Analytical Issues Associated with Application of EPA's Proposed 1600 Series Trace Metals Methods to Pulp and Paper Effluents, 1998 Environmental Conference Proceedings

Studies to characterize the efficacy of EPA’s proposed 1600 Series “ultra-trace” metals methods when applied to nine pulp and paper effluents have been performed. Specific methods and analytes examined were EPA Methods 1631 (Hg), 1632 (As), and 1638 (Ag, Al, As, Ba, Be, Cd, Cr, Cu, Mn, Ni, Pb, Sb, Se, Tl, Zn). All analyses were for total recoverable metals, and extensive field blank analyses were performed to evaluate the potential for field sampling contamination at the nine mill sites. Evaluations of 1631 suggest that the method is applicable to final effluents, although sample-specific Method Detection Limits (MDLs) may be greater than 1 ppt. Evaluations of 1632 showed that the major source of background As was the reducing agent (NaBH4). Due to As background from reagents, EPA’s MDL and ML could not be achieved. Reagent consumption was also observed, and could have additional sample-specific impact on As MDLs. In addition, many effluents contained organic As species, meaning that rote application of 1632 will underestimate total As. Evaluations of 1638, coupled with some confirmatory analyses, showed that ICP-MS measurements of As, Cr, and Se in pulp and paper effluents are subject to positive interferences, making Methods 1638 and 200.8 unreliable for these determinations. Atmospheric deposition was observed to contribute measurable concentrations of some metals when sample containers were left open for 24 h at some mill sites. However, field sampling contamination was not observed as a source of analytical bias for any metal, at any site, when grab samples were collected using only reasonable caution.