Determination of copper oxinate used as fungicide and antiseptic

In the work reported by Darbey, the sample was treated with hot dilute hydrochloric acid to leach the contained oxine. Then, the color intensity of the solution was measured at 365 mμ. However, this method is seriously affected by iron and also by some organic substances, which show appreciable absorption at 365 mμ. In the present method recommended by the authors, the sample is treated with phosphoric acid in order to eliminate the absorption of iron (Fig. 1-(3)), and the absorbancy of the solution is directly measured at 360 mμ (1st procedure). When colored organic materials are present in the sample, the following method is recommended (2nd procedure). The acid solution (oxine