Study on the chromogenic reaction of copperII with 1-(2-benzothiazolylazo)-2-hydroxy-3-naphthoic acid and its application

A new reagent 1-(2-benzothiazolylazo)-2-hydroxy-3-naphthoic acid(BTAHN) has been synthesized and its chromogenic reaction with copper * has been studied by the spectrophotometric method in detail.The results show that in the medium of pH 6.0-8.5,copper* reacts with the reagent BTAHN to form a stable blue complex(1∶2).The absorption maximum peak of this complex lies at 590 nm with an apparent molar absorptivity e_(590) of 2.94×10~4 L·mol~(-1)·cm~(-1) and Beer's law is obeyed in the copper* concentration range of 0-20 μg/25 mL.The proposed method has been applied to the direct determination of trace amounts of copper in metal and alloy standard samples and tea samples with satisfactory results.