Improved gas chromatographic-mass spectrometric assay for haloperidol utilizing ammonia chemical ionization and selected-ion monitoring.

An improved method for the analysis of haloperidol in human serum, utilizing gas chromatography-ammonia chemical ionization mass spectrometry is described. A tetradeutero analogue of haloperidol is utilized as the internal standard, while a second drug, thioridazine, is added as a priming compound. The characteristic high sensitivity and selectivity of selected-ion monitoring combined with the added accuracy provided by incorporation of a labeled internal standard provide a reliable method for the quantitation of low levels of haloperidol.