Simultaneous determination of N,N-dimethylformamide, N-monomethylformamide and N-hydroxymethyl-N-methylformamide in rat plasma by capillary gas chromatography.

A capillary gas chromatographic method with nitrogen-phosphorus detection for the simultaneous quantitative determination of N,N-dimethylformamide, and its two metabolites, N-monomethylformamide and N-hydroxymethyl-N-methylformamide, in rat plasma has been developed. The method involves a single extraction step with ethyl acetate-acetone (4:1, v/v). The extract is injected into a fused-silica capillary column coated with Carbowax 20M. A temperature gradient (65-110 degrees C) is applied, and the three products can be separated within 10 min. The quantitation limits, using 25 microliters of rat plasma, for N,N-dimethylformamide, N-monomethylformamide and N-hydroxymethyl-N-methylformamide are 0.4, 0.4 and 2 micrograms/ml, respectively. This method is suitable for toxicokinetic studies in rats.