Determination of specific urinary thioethers derived from acrylonitrile and ethylene oxide

A simple analytical method has been developed for the determination of specific urinary thioethers. Mercapturic acids present in urine are first de-acetylated enzymatically or by acid hydrolysis. Cysteine conjugates thus formed are reacted with o-phthalaldehyde and mercaptoethanol, yielding fluorescent derivatives, which are further separated by high-performance liquid chromatography (HPLC) in a reverse-phase system. The method is applicable to the determination of the following thioethers: 2-hydroxyethylmercapturic acid (N-acetyl-S-2-hydroxyethyl-L-cysteine; HMA), carboxymethylmercapturic acid (N-acetyl-S-carboxymethyl-L-cysteine; CAMA) and 2-cyanoethylmercapturic acid (N-acetyl-S-2-cyanoethyl-L-cysteine; CYMA), and the corresponding cysteine conjugates, S-2-hydroxyethyl-L-cysteine (HCYS), S-2-carboxymethyl-L-cysteine (CACYS) and S-2-cyanoethyl-L-cysteine (CYCYS). The excretion pattern of these thioethers in rats exposed to acrylonitrile and various rodents exposed to ethylene oxide is reported. Thioether excretion can be dependent on species and route of administration. The analytical procedure may prove to be applicable to the biological monitoring in humans of exposure to acrylonitrile, ethylene oxide, vinyl chloride, 1,2-dibromoethane and 1,2-dichloroethane.