Application of dual wavelength spectrophotometry and absorbance ratio method in analysis of compound preparations

The dual wavelength spectrophotometry has been used for determination of amidopyrine and barbital in amidopyrine-barbital without the need for preliminary separation. This method can only be used in dual wavelength spectrophptometer. The method is rapid and very simple to operate. The good results have been obtained. The recovery of amidopyrine and barbital is 99.92+0.13%, 99.24+0.54% respeclively (mean+SD). So the accuracy and precision meet the requirements of analysis of pharmaceutical preparations.