High-Performance Liquid Chromatography of Alprazolam in Postmortem Blood Using Solid-Phase Extraction

Screening and analysis of the numerous benzodiazepines presents a challenge for the forensic toxicologist. The newer benzodiazepines, which are prescribed in daily dose regimens of 0.5-3 mg, are particularly difficult to screen and analyze. Frequently, history or careful investigation by the medical examiner is the only clue that the laboratory has to follow. We describe four cases involving alprazolam and the modification of an existing serum high-performance liquid chromatographic (HPLC) procedure, which allowed us to analyze whole blood. This HPLC procedure for alprazolam uses a protein precipitation step followed by solid-phase extraction. The method is sensitive to 18 ng/mL and linear from 18 to 200 ng/mL. Reproducibility was determined by extracting and analyzing duplicate samples on five separate occasions. The recovery averaged 84% using postmortem blood spiked with 18 and 150 ng/mL alprazolam.