Identification of low molecular weight carbohydrates employing new binary mixtures for matrix-assisted laser desorption/ionisation mass spectrometry

Various energy‐absorbing substances, aminopyrazine (AP), 4,4'‐azodianiline (ADA), and 1‐chloro‐4‐hydroxyisoquinoline (CHIQ), together with their binary mixtures with existing acidic MALDI matrices were subjected to matrix‐assisted laser desorption/ionisation mass spectrometry (MALDI‐MS) and evaluated for the analysis of low molecular weight carbohydrates. The newly introduced systems, especially AP and the combination of 2,5‐dihydroxybenzoic acid and aminopyrazine (DHB‐AP), have solved almost all the existing problems of the generally low sensitivity of carbohydrate analysis and of the strong background noise produced from single acidic matrices. In fact, especially at a mixing ratio of 3:1 (DHB/AP), outstanding results could be achieved, enabling the detection of analytes down to a concentration of 4 fmol/µL with mass accuracy of 37 ppm. The performance of the system was finally proven by analysing dextrins and biological samples each of which showed excellent signal intensity and signal‐to‐noise ratio. Copyright © 2008 John Wiley & Sons, Ltd.