title: In-beam electron ionization mass spectra of penicillins.
abstract: The characteristics of in-beam electron ionization mass spectra of 6-aminopenicillanic acid and several penicillins, which yield no detectable molecular ion peaks using a conventional direct-insertion probe, have been established. The spectra of all compounds studied, with the exception of amoxicillin, exhibited molecular ion or (M+1) peaks with spectral features similar to the reported methyl ester or amide derivatives of the compounds. The fragmentation of penicillin G on electron impact under in-beam conditions can be described on the basis of data from mass analyzed ion kinetic energy spectrometry. A desorption technique utilizing polyethylene glycol 4000 was used as a means of obtaining satisfactory spectra of ampicillin and amoxicillin.
mesh_terms: D000667:Ampicillin / Q000032:analysis; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D013058:Mass Spectrometry / Q000379:methods; D010397:Penicillanic Acid / Q000032:analysis / Q000031:analogs & derivatives; D010404:Penicillin V / Q000032:analysis; D010406:Penicillins / Q000032:analysis*
chemical_list: D010406:Penicillins; D000667:Ampicillin; D010397:Penicillanic Acid; C004408:aminopenicillanic acid; D010404:Penicillin V