Spectrophotometric determination of atropine sulfate in the presence of phenylmercury (II) acetate.

Two-component spectrophotometric method of analysis using 2 wavelengths, the method of least squares using absorbances, the method using 2-orthogonal function coefficients, and the method of least squares using orthogonal function coefficients have been applied to the determination of atropine sulfate in the presence of phenylmercury (II) acetate, compounds whose spectra overlap. The first method gave erroneous results; the second method gave satisfactory results for synthetic mixtures. The fourth method was superior, especially in the presence of irrelevant absorption. It has been successfully used for determining atropine sulfate in injection solutions in which a cubic irrelevant absorption was present. Results were in good agreement with those obtained by the official method.