Determination of trace amount Cu with the CAS-CTMAB dual-wavelength spectrophotometry

Green compound of Cu with CAS in the presence of CTMAB are studied under the condition of pH=7.5~9.0.The absorption maximum of reagen and its complex are at 420nm and 624nm respectively.The apparent molar absorptivity of the complex for the dual-wavelength spectrophotometry is 1.12×10~5.Beer's law is obeyed in the range of 0~20mg/L.The method is applied to the determination of copper in steel and the result is satisfactory.