Thin-layer chromatographic methods for the separation and identification of organomercury compounds have been developed and applied to the examination of commercial-quality organomercurials and seed-dressing formulations. The organomercury compounds, in the form of their chlorides, are separated on silica gel by continuous development with cyclohexane-acetone (4 + 1), and detected as orange-brown spots by spraying the plate successively with copper sulphate and sodium sulphite-potassium iodide reagents. If organomercury salts other than chlorides are present, they must be converted into the chlorides by adding aqueous sodium chloride solution to the spotting solvent.

A method for the semi-quantitative assay of inorganic mercury [as mercury(II)] in the compounds, at levels between 1 and 14 per cent., is also described. The inorganic mercury [as mercury(II) chloride] is separated by using carbon tetrachloride-acetone (7 + 3) as the developing solvent and is determined by visual comparison with standards.

Little or no mercury-containing impurity was found in samples of phenylmercury nitrate, phenylmercury acetate and phenylmercury chloride examined, but methoxyethylmercury chloride and ethoxyethylmercury chloride samples contained as many as five mercury-containing impurities and up to 12 per cent. of inorganic mercury compounds.