Project Title: Development of Single Analytical Method for Simultaneously Determining Dioxins and Dioxin-like PCBs in Ambient Air

Applicant: The Hong Kong Baptist University (Dr Zongwei CAI)

Total Approved Grant: $148,888.80

Duration: 1/2/2005 to 31/1/2006

Project Status/Remarks: Completed

Dioxins and dioxin-like PCBs are currently analyzed by using separated procedures in Hong Kong.  In particular, double samplings are currently needed for air analysis.  This project will focus on developing single analytical procedure for simultaneously analyzing dioxins and dioxin-like PCBs. The method development will be based on individual standard analytical methods and more importantly, on intensive experience with dioxins and dioxin-like PCBs analyses in ambient air.  The outcome of this project will benefit both current and future dioxin monitoring programs in Hong Kong.

Summary of the Findings/Outcomes:
The current standard methods (e.g., US-EPA, EU and WHO methods) involve two separated sample preparation procedures and HRGC/HRMS analyses for dioxins and dioxin-like PCBs, which is time-consuming and costly. The separated analyses particularly hinder environmental monitoring and academic research on ambient dioxins and dioxin-like PCBs because the air sample often cannot be separated into two portions. Thus, this project aims to develop method for simultaneously analyzing dioxins and dioxin-like PCBs in one single sample. Method development based on individual standard analytical procedure for simultaneously analyzing seventeen 2,3,7,8-chlorine substituted PCDD/Fs and twelve WHO-specified dioxin-like PCBs in air samples was conducted. The performances of various chromatography columns with different elution solvent mixtures on the separation of the PCBs from the PCDD/Fs and the further cleanup for PCBs were examined and compared. The obtained results showed that acidic alumina chromatography column could not be used to separate dioxins and dioxin-like PCBs because they were eluted out together. However, the separation could be achieved by using either florisil or activated carbon column. Further investigation indicates that the florisil column was found to be most suitable for the separation. Efficient separation of dioxins and dioxin-like PCBs has been achieved and validated with clean sample extracts and acceptable recoveries.