Abstract

Organochlorine compounds were extracted from soils of major cocoa plantations in Ondo State of Nigeria by supercritical fluid extraction and their concentrations were determined by electron capture detector – gas chromatography. The percentage recoveries for the optimized extraction temperatures were 89.99 ± 0.05 to 105.24 ± 0.04 at 60°C and 63.88 ± 1.12 to 93.33 ± 0.15 at 80°C while the analytes were not detected at 50 and 100°C. The extraction pressure was also optimized and percentage recoveries were 54.13 ± 5.03 to 87.98 ± 10.56 and 89.99 ± 0.05 to 105.24 ± 0.04 at 200 and 300 Bar, respectively. Results of routine analysis using the optimized conditions (60°C, 300 Bar) showed that soils of the study area are contaminated by organochlorine compounds (OCCs) in varied degree which ranged from ND to 40.55 ±1.54 µg/g which may be due to pesticide application on cocoa plantations for the control of insect pests and diseases in the study area.

Key words: Organochlorine pesticides (OCPs), soil, supercritical fluid extraction, electron capture detector – gas chromatography (ECD-GC).