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EVALUATION OF ON-SITE ANALYTICAL METHODS FOR TNT AND RDX IN COMPOST RESIDUES

A field demonstration was conducted to assess the performance of on-site analytical methods for explosives 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in compost residues during full-scale composting at the Umatilla Army Depot Superfund site in Hermiston, Oregon. Compost samples were analyzed by each of the on-site methods and these results were compared to EPA SW-846 Method 8330 laboratory analysis using high performance liquid chromatography (HPLC).

The on-site methods evaluated include the EnSys TNT and RDX colorimetric test methods (EPA SW-846 Methods 8515 and 8510), with and without organic matrix interference cleanup steps, and the DTECH TNT and RDX immunoassay test methods (EPA SW846 Methods 4050 and 4051).

All analyses were conducted from a single acetone extract in an effort to reduce the effects of soil heterogeneity. Accuracy of the on-site methods were evaluated using linear regression analysis and relative percent difference (RPD) comparison criteria.

Over the range of conditions tested, the colorimetric methods for TNT and RDX with organic matrix interference cleanup steps showed the highest accuracy. Significant differences were noted for samples run by the colorimetric methods with and without the organic matrix interference cleanup steps.

The immunoassay TNT and RDX methods also showed reasonable accuracy for analysis of compost residues. Additional testing of compost mixtures will be conducted for the pilot scale composting trials at the Naval Surface Warfare Center (NSWS) site in Crane, Indiana.

Key words: explosives, TNT, RDX, on-site analytical methods, composting