On-line Monitoring System of P_5CDF Homologues in Waste Incineration Plants Using VUV-SPI-IT-TOFMS

摘要

It usually takes a few weeks to analyze dioxin concentrations and dioxin-TEQ (toxicity equivalency quantity) in fluegases from municipal solid waste (MSW) incinerators by a standard method provided by Japanese industrial standard (JIS 0311). To reduce the required time for analysis, we have developed a new on-line measuring system for furans homologues. This system is composed of a sensitive and robustvacuum ultraviolet (VUV) single-photon ionization(SPI) ion trap (IT) time-of-flight mass spectrometer (VUV-SPI-IT-TOFMS) and automatic sampling/concentrating process. In this work, pentachloro-dibenzofuran (P_5CDF) was selected as an index homologue in chlorinated dibenzo-p-dioxin/ furan homologues (DXNs) because its concentration and I-TEF (international toxicity equivalency factor), which are 2,3,4,7,8-P_5CDF is 0.5 and 1,2,3,7,8-P_5CDF is 0.05, are high and the concentration correlates closely with the total amount of dioxin-TEQ. The lowest detectable limit, 1 pg (0.001 ng-TEQ/m~3 N) was demonstrated by laboratory tests. This system underwent a field test at several actual MSW plants and the tests revealed the following: (a) This system is applicable for dioxin-TEQ evaluation from actual MSW incinerators, (b) It can continuously monitor P_5CDF in a fluegas for 7 months, (c) The frequency of the measurements is once every 2-6 h, depending on the concentration of P_5-CDF.