膜进样-单光子电离/化学电离-质谱仪在线检测水中VOCs  

Development of a Membrane Inlet-Single Photon Ionization/Chemical Ionization-Mass Spectrometer for Online Analysis of VOCs in Water

作　　者：花磊[1,2] 吴庆浩[1,2] 侯可勇[1] 崔华鹏[1,2] 陈平[1,2] 赵无垛[1,2] 谢园园[1,2] 李海洋[1] 

机构地区：[1]中国科学院大连化学物理研究所,大连116023 [2]中国科学院研究生院,北京100049

出　　处：《环境科学》2011年第12期3628-3634,共7页Environmental Science

基　　金：中国科学院仪器装备计划项目(YZ200907;KZCX2-YW-JS402);辽宁省博士启动基金项目(Y034090105)

摘　　要：介绍了自行研制的膜进样-单光子电离/化学电离-飞行时间质谱仪.光子能量为10.6 eV的真空紫外灯作为单光子电离的光源,同时利用光电子电离产生O 2+试剂离子,用于待测物分子的化学电离,通过调节电离区的电场条件可在2 s之内实现2种电离模式的快速切换.水中挥发性有机物(VOCs)以50μm的硅橡胶膜进行快速富集,膜后加入吹扫气加快样品脱附,吹扫气体还可抑制质谱分析器中油气本底,提高信噪比.SPI模式下,甲基叔丁基醚的检出限达到2μg·L-1(10 s分析时间);SPI-CI模式下,三氯甲烷检出限达到1μg·L-1(10 s分析时间).该仪器已成功应用于模拟加油站附近地下水中的甲基叔丁基醚和饮用水消毒副产物中的挥发性有机物的快速检测.结果表明该仪器在水中挥发性有机物在线检测方面有着广阔的应用前景.A home-made membrane inlet-single photon ionization/chemical ionization-time-of-flight mass spectrometer has been described.A vacuum ultraviolet（VUV） lamp with photon energy of 10.6 eV was used as the light source for single photon ionization（SPI）.Chemical ionization（CI） was achieved through ion-molecule reactions with O＋2 reactant ions generated by photoelectron ionization.The two ionization modes could be rapidly switched by adjusting electric field in the ionization region within 2 s.Membrane inlet system used for rapid enrichment of volatile organic compounds（VOCs） in water was constructed by using a polydimethylsiloxane（PDMS） membrane with a thickness of 50 μm.A purge gas was added to accelerate desorption of analytes from the membrane surface.The purge gas could also help to prevent the pump oil back-streaming into the ionization region from the analyzer chamber and improve the signal to noise ratio（S/N）.Achieved detection limits were 2 μg·L-1 for methyl tert-butyl ether（MTBE） in SPI mode and 1 μg·L-1 for chloroform in SPI-CI mode within 10 s analysis time,respectively.The instrument has been successfully applied to the rapid analysis of MTBE in simulated underground water nearby petrol station and VOCs in disinfected drinking water.The results indicate that the instrument has a great application prospect for online analysis of VOCs in water.

关 键 词：飞行时间质谱 膜进样 单光子电离 化学电离 挥发性有机物 在线检测 

分 类 号：X832[环境科学与工程—环境工程]