Estimation of plasma lorazepam by gas-liquid chromatography and a benzene extraction

Plasma lorazepam can be easily and reliably estimated using a simple single stage benzene extraction and gas-lizuid chromatography with flunitrazepam as the internal standard. Reproducible results within the clinical range of plasma levels were obtained. This method permits the extraction and chromatographing of 40 samples in approximately 7 1/2 hours.