As a prelude to a field demonstration of the fungal treatment technology by the SITE Program, a field treatability study was performed to select optimal fungal species and loading rates using the site-specific soil matrix contaminated with wood preserving wastes: PCP and PAHs. During the field treatability study, differences in extraction methods of two laboratories performing soil analyses were noted. The technology developer, USDA Forest Service's Forest Products Laboratory, utilized n-hexane:acetone (1:1) as the extraction solvent; the SITE Program subcontracted laboratory used methylene chloride via USEPA SW-846 Method 3550. Other differences were also noted. A comparison of the two extraction solvents on a quantity of soil obtained from the site and contaminated at high and low level concentrations was undertaken. Precision, accuracy, and reproducibility were the primary evaluation criteria. Limits of acceptability were matrix (PCP) spike recovery greater than 17% and relative percent difference between duplicate matrix spike pairs less than 47%.