Spectrophotometric determination of micro copper in alloys with m-carboxy-antipyrylazo as chromogenic reagent

The color reaction of copper with m-carboxy-antipyrylazo and its application was studied.In 0.04-0.16 mol/L HAc medium,copper reacts with m-carboxy-antipyrylazo to form a blue complex.The apparent molar absorptivity is 2.92×104 L·mol-1·cm-1 at 640 nm.Beer's law was obeyed for copper in the range of 0-0.6 μg/mL.The complex is stable for 24 h.The method has better selectivity and higher tolerance amount of foreign ions,(Mg2+,Ni2+,Co2+,Al3+ and Zn2+)than other methods.It has been applied to determine copper in aluminium alloys and zinc alloys with the relative standard deviation(n=6)of 0.55%-1.30%,and the results are in good agreement with the certified values.