Comparison of supercritical fluid and soxhlet extraction methods for the determination of chlorothalonil from cranberry bog soils

The development and validation of an analytical method to determine the concentration of chlorothalonil from cranberry bog soil using supercritical fluid extraction (SFE) are reported. A self-built supercritical fluid extractor using CO2 as the supercritical fluid (SCF) was used. The recovery of chlorothalonil was optimized by varying extraction temperature, pressure, time (static and dynamic), organic modifiers, and SCF flow rate. This method was then compared to a Soxhlet extraction procedure. SFE had more consistent performance than the Soxhlet extraction method for the recovery of chlorothalonil from both fortified bog soils and field samples. SFE provided cleaner extracts, had shorter extraction times, and used less organic solvent than the Soxhlet extraction method. This result is consistent with other SFE methods for determining pesticides from various environmental matrices. Thus, SFE is a preferred method for the extraction of chlorothalonil from cranberry bog soil.