二次纳流电喷雾电离耦合超高分辨质谱检测人体呼出气中相对高分子量化合物

二次电喷雾电离源耦合超高分辨质谱(SESI-UHRMS)有望检出人体呼出气中分子量大于300的相对高分子量化合物,这些化合物的发现将有助于更准确地理解呼出气中挥发性有机化合物(VOCs)的来源、产生机制以及SESI源电离机理,更好地实现SESI-UHRMS的转化应用.本研究自组装nanoSESI源(尚无商业产品)耦合四极杆-静电场轨道阱质谱(最高质量分辨率1.2×10~5),考察了该装置对健康人体呼出气中分子量为300~500化合物的检出情况.结果表明,所搭建的nanoSESI-UHRMS装置检测人体呼出气的重现性好、灵敏度高,可检出数十种分子量为300~500的化合物.根据这些化合物在单次呼气过程中信号强度随时间变化的趋势,推断其来源分别为内源性和外源性;各化合物的元素组成主要包括C,H,N和O,环-双键当量(RDB)的均值为(4.5±3.1),表明检出的化合物可能为醛酮或不饱和脂肪酸,容易在SESI源中被电离.本研究初步验证了自组建nanoSESI-UHRMS检测人体呼出气中相对高分子量化合物的可行性,为后续进一步开展方法应用奠定了基础.

Identification of Relatively High Molecular Weight Compounds in Human Breath Using Secondary Nano Electrospray Ionization Ultrahigh Resolution Mass Spectrometry

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 unsaturated compounds are characterized with high ionization efficiency in SESI, and thus readily detected by nanoSESI-UHRMS.