核固红-溴酸钾催化动力学光度法测定痕量钒

CATALYTIC PHOTOMETRIC DETERMINATION OF TRACES OF VANADIUM(Ⅴ) BY THE OXIDATION OF NUCLEAR FAST RED WITH POTASSIUM BROMATE

在pH2.5～2.9的硫酸溶液中,微量钒(Ⅴ)能显著催化溴酸钾氧化核固红(1氨基2,4二羟基蒽醌3磺酸钠)(C.I.No.60760)褪色。研究了反应的动力学行为,建立了测定痕量钒的催化动力学分析方法。该方法的检出限为1.9×10-6g·L-1,线性范围为0.03～1.5μg/25mL,用于测定中草药及食品中痕量钒,结果满意。

In a dil. H_2SO_4 solution of pH 2.5~2.9, the oxidation of nuclear fast red by potassium bromate (resulting color-fading of the dyestuff) was catalyzed by the presence of trace amounts of vanadium(Ⅴ). The conditions of the color-fading oxidation reaction were optimized, and the kinetic parameters were also studied. The catalytic oxidation reaction was carried out at 90±0.5 ℃ for 10min. After cooling to room temperature, the absorbances of the catalytic reaction system (A) and of the non-catalytic reaction system (A_0) were measured at (515 nm), using water as the reference solution. Linear relationship between values of lg(A_0/A) and concentration of vanadium(Ⅴ) was found to keep in the range of 0.03~1.5 μg of V(Ⅴ) in 25 mL of solution. Detection limit of the method was found to be 1.9×10^(-6)g·L^(-1). Satisfactory results were obtained in its application to the analysis of some Chinese medicine and some foodstuff samples.