The gas chromatographic mass spectrometric analysis of the new antitumor drug indicine-N-oxide utilizing a novel reaction accompanying trimethylsilylation

Indicine‐N‐oxide was analyzed by gas chromatography mass spectrometry with nanogram sensitivity after trimethylsilylation. Two different products were produced by altering the conditions of this reaction. Mass spectral evidence is presented to show that one of these was the expected trisubstituted pyrrolizidine product while the other was a trisubstituted pyrrole. The latter derivative is useful for distinguishing between indicine‐N‐oxide and indicine which does not form this novel product under the same conditions. Analgous pyrrole and pyrrolizidine products were formed from heliotrine‐N‐oxide, a compound that can serve as an internal standard for measuring indicine‐N‐oxide and its metabolites in biological samples. A method for purifying such samples by strong cation exchange chromatography prior to derivatization is also discussed.