Validation studies for a new supercritical fluid extraction method for the isolation of hydrophobic organic compounds from filtered suspended solids

A newly developed SFE scheme (consisting of filtration, drying, and extraction steps optimized in two earlier studies) for the isolation of hydrophobic organic compounds from filtered suspended solids has been validated. Accuracy and precision data for the method were obtained for selected polynuclear aromatic hydrocarbons relative to certified and in-house Soxhlet values, using a standard reference material sample (EC-1 from Environment Canada). Compared to in-house results using EPA Method 3561, the recoveries from the optimized SFE step alone were much better, with an overall average accuracy of 101% and precision of 9% R.S.D., versus 74 and 13% for Method 3561, respectively. Unlike most SFE validation studies which validate only the SFE step, this study was able to validate the SFE scheme starting from the drying step to the final SFE step. The combined steps showed an overall average accuracy of 91%, with a precision of 8% R.S.D.. With this accuracy and precision, the newly developed SFE scheme has been proven to be acceptable. (C) 1997 Elsevier Science B.V.