Identification of an acidic metabolite of N-nitrosodiethanolamine isolated from rat urine.

N-Nitrosodiethanolamine metabolism was studied in order to clarify the mechanism(s) by which this compound elicits its carcinogenic effect. Samples of 24 h urine from rats given a single dose of N-nitrosodiethanolamine were collected. Gas chromatographic thermal energy analyses showed the presence of only one compound containing the nitroso moiety besides N-nitrosodiethanolamine. This compound was identified as the acidic derivative N-(2-hydroxyethyl)-N-carboxymethylnitrosamine by comparison with an authentic standard by means of gas chromatographic mass spectrometric analysis of the trimethylsilyl or pentafluorobenzyl esters. The amount of N-(2-hydroxyethyl)-N-carboxymethylnitrosamine excreted in the 24 h urine was about 6% of the N-nitrosodiethanolamine administered.