Development of an Analytical Method for the Determination of Explosive Residues in Soil. Part 3. Collaborative Test Results and Final Performance Evaluation

A collaborative test of a method for the determination of nitroaromatic and nitramine explosives in soil was conducted at eight laboratories. The method involves extraction of a 2.00-g-portion of soil with 10.0 mL of acetonitrile in a sonic bath, dilution of 5.00 mL of soil extract with 5.00 mL of aqueous CaCl2, filtration and determination by RP-HPLC-UV at 254nm. Certified reporting limits (CRLs) and method detection limits (MDLs) were obtained for HMX, RDX, TNT and ten other analytes. Values ranged from 0.07 to 2. 15 microg/g for the CRLs and from 0.03 to 1.27 microg/g for the MDLs. The collaborative test was conducted under the auspices of the Association of Official Analytical Chemists. The analytes (HMX, RDX, TNB, DNB, tetryl, TNT and 2,4-DNT) were measured in eight-field-contaminated soils and eight spiked standard matrix soils. Both sets of eight consisted of four individual samples in duplicate. Concentrations ranged from the limits of detection to nearly 1000 microg/g. The results were evaluated by means of analysis of variance and regression analysis with and without the inclusion of data identified as outliers. Keywords: Chemical analysis; Collaborative tests; Explosives; Soils; Soil contamination; Soil extraction; Calcium chloride. (KT)