Spectrophotometric Determination of Trace Amount of Zinc with the Reaction System of Zn(Ⅱ)-Potassium Thiocyanate-Safranine T

In an acetate buffer medium of pH 3.6, and in the presence of Triton X-100, a stable ion association complex was formed between Zn(Ⅱ), in the form anionic complex of Zn(SCN)64-, and safranine T (ST+), having its empirical formula ［ST］4［Zn(SCN)6］. The absorption maximum of the ion association complex was found at the wavelength of 482 nm. Lambert-Beer′s law was obeyed in the concentration range of 0.006-0.70 mg·L-1 for Zn(Ⅱ), with its apparent molar absorptivity of 5.41×104L·mol-1·cm-1. The proposed method was used in the analysis of 2 river water samples for their zinc contents, the results obtained were in consistency with the results found by the dithizone-photometric method. Tests for recovery was made by standard addition method using the river water samples as matrixes, value of average recovery was found to be 99.4% with RSD′s (n=5) less than 3.5%.