Bruderer Tobias, Gaugg Martin T, Cappellin Luca, Lopez-Hilfiker Felipe, Hutterli Manuel, Perkins Nathan, Zenobi Renato, Moeller Alexander
Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, 8093 Zurich, Switzerland.
Division of Respiratory Medicine, University Children's Hospital Zurich and Children's Research Center Zurich, 8032 Zurich, Switzerland.
J Am Soc Mass Spectrom. 2020 Jul 13. doi: 10.1021/jasms.0c00059.
The analysis of volatiles is of high relevance for a wide range of applications from environmental air sampling and security screening to potential medical applications. High-resolution mass spectrometry methods offer a particularly wide compound coverage, sensitivity, and selectivity. Online approaches allow direct analysis in real time without the need for sample preparation. For the first time, we systematically compared the analysis of volatile organic compounds with secondary electrospray ionization (SESI) and proton transfer reaction (PTR) high-resolution mass spectrometry. The selected instruments had comparable mass resolving powers with /Δ ≥ 15000, which is particularly suitable for nontargeted analysis, for example, of exhaled breath. Exhalations from 14 healthy adults were analyzed simultaneously on both instruments. In addition, 97 reference standards from nine chemical classes were analyzed with a liquid evaporation system. Surprisingly, in breath, we found more complementary than overlapping features. A clear mass dependence was observed for each method with the highest number of detected / features for SESI in the high mass region (/ = 150-250) and for PTR in the low mass region (/ = 50-150). SESI yielded a significantly higher numbers of peaks (828) compared to PTR (491) among a total of 1304 unique breath / features. The number of signals observed by both methods was lower than expected (133 features) with 797 unique SESI features and 374 unique PTR features. Hypotheses to explain the observed mass-dependent differences are proposed.
挥发性物质的分析对于从环境空气采样、安全筛查到潜在医学应用等广泛领域都具有高度相关性。高分辨率质谱方法具有特别广泛的化合物覆盖范围、灵敏度和选择性。在线方法允许实时直接分析，无需样品制备。我们首次系统地比较了采用二次电喷雾电离（SESI）和质子转移反应（PTR）高分辨率质谱对挥发性有机化合物的分析。所选仪器具有相当的质量分辨率，/Δ≥15000，这特别适用于非靶向分析，例如对呼出气体的分析。在这两种仪器上同时分析了14名健康成年人的呼气。此外，使用液体蒸发系统分析了来自九个化学类别的97种参考标准品。令人惊讶的是，在呼出气体中，我们发现互补特征多于重叠特征。观察到每种方法都有明显的质量依赖性，在高质量区域（/ = 150 - 250）中SESI检测到的/特征数量最多，在低质量区域（/ = 50 - 150）中PTR检测到的/特征数量最多。在总共1304个独特的呼气/特征中，与PTR（491个）相比，SESI产生的峰数量显著更多（828个）。两种方法观察到的信号数量低于预期（133个特征），其中有797个独特的SESI特征和374个独特的PTR特征。本文提出了解释观察到的质量依赖性差异的假设。
