Measurement of ethyl carbamate in blood by capillary gas chromatography/mass spectrometry using selected ion monitoring.

Methodology is presented for convenient, reproducible and direct measurement of blood concentrations of ethyl carbamate, an experimental animal carcinogen. Extraction techniques requiring 20 microliters of blood and selected ion monitoring using ethyl (13C, 15N)carbamate as internal standard enabled quantification of ethyl carbamate concentrations ranging from 50 ng ml-1 to 100 micrograms ml-1. Coefficients of variation at several representative concentrations averaged less than 4%. The method was used to determine the time course of elimination of ethyl carbamate from mice receiving doses of 125 mumol kg-1.