Development of an Analytical Method for the Determination of Explosive Residues in Soil. Part 2. Additional Development and Ruggedness Testing.

摘要

The analytical method for determination of explosive residues in soil developed by Jenkins and Walsh (1987) was tested and modified to improve its usability. The major modification is the use of an aqueous CaCl2 solution to achieve flocculation and settling of suspended particulates prior to filtration. Ruggedness testing demonstrated that the method is not sensitive to minor modifications in analytical protocol. Specific studies indicated that the following had negligible effects on determined soil concentrations: the degree of grinding prior to extraction with acetonitrile, the ratio of soil mass to extraction solvent volume, the kind of mixing (vortex mixing or manual shaking) used prior to ultrasonic bath extraction, the concentrations of CaCl2 used for flocculation, the length of time allowed after flocculation before samples were filtered, and the number of samples processed simultaneously in the ultrasonic bat. Specific studies were conducted to determine how long stock and working standards and soil extracts were stable. The combined analyte stock solution is good for at least a year, and the combined working standard is good for at least 28 days. Results indicated that soil extracts can be held for at least two months before being analyzed without measurable analyte loss. Care needs to be taken to ensure that air drying is not conducted in direct sunlight; otherwise losses of TNT will result. The authors recommend a full collaborative test of the method to define performance characteristics in everyday use. Keywords: Chemical analysis; Explosives; Soils; Soil contamination. (kt)