Fast atom bombardment mass spectrometry of some penicillins

Barber, M.; Bordoli, Robert S.; Sedgwick, R. D.; Tyler, Andrew N.; Green, Brian N.; Parr, Victor C.; Gower, John L.

doi:10.1002/bms.1200090104

Cited by 52 publications

(10 citation statements)

References 3 publications

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“…Cleavage of the strained lactam ring, however, appears to take precedence. This is substantiated by other desorption/ionization techniques in which intense fragment ions are observed corresponding to protonated species arising from cleavage of the (3-lactam ring of the penicillin (38). The free acid form of the penicillins studied to date by other DI techniques have given results comparable to that in Figure 3.…”

Section: Resultssupporting

confidence: 53%

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Desorption/ionization mass spectrometric technique for the analysis of thermally labile compounds based on thermionic emission materials

Bombick¹,

Allison²

1987

Anal. Chem.

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When a thermally labile analyte Is placed on a potassium thermionic emitter and heated, Ions representative of the sample are formed. This has been developed Into a new Ionization technique which utilizes a thermionic emitter probe that can be used with any mass spectrometer having a direct Insertion probe. A possible mechanism for this Ionization method is discussed. The proposed mechanism Involves the gas-phase addition of emitted potassium Ions to neutrals desorbed from the surface. This Ionization method Is referred to as K+IDS (K+ Ionization of desorbed species). Examples of K+IDS spectra are given for a variety of compounds Including saccharides, pharmaceuticals, peptides, steroids, and polymers. The analysis of mixtures Is also demonstrated here.In addition to the K+ Ionization of desorbed species, surface Ionization can occur. Surface Ionization Is demonstrated for the class of compounds that Includes xanthine and theophylline. Surface Ionization can also occur for thermally labile compounds, producing negative Ions; this Is shown here by use of a peptide as an example.

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Section: Resultssupporting

confidence: 53%

“…Most of these compounds are thermally labile. As an example the ß-lactam antibiotics have been studied by Py-MS (36) and by various DI methods (37,38). Pyrolysis methods almost always lead to low molecular weight products and consequently compound identification relies upon matching pyrolysis mass spectra to known spectra.…”

Section: Resultsmentioning

confidence: 99%

Desorption/ionization mass spectrometric technique for the analysis of thermally labile compounds based on thermionic emission materials

Bombick¹,

Allison²

1987

Anal. Chem.

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“…Fragmentation patterns vary, depending on ring size and the nature and position of the substituents. The fragmentation patterns of j3-1actam antibiotics [11][12][13][14][15][16][17], steroidal lactams [18][19][20], and other complex lactams [21][22][23][24][25] following electron impact ionization, chemical ioniza-tion, fast-atom bombardment ionization, and collisional activation have also been reported; however, the bimolecular reactions of simple lactams and dissociation reactions of the reaction products have not been studied systematically.…”

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confidence: 99%

Selective ion-molecule reactions of lactams with dimethyl ether ions

McCarley

Brodbelt

1993

J. Am. Soc. Mass Spectrom.

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The ion-molecule reactions of dimethyl ether ions CH3OCH3 (+) and (CH3OCH3)H(+), and four- to seven-membered ring lactams with methyl substituents in various positions were characterized by using a quadrupole ion trap mass spectrometer and a triple-quadrupole mass spectrometer. In both instruments, the lactams were protonated by dimethyl ether ions and formed various combinations of [M + 13] (+), [M + 15] (+), and [M + 45] (+) adduct ions, as well as unusual [M + 3] (+) and [M + 16] (+) adduct ions. An additional [M + 47] (+) adduct ion was formed in the conventional chemical ionization source of the triple-quadrupole mass spectrometer. The product ions were isolated and collisionally activated in the quadrupole ion trap to understand formation pathways, structures, and characteristic dissociation pathways. Sequential activation experiments were performed to elucidate fragment ion structures and stepwise dissociation sequences. Protonated lactams dissociate by loss of water, ammonia, or methylamine; ammonia and carbon monoxide; and water and ammonia or methylamine. The [M + 16] (+) products, which are identified as protonated lactone structures, are only formed by those lactams that do not have an N-methyl substituent. The ion-molecule reactions of dimethyl ether ions with lactams were compared with those of analogous amides and lactones.

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“…The experimental results from the series of compounds PtLAC12 (2-6) and PtLALB (7)(8)(9)(10)(11)(12)(13) are summarized in Tables 2 and 3, respectively. The results obtained with cisplatin and potassium tetrachloroplatinate (K,PtCI,) are summarized in Table 2 and footnote b to Table 2, respectively.…”

Section: Figures 1 and 2 Illustrate Typical Positive And Negativementioning

confidence: 99%

Fast atom bombardment mass spectrometry of cisplatin analogs

Siegel¹,

Bitha²,

Child³

et al. 1986

Biol. Mass Spectrom.

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Cisplatin analogs of the type PtLACl2 and PtLALB are thermally unstable, non-volatile and highly insoluble. For these platinum coordination complexes, LA is a bidentate amine ligand and LB is a bidentate carboxylate ligand. Mass spectral data for structural elucidation of these compounds are absent in the literature because they are difficult to ionize. Nevertheless, a routine fast atom bombardment mass spectroscopic method has been developed utilizing the mixed solvent system of dimethyl sulfoxide:thioglycerol in a ratio of about 1:3 v/v. Using both positive and negative ionization modes, structurally significant ions were observed from representative molecules of the two named classes of compounds. [M-H]- ions were observed in both structural classes while [M + H]+ ions were observed only in the PtLALB class of compounds. Additional ions observed are rationalized in terms of the condensed-phase solution chemistry of the cisplatin analogs and the mixed solvent system when exposed to the fast atom beam. The two mechanisms causing ionization of the cisplatin analogs in the condensed phase appear to be: displacement of the ligands with dimethyl-sulfoxide and addition of chloride and the ionized solvents [dimentyl sulfoxide + H]+ and [thioglycerol - H]- to the cisplatin analogs. It is hypothesized that the addition reactions of the ionized solvents occur because of the differences in the basicity of the solvents and their reactivity in forming platinum(II)-sulfur bonds.

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Fast atom bombardment mass spectrometry of some penicillins

Cited by 52 publications

References 3 publications

Desorption/ionization mass spectrometric technique for the analysis of thermally labile compounds based on thermionic emission materials

Desorption/ionization mass spectrometric technique for the analysis of thermally labile compounds based on thermionic emission materials

Selective ion-molecule reactions of lactams with dimethyl ether ions

Fast atom bombardment mass spectrometry of cisplatin analogs

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