Influence of temperature, pressure, modifier, and collection mode on supercritical CO2 extraction efficiencies of Diuron from sugar cane and orange samples

The effects of temperature, pressure, modifier, and collection mode in the supercritical fluid extraction (SFE) of the herbicide Diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) in real sugar cane and orange samples were evaluated. The extraction efficiencies were directly compared to those achieved using solid–liquid extraction (SLE) described in the literature with identical clean-up and analysis by high resolution gas chromatography–electron capture detection (HRGC/ECD). The SFE recoveries at temperatures lower than 80°C and pressure lower than 150 atm were typically lower than that obtained by SLE; however, an increase in the temperature and pressure increased the efficiencies of SFE over SLE. The results showed that under certain conditions CO2 in the supercritical state presented higher extraction power than SLE (extracted ca. 10% more pesticide), showing it to be a suitable method for pesticide residue analysis.