质子转移反应质谱法测量呼气丙酮的影响因素分析

Analysis of Influence Factors for the Breath Acetone Measurement by Proton Transfer Reaction Mass Spectrometry

丙酮是人体呼出气体中含量最高的挥发性有机物之一,它与糖尿病、肺癌等疾病有着一定的关系。本研究通过注射法配制了不同二氧化碳浓度和湿度下的丙酮混合气体,应用质子转移反应质谱(PTRMS)法对Tedlar采样袋中的丙酮混合气体进行浓度检测,研究二氧化碳浓度、气体湿度、氧气离子浓度和一氧化氮离子浓度等因素对丙酮浓度测量结果的影响,并推导出修正公式。结果表明:二氧化碳浓度和气体湿度的增加不会对丙酮离子的计数值产生明显影响,但会增加水合氢离子团簇离子的含量;氧气离子浓度的增加会提高丙酮碎片离子的含量;一氧化氮离子的测量浓度很低,对丙酮测量结果的影响可以忽略不计;以上各影响因素在使用修正公式后,可以有效地抑制影响,优化实验结果。

Acetone is one of the highest levels of volatile organic compounds（VOCs）in the gas of human body exhaled breath.Researches show that acetone from human exhaled breath has a certain relationship with a series of diseases,such as diabetes,lungcancer and so on.Acetone mixed gas with different carbon dioxide concentration and relative humidity was prepared by syringe method in Teldar bags.Then proton transfer reaction mass spectrometry（PTR-MS）was used to investigate acetone mixed gas in Teldar bags in order to obtain the acetone concentrations.The experiment aimed at studying the influence of the carbon dioxide concentration,the relative humidity,oxygen ion concentration and nitric oxide ion concentration to acetone concentration measurement.Also the concentration correction formula was deduced.The results show that the increases of carbon dioxide concentration and relative humidity of the mixed gas have no obvious influence on the count of acetone ions,but they can increase concentration ratio of protonated water clusters to protonated water in the drift tube and increase the possibility of acetone molecule and water cluster ions reaction.Oxygen ions will react with acetone molecules,so the increase of oxygen ions concentration can enhance the content of acetone fragment ions,which influence the measurement accuracy of breath acetone by PTR-MS.The measuring concentration of nitric oxide ions is so low that the influence on the result can be negligible.The concentration correction formula can effectively inhibit the effect of carbon dioxide,relative humidity and oxygen ions.