Oligosaccharide profiling: the facile detection of mono-, di- and oligosaccharides by electrospray orthogonal time-of-flight mass spectrometry using 3-aminophenylboronic acid derivatization

Monosaccharides, disaccharides and larger carbohydrates can be derivatized using 3-aminophenylboronic acid (3-APBA), This procedure is carried out at low pH (2.7-3.0) and allows the use of positive ion mode electrospray ortho gonal time-of-flight mass spectrometry (ES-OTOFMS) to analyze the resulting boronate complexes. A carbohydrate profile map of a complex carbohydrate m ixture, honey, was prepared which displayed superior sensitivity when compa red with lithium ion cationization, Complexes formed using simple mono- and disaccharides show that facile in situ derivatization leads to an equilibr ium mixture; which is reproducible for a specific set of electrospray condi tions. D-Glucose could be detected at 5 mu M concentration using the standa rd instrument spray interface. Lower detection levels of approximately 500 nM could be achieved using a nanospray device. The 3-APBA complexes are obs erved on instruments employing a low temperature interface (140-150 degrees C) which allows formation of the boronate species while still promoting ef ficient desolvation of the ions. The spectral identification of 3-APBA comp lexed carbohydrates in complex mixtures is facilitated by the easily observ ed I mass unit separated peak pair bearing the 1:4 ratio resulting from the natural isotopic abundance of B-10 and B-11. Copyright (C) 2000 John Wiley & Sons, Ltd.