Screening procedure for benzodiazepines in biological fluids by high-performance liquid chromatography using a...

A sensitive and specific determination of benzodiazepines in biological fluids is described, based on reversed-phase high-performance liquid chromatography. The compounds are extracted with a C2 AASP cartridge within 5 min. The recovery ranges from 92 to 104% and is independent of the concentration. Using a suitable gradient elution, complete separation of nineteen benzodiazepines is achieved in 50 min with detection limits of less than 3 ng/ml in urine and 5 ng/ml in other biological fluids. Using a rapid-scanning multichannel detector, the identities of the benzodiazepines can be confirmed. Prazepam is employed as internal standard. The precision and accuracy of the described method are suitable for monitoring benzodiazepine levels in clinical studies and an example is given.