Modification of the Carbon Disulfide Evolution Method for Dithiocarbamate Residues

Abstract

A study was made of the analytical method for dithiocarbamate fungicide residues based on decomposition by hot mineral acids to the amine and carbon disulfide and colorimetric measurement of the carbon disulfide. Increased recoveries are obtained by the following modifications: adding a reducing agent (stannous chloride) to the sample before treatment with hot acid; svibstituting diluted sodium hydroxide for lead acetate solution to remove hydrogen sulfide and other interferences; and using boiling diluted hydrochloric acid. With these modifications, recoveries of N,N-dimethyldithiocarbamates from crops ranged from 85.3 to 103.8% (average 94.7%). Ethylenebisdithiocarbamates, with the exception of zineb (range 89.1–96.8%, average 92.0%), gave appreciably lower recoveries, indicating further study is necessary.