dispersive solid-phase extraction materials for the cleanup of tea for the first time. Compared to the literature, the amount of PSA and GCB was greatly reduced. A multi-residue method combined with liquid chromatography-tandem mass spectrometry was validated for rapid determination of 25 pesticide residues in tea. Green tea, black tea, and white tea were selected as matrixes, representing the majority of tea types. Recoveries ranged from 71.1 to 108.3 % and consistent relative standard deviations < 13.6 % for all 25 pesticides. Graphene has significant potential as a promising new adsorbent for pesticide residue analysis of teas. This method can be used to analyze tea samples with different degrees of fermentation.