title: Mass spectrometric analysis of cardiac glycosides by the desorption/ionization technique potassium ion ionization of desorbed species.
abstract: The analysis of cardiac glycosides by the desorption/ionization (D/I) mass spectrometric technique potassium ion ionization of desorbed species (K+IDS) is presented. K+IDS mass spectra of digitonin, digoxin, digoxigenin, digitoxin and ouabain are discussed to demonstrate the capabilities of this D/I method. The K+IDS analysis consists of two steps: thermal desorption of neutral molecules representative of the analyte, followed by gas-phase addition of K+ ions to these species. Structural and molecular weight information of the cardiac glycosides is obtained with the K+IDS technique. The most intense peak in the K+IDS mass spectrum of an analyte, M, is frequently the [M]K+ ion. Interpretation of the K+IDS mass spectra is simple, since one thermal degradation mechanism dominates. This mechanism is a 1,2-elimination process. A variation of the original K+IDS technique, performed by changing the ionizing metal from K+ to Na+ (i.e. Na+IDS), is presented for the analysis of digoxin. The Na+IDS mass spectrum of digoxin contains more structural information than the K+IDS mass spectrum of that compound. This may lead to a means of controlling the types of information obtainable with this D/I technique by varying the cation that is thermionically generated. K+IDS analyses can be performed rapidly, no sample derivatization is necessary, no matrix is required and little instrument modification is necessary.
authors.affiliation: Department of Chemistry, Michigan State University, East Lansing 48824.
authors.forename: K J
authors.initials: KJ
authors.lastname: Light
authors.forename: D B
authors.initials: DB
authors.lastname: Kassel
authors.forename: J
authors.initials: J
authors.lastname: Allison
mesh_terms: D002301:Cardiac Glycosides / Q000032:analysis*; D004072:Digitonin / Q000032:analysis; D004076:Digoxigenin / Q000032:analysis; D004077:Digoxin / Q000032:analysis; D013058:Mass Spectrometry; D010042:Ouabain / Q000032:analysis; D011188:Potassium / Q000032:analysis
chemical_list: D002301:Cardiac Glycosides; D010042:Ouabain; D004077:Digoxin; D004072:Digitonin; D004076:Digoxigenin; D011188:Potassium