Spectrophotometric determination of nitrazepam in tablets

A sensitive spectrophotometric method is reported for the determination of nitrazepam either in pure form or in tablets. The method is based on reduction with zinc dust and calcium chloride followed by reaction with sodium pentacyanoaminoferrate(II) to give a violet product having an absorbance maximum at 560 nm. Beer's law is obeyed over the concentration range 1-20 mug ml in the final solution. The common excipients in tablets do not interfere. The recovery and precision are similar to those of the official B.P. method.