Application of the sodium diethyldithiocarbamate reaction to the micro-colorimetric determination of copper in organic substances.

WHEN an aqueous solution of sodium diethyldithiocarbamate is added to a solution containing copper the normal copper salt of diethyldithiocarbamic acid, which has a golden-brown colour, is formed. Callan and Henderson [1929], who discovered this reaction, applied their method with satisfactory results to the determination of copper in inorganic substances, but were not concerned with biological material. Of the colorimetric methods which have been proposed for estimating the copper content of biological material the Biazzo [1926] method as developed by Elvehjem and Lindow [1929] has been most used. Apart from the fact that the accuracy of this method has been recently questioned [see Ansbacher, Remington and Culp, 1931; Walker, 1930; Drabkin and Waggoner, 1930] the carbamate reaction has, at the outset, certain important advantages over it, since the latter is at least ten times more sensitive and gives the same colour with copper irrespective of the PH of the solution. The work described in this paper was undertaken because we believed that to study further the role of copper in metabolism, and to clarify our present knowledge in this regard, more accurate methods were required for the determination of copper in organic materials.