title: Ammonia gas: an improved reagent for chemical ionization mass spectrometry of bile acid methyl ester acetates.
abstract: The ammonia chemical ionization mass spectra of 28 methyl ester acetate derivatives of bile acids and related compounds have been determined by gas-liquid chromatography-mass spectrometry. Advantages of ammonia ionization over the previously studied isobutane ionization include a 130-270% enhancement in the sensitivity of base peak monitoring, and direct determination of molecular weight from the base peak (M + NH4+) in the mass spectrum of any of the derivatives. Minor ions in the ammonia spectra also allow selective detection of 3-keto compounds and can indicate unsaturation or double bond conjugation in the molecule. The significance of these studies for the detection and quantitation of bile acids is discussed.
mesh_terms: D000641:Ammonia; D001647:Bile Acids and Salts / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D007202:Indicators and Reagents
chemical_list: D001647:Bile Acids and Salts; D007202:Indicators and Reagents; D000641:Ammonia