Identification of the Carboxylic Acid Functionality by Using Electrospray Ionization and Ion-Molecule Reactions in a Modified Linear Quadrupole Ion Trap Mass Spectrometer

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• 作者：Steven C. Habicht ; Nelson R. Vinueza ; Enada F. Archibold ; Penggao Duan ; Hilkka I. Kenttä ; maa
• 刊名：Analytical Chemistry
• 出版年：2008
• 出版时间：May 1, 2008
• 年：2008
• 卷：80
• 期：9
• 页码：3416 - 3421
• 全文大小：161K
• 年卷期：v.80,no.9(May 1, 2008)
• ISSN：1520-6882

文摘

A mass spectrometric method has been developed for theidentification of the carboxylic acid functional group inanalytes evaporated and ionized by electrospray ionization(ESI). This method is based on gas-phase ion-moleculereactions of ammoniated ([M + NH₄]⁺) and sodiated ([M+ Na]⁺) analyte molecules with trimethyl borate (TMB)in a modified linear quadrupole ion trap mass spectrometer. The diagnostic reaction involves addition of thedeprotonated analyte to TMB followed by the eliminationof methanol. A variety of analytes with different func-tionalities were examined, and this reaction was onlyobserved for molecules containing the carboxylic acidfunctionality. The selectivity of the reaction is attributedto the acidic hydrogen present in the carboxylic acidgroup, which provides the proton necessary for theelimination of methanol. The diagnostic products areeasily identified based on the m/z value of the production, which is 72 Th (thomson) greater than the m/zvalue of the charged analyte, and also by the character-istic isotope pattern of boron. The applicability of thismethod for pharmaceutical analysis was demonstrated forthree nonsteroidal anti-inflammatory drugs: ibuprofen,naproxen, and ketoprofen.