Studies Of Highly Sensitive Polarographic Adsorptive Complex (catalytic) Wave Of Antimony(Ⅲ)

In this paper, several new methods are described for the determination of antimony(Ⅲ) based on the polarographic adsorptive complex wave and polarographic adsorptive catalytic wave on the dropping mercury electrode.This paper consists of three chapters:In chapter one, the ternary complex of antimony(Ⅲ),tiron and cetyltrimethylammonium bromide has been studied in detail, which displays a sharp wave on the dropping mercury electrode in the medium of 0.04mol/L H3PO4. The peak potential is at about -0.44V(vs.SCE). the second-order derivative peak height is linear with the concentration of antimony(Ⅲ) in the rang of 8.2×10-10～2.0×10-6 mol/L,and the detection limit is as low as 4×10-10mol/L. The molar ratio of each component in the ternary complex has been determined as nSb(Ⅲ):ntiron : nCTMAB = 1: 1: 1. Several electrochemical methods have been used to investigate the properties of polarographic wave and electrode reaction mechanism ,the function of CTMAB in the system has been discussed. The method has been successfully used to the determination of antimony in arsenous oxide. In chapter two, a sensitive polarographic adsorptive complex wave of antimony(Ⅲ)-pyrogallolred-thiourea system has been investigated in dilute H3PO4 solution for the first time. A ternary complex of antimony(Ⅲ)-pyrogallolred-thiourea formed in the solution. The optimal experimental conditions were found to be the use of 0.08mol/L H3PO4, 1.5×10-5mol/L pyrogallolred and 1.5×10-5mol/L thiourea. The peak potential appears at about -0.30V(vs.SCE). The peak height is linearly proportional to the concentration of antimony(Ⅲ) over a rang of 4.1×10-10～2.1×10-6 mol/L, the linear regression equation isIp(μA/S2 ) = 7.3162C (μg/L) + 0.0542, the correlative coefficient is 0.9993, the limit of detection is as low as 2×10-10 mol/L. Several methods such as UV-UIS spectrophotometry and voltammetry have been used to investigate the properties of the complex and electrode reaction mechanism . The method has been used to determination of antimony in copper alloys with satisfactory results.In chapter three, a sensitive polarographic adsorptive catalytic wave of antimony(Ⅲ)-rutin complex was proposed by using single-sweep polarography in a 0.12mol/L chloroacetate buffer solution(pH3.2) containing 5×10-6 mol/L Se(Ⅳ). The presence of selenium(Ⅳ) can pull the peak potential to the positive direction and enhance the sensitivity. The peak potential appears at about -0.33V(vs.SCE). The peak height is linearly proportional to the concentration of antimony(Ⅲ) over a rang of 1.6×10-9～5.0×10-6 mol/L, the limit of detection is as low as 4×10-10 mol/L. The properties of polarographic wave were proved to be an adsorptive catalytic wave, and the electrode reaction mechanism was discussed. The function of selenium(Ⅳ) was investigated in detail. The method has been used to determination of antimony in zinc alloys with satisfactory results.In a word, we have established several new methods for the determination of antimony. These systems have high sensitivity, better selectivity, wide linear rang and good stability. All these advantages make these methods full of practical value.