High Ion Yields of Carbohydrates from Frozen Solution by UV-MALDI

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• 作者：Chi-Wei Liang ; Po-Jul Chang ; Yu-Jiun Lin ; Yuan-Tseh Lee ; Chi-Kung Ni
• 刊名：Analytical Chemistry
• 出版年：2012
• 出版时间：April 17, 2012
• 年：2012
• 卷：84
• 期：8
• 页码：3493-3499
• 全文大小：288K
• 年卷期：v.84,no.8(April 17, 2012)
• ISSN：1520-6882

文摘

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鈥?0 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 (伪-cyano-4-hydroxycinnamic acid and sinapinic acid) and ionic liquids (2,5-dihydroxybenzoic acid + pyridine and 伪-cyano-4-hydroxycinnamic acid + butylamine) were investigated, and possible mechanisms are discussed.