Spectrophotometric determination of copper and iron in magnesium alloy with nitroso-R-salt

A spectrophotometric method for the determination of copper and iron in magnesium alloy was established in this study. In acid system, copper and iron could react with nitroso-R-salt to form a yellow green complex with λmax(Cu)=450 nm and λmax(Fe)=720 nm. The apparent molar absorptivity of copper and iron complexes were 1.1 × 104 L·mol-1·cm-1 and 0.7 × 104 L·mol-1·cm-1, respectively. The calibration curve was linear over the range of 0.2-12 μg/mL and 0.1-16 μg/mL for copper and iron respectively. The method has been applied to the determination of copper and iron in magnesium alloy with the relative standard deviation of 2.06%-3.25%. The results are accordant with those obtained by AAS.