High-performance liquid chromatographic investigation of the interaction of phenylmercuric nitrate and sodium metabisulphite in eye drop formulations.

The degradation of phenylmercuric nitrate in the presence of sodium metabisulphite in eye drop formulations has been investigated using a stability-indicating high-performance liquid chromatographic (HPLC) method. HPLC methods have been developed for the quantitation of the principal degradation products (diphenyl-mercury, benzenesulphonic acid and benzenesulphinic acid) and a mechanism is proposed for their formation. The pharmaceutical significance of the interaction is briefly discussed.