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Interlaboratory Validation of the Leaching Environmental Assessment Framework (LEAF) Method 1314 and Method 1315
Garrabrants, A., D. Kosson, R. DeLapp, P. Kariher, P. Seignette, H. van der Sloot, L. Stefanski, AND M. Baldwin. Interlaboratory Validation of the Leaching Environmental Assessment Framework (LEAF) Method 1314 and Method 1315. US Environmental Protection Agency, Cincinnati, OH, EPA/600/R/12/706, 2012.
This is the 2nd report documenting the interlaboratory validation for Methods 1314 and 1315. This reesarch is being used to support the adoption of the LEAF Methods into SW-846 - the official compendium of methods for US EPA. These methods will result in providing comparable data across a broad range of materials and scenarios including land disposal and use of alternative materials in engineering and commerical applications.
This report summarizes the results of an interlaboratory study conducted to generate precision estimates for two leaching methods under review by the U.S. EPA’s OSWER for inclusion into the EPA’s SW-846: Method 1314: Liquid-Solid Partitioning as a Function of Liquid-solid Ratio using an Up-flow Percolation Column Procedure, and Method 1315: Mass Transfer Rates in Monolithic and Compacted Granular Materials using a Semi-dynamic Tank Leaching Procedure. The validation study was designed based on the approach recommended by the EPA in Guidance for Methods Development and Methods Validation for the RCRA Program. Prior to the start of testing, the study design, approaches and procedures, and data quality indicator goals were documented in an EPA-approved quality assurance project plan. For each of the LEAF methods, the validation study targeted results from two study materials selected to challenge the method with a variety of materials that might plausibly be tested by these methods. For the percolation column test, Method 1314, the study materials included contaminated smelter site soil and brass foundry sand. For validation of the Method 1315 mass transfer test, both monolithic and granular materials were tested through use of a cementitious solidified waste analog and a contaminated smelter site soil. The number of laboratories participating in the Method 1314 validation was seven and where provided columns and pumps, ensuring consistent equipment for all participating laboratories. For Method 1315, ten laboratories were asked to participate in the validation study. All ten laboratories provided analytical samples for the first study material (material code SWA) and eight laboratories were provided analytical samples for the second study materials. The concentrations of ten selected analytes from each test and study material were analyzed by inductively coupled plasma-optical emission spectroscopy and the results were used to determine method precision based on a statistical approach adapted to this validation study. The mean precision for Method 1314 cumulative mass release for ten analytes in each of two study materials was the measured value ±6% repeatability, expressed as a repeatability relative standard deviation (RSDr) and the measured value ±16% reproducibility, expressed as reproducibility relative standard deviation (RSDR). This level of precision is consistent with the precision values reported for a European percolation column test, DIN 15928 (DIN, 2009). Method precision for Method 1314 eluate concentrations collected directly from the participating laboratories was approximately twice of the method precision for cumulative release at the measured value ±12% repeatability and the measured value ±24% reproducibility. For Method 1315, method precision was based on mean interval flux and cumulative release rather than eluate concentrations since these eluate concentrations are not recommended under LEAF for use in environmental assessment. The Method 1315 precision for mean interval flux was the measured value ±12% repeatability and the measured value ±30% reproducibility while the precision for cumulative release was 8% repeatability and 21% reproducibility. The cumulative release precision after 14-days of leaching compared favorably to the reported precision for 16-day release from NEN 7345, a Dutch standard monolithic leaching test. For both Method 1314 and Method 1315, the distribution of reproducibility estimates for individual analytes was considerably better than the reproducibility distribution reported for TCLP.