Analysis of polychlorinated dibenzofurans and polychlorinated dibenzo-/ital p/-dioxins in transformers and capacitors: Volume 2, Formation of PCDF (polychlorinated dibenzofurans) and PCDD (polychlorinated dibenzo-/ital p/-dioxins) in Askarel and contaminated mineral oil equipment: Final report

A study was conducted by five independent laboratories to evaluate methods for the measurement of trace levels of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) in utility dielectric liquids. Each laboratory evaluated a different analytical method. The method evaluated by Battelle involved spiking with labelled internal standards, analyte enrichment by column chromatography/high resolution mass spectrometry (HRGC/HRMS). Baseline analyses of five dielectric fluids were conducted by each laboratory as an initial test of their methods. The variability of results between the five methods was within expectations, and the five methods were deemed suitable for round robin evaluation. The in-service liquids used in this study were found to have relatively low levels of PCDDs and trace amounts of PCDF. Liquids from transformers with more than 25 years of service had higher PCDF levels than liquids from newer transformers. Liquids from utility appliances exposed to thermal and electrical stresses did not have elevated PCDD or PCDF levels. PCDF levels increased as the Aroclor number (and relative amount of chlorination) increased. 1 fig., 22 tabs.