EXTRACTION OF ORGANIC POLLUTANTS FROM SOLID SAMPLES USING MICROWAVE-ENERGY

This study, which is part of an ongoing U.S. Environmental Protection Agency (EPA) research program, carried out by the Environmental Monito ring Systems Laboratory-Las Vegas, addresses new sample preparation te chniques that (a) prevent or minimize pollution in analytical laborato ries, (b) improve target analyte recoveries, and (c) reduce sample pre paration costs, We present here additional evaluation results of the m icrowave-assisted extraction (MAE) procedure (described previously in this journal) for 187 compounds and four Aroclors listed in the EPA Me thods 8250, 8081, and 8141A, Our results demonstrate that most of thes e compounds can be recovered in good yields from the matrices investig ated. For example, recoveries ranged from 80 to 120% for 79 of the 95 compounds listed in Method 8250, 38 of the 45 organochlorine pesticide s listed in Method 8081, and 34 of the 47 organophosphorus pesticides listed in Method 8141A. When recoveries from freshly spiked soil sampl es were compared with those from aged samples, we found that recoverie s usually decreased; as expected, there was more spread in recoveries with increased aging time, For 15 compounds in a reference soil, the r ecoveries of 14 compounds by MAE were equal, to or better than recover ies obtained by Soxhlet extraction (naphthalene being the exception); for selected organochlorine pesticides, recoveries from spiked soil sa mples were at least 7% higher for MAE than for either Soxhlet or sonic ation extraction,