Determination of Internal Energy Distributions of Laser Electrospray Mass Spectrometry using Thermometer Ions and Other Biomolecules
作者:Paul M. Flanigan、Fengjian Shi、Johnny J. Perez、Santosh Karki、Conrad Pfeiffer、Christian Schafmeister、Robert J. Levis
DOI:10.1007/s13361-014-0936-6
日期:2014.9.1
The internal energy distributions for dried and liquid samples that were vaporized with femtosecond duration laser pulses centered at 800 nm and postionized by electrospray ionization-mass spectrometry (LEMS) were measured and compared with conventional electrospray ionization mass spectrometry (ESI-MS). The internal energies of the mass spectral techniques were determined by plotting the ratio of the intact parent molecular features to all integrated ion intensities of the fragments as a function of collisional energy using benzylpyridinium salts and peptides. Measurements of dried p-substituted benzylpyridinium salts using LEMS resulted in a greater extent of fragmentation in addition to the benzyl cation. The mean relative internal energies, were determined to be 1.62 ± 0.06, 2.0 ± 0.5, and 1.6 ± 0.3 eV for ESI-MS, dried LEMS, and liquid LEMS studies, respectively. Two-photon resonances with the laser pulses likely caused lower survival yields in LEMS analyses of dried samples but not liquid samples. In studies with larger biomolecules, LEMS analyses of dried samples from glass showed a decrease in survival yield compared with conventional ESI-MS for leucine enkephalin and bradykinin of ~15% and 11%, respectively. The survival yields for liquid LEMS analyses were comparable to or better than ESI-MS for benzylpyridinium salts and large biomolecules.
用800 nm的飞秒激光脉冲蒸发的干燥和液体样本的内部能量分布,经过电喷雾离子化-质谱(LEMS)测量,并与传统的电喷雾离子化质谱(ESI-MS)进行了比较。通过使用苄基吡啶盐和肽,绘制完整母分子特征与所有碎片的离子强度总和比例作为碰撞能量的函数,确定了质谱技术的内部能量。使用LEMS测量干燥的p-取代苄基吡啶盐,除了苄基阳离子外,发现了更大的碎片化程度。ESI-MS、干燥LEMS和液体LEMS研究的平均相对内部能量分别为1.62 ± 0.06、2.0 ± 0.5和1.6 ± 0.3 eV。激光脉冲的双光子共振可能导致LEMS分析干燥样本的生存率较低,但对液体样本则没有影响。在对较大生物分子的研究中,玻璃中干燥样本的LEMS分析与传统的ESI-MS相比,白藜芦醇和缓激肽的生存率分别减少约15%和11%。对于液体LEMS分析,苄基吡啶盐和大型生物分子的生存率可与或优于ESI-MS。