Simultaneous spectrophotometric determination of analgin and lidocaine hydrochloride in injection solutions

Two new spectrophotometric methods for the simultaneous determination of analgin and lidocaine hydrochloride in their binary mixture are described. In the first method, derivative spectrophotometry, dA/d lambda values were measured at 291.8 and 232.8 nm for analgin and lidocaine hydrochloride, respectively, in the first derivative spectra of their combination. The relative standard deviation of the method was found to be 0.23% for analgin and 1.19% for lidocaine hydrochloride. In the second method, extractive and first derivative spectrophotometry, analgin and lidocaine hydrochloride were extracted into chloroform in the presence of solid cobalt nitrate and potassium thiocyanate and the quantification of lidocaine hydrochloride was performed by reading the absorbency of the chloroform layer at 625.0 nm. The determination of analgin was carried out by measuring the dA/d lambda values at 290.0 nm in the first derivative spectra of the same layer. The relative standard deviation of the method was found to be 1.20 and 1.25% for analgin and lidocaine hydrochloride, respectively. These two methods have been successfully applied to an injection solution containing these drugs.