Mass-selected reagent ion chemical ionization and multiple tandem mass spectrometry techniques in an ion trap mass spectrometer for structural analysis

✍ Scribed by Mayran Sharifi; Jacques Einhorn

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 273 KB
• Volume: 11
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(199707)11:11<1185::aid-rcm890>3.0.co;2-v

✦ Synopsis

Mass

-selected reagent ion chemical ionization (CI) performed in an ion trap instrument is an efficient tool to investigate gas-phase ion reactivities and therefore to find out new and/or optimized applications for structural analysis. For instance, it was shown that the C 3 H 6 O + . (58 mass units) molecular ion originated from vinyl methyl ether (VME) should necessarily be used alone (i.e. unit-mass selected) to produce significant diagnostic-ions for double bond location in aliphatic alkenes. Regarding the assignment of epoxides, the previous NO + /CI method was adapted for an optimal use in the trap through isolation of NO + cation from N 2 O (instead of NO) plasma and production of the acylium diagnostic-ions via CID of [M -H] + formed by NO + -induced hydride abstraction. New alkylation ion-products, e.g. RCH == O + -alk, were also found to characterize isomeric epoxides as a result of either an initial electrophilic addition of the C 2 H 5 + cation (with saturated epoxides) or a methyl-transfer from [VME] + . (with α,β-unsaturated epoxides). The multiple tandem mass spectrometry (MS n ) capabilities of the ion trap were essential to achieve reagent ion mass-selection, structural assignment of the diagnostic-ions, or to provide further selectivity.