Simultaneous extraction of selected benzodiazepines and benzodiazepine-glucuronides from urine by immunoadsorption

A rapid and selective cleanup procedure based on immunoadsorption is described for the simultaneous extraction of diazepam and its free or glucuronidated metabolites nordiazepam, temazepam, and oxazepam from urine. The method can also be used for the extraction of lorazepam and lorazepam-glucuronide. Because the samples do not have to be hydrolyzed before extraction, valuable information is preserved. With the exception of lorazepam-glucuronide, recoveries between 86 and 100% were obtained at spiking levels up to 200 ng of benzodiazepine or glucuronide per milliliter of urine. Using methanol/water (90:10, v/v) as an eluent, the immunoadsorber could be used at least 20 times. High-performance liquid chromatograms of urine samples from patients receiving low therapeutic dosages of diazepam or lorazepam are shown to demonstrate the high purity of the extracts.