Kageyama Kaneshima Ami, Motoyama Akira, Takayama Mitsuo
Mass Spectrometry Laboratory, Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan.
Mass Spectrom (Tokyo). 2019;8(1):A0077. doi: 10.5702/massspectrometry.A0077. Epub 2019 Nov 30.
The influence of solvent composition and surface tension on the signal intensity of deprotonated molecules [M-H] in electrospray ionization mass spectrometry (ESI MS) was evaluated using alanine (Ala), threonine (Thr) and phenylalanine (Phe), which have differing levels of hydrophobicity. The surface tension of the ESI solution was varied by changing the ratio of the organic solvents methanol (MeOH) and acetonitrile (MeCN) in water (HO). In ESI MS, the signal intensity of all the amino acids was increased with decreasing surface tension for the two solutions, HO/MeOH and HO/MeCN. The use of HO/MeCN was more favorable for achieving a strong signal for the analytes compared to HO/MeOH. The smaller vaporization enthalpy of MeCN compared to MeOH was proposed as one of the most plausible explanation for this. The order of the signal intensity of amino acids was Phe>Thr>Ala, the same order as their hydrophobicity. It can be practically concluded that the use of solutions with lower surface tensions and lower vaporization enthalpies would result in higher signal intensities in ESI MS.
使用具有不同疏水程度的丙氨酸（Ala）、苏氨酸（Thr）和苯丙氨酸（Phe），评估了溶剂组成和表面张力对电喷雾电离质谱（ESI MS）中去质子化分子[M-H]信号强度的影响。通过改变水（HO）中有机溶剂甲醇（MeOH）和乙腈（MeCN）的比例来改变ESI溶液的表面张力。在ESI MS中，对于HO/MeOH和HO/MeCN这两种溶液，所有氨基酸的信号强度均随表面张力的降低而增加。与HO/MeOH相比，使用HO/MeCN更有利于获得分析物的强信号。MeCN与MeOH相比具有较小的汽化焓，这被认为是对此现象最合理的解释之一。氨基酸信号强度的顺序为Phe>Thr>Ala，与它们的疏水性顺序相同。可以实际得出结论，使用具有较低表面张力和较低汽化焓的溶液将导致ESI MS中更高的信号强度。
