Fractionating Determination of Micro-amounts of Stannous Sulfide and Ferrous Sulfide on the Surface of Tin-plate by the Spectrophotometric Method

Abstract

This paper describes an analytical method for the fractionating determination of stannous sulfide and ferrous sulfide formed on the surface of some tinplates…the tinplate treated by dipping in potassium polysulfide solution and the inner face of the can of foods containing sulfide. The method is based on the difference in solubility between the sulfide and iron matrix in an dilute hydrochloric acid solution. The outline of procedure is as follows:
To dissolve all the sulfide on the surface, sample fixed in the special dissolving vessel made of acrylic acid resin is treated with 20ml of 4N hydrochloric acid at room temperature for 20 minutes under the passing of nitrogen gas. Evolved hydrogen sulfide is absorbed in zinc acetate solution and sulfur as sulfide is determined by the methylene-blue spectrophotometric method. Then, iron in the solution is determined by the o-phenanthroline spectrophotometric method. The micro-amounts of stannous sulfide and ferrous sulfide on the surface of the sample are calculated from these analytical values.
By this method, several samples were analysed and the satisfactory results were obtained.