Spectrophotometric Determination of Diazepam

Diazepam reacts with ninhydrin at pH range 12-12.5 to give a violet color having maximum absorbance at 530 nm wavelength. The reaction is specific for diazepam and provides a basis for its spectrophotometric determination. The color reaction obeys Beer's law from 0.1 to 2 mg/10 mL of diazepam. Coefficient of variation and confidence limit determination are 0.06 and 0.0041%, respectively. The relative standard deviation is 1.5%. The quantitative assessments of tolerable amount of other drugs have also been studied.