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Chloride anion attachment in negative ion electrospray ionization mass spectrometry†
Author(s) -
Cole Richard B.,
Zhu Junhua
Publication year - 1999
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/(sici)1097-0231(19990415)13:7<607::aid-rcm530>3.0.co;2-2
Subject(s) - chemistry , electrospray ionization , ion , mass spectrometry , ion mobility spectrometry–mass spectrometry , direct electron ionization liquid chromatography–mass spectrometry interface , chromatography , sample preparation in mass spectrometry , chloride , extractive electrospray ionization , ionization , analytical chemistry (journal) , chemical ionization , organic chemistry
An approach to enable negative ion electrospray ionization (ESI) mass spectrometric detection of analytes that lack acidic sites and thus exhibit weak [M−H] − signals has been developed. The method relies upon attachment of Cl − ions present in electrosprayed solutions of chlorinated solvents such as chloroform. Attachment of these chloride ions to form [M+Cl] − ions was observed for compounds characterized by p K a values as high as 27 (aniline). Low‐energy collision‐induced dissociation (CID) mass spectra of the chloride adducts produced [M−H] − and Cl − . For analytes that have gas‐phase acidities lower than HCl, CID of [M+Cl] − at higher laboratory energies (e.g., above 20 eV) can dramatically promote initial formation of [M−H] − , and lead to production of structurally informative daughter ions via consecutive decompositions. Copyright © 1999 John Wiley & Sons, Ltd.