Abstract
A new spectrophotometric method for the determination of tin in canned food is proposed. A small amount of tin (IV) can be selectively extracted into nitrobenzene, when a moderate amount of tris-(1, 10-phenanthroline)-iron (II) chelate cation and a large excess of oxalic acid are contained in the aqueous phase. Thus, tin (IV) can be determined spectrophotometrically by measuring the absorbance of the extract at 516 mμ. To obtain optimum conditions for the determination of tin in canned foods, various factors were examined. A maximum extraction is obtained at pH 0.8-1.8, when an excess of at least 30-fold molar amount of the phenanthroline-iron (II) chelate and 1000-fold molar amount of oxalic acid to that of tin are present. Possible composition of the extracted species is suggested to be [Fe (phen.)3]2+[Sn (C2O4)3]2-. Beer's law is obeyed up to about 60 μg of tin in aqueous solution. The effect of several ions on this method was examined. Satisfactory results were obtained by applying the proposed method to the analysis of tin in several canned foods.
