Neubert Hendrik, Halket John M, Fernandez Ocaña Mireia, Patel Raj K P
Drug Control Centre, King's College London, London, United Kingdom.
J Am Soc Mass Spectrom. 2004 Mar;15(3):336-43. doi: 10.1016/j.jasms.2003.11.002.
Large signals from alpha-cyano-4-hydroxycinnamic acid (CHCA) matrix complexes with sodium and potassium ions were found to interfere with sensitive matrix-assisted laser desorption/ionization (MALDI) analysis of a hydrochloric acid digest of gelatine preparations. The nature of some selected matrix clusters was investigated by conventional post-source decay and LIFT-TOF/TOF experiments. The matrix clusters fragmented readily by neutral evaporation to give smaller sized matrix cluster species without matrix disintegration. Their characterization distinguished them from peptide signals, in particular from those that had the same nominal mass and differed only in the fractional part of the mass as encountered for gelatine-derived peptides. Knowledge of the molecular composition of these cluster species allowed using them for internal calibration of the MALDI mass spectra. The hydrolytic peptides could be analyzed with increased sensitivity when using 2,5-dihydroxy benzoic acid (DHB) as the MALDI matrix.
研究发现，α-氰基-4-羟基肉桂酸（CHCA）与钠离子和钾离子形成的基质配合物产生的大信号，会干扰明胶制剂盐酸消化产物的灵敏基质辅助激光解吸/电离（MALDI）分析。通过传统的源后衰变和LIFT-TOF/TOF实验研究了一些选定基质簇的性质。基质簇通过中性蒸发很容易碎裂，形成尺寸较小的基质簇物种，且不会发生基质分解。它们的特征将它们与肽信号区分开来，特别是与那些具有相同标称质量、仅在质量分数部分不同的肽信号区分开来，明胶衍生肽就会出现这种情况。了解这些簇物种的分子组成后，可将它们用于MALDI质谱的内标校准。当使用2,5-二羟基苯甲酸（DHB）作为MALDI基质时，水解肽的分析灵敏度会提高。
