Spectrophotometric determination of copper with 2,7-bi(5-carboxy-1,3,4-triazolylazo)-chromotropic acid

The conditions of color reaction of a new reagent 2,7-bi(5-carboxy-1,3,4-triazolylazo)-chromotropic acid(BCTZACA) with copper? were presented.The results showed that the new color reagent had reacted with copper ? to form a stable purple complex in the medium of HAc-NaAc(pH 5.0) at (max)=570 nm.The apparent molar absorptivity was 4.5810~4 Lmol~(-1)cm~(-1). Beer's law was obeyed in the concentration range of 0-0.8 mg/L for Cu?.The method has been applied to the direct determination of copper in aluminium alloy and magnesium alloy with satisfactory results.The recovery of standard addition and RSDs were 101.8%-102.0% and 1.9%-3.6% (n=6),respectively.