Atmospheric pressure matrix assisted laser desorption/ionization mass spectrometry
Atmospheric pressure matrix assisted laser desorption/ionization mass spectrometry
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DOI：
10.1021/ac990998k
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发表时间：
2000-02-15
影响因子：
7.4
通讯作者：
Burlingame, AL
中科院分区：
文献类型：
--
作者：
Laiko, VV;Baldwin, MA;Burlingame, AL
介绍了一种新型的生物质谱仪电离源，它结合了大气压(AP)电离和基质辅助激光解吸/电离(MALDI)，离子从大气压电离区到高真空的转移是由氮气气动辅助(PA)实现的，因此缩写为PA-AP MALDI，PA-AP MALDI很容易与正交加速飞行时间(OaTOF)质谱仪上的电喷雾电离互换。样品制备与传统的真空MALDI相同，并使用相同的基质化合物，如α-氰基-4-羟基肉桂酸。将该离子源在OaTOF质谱仪上的性能与传统的真空MALDI-TOF离子源在多肽分析中的性能进行了比较，PA-AP MALDI可以检测混合物中低飞摩尔的多肽，具有良好的信噪比，对蛋白质消化中单个多肽的检测具有较低的分辨率。这种方法产生的多肽离子一般不表现出亚稳态碎裂，而被PA-AP MALDI电离的寡糖显示出几个结构上具有诊断意义的碎片离子。PA-AP MALDI的总样品消耗量高于真空MALDI，因为离子转移到真空系统的效率相对较低。这种电离方法能够为胰岛素等小蛋白质产生质子化分子离子，但这些离子往往会与基质材料形成簇状。OaTOF质谱计对单电荷高质量离子的局限性使得很难评估较大蛋白质的电离。
sA novel ionization source for biological mass spectrometry is described that combines atmospheric pressure (AP) ionization and matrix-assisted laser desorption/ionization (MALDI), The transfer of the ions from the atmospheric pressure ionization region to the high vacuum is pneumatically assisted (PA) by a stream of nitrogen, hence the acronym PA-AP MALDI, PA-AP MALDI is readily interchangeable with electrospray ionization on an orthogonal acceleration time-of-flight (oaTOF) mass spectrometer, Sample preparation is identical to that for conventional vacuum MALDI and uses the same matrix compounds, such as alpha-cyano-4-hydroxycinnamic acid. The performance of this ion source on the oaTOF mass spectrometer is compared with that of conventional vacuum MALDI-TOF for the analysis of peptides, PA-AP MALDI can detect low femtomole amounts of peptides in mixtures with good signal-to-noise ratio and with less discrimination for the detection of individual peptides in a protein digest. Peptide ions produced by this method generally exhibit no metastable fragmentation, whereas an oligosaccharide ionized by PA-AP MALDI shows several structurally diagnostic fragment ions. Total sample consumption is higher for PA-AP MALDI than for vacuum MALDI, as the transfer of ions into the vacuum system is relatively inefficient. This ionization method is able to produce protonated molecular ions for small proteins such as insulin, but these tend to form clusters with the matrix material. Limitations of the oaTOF mass spectrometer for singly charged high-mass ions make it difficult to evaluate the ionization of larger proteins.