High ion yields of carbohydrates from frozen solution by UV-MALDI.


An aqueous acetonitrile solution containing oligosaccharides (maltopentaose and polysaccharides) and a matrix (2,5-dihydroxybenzoic acid) was frozen at 100 K for mass analysis using ultraviolet matrix-assisted laser desorption/ionization (UV-MALDI). Compared with conventional UV-MALDI (i.e., using a dry analyte/matrix mixture), a frozen solution generates more oligosaccharide ions and less fragments from postsource decay. Furthermore, the ion signal is long-lasting, and the analyte distribution features enhanced homogeneity. The ion generation efficiency for this procedure is 20-30 times greater than that for a conventional dried mixture. Interestingly, the percentages for maltopentaose fragmentation from postsource decay for the frozen samples are close to zero (<2%), as compared with the 17% and 40% values found for dried samples at low and high laser fluences, respectively. Comparisons with other UV matrixes (α-cyano-4-hydroxycinnamic acid and sinapinic acid) and ionic liquids (2,5-dihydroxybenzoic acid + pyridine and α-cyano-4-hydroxycinnamic acid + butylamine) were investigated, and possible mechanisms are discussed.

DOI: 10.1021/ac3000896

Cite this paper

@article{Liang2012HighIY, title={High ion yields of carbohydrates from frozen solution by UV-MALDI.}, author={Chi-Wei Liang and Po-Jul Chang and Yu-Jiun Lin and Y T Lee and Chi-Kung Ni}, journal={Analytical chemistry}, year={2012}, volume={84 8}, pages={3493-9} }