Study of Substituted Phenethylamine Fragmentation Induced by Electrospray Ionization Mass Spectrometry and Its Application for Highly Sensitive Analysis of Neurotransmitters in Biological Samples
Study of Substituted Phenethylamine Fragmentation Induced by Electrospray Ionization Mass Spectrometry and Its Application for Highly Sensitive Analysis of Neurotransmitters in Biological Samples
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DOI：
10.1021/jasms.1c00173
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发表时间：
2021-07-22
影响因子：
3.2
通讯作者：
Todoroki, Kenichiro
中科院分区：
文献类型：
--
作者：
Asakawa, Daiki;Sugiyama, Eiji;Todoroki, Kenichiro
尽管配备电喷雾电离（ESI）的液相色谱 - 串联质谱（LC - MS/MS）广泛用于代谢物分析，但取代苯乙胺在ESI源内碰撞诱导解离（CID）过程中通常会发生裂解。意外的裂解不仅妨碍明确的鉴定，还影响准确的代谢物定量。ESI源内CID会导致缺乏β - 羟基的取代苯乙胺发生N - Cα键解离，产生具有螺[2.5]辛二烯鎓结构的碎片离子。相反，具有β - 羟基的苯乙胺通过ESI源内CID诱导的水丢失生成取代的2 - 苯基氮丙啶。ESI源内CID产生的碎片离子产率可分别通过采用密度泛函理论计算确定的分析物离子的解离速率常数和利用温度计离子的存活产率法确定的内部能量来估算。β - 羟基的存在会极大地增强裂解，而N - 甲基化则抑制裂解。特别是，含有β - 羟基和伯胺基团的章鱼胺和去甲肾上腺素产生的碎片离子信号比质子化分子更强。关于小鼠大脑中苯乙胺的定量分析，在多反应监测（MRM）中用作前体的去甲肾上腺素碎片离子在所得光谱中提供的信噪比高于质子化的去甲肾上腺素。本方法能够高灵敏度地对取代苯乙胺进行定量分析。
Although liquid chromatography-tandem mass spectrometry (LC-MS/MS) equipped with electrospray ionization (ESI) is widely employed for metabolite analysis, substituted phenethylamines commonly undergo fragmentation during ESI in- source collision- induced dissociation (CID). Unexpected fragmentation hampers not only unambiguous identification but also accurate metabolite quantification. ESI in-source CID induces N-Ca bond dissociation in substituted phenethylamines lacking a beta-hydroxy group to produce fragment ions with a spiro[2.5]octadienylium motif. In contrast, phenethylamines with a beta-hydroxy group generate substituted 2-phenylaziridium through ESI in-source CID-induced H2O loss. The fragment ion yield produced by ESI in-source CID can be estimated by the dissociation rate constant and internal energy of the analyte ion, determined by employing density functional theory calculations and the survival yield method using a thermometer ion, respectively. Fragmentation is strongly enhanced by the presence of an beta-hydroxy group, whereas N-methylation suppresses fragmentation. In particular, octopamine and noradrenaline, which contain an beta-hydroxy and primary amine groups, produce more intense fragment ion signals than protonated molecules. Regarding the quantitative analysis of phenethylamines present in the mouse brain, the noradrenaline fragment ion used as the precursor in multiple reaction monitoring (MRM) provided a higher signal-to-noise ratio in the resulting spectra than protonated noradrenaline. The present method allows for the quantitative analysis of substituted phenethylamines with high sensitivity.