Dioxin analysis in water by using a passive sampler and CALUX bioassay

Passive sampling of organic pollutants is a new trend in environmental monitoring and analysis. Passive samplers are being developed to overcome the drawbacks of the conventional snapshot sampling approach. The ceramic toximeter is a promising passive sampler for monitoring dioxin-contaminated surface and ground waters. It consists of an alumina cylinder lined with a thin coating of titania and a pore diameter of 0.05 μm. The cylinder serves as a diffusion barrier limiting the analyte transport to molecular diffusion only, as well as a container for a selective trapping material of a high capacity and affinity towards the chemical(s) of concern. The cylinder is closed from both sides with PTFE caps. The ceramic toximeter was filled with activated carbon as the trapping material and has been tested in vitro for the sampling of dioxin-contaminated water. In addition, the utilization of the CALUX bioassay technique for analyzing the trapped dioxin has greatly reduced the time and costs for dioxin scanning in aqueous media. Exposure times varied between 1 and 7 days in a solution of 1.35 ng-TCDD L−1 (TCDD is 2,3,7,8-tetrachlorodibenzodioxin). The mean effective molecular diffusion coefficient of TCDD in the toximeter amounts to 11.9 × 10−6 m2 d−1 while the minimum concentration detectable in an aquatic system after 30 days of exposure amounts to 0.89 pg-TCDD L−1.