Asakawa Daiki, Mizuno Hajime, Toyo'oka Toshimasa
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, Umezono 1-1-1, Tsukuba, Ibaraki, 305-8568, Japan.
Laboratory of Analytical and Bioanalytical Chemistry, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.
J Am Soc Mass Spectrom. 2017 Dec;28(12):2561-2568. doi: 10.1007/s13361-017-1795-8. Epub 2017 Sep 5.
The formation mechanisms of singly and multiply charged organophosphate metabolites by electrospray ionization (ESI) and their gas phase stabilities were investigated. Metabolites containing multiple phosphate groups, such as adenosine 5'-diphosphate (ADP), adenosine 5'-triphosphate (ATP), and D-myo-inositol-1,4,5-triphosphate (IP) were observed as doubly deprotonated ions by negative-ion ESI mass spectrometry. Organophosphates with multiple negative charges were found to be unstable and often underwent loss of PO, although singly deprotonated analytes were stable. The presence of fragments due to the loss of PO in the negative-ion ESI mass spectra could result in the misinterpretation of analytical results. In contrast to ESI, matrix-assisted laser desorption ionization (MALDI) produced singly charged organophosphate metabolites with no associated fragmentation, since the singly charged anions are stable. The stability of an organophosphate metabolite in the gas phase strongly depends on its charge state. The fragmentations of multiply charged organophosphates were also investigated in detail through density functional theory calculations. Graphical Abstract.
研究了通过电喷雾电离（ESI）形成单电荷和多电荷有机磷酸酯代谢物的机制及其气相稳定性。通过负离子ESI质谱法观察到含有多个磷酸基团的代谢物，如腺苷5'-二磷酸（ADP）、腺苷5'-三磷酸（ATP）和D-肌醇-1,4,5-三磷酸（IP）作为双去质子化离子。发现带有多个负电荷的有机磷酸酯不稳定，尽管单去质子化分析物稳定，但它们经常会发生PO的损失。负离子ESI质谱图中由于PO损失而产生的碎片可能会导致分析结果的错误解读。与ESI相反，基质辅助激光解吸电离（MALDI）产生单电荷有机磷酸酯代谢物且无相关碎片，因为单电荷阴离子是稳定的。有机磷酸酯代谢物在气相中的稳定性强烈取决于其电荷状态。还通过密度泛函理论计算详细研究了多电荷有机磷酸酯的碎片化。图形摘要。
