Vacuum Ultraviolet Photon Ionization Mass Spectrometer for Detection of Dioxin Precursors

Waste incineration is considered as a main source of dioxins. During the generation of dioxins, dioxin precursors, such as polychlorinated benzenes (PCBz), polychlorinated phenols (PCPh), polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) etc. have been proved to be produced with much higher concentrations than dioxins, which are determined to be closely related to dioxin toxic equivalents. Therefore, online monitoring of these precursor compounds has been becoming one of the main research directions of dioxin detection. In this study, a novel method for online detection of these dioxin precursors in gas phase was developed by nanosecond vacuum ultraviolet single photon ionization technique, combined with time-of-flight mass spectrometer. This setup was evaluated by monitoring chlorobenzene, polychlorinated phenols and naphthalene in gas phase. The results show that there is a linear relation between the parent ion intensity and the chlorobenzene concentration ranged from 5 ppb to 100 ppb.

Nanosecond vacuum ultraviolet (VUV, 118 nm) by frequency tripling of the 3rd harmonic output of a YAG laser in xenon/argon mixture was optimized. The VUV single photon ionization technique, combined with time-of-flight mass spectrometer, was developed for monitoring chlorobenzene. Linear dependence of the ion intensity on the concentration in the range of 5–100 ppb was obtained.Figure optionsDownload as PowerPoint slide