Synthesis of a New Triazene Reagent and Its Application to the Color Reaction with Gold(Ⅲ) Ion

A new reagent, 1-(4-antipyrinyl)-3-(sulfanilic acid)-triazene (ASTA), was synthesized by the reaction between 4-antipyrine and sulfanilic acid. Molecular composition and structure of ASTA were determined by FT-IRS. It was found that in a Na2B4O7-NaOH buffer medium of pH 10.3 containing Triton X-100, a stable coordination complex (R∶Au3+=2∶1) was formed by the reaction of ASTA with gold ion, having the absorption maximum at 496 nm. Linear relationship between values of absorbance and concentration of Au(Ⅲ) ion was obtained in the range of 0.06-1.05 mg·L-1. Detection limit (3S/N) found was 0.02 mg·L-1. The apparent molar absorptivity of the color system was found to be 1.8×105L·mol-1·cm-1. The proposed method was applied to the determination of Au(Ⅲ) in gold ore samples, and the results obtained were in consistency with those obtained by AAS. Values of recovery were found in the range of 109.0%-118.2% and RSD (n=6) was less than 4.0%.