Organochlorine (OC) pesticide residues in soils of major cocoa plantations in Ondo State, Southwestern Nigeria

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).