Catalytic kinetic spctrophotometric determination of trace copper (II) with 2,7-bi(5-carboxy-1,3,4-triazole)-H acid and hydrogen peroxide

The fading reaction and kinetic condition between copper (Ⅱ) and 2,7-bi(5-carboxy-1,3,4-triazole)-H acid(i.e.2,7-bi(5-carboxy-1,3,4-triazole)-1-amino-8-naphthol-3,6-disulfonic acid,BCTZAHA) were studied.A catalytic kinetic spctrophotometric determination method of trace copper was established based on the linear relationship between fading reaction extent and the content of copper (Ⅱ) in certain range.In the medium of NH3·H2O-NH4Cl buffer solution at pH 10.0,the maximum absorption wavelength of fading system was at 540 nm.The calibration curve was linear for copper (Ⅱ) in the range of 0.001～0.04 mg/L.The linear regression equation was △A=22.124 2 ρ+0.001 07(ρ: mg/L)with correlation coefficient of 0.999 1.The detection limit was 1.32×10-11 g/mL.The method had been applied to the direct determination of trace copper in river water,tap water and well water samples without separation.The results were in good agreement with the values obtained by atomic absorption spectrometry(AAS).