A rapid analytical method based on microwave-assisted extraction for the determination of drugs of abuse in vitreous humor

Robust and simple validated analytical methods are required in postmortem toxicology to confirm immunoassay screening analysis of drugs of abuse. In this work, microwave-assisted extraction (MAE) was evaluated as an alternative method for extraction of target compounds such as cocaine, benzoylecgonine, cocaethylene, morphine, codeine, 6-monoacetylmorphine, methadone, and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine from vitreous humor. The MAE procedure parameters, namely, extraction temperature, time, and solvent volume, were optimized using a central composite design and applying desirability functions. The optimal conditions for extraction were 80 °C, 8 min, and 15 mL of dichloromethane solvent. The MAE–high-performance liquid chromatography–diode-array detection method was validated, showing its capability for the detection of concentrations in the range from 33 to 76 ng mL−1 and recoveries in the range from 87 to 99.3% for all drugs. The MAE-based method was tested for 15 vitreous humor samples from forensic cases and its performance was compared with that of a solid-phase extraction method previously developed by our group. In general, better recovery and precision were achieved with the use of the MAE-based procedure.