Spectrophotometric determination of trace copper in water with co-enhanced sensitivity of mixed surfactants

The enhanced sensitivity effect of mixed surfactants containing CTMAB and OP on color reaction of chrome azurol S(CAS) with copper(Ⅱ) was studied,and a new method to determine trace copper in water by spectrophotometry was established.The results showed that Cu2+ reacts with CAS,CTMAB and OP to form a green blue complex in the NaAc-Na2HPO4 buffer solution at pH 9.0.The maximum absorption wavelength was 609 nm.The apparent molar absorptivity was 9.85×104 L·mol-1·cm-1.The absorbance showed good linearity with Cu2+ in the range of 0-1.2 mg/L,and the correlation coefficient is 0.999 8.The detection limit of this method is 0.002 2 μg/mL.The proposed method has been applied to the determination of Cu2+ in tap water and lake water samples with the relative standard deviation of 1.49% and 3.08%,and the recovery of 97%-103%.