Reference method for PCDDs and PCDFs in pulp and paper mill effluents: section 1

Section 1: Summary

A 1-L sample of pulp effluent is initially separated into solid and liquid phases by suction filtering the sample through a glass fibre filter. The solid phase is air-dried overnight before undergoing a Soxhlet extraction with toluene. The liquid phase is extracted with dichloromethane in a separatory funnel. Before filtration, the sample is spiked with a surrogate standard mixture of isotopically-labelled polychlorinated dibenzo-para-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) congeners.

The two extracts are combined, concentrated, and then passed through a series of columns which remove, by reaction and/or selective adsorption, the bulk of the organic matrix co-extracted with PCDD/PCDF. One resulting fraction is concentrated to a known small volume for analysis.

Qualitative/quantitative analysis for PCDD/PCDF is performed with a high-resolution gas chromatograph/high-resolution mass spectrometer/computerized data system (HRGC/ HRMS/DS). Two characteristic ions are selectively monitored for each PCDD/PCDF congener group. Analyte identification is confirmed when target ions are detected in the correct abundance ratio within established retention time windows. Quantification is based on the use of surrogates (isotopically-labelled compounds added before sample workup) as internal standards. Two other isotopically-labelled standards, added to sample extracts immediately before analysis, serve as recovery standards for the quantification of surrogate recovery.