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Use of procaine and procainamide as derivatizing co‐matrices for the analysis of oligosaccharides by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Author(s) -
Lavanant Hélène,
LoutelierBourhis Corinne
Publication year - 2012
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.6223
Subject(s) - chemistry , derivatization , mass spectrometry , matrix assisted laser desorption/ionization , chromatography , procainamide , glycosidic bond , protonation , analytical chemistry (journal) , ion , desorption , organic chemistry , adsorption , medicine , enzyme
RATIONALE Analysis of oligosaccharides by matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry often yields only alkali metal cation adducts, which results in lower fragmentation yields and difficulty to retrieve sequence information. Derivatization by reductive amination may be used to promote Y‐type glycosidic cleavages. However, this involves time‐consuming preparations and purifications with sample loss. Here, procaine and procainamide were used directly as co‐matrices with 2,5‐dihydroxybenzoic acid (DHB). METHODS Acidified 10 g/L procaine hydrochloride or procainamide hydrochloride solutions in water/acetonitrile were added to the oligosaccharide solution one minute before preparing our MALDI targets using DHB with the dried‐droplet method. This simple protocol resulted in deposits of very fine homogeneous crystals. RESULTS Positive ion mass spectra, easily acquired in an automated mode, presented a high percentage of oligosaccharides derivatized as Schiff base or glycosylamine notably detected as protonated molecules [M + H] + . The high abundance of procaine or procainamide on the target did not impede the ionization process, improved the signal‐to‐noise ratio and eliminated the need to search for 'sweet spots'. Fragmentation of the protonated precursor ions of the derivatives largely favored Y‐type glycosidic cleavages. CONCLUSIONS This easy and fast sample preparation, involving low toxicity and easily accessible chemicals, allowed the selection of protonated molecules as precursor ions for post‐source decay analyses. This opened the possibility of simplifying sequence retrieval in routine oligosaccharide analyses. Copyright © 2012 John Wiley & Sons, Ltd.