31. The Determination of Copper and Iron in Dairy Products

Abstract

1. Two colorimetric methods for determination of copper have been described, viz. the xanthate and the sodium diethyl-dithio-carbamate. Both methods have given satisfactory results but the carbamate method has proved to be more sensitive and less liable to error from possible contamination than the xanthate method. 2. The colorimetric determination of iron by the modification of the ferric thiocyanate method has been proved to give a very high degree of accuracy and excellent results have been obtained. 3. A method of wet ashing has been described whereby organic matter is oxidised by the use of concentrated sulphuric acid and sodium nitrate and copper and iron extracted from the fat. 4. A number of results are given showing the amount of copper and iron contamination that the cream is subjected to during the course of butter manufacture, and the distribution of copper and iron in the cream, butter and buttermilk.