Reference method for dibenzofuran and dibenzo-p-dioxin in defoamers: foreword

Foreword

The use of defoamers contaminated with non-chlorinated dibenzofuran (DBF) and dibenzo-p-dioxin (DBD) in chlorine bleaching pulp mills has been shown to significantly increase the 2378-TCDF and 2378-TCDD levels of the final bleached pulp. To reduce amounts of these toxicants in pulp mill discharges, Environment Canada is developing regulations that will establish the maximum concentrations of DBF and DBD in defoamers for those applications.

This report is an analytical method for the determination of DBF and DBD in defoamers at low (ng/g) levels. It will be referenced in the regulations and has been developed jointly by the Pulp and Paper Research Institute of Canada (PAPRICAN) and Environment Canada.

In this method, defoamers are steam-extracted and the extract in iso-octane is cleaned up on a basic alumina column. Final analysis is performed by gas chromatography-mass spectrometry (GC-MS) in the selected ion-monitoring made and the extraction recoveries of native DBD and DBF are monitored by using DBF-d₈ and DBD-d₈ as surrogates. Confirmation of DBD and DBF was done by comparing the ratio of peak areas for the quantitation and confirmation ions of each compound in the standard and the sample. Based on a 5.00 g sample and a final volume of 0.5 mL, the method detection limit is 1 ng/g for both DBF and DBD.