title: An in-source stretched membrane inlet for on-line analysis of VOCs in water with single photon ionization TOFMS.
abstract: An in-source, stretched, hollow fiber membrane (HFM) inlet has been developed to improve the sensitivity of on-line time-of-flight mass spectrometry (TOFMS) with a vacuum ultraviolet (VUV) lamp based single photon ionization (SPI) source for the direct analysis of liquid samples. A 2-cm HFM was stretched to 8 cm in length, and placed in the ion source and directly under the VUV lamp window with a distance of 15 mm. Compared with the conventional flow-through configuration under the same experimental conditions, the signal intensities of selected volatile organic compounds (VOCs) of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), benzene, toluene and p-xylene were increased over 5-fold in magnitude, and the response time was shortened to one-third. The limits of detection (LOD) of MTBE, ETBE, benzene, toluene and p-xylene ranged from 0.25 to 1.3 μg L(-1) with a measurement time of 60 s, and three orders of linear range were obtained with correlation coefficients of 0.9972-0.9992. The present results suggest that the in-source stretched HFM is a simple and effective way to increase the sensitivity and shorten response time of the membrane inlet, and we believe that it will also be beneficial to other types of on-line mass spectrometer for the on-line analysis of VOCs in water with a VUV lamp based SPI ion source.
authors.affiliation: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China. hli@dicp.ac.cn.
authors.forename: Keyong
authors.initials: K
authors.lastname: Hou
authors.forename: Fanglong
authors.initials: F
authors.lastname: Li
authors.forename: Wendong
authors.initials: W
authors.lastname: Chen
authors.forename: Ping
authors.initials: P
authors.lastname: Chen
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Xie
authors.forename: Wuduo
authors.initials: W
authors.lastname: Zhao
authors.forename: Lei
authors.initials: L
authors.lastname: Hua
authors.forename: Kemei
authors.initials: K
authors.lastname: Pei
authors.forename: Haiyang
authors.initials: H
authors.lastname: Li