Determination of phenylmercuric nitrate in pharmaceuticals by HPLC.

Abstract

Phenylmercuric nitrate (PMN) is commonly used in pharmaceutical preparations as an antimicrobial preservative in a concentration of lo-20 mg 1-l. Few methods have been reported for the analysis of organomercurial compounds. Although atomic absorption spectrophotometry has been applied [l], highperformance liquid chromatographic methods with UV detection have been described as more specific; these methods involve the analysis of PMN after chloroform extraction [2] or after chelation of organic mercury with substituted dithiocarbamates 13, 41. In particular, the chelation of PMN by morpholinedithiocarbamate was developed by Parkin [4]; the reaction was shown to be rapid and to result in the formation of a compound with a suitable molar absorptivity in the UV range. The present study was undertaken to validate a rapid and sensitive method for the direct determination of PMN in a nasal pharmaceutical formulation. Since it has been shown that organomercurial compounds may be sorbed into plastics [l, 51 the possible loss of PMN from a nasal solution packed in glass or plastic containers was assessed in this study.