The Micro-Determination of Gold in Biological Fluids and Tissues.

The increasing interest in the use of gold salts as chemotherapeutic agents in the treatment of certain diseases (Hartfall, et al., 1937) has made apparent the necessity of an accurate, specific, and sensitive method for the determination of gold in various biological materials. Moreover, the lack of information regarding the metabolism and pharmacology of this element further emphasizes this need. Previous methods have employed either an electrolytic precipitation, a colorimetric reaction, or a titrimetric procedure. The electrolytic methods such as those of Cadwell and Leavell (1919), and Lombolt (1926), involve too many technical difficulties to be of practical value. The numerous colorimetric methods (Stanbury, 1932; Leulier, Bernard, and Loisy, 1937) lack both specificity and accuracy. The method of Merejkovsky (1933) seems to be specific and is probably the best, but the large blank from the reagent itself and the inadequate directions of the author make it impossible to duplicate the original results. The iodometric titration first employed by Peterson (1898) and modified most recently by Hansborg (1925) cannot be applied to tissues and blood because the ferric iron present in these substances interferes with the reaction. This difficulty has been overcome by Tukats (1933) by a preliminary precipitation of the gold with oxalic acid. However, this preliminary procedure makes it impossible to apply the method to the determination of very small quantities of gold. Pollard (1937) determined gold after conversion to thZ chloride by titration with hydroquinone using o-dianisidine as an indicator. In order to secure quantitative results it was necessary for other inorganic salts to be absent. This condition was obtained by a preliminary precipitation of the gold from the original substance by use of a hydrochloric acid solution of tellurium saturated with sulphur trioxide. A modification of this method for use with urine (Jamieson and Watson, 1938) required large volumes of urine and was limited in sensitivity. Because none of these methods are entirely adequate, it was thought it would be of value to develop an accurate and specific modification of Pollard's (1937) procedure for the quantitative determination of gold in small amounts of blood, urine, and tissue.