Dilute-and-shoot and quechers modified in house for determination of multimycotoxins in cocoa

Abstract

Due to the high complexity of the cocoa matrices, a modification to the dilute-and-shoot and QuEChERS methods was proposed for the simultaneous analysis of 42 mycotoxins. The modification allowed an efficient extraction with reduced co-extractives of the matrix without clean up step with LCMS/MS analysis. The ideal condition was: extraction of the cocoa paste with a ratio of 6:4 ACN/H2O (v/v), followed by partitioning of the extractive phase with addition of 3g of NaCl, stirring on a shaker table for 60min and freezing for 15min at -70ºC, the mixture was centrifuged and the supernatant collected for analysis. The performance of the proposed method was evaluated for 35 mycotoxins, considering the recovery range of 70-120% and RSD less than 20%, 5 mycotoxins presented an unsatisfactory result one of the levels of fortification. LD's ranged in between 1.3-27.6μg kg-1. The limits of aflatoxins and ochratoxins defined in the legislation for cocoa were met.