Decomposition of thimerosal in aqueous solution and its determination by high-performance liquid chromatography

Studies on the decomposition of thimerosal in aqueous solution have confirmed that thiosalicylic acid and ethylmercuric hydroxide are the initial products. On prolonged reaction, thiosalicylic acid was oxidized to 2,2'-dithiosalicylic acid, while ethylmercuric hydroxide was reduced to elemental mercury. As a result, a specific, reverse-phase high-performance liquid chromatographic assay has been developed for thimerosal in the presence of its decomposition products. By comparison, an existing colorimetric assay procedure employing dithizone was shown to be not fully specific. The presence of sodium chloride in the solution accelerated the decomposition of thimerosal. There was evidence that thimerosal was sorbed onto plastic containers on storage.