Spectrophotometric Determination of Trace Amount of Nickel in Drinks with Eriochrome Black T as Chromogenic Reagent

In a H2B4O7-KCl-NaOH buffer solution of pH 10.0, a stable coordination complex was formed by the reaction of Ni(Ⅱ) with sodium 1-(1-hydroxy-2-naphthylazo-6-nitro-2-naphthalene-4-sulfonate as chromogenic reagent, having its absorption maximum at the wavelength of 533 nm. Value of apparent molar absorptivity was found to be 5.19×104L·mol-1·cm-1. Linear relationship between values of absorbance and mass concentration of Ni(Ⅱ) was in the range within 1.2 mg·L-1. The proposed method was applied to the determination of Ni(Ⅱ) in drink samples, giving results in consistency with those obtained by AAS. Values of recovery and RSD′s (n=9) found were in the ranges of 99.6%-100% and 1.4%-1.9%, respectively.