Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, OH, 45701, USA.
College of Sciences, Agricultural University of Hebei, Baoding, Hebei, 071001, China.
J Am Soc Mass Spectrom. 2017 Jun;28(6):1005-1012. doi: 10.1007/s13361-016-1450-9. Epub 2016 Aug 25.
Online detection of methanol electro-oxidation reaction products [e.g., formaldehyde (HCHO)] by mass spectrometry (MS) is challenging, owing to the high salt content and extreme pH of the electrolyte solution as well as the difficulty in ionizing the reaction products. Herein we present an online ambient mass spectrometric approach for analyzing HCHO generated from methanol electro-oxidation, taking the advantage of high salt tolerance of desorption electrospray ionization mass spectrometry (DESI-MS). It was found that HCHO can be detected as PhNHNH=CH (m/z 121) by DESI after online derivatization with PhNHNH. With this approach, the analysis of HCHO from methanol electro-oxidation by MS was carried out not only in acidic condition but also in alkaline media for the first time. Efficiencies of different electrodes for methanol oxidation at different pHs were also evaluated. Our results show that Au electrode produces more HCHO than Pt-based electrodes at alkaline pH, while the latter have higher yields at acidic solution. The presented methodology would be of great value for elucidating fuel cell reaction mechanisms and for screening ideal fuel cell electrode materials. Graphical Abstract ᅟ.
在线通过质谱法（MS）检测甲醇电氧化反应产物[例如甲醛（HCHO）]具有挑战性，这是由于电解质溶液的高盐含量和极端 pH 以及反应产物的电离困难所致。在此，我们提出了一种在线环境质谱分析方法，用于分析甲醇电氧化产生的 HCHO，利用解吸电喷雾电离质谱（DESI-MS）对高盐度的耐受性。研究发现，HCHO 可以通过 DESI 与 PhNHNH 在线衍生化后检测到 PhNHNH=CH（m/z 121）。通过这种方法，首次在酸性和碱性条件下通过 MS 对甲醇电氧化产生的 HCHO 进行了分析。还评估了不同电极在不同 pH 值下对甲醇氧化的效率。我们的结果表明，在碱性 pH 下，金电极比基于 Pt 的电极产生更多的 HCHO，而后者在酸性溶液中的产率更高。所提出的方法对于阐明燃料电池反应机制和筛选理想的燃料电池电极材料具有重要价值。
