Round Robin Analyses: (1) EP Toxicity Test: (2) ASTM Water Leach Test

Abstract

The Natural Resources Research Institute supervised and evaluated a round robin analyses for the EP Toxicity and ASTM Water Leach tests on samples of incinerator fly ash. Samples were distributed to 14 laboratories for analyses. The leachates were analyzed for Pb, Cd, Hg, As and Se. Statistical analyses of the Pb and Cd data from the EP Toxicity tests give unreliable results for Pb with somewhat better reproducibility for the Cd. The Pb variability within, and between laboratories was very high and a single data point or single test result would be statistically meaningless. The corresponding analyses for Cd are somewhat better. The results for Hg, As and Se are too low for proper evaluation. The results from the ASTM Water Leach test were inconclusive because much of the data reported was below the limits of detection. We assume that the wide variations among the values reported for Pb are in large part related to the extraction step; i.e., the Cd data are better and the Cd compounds are more readily soluble. The data do not permit differentiation between errors related to extraction and those related to the analytical step. It appears logical that the control parameters applied to the extraction procedure are not sufficiently precise.