Premium
Recognition of quaternary ammonium compounds using mass spectrometry
Author(s) -
Fisher Dixie L.,
Arthur Moseley M.,
Mullis James O.,
Norwood Daniel L.,
Baillie Thomas A.
Publication year - 1994
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/rcm.1290080113
Subject(s) - chemistry , protonation , ion , ammonium , mass spectrometry , cluster (spacecraft) , protein quaternary structure , amine gas treating , quaternary , chromatography , organic chemistry , geology , biochemistry , protein subunit , computer science , gene , programming language , paleontology
Liquid secondary‐ion mass spectrometry (LSIMS) experiments were performed on a series of model quaternary ammonium chlorides [M Q + Cl − ] in order to develop a strategy, via an understanding of cluster‐ion formation, for recognition of quarternary ammonium structures. Model structures contained a single quaternary site and various other structural features (for example, conjugated quaternary systems and carboxylic acid groups), using amine hydrochlorides as controls. Cluster ions were examined with both positive‐ and negative‐ion LSIMS, using a range of matrix modifiers. Precursor scans, or ‘molecular weight confirmation scans’, of M Q +(the charged molecular ion of quaternary ammonium compounds) and [M+H] + ions were used to assist in the observation of cluster ions and to unambiguously demonstrate precursor/product relationships. Positive‐ion experiments typically showed dimeric clusters of [2M Q + A] + (A=anion) and [2M Q −H] + ions, while negative ion experiments produced [M Q + 2A] − ions. Observation of these cluster ions coupled with the lack of an [M−H] − ion are a distinguishing feature of quaternary amines. Additional cluster ions were targeted for distinguishing between protonated amines and quaternary amonium compounds containing a carboxylic acid group. A strategy for recognizing and distinguishing quaternary ammonium structures using LSIMS is proposed, and some initial experiments with thermospray and electrospray are discussed.