Kinetic spectrophotometric determination of trace copper(II) ions by their catalytic effect on the reduction of brilliant cresyl blue by ascorbic acid

摘要

In the present study, a novel catalytic-kineticspectrophotometric method was developed for the determination of traceamounts of copper. It is based on the catalytic effect of Cu(II) onthe reduction of brilliant cresyl blue (BCB) by ascorbic acid in pH5.0 acetate buffer medium. The reaction was monitoredspectrophotometrically by measuring the decrease in absorbance of BCBat 624 nm. The operating conditions regarding concentration ofreagents, pH, time, and temperature were established and optimized indetail. The working curve was linear in the concentration range of0.1-5.0 mu g L^{-1}. The maximum percentage error and standarddeviation for 5 replicate determination of the 3 mu g L^{-1} Cu(II)were 3.20 and 0.45, respectively. The detection limit andquantification limit were 0.025 and 0.086 mu g L^{-1}, respectively.The procedure was successfully applied to determination of dissolvedcopper levels of 3 different natural spring waters and artificiallyprepared wastewater samples. The accuracy of the proposed kineticmethod was tested by means of 5 replicate analyses of the certifiedstandard materials, SRM 1640, based on 2 independent methods.