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

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.