Determination of ethylenebisdithiocarbamate and propylenebisdithiocarbamate fungicides in food using liquid chromatography tandem mass spectrometry

Dithiocarbamates (DTCs) are nonsystemic, protective fungicides used all over the world to protect fruits, vegetables, and herbs from several fungal infections. Hence, it is very important to detect and quantify their residue in food. In this work, a rapid and sensitive protocol has been validated for the determination of DTCs subclasses, ethylenebisdithiocarbamate (EBDC) and propylenebisdithiocarbamate (PBDC) fungicides in fruits, vegetables, and herbs. The method was based on the decomposition of EBDC and PBDC in an alkaline medium followed by methylation into dimethyl ethylenebisdithiocarbamate (EBDC-dimethyl) and dimethyl propylenebisdithiocarbamate (PBDC-dimethyl), respectively. This was followed by applying citrate buffer acetonitrile-based QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation technique. The method validation was performed according to the European quality control guidelines (SANTE/12682/2019). The precision and trueness of the method were determined from recovery experiments on six replicates of spiked blank samples at 0.01, 0.05, and 0.1 mg/kg for each commodity. The mean recoveries of EBDC-dimethyl and PBDC-dimethyl ranged from 79–119% and 74–120%, respectively. The RSD value for both analytes was in the range of 2–20. The only exception was PBDC-dimethyl in fennel matrix at 0.01 mg/kg. The limit of quantification of the method was 0.01 mg/kg with the exception of PBDC-dimethyl in fennel, which was 0.05 mg/kg.