Adsorptive Wave of Complex of Gallium (Ⅲ)-Eriochrome Blue Black R and Its Analytical Application
Zhou Qinghai , Zhang Shengyuan (Department of Chemical Engineering, Guangdong Institute of Technology, Guangzhou 510090)
In the buffer solution of 0. 012 mol/L acetic acid-0. 1 mol/L sodium acetate (pH 5. 60) , the reductive wave of eriochrome blue black R (EBBR) (PI) was observed at-0. 34 V(vs. SCE) and in the presence of gallium (Ⅲ) a new sensitive polarographic wave of Ga (Ⅱ)-EBBR complex (p2) yielded at -0. 55 V (vs. SCE). The peak height of p2 was directly proportional to the concentration of Ga(Ⅱ) in the range of 0. 2 to 15. 0 μg/25ml. The standard regression equation is y = 0. 1854+2. 8876x. and the relative coefficient is 0. 9990. The detection limit was 4 ng/ml. The mechanism of electrode reaction was studied by various methods. The wave(p2) was confirmed to be an adsorptive complex wave. The proposed method has been used for the determination of trace gallium in ores and metallic materials after prior separation by solvent extraction with satisfactory results.