MATRIX EFFECTS ON THE FRAGMENTATION OF VITAMIN-B-12 IN PLASMA DESORPTION MASS-SPECTROMETRY

A continuing effort in mass spectrometry is to optimize desorption/ion ization processes in order to enhance analyte ion yields and reduce fr agmentation. The effect of small carbohydrate and amino acid matrices on the yield of secondary ions from vitamin B-12 (cyanocobalamin) was examined using plasma desorption mass spectrometry. The extent of the corrin decomposition is dependent upon the matrix-to-analyte ratio. Th e enhanced yields of the high-mass fragment ion [M-CN+H](+) and the io ns corresponding to protonated molecules, however, are dependent upon both the matrix-to-analyte ratio and the nature of the matrix. (C) 199 7 by John Wiley & Sons, Ltd.