Coulometry-assisted quantitation in spray ionization mass spectrometry
Coulometry-assisted quantitation in spray ionization mass spectrometry
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DOI：
10.1002/jms.4628
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发表时间：
2020-08-16
影响因子：
2.3
通讯作者：
Zare, Richard N.
中科院分区：
文献类型：
--
作者：
Song, Xiaowei;Chen, Hao;Zare, Richard N.
混合物中目标分析物的浓度可以通过库仑测量与喷雾电离质谱法的结合来量化。丝网印刷在聚合物支架上的三电极系统既充当电化学氧化的库仑分析平台，又充当喷雾电离的样品装载尖端。将一滴分析物溶液加载到尖端后，采取两个步骤来实施定量。首先，通过循环伏安法优化电化学氧化电位，然后进行库仑测量，以计算固定时间段（5秒）内恒定低电压下氧化分析物的量。然后，向尖端施加高电压（+4.5 kV）以触发喷雾电离，以通过质谱法测量天然分析物离子的氧化产率及其氧化产物离子强度。分析物的天然浓度通过氧化产物浓度（基于库仑定律）和氧化产率（假设母体和氧化产物具有几乎相同的电离效率，通过质谱 [MS] 估算）进行量化。该工作流程的优点是无需任何构建定量曲线的标准。选择几种模型化合物（酪氨酸、多巴胺和血管紧张素 II）进行方法验证。事实证明，该策略是可行的，对于包括内源代谢物和肽在内的不同物种的广泛覆盖，准确率约为 15%。作为其可能的实际应用的一个例子，它最初被用来进行尿液中的胆红素测定。
The concentration of target analyte in a mixture can be quantified by combining coulometric measurements with spray ionization mass spectrometry. A three-electrode system screen printed on the polymer support acts both as the coulometry platform for electrochemical oxidation and the sample loading tip for spray ionization. After loading a droplet of the analyte solution onto the tip, two steps were taken to implement quantitation. First, the electrochemical oxidation potential was optimized with cyclic voltammetry followed by coulometric measurements to calculate the amount of oxidized analyte under a constant low voltage within a fixed period of time (5 s). Then, a high voltage (+4.5 kV) was applied to the tip to trigger spray ionization for measuring the oxidation yield from the native analyte ion and its oxidized product ion intensities by mass spectrometry. The analyte's native concentration is quantified by dividing the oxidized product's concentration (based on Coulomb's law) and the oxidation yield (estimated from mass spectrometry [MS] assuming that the parent and oxidation product have nearly the same ionization efficiencies). The workflow has an advantage in being free of any standard for constructing the quantitation curve. Several model compounds (tyrosine, dopamine, and angiotensin II) were selected for method validation. It was demonstrated that this strategy was feasible with an accuracy of similar to 15% for a wide coverage of different species including endogenous metabolites and peptides. As an example of its possible practical use, it was initially employed to make a bilirubin assay in urine.