Study on the determination of trace nickel in aluminum alloy by cloud point extraction-spectrophotometry

In Na2B4O7-NaOH buffer solution at pH 9.5 in the presence of nonionic surfactant Triton X-114,the complex formed by 1-(4-nitrophenyl)-3-(5,6-dimethyl-1,2,4-triazole)-triazene(NPDMTT) with Ni2+ could be extracted into surfactant Triton X-114.After phase separation by centrifuging,the content of nickel in surfactant enrichment phase was determined by spectrophotometry using 475 nm and 540 nm as measuring wavelength.The experimental results showed that,after diluting the surfactant enrichment phase with ethanol(1∶2),the measured apparent molar absorptivity of complex was 7.293×105 L·mol-1·cm-1.The linear range of calibration curve was 0-0.14 μg/mL with correlation coefficient of 0.999 3.The proposed method was applied to the determination of nickel in aluminum alloy samples,and the results were consistent with reference values.The relative standard deviation(RSD,n=6) was less than 3 %.