Color Matters—Material Ejection and Ion Yields in UV-MALDI Mass Spectrometry as a Function of Laser Wavelength and Laser Fluence
Color Matters—Material Ejection and Ion Yields in UV-MALDI Mass Spectrometry as a Function of Laser Wavelength and Laser Fluence
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颜色很重要——UV-MALDI 质谱中的材料喷射和离子产率与激光波长和激光通量的函数关系
DOI：
10.1007/s13361-013-0699-5
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发表时间：
2013
影响因子：
3.2
通讯作者：
Dreisewerd
中科院分区：
文献类型：
--
作者：
Soltwisch;Jaskolla;Dreisewerd
基质辅助激光解吸/电离质谱（MALDI-MS）作为生物分子科学中广泛使用的分析工具的成功强烈地建立在有效的激光-材料相互作用的基础上，该相互作用导致基质和嵌入的生物分子的软共解吸和电离。为了获得感兴趣的分析物的最大化的离子产率，通常需要调谐波长和注量两者以匹配所使用的基质的特定光学吸收分布。然而，通常只有激光与固定的发射波长为337或355 nm用于MALDI-MS。在这里，我们采用了波长可调染料激光器和记录的中性物质喷射和MS离子数据在宽的波长和能量密度范围之间的280和377.5 nm。以α-氰基-4-羟基肉桂酸（HCCA）、4-氯-α-氰基肉桂酸（ClCCA）、α-氰基-2，4-二氟肉桂酸（DiFCCA）和2，5-二羟基苯甲酸（DHB）为基质，以几种多肽为分析物进行了研究。材料喷射的记录通过采用光声方法实现。通过光声信号和离子信号的划分，得到相对离子产率。以这种方式，可以识别获得最大离子产率的不同波长/注量区域。对于所测试的基质，对于对应于相应基质的高光学吸收区域的波长和在高于基质和波长依赖性离子检测阈值注量约2-3倍的注量，实现了最佳结果。通过光声方法探测的材料喷射与准热模型非常吻合，而S形函数则可以对离子信号-注量关系进行经验描述。
The success of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) as a widely employed analytical tool in the biomolecular sciences builds strongly on an effective laser–material interaction that is resulting in a soft co-desorption and ionization of matrix and imbedded biomolecules. To obtain a maximized ion yield for the analyte(s) of interest, in general both wavelength and fluence need to be tuned to match the specific optical absorption profile of the used matrix. However, commonly only lasers with fixed emission wavelengths of either 337 or 355 nm are used for MALDI-MS. Here, we employed a wavelength-tunable dye laser and recorded both the neutral material ejection and the MS ion data in a wide wavelength and fluence range between 280 and 377.5 nm. α-Cyano-4-hydroxycinnamic acid (HCCA), 4-chloro-α-cyanocinnamic acid (ClCCA), α-cyano-2,4-difluorocinnamic acid (DiFCCA), and 2,5-dihydroxybenzoic acid (DHB) were investigated as matrices, and several peptides as analytes. Recording of the material ejection was achieved by adopting a photoacoustic approach. Relative ion yields were derived by division of photoacoustic and ion signals. In this way, distinct wavelength/fluence regions can be identified for which maximum ion yields were obtained. For the tested matrices, optimal results were achieved for wavelengths corresponding to areas of high optical absorption of the respective matrix and at fluences about a factor of 2–3 above the matrix- and wavelength-dependent ion detection threshold fluences. The material ejection as probed by the photoacoustic method is excellently fitted by the quasithermal model, while a sigmoidal function allows for an empirical description of the ion signal–fluence relationship.