Screening of pesticide-contaminated soil by supercritical fluid extraction (SFE) and high-performance thin-layer chromatography with automated multiple development (HPTLC/AMD)

A method for screening of pesticide-contaminated soil was developed. The extraction is carried out by supercritical carbon dioxide (CO₂) with methanol as a modifier. The different components of the extracts are separated by high-performance thin-layer chromatography with automated multiple development (HPTLC/AMD) and evaluated densitometrically. The technique can be carried out without any previous clean-up step. Compared with other extraction techniques, SFE has the advantages of reducing the amount of co-extracted soil contents, which can seriously deteriorate the results. A 35-step development of the TLC-plate with gradient elution offers an application over a wide range of polarity. Migration data for 107 pesticides, recoveries and detection limits for 20 pesticides were determined.