Positive- and negative-ion mass spectrometry of butyrophenones

Abstract

Positive-ion electron-impact (EI), positive-ion chemical ionization (CI) and medium-pressure negative-ion CI mass spectra of ten butyrophenones are presented. Low-pressure (0.01 Torr) negative CI spectra are also presented for some compounds. In the positive EI mode, a peak at m/z 42, which corresponded to the propyl group, appeared for all compounds; a peak at m/z 123 was also common to all compounds except for the two with a bis(fluorophenyl) group. Molecular ions were generally very small or missing in the positive EI mode. In the positive CI mode, strong [M+H] + quasi-molecular peaks generally appeared together with [M+C 2H 5] + peaks; [M−F] + peaks appeared in many compounds and [M−OH] + peaks also appeared for compounds having a hydroxypiperidinyl group. In the negative CI mode with a 1 Torr chamber pressure, their spectra were generally simple with [M−H] − quasi-molecular ions; anions of liberated halogens were not observed except for bromine at this pressure. In the negative CI mode at low pressure (0.01 Torr), some fragment peaks in the lower mass range appeared in addition to the quasi-molecular ions; halogen peaks ( m/z 19 or 35) and anions at m/z 95, which corresponded to the fluorophenyl group, appeared in most spectra recorded at this pressure. An procedure for the extraction of butyrophenones from human urine and plasma and their separation by gas chromatography was also developed to serve for their identification in forensic science practice.