Hsu Fu-Jen, Liu Te-Lin, Laskar Amzad Hussain, Shiea Jentaie, Huang Min-Zong
Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan.
Rapid Commun Mass Spectrom. 2014 Sep 30;28(18):1979-86. doi: 10.1002/rcm.6989.
The elucidation of chemical reaction mechanisms has attracted tremendous interest in recent years. Here, gravitational sampling electrospray ionization mass spectrometry (GS-ESI-MS) is used to explore a simple method for the real-time monitoring of chemical and biochemical reactions.
A sample solution in a stainless steel sample well is directly delivered through a fused-silica capillary due to the forces of gravity, capillary action, and electroosmotic flow (EOF). Analyte ions are continuously generated via electrospray ionization from the capillary tip when a high voltage is applied on the sample well.
Liquid solutions (<5 μL) of small organic compounds (e.g., crystal violet) and large biomolecules (e.g., reserpine, angiotensin II, and insulin) were directly analyzed via GS-ESI-MS. In addition, the technique was successfully applied to continuously monitor chemical [e.g. chelation of ethylenediaminetetraacetic acid (EDTA) with copper(II), and addition-elimination of aminophenol and acetic anhydride] and biochemical (e.g., unfolding of cytochrome c) reactions in real time, where chelation complexes, reaction intermediates, and protein conformation changes were observed.
GS-ESI-MS is a very simple modification of the ESI technique that does not require sample delivery pumps or nebulizer gases. It is particularly suitable for the analysis of liquid samples and the real-time monitoring of inorganic/organic chemical or biochemical reactions.
近年来，化学反应机理的阐明引起了极大的关注。在此，重力采样电喷雾电离质谱（GS-ESI-MS）被用于探索一种实时监测化学和生化反应的简单方法。
由于重力、毛细作用和电渗流（EOF）的作用，不锈钢样品池中 的样品溶液通过熔融石英毛细管直接输送。当在样品池上施加高电压时，分析物离子通过毛细管尖端的电喷雾电离连续产生。
通过GS-ESI-MS直接分析了小有机化合物（如结晶紫）和大生物分子（如利血平、血管紧张素II和胰岛素）的液体溶液（<5 μL）。此外，该技术成功地应用于实时连续监测化学[如乙二胺四乙酸（EDTA）与铜（II）的螯合，以及氨基酚与乙酸酐的加成消除]和生化（如细胞色素c的去折叠）反应，观察到螯合络合物、反应中间体和蛋白质构象变化。
GS-ESI-MS是对ESI技术的一种非常简单的改进，不需要样品输送泵或雾化气体。它特别适用于液体样品的分析以及无机/有机化学或生化反应的实时监测。
