Trends in techniques for the extraction of drugs and pesticides from biological specimens prior to chromatographic separation and detection

The isolation of non-volatile organic poisons from biological specimens is often difficult and time consuming. This paper surveys the isolation of common drugs and pesticides from biological specimens, including serum, blood and tissue, and the effect of experimental variables on the recovery of compounds, with emphasis on recent trends in extraction techniques and new methods under development, particularly those applicable to forensic toxicology. Traditional liquid-liquid extraction techniques are increasingly being replaced by or used in combination with newer extraction techniques such as solid-phase and supercritical fluid extraction. The potential advantages and problems encountered when incorporating these new methodologies in the isolation of drugs and pesticides from biological matrices are discussed. Although early implementation of solid-phase extraction techniques in forensic toxicology has been hampered by a variety of problems, including extract quality, reproducibility and selectivity, improvements in sorbent quality and elution solvents continue to facilitate their replacement of traditional liquid-liquid extraction methods. Future developments in supercritical fluid extraction should allow this technique to develop in an extremely powerful quantitative tool for the isolation of drugs and pesticides either from solid-phase sorbents or from their endogenous matrices.