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Abstract
A large number of aqueous samples collected from process and effluent streams of the organic chemicals industry were analyzed by 3 laboratories using atomic absorption spectrophotometry for 13 trace elements on the Environmental Protection Agency (EPA) list of 129 priority pollutants. The digestion procedures used to prepare the samples for analysis differed slightly in each laboratory. In two of the participating laboratories, sample preparation procedures were designed to recover metal species soluble in hot nitric acid, i.e., metals which are present in the sample primarily in the ionic state. One laboratory used digestion techniques aimed at the recovery of “total” metals, i.e., both metals which are in the ionic state and metals which are covalently bound in organic molecules. Recovery of covalently bound metals requires more rigorous digestion conditions, which can result in losses of ionic metals during sample preparation.