Effects of humidity, CO2 and O2 on real-time quantitation of breath biomarkers by means of PTR-ToF-MS
Effects of humidity, CO2 and O2 on real-time quantitation of breath biomarkers by means of PTR-ToF-MS
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DOI：
10.1088/1752-7163/aa9eea
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发表时间：
2018-04-01
影响因子：
3.8
通讯作者：
Miekisch, Wolfram
中科院分区：
文献类型：
--
作者：
Trefz, Phillip;Schubert, Jochen K.;Miekisch, Wolfram
质子转移反应飞行时间质谱（PTR-ToF-MS）代表了一种用于实时分析人体呼吸中VOC分布的有吸引力的工具。通过直接MS对呼吸VOC进行定量可能会受到基质的影响，因为人的呼吸不仅含有ppbV-pptV水平的数百种VOC，而且是水饱和的，含有百分比水平的CO2。临床研究中呼吸生物标志物的研究需要定量和可比的结果。因此，我们系统地评估了湿度，CO2和O-2对PTR-MS分析结果的影响。我们研究了20多种VOCs，包括醛，酮，芳香族化合物和烃与不同的样品湿度，CO2和O-2含量。还讨论了数据处理的影响（例如，归一化为H3 O+离子计数）。当样品中的湿度增加到呼吸水平时，观察到H3 O+计数增加约20%。干燥和潮湿的样品之间的测量的VOC强度的大的差异。数据归一化到H3 O+或水簇不能完全补偿湿度依赖的影响。然而，由于大多数挥发性有机化合物的测定线性地依赖于整个研究范围内的湿度，基于因子的校正似乎是可能的。在干燥样品中CO2的影响比在潮湿样品中更明显，但对结果的影响很小。O-2的影响也是如此。为了在临床研究中对VOC进行可靠的定量和VOC研究的标准化，PTR-MS分析需要适应良好的校准标准。
Proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) represents an attractive tool for the real-time analysis of VOC profiles in human breath. Quantification of breath VOCs by means of direct MS may be affected by the matrix, as human breath not only contains several hundred VOCs at the ppbV-pptV level, but is water saturated and contains percentage levels of CO2. Investigation of breath biomarkers in clinical studies requires quantitative and comparable results. We therefore systematically assessed the effect of humidity, CO2 and O-2 on the results of PTR-MS analysis. We investigated more than 20 VOCs, including aldehydes, ketones, aromatic compounds and hydrocarbons with different sample humidity, CO2 and O-2 content. The influence of data processing (e.g. normalization to the H3O+ ion count) was also addressed. An increase of the H3O+ count of about 20% was observed when the humidity in the sample was increased to breath levels. Large differences regarding the measured VOC intensities were found between the dry and humid samples. Data normalization to the H3O+ or water-clusters could not fully compensate for the humidity-dependent effects. However, as the determination of most VOCs linearly depends on the humidity over the whole investigated range, factor-based correction seems possible. The effects of CO2 were more pronounced in the dry samples than in the humid samples but only had a minor influence on the results. The same was true for the influence of O-2. For the reliable quantification of VOCs in clinical studies and for the standardization of VOC research, well-adapted calibration standards are required for PTR-MS analysis.