The application of supercritical fluid extraction to cocaine and its metabolites in blood and urine

Supercritical fluid extraction (SFE) is emerging as a valuable analytical technique for use as an alternative to conventional solid-phase (SPE) and liquid-liquid extraction techniques. It is a relatively new technique based on the use of supercritical fluids for the isolation of analytes from various matrices and is attracting great interest because of the increasing need for a simple, rapid, environmentally friendly, automated, and selective extraction method. A new method using SFE procedures for the extraction of cocaine and its major metabolites, benzoylecgonine and ecgonine methyl ester, from whole blood and urine was developed. This study has shown that cocaine and its metabolites can be successfully extracted from blood and urine using SFE techniques. Levels measured using SFE have shown analyte recovery better than 70% for cocaine, better than 40% for benzoylecgonine, and better than 85% for ecognine methyl ester from whole blood and urine. Good run-to-run reproducibility was observed between each extraction with limits of detection and quantitation of 1 ng and 10 ng based on 200 μL of blood and urine. A comparison between SPE and developed SFE techniques was investigated to observe if a correlation existed between the two methods. Studies proved that a correlation did exist between the two methods for spiked blood and urine samples with comparative results. This paper details a procedure for the extraction of cocaine and its metabolites from blood and urine.