IDENTIFICATION OF RELATIVELY HIGH MOLECULAR WEIGHT COMPOUNDS IN HUMAN BREATH USING SECONDARY NANO ELECTROSPRAY IONIZATION ULTRAHIGH MASS SPECTROMETRY
HUANG Lei, LI Xue, XU Meng, HUANG Zhengxu, ZHOU Zhen
Human breath contains thousands of volatile organic compounds (VOCs), which would be potentially helpful for studying disease diagnosis and environmental exposure. However, owing to limitations in current analytical methods, only the compounds with molecular weights <300 have been widely reported in exhaled human breath. In this study, a high performance homemade secondary nanoelectrospray ionization source coupled with ultrahigh resolution mass spectrometer (nanoSESI-UHRMS) was set up and applied to investigating the presence of compounds with relatively high molecular weight (RHMW) (300—500) in healthy human breath. The results indicated that 29 RHMW compounds have been detected in real time by nanoSESI-UHRMS. These organic compounds mostly consist of C, H, N and O atoms, and the average of ring-double bond equivalent (RDB) values is (4.5 ± 3.1), implying they are most likely to be ketones, aldehydes and fatty acids. These unsatured compounds are characterized with high ionization efficiency in SESI, and thus readily detected by nanoSESI-UHRMS.