GC/ECD determination of ethylenethiourea residues in tobacco leaves

Ethylenethiourea (ETU) is one of the degradation products of ethylene-bisdi thiocarbamates (EBDCs), a largely used fungicide in agricultural crops. Sin ce its recognized carcinogenic toxicity to humans, accurate and reliable de termination of the residue level of ETU in food and agricultural products h as become of great importance. Tobacco leaves before and after treatment wi th increasing rates of a formulation of Mancozeb (a commercial dithiocarbam ate) were extracted for ETU and its trifluoroacetylated S-benzyl derivative analyzed by gas chromatography with an electron capture detector (GC/ECD). This method is precise and sensitive for small amounts of ETU residues and represents a valid alternative to traditional spectrophotometric analysis of CS, which is the other degradation product of dithiocarbamates. Particul ar care must be paid to analyze the ETU derivative right after synthesis be cause of its rapid degradation with time.