Analysis of six benzodiazepines in vitreous humor by high-performance liquid chromatography-photodiode-array detection.

The purpose of this study was to validate a high-performance liquid chromatography-photodiode-array detetion method for the determination of six benzodiazepines in vitreous humor. The sample preparation was carried out using solid-phase extraction with Oasis HLB cartridges and 10% acetic acid/MeOH as elution solvent. The vitreous humor is less affected by postmortem changes and is a very useful sample when blood or urine specimens are not available. Linear curves for bromazepam, alprazolam, lorazepam, lormetazepam, diazepam, and tetrazepam were obtained within the range 0.03-3 μg/mL, with coefficients of correlation lower than 0.999. The limit of detection was 3 ng/mL, and the lower limit of quantification was 30 ng/mL for each benzodiazepine. Intra- and interassay for precision and accuracy provided results less than 16.81% and 16.78%, respectively. Recoveries were higher than 68.51% in all cases. Finally, the method was applied to determine benzodiazepines in vitreous humor from intoxicated patients.