OPTIMIZATION OF SUPERCRITICAL-FLUID DERIVATIZATION AND EXTRACTION OF CRESOLS IN SOIL SAMPLES USING FACTORIAL-DESIGNS

Two- and three-factorial designs have been used to optimize the superc ritical fluid acetylation-extraction of o-cresol, m-cresol and p-creso l in soil samples. Overall, nine variables (carbon dioxide flow rate, fluid density, extraction cell temperature, static extraction time, no zzle and trap temperatures, amount of derivatizing reagent, amount of pyridine, and contact time between the derivatizing reagents and the s ample) were considered. The results suggest that only extraction cell temperature and the amount of derivatizing reagent are statistically s ignificant to the overall extraction yield, as is the extractant flow rate to the kinetics. Special attention was paid to developing suitabl e test materials for these types of optimization processes. The proced ure was validated by processing a certified reference material. (C) 19 96 John Wiley & Sons, Inc.