Identification and differentiation of alkylamine antihistamines and their metabolites in urine by computerized gas chromatography-mass spectrometry.

A gas chromatographic-mass spectrometric screening procedure is described for the identification and differentiation of the following alkylamine antihistamines and their metabolites in urine: azatadine, benzquinamide, brompheniramine, chlorphenamine, (clofedanol), cyproheptadine, dimetindene, ketotifen, mebhydroline, phenindamine, pheniramine, pyrrobutamine, terfenadine and tolpropamine. After acid hydrolysis of the conjugates, extraction and acetylation, the urine samples were analysed by computerized gas chromatography-mass spectrometry. Using ion chromatography with the selective ions m/z 58, 169, 203, 205, 230, 233, 262 and 337, the presence of alkylamine antihistamines and/or their metabolites was indicated. The identity of positive signals in the reconstructed ion chromatograms was confirmed by a visual or computerized comparison of the stored full mass spectra with the reference spectra. The ion chromatograms, reference mass spectra and gas chromatographic retention indices (OV-101) are documented. The procedure presented is integrated in a general screening procedure (general unknown analysis) for several groups of drugs.