32860-62-1Relevant articles and documents
ENHANCEMENT OF PROTONATED MOLECULAR IONS AND AMMONIUM*MOLECULAR ION COMPLEXES IN DIRECT-LIQUID-INTRODUCTION-MASS SPECTROMETRY OF CARBOHYDRATES
Lau, James M.,McNeil, Michael,Darvill, Alan G.,Albersheim, Peter
, p. 101 - 112 (1988)
Addition of ammonium acetate to the mobile phase in direct-liquid-introduction mass spectrometry enhances the abundance of the protonated molecular ion or ammonium*molecular ion complex for compounds of biological interest.The efficacy of the method was investigated by comparing mass spectra obtained, with and without ammonium acetate, for a variety of underivatized, per-O-acetylated, and per-O-alkylated carbohydrates, and for several underivatized peptides.The mass spectra of the per-O-alkylated carbohydrates obtained by direct-liquid-introduction mass spectrometry with ammonium acetate were also compared to those obtained by thermospray mass spectrometry.
Congruent strategies for carbohydrate sequencing. 1. Mining structural details by MSn
Ashline, David,Singh, Suddham,Hanneman, Andy,Reinhold, Vernon
, p. 6250 - 6262 (2008/02/03)
This report is the first in a series of three focused on establishing congruent strategies for carbohydrate sequencing. The reports are divided into (i) analytical considerations that account for all aspects of small oligomer structure by MSn disassembly, (ii) database support using an ion fragment library and associated tools for high-throughput analysis, and (iii) a concluding algorithm for defining oligosaccharide topology from MSn disassembly pathways. The analytical contribution of this first report explores the limits of structural detail exposed by ion trap mass spectrometry with samples prepared as methyl derivatives and analyzed as metal ion adducts. This data mining effort focuses on correlating the fragments of small oligomers to stereospecific glycan structures, an outcome attributed to a combination of metal ion adduction and analyte conformation. Facile glycosidic cleavage introduces a point of lability (pyranosyl-1-ene) that upon collisional activation initiates subsequent ring fragmentation. Product masses and ion intensities vary with interresidue linkage, branching position, and monomer stereochemistry. Excessive fragmentation is the property of small oligomers where collisional energy within a smaller number of oscillators dissipates through extensive fragmentation. The procedures discussed in this report are unified into a singular strategy using an ion trap mass spectrometer with the sensitivity expected for electron multiplier detection. Although a small set of structures have been discussed, the basic principles considered are fully congruent, with ample opportunities for expansion.