Improvement on analysis of ethylenebisdithiocarbamate fungicide by 1,2-benzenedithiol derivatization-HPLC method

The traditional analysis of ethylenebisdithiocarbamate(EBDCs) fungicides by 1,2-benzenedithiol derivatization coupled with high performance liquid chromatography was improved by adding antioxidants vitamin C and THF to increase the stability of the reaction product. Four EBDCs fungicides including 70% mancozeb wettable power(WP), 68% metalaxyl-m mancozeb water dispersible granule(WG), 68% cymoxanil mancozeb WG and 55% pyraclostrobin metiram WG were used to validate this method. The results showed that the derivatization condition could be optimized by using 12 mmol/L 1,2-benzenedithiol, with EDTA(pH 9.3)/DTPA(pH 10.0) as decomplexants for mancozeb/metiram, simultaneously adding 4%(V:V) of tetrahydrofunan and vitamin C(40 mg/L). The determinants of EDBCs fungicides, with the exception of 55% pyraclostrobin metiram WG, were stable and quantificationally detectable with relative standard deviation less than 5% within 48 h. The improved method was demonstrated to be target-specific, inactive to EBDCs' metabolites like ethylenethiourea and CS2, and time-saving, which makes it practical for large-scale detection of EBDCs chemicals.