Flow injection stopped-flow kinetic determination of the anxiolytic sedative bromazepam in dosage forms

A highly selective and accurate flow injection (Fl) method for the determination of bromazepam has been developed. The method is based on the chelation of bromazepam with iron(u) to form a complex that absorbs at a maximum wavelength of 585 nm. Optimization of Fl and chemical parameters is achieved by the univariate and the computerized modified simplex methods. The drug (157 μl) is injected into 0.072 mol dm^-3 iron(II) solution, both previously prepared in 0.02 mol dm^-3 HCl, at a flow rate of 3.81 ml min^-1 and allowed to mix and react in a coil (100 cm × 0.5 mm i.d.) for a fixed time of 300 s. A relative standard deviation of 0.66% with a recovery of 99.9% is achieved and the method is suitable for the determination of bromazepam in tablet formulations.