Determination of lorazepam in plasma by electron capture GLC

A method is described for the determination of lorazepam plasma levels involving extraction from the sample and analysis of the intact lorazepam by electron capture gas-liquid chromatography. Using mass spectrometry it is demonstrated, that lorazepam shows a thermal rearrangement under gas chromatographic conditions. The limit of detection is 0.01 mg/l and the assay shows a linearity from 0.01-0.80 mg lorazepam per liter of plasma.