STUDY ON THE EXTRACTION SYSTEM OF Cu(Ⅱ)-PAN-TWEEN 80 IN THE PRESENCE OF AMMONIUM SULFATE AND ITS APPLICATION

The solid-liquid extraction system of 1-(2-pyridylazo)-2-naphthol (PAN) and Tween-80 for Cu(Ⅱ) using (NH4)2SO4 as salting-out agent was studied and the extraction condition was optimized.In a phosphate buffer medium of pH 6.8-8.5,and by the addition of solid (NH4)2SO4,the coordination complex of Cu(Ⅱ)-PAN was quantitatively extracted into Tween-80 which was separated as solid phase.The co-existing ions,Fe(Ⅲ)、 Al3+、 Co2+、 Ni2+ and Zn2+,were quantitatively separated in this extraction.The apparent molar absorptivity was found to be 7.35×104L·mol-1·cm-1 at the absorption maxima (560 nm) of the coordination complex.Beer′s law was kept in the range of 0-14 μg of Cu(Ⅱ) per 10 mL of solution.In its application to the determination of micro amounts of copper in samples of rice and tea,values of RSD (n=7) obtained were less than 4.1%,and recoveries found were in the range of 98.6% to 103.9%.