Extraction of pentachlorophenol and tetrachlorophenol residues from field-contaminated carrots and potatoes: comparison of several methods.

A number of solvent extraction systems were investigated for their efficiency in removing residues of pentachlorophenol (PCP) and tetrachlorophenol (TCP) from field-contaminated carrots and potatoes. Greatest numerical yields of PCP and TCP, for both carrots (9 and 5 ng/g, respectively) and potatoes (147 and 11 ng/g, respectively), were obtained by Soxhlet extraction with acidified acetone for 44 hr. Within the limits of experimental error, equivalent results could be obtained by using a 20 hr Soxhlet extraction with acidified acetone for carrots, and a 5 min blending with acidified acetone for potatoes. Extracts were reacted with diazoethane to form the ethyl ethers of PCP and TCP, followed by cleanup on a Florisil column. A gas-liquid chromatograph equipped with a 63Ni linearized electron capture detector was used for identification and quantitation.