EVALUATION OF SOXTEC EXTRACTION PROCEDURE FOR EXTRACTING ORGANIC-COMPOUNDS FROM SOILS AND SEDIMENTS

A study was carried out to evaluate the Soxtec extraction of 29 target compounds (7 nitroaromatic compounds, 3 haloethers, 7 chlorinated hyd rocarbons, and 12 organochlorine pesticides) from spiked sandy clay lo am and clay loam. The study also compared 2 solvent mixtures (hexane-a cetone (1 + 1) and methylene chloride-acetone (1 + 1)) and investigate d the effect on method recovery of 5 factors (matrix type, spike level , anhydrous sodium sulfate addition, total extraction time, and immers ion/extraction time ratio), their 2-way interactions, and a 3-way inte raction (matrix x spike x time). Of the 5 factors investigated, matrix type, spike level, and total extraction time had a significant effect on method performance at the 5% significance level for 16 of the 29 t arget compounds (4 compounds were not recovered at all, and analysis o f variance was not significant at the 5% significance level for 9 comp ounds). Anhydrous sodium sulfate addition and immersion/extraction tim e ratio had insignificant effects for all but one of the target compou nds. This effect may have been a random occurrence. The data indicate that the 2 solvents performed equally well and 4 compounds were not re covered at all. These 4 compounds were apparently lost from the spiked matrix. Experiments were performed to determine compound recovery at each step in the extraction procedure. Limited experimental work was p erformed with 64 basic/neutral/acidic compounds spiked onto clay loam and with 3 standard reference materials certified for polynuclear arom atic hydrocarbons. From the 64 compounds spiked onto clay loam at 6 mg /kg, 20 had recoveries of greater than 75%, 22 had recoveries from 50 to 74%, 12 had recoveries from 25 to 49%, and 10 had recoveries of les s than 25%.