Congener Specific Determination of Polychlorinated Naphthalenes in Landfill Leachate by Gas Chromatography High Resolution Mass Spectrometry

摘要

An isomer specific analytical method for the determination of the polychlorinated naphthalenes (PCNs: DiCNs-OcCN) in leachate samples was developed by using gas chromatography with high resolution mass spectrometry (GC/HRMS). Leachate samples were flocculated and the flocks were extracted by using Dean-Stark soxhlet extraction. Sample extracts were cleaned up using multilayer silica gel column (silica gel/H_2 SO_4 silica gel/AgNO_3 silica gel), followed by carbon dispersed silica gel column automatically by using SPD-600GC. The method achieved PCNs recovery rate of 81-105% with instrument detection limits (IDLs) between 0.05 and 0.1 pg and method detection limits (MDLs) between 0.4 and 4 pg/L for the leachate extracts. The concentrations of the PCNs in leachate samples obtained by the method ranged from < MDLs to 490 pg/L. The detected PCNs were mainly composed by low-chlorinated components, and the PCNs were reduced by a process in water treatment plant of the landfill. This analytical method was one of the most comprehensive isomer-specific methods available at the present and based on the existing techniques used for the quantification of polychlorinated dioxins and furans, and therefore would be readily adopted by other laboratories.