Development and validation of a sensitive liquid chromatography-tandem mass spectrometry method for the analysis of Mancozeb residues in cauliflower: Risk assessment of real samples

Abstract

The Dithiocarbamate (DTC) group represents one of the largest consumed fungicides. Presently the most extensively used UV–Visible spectrophotometric method for quantification of DTCs suffers from a lack of sensitivity for trace level detection of residue, poor stability, poor reproducibility, inability to determine LOD, LOQ and chances of matrix interference. In this study a sensitive residue analysis method has been developed and validated for the estimation of dithiocarbamate fungicide, Mancozeb, in cauliflower. Mancozeb was derivatized to a yellow coloured cupric dithiocarbamate complex, which was quantified with mass confirmation by LC–MS/MS. The LC-MS/MS method is considerably more sensitive (LOQ 0.01 µg g^-1) than the UV–Visible (LOQ 0.1 µg g^-1), specific (unique MRM transitions), accurate (recovery ∼93 %), precise (HorRat ∼0.3 at LOQ), rugged and associated with well acceptable uncertainty. 80 % of the real samples of cauliflower collected contain residues of DTCs above LOQ. Risk assessment of the real sample with the highest DTC contamination (0.18 µg g^-1) was conducted. The Theoretical Maximum Residual Contribution (TMRC) of 0.027 mg of Mancozeb/person/day in the Katrain sample was found to be much less than the Maximum Permissible Intake (MPI) of 1.65 mg of mancozeb/person/day and it can be considered safe for human consumption.