False positives in dithiocarbamate analysis: a review of the literature

摘要

Dithiocarbamate fungicides are commonly used in agriculture, however the determination of the associated residues in foodstuffs can be problematic due to their lack of stability during storage and extraction and poor solubility in both organic and aqueous solvents. There are three classes of dithiocarbamates; dimethyldithiocarbamates (e.g. ziram, thiram), ethylenebisdithioarbamates (e.g. mancozeb, zineb) and propylenebisdithiocarbamates (e.g. propineb). For compliance with both national and international MRLs, the current residue definition of dithiocarbamates is 'the total residues arising from the use of any dithiocarbamate fungicide, determined as CS_2'. Although methods specific to individual dithiocarbamates are under development, the method that is commonly used to determine dithiocarbamate residues by monitoring laboratories involves the acid digestion of the sample which evolves carbon disulfide (CS_2), which is then measured by either headspace gas chromatography or spectrophotometry.