Determination of Dioxins in Atmospheric Deposition by HRGC/HRMS

A method was evaluated for the determination of seventeen 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in atmospheric deposition with isotope dilution-high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). Sample extracts were cleaned up successively through multi-layer silica gel, alumina, and silica gel columns. Precision and recoveries of the entire procedure were evaluated by replicate analysis (n=4) of PCDD/Fs standard solutions, with RSD below 7.1% and the recoveries in the range of 62%-103%. The method was also validated by replicate analysis (n=3) of certified reference materials. The found values were in agreement with those certified with RSD below 15%. The detection limits were 0.1 pg for 2,3,7,8-TCDF, 0.2 pg for 2,3,7,8-TCDD, and 0.8 pg for OCDD. Using this method, PCDD/Fs were analyzed in an atmospheric deposition sample, with the deposition flux of 14.02 pg TEQ m−2·day−1.