萃取催化动力学光度法测定痕量钒

Determination of Trace Vanadium by Extraction-Catalytic Kinetic Spectrophotometry

本文研究了在柠檬酸介质中，利用钒（Ⅴ）催化溴酸钾氧化二苯碳酰二肼的指示反应，用萃取平衡控制反应时间和水相中二苯碳酰二肼的浓度及反应程度，建立了萃取催化动力学光度法测定痕量钒的新方法。方法的检出限为9．8×10－10g／L（20℃），8．3×10－10g／L（25℃）。线性范围为0．0020～0．80mg／L（20℃），0．0016～0．60mg／L（25℃）。用本法测定了岩石中的钒含量，结果满意。

In this paper a new extraction-catalytic kinetic spectrophotometric method for the determination of trace vanadium is studied. The method is based on the vanadium(V ) catalyzed oxidation of diphenylcarbazide by potassium bromate in citric acid medium. The reaction time, concentraction of diphenylcarbazide in aqueous phase and degree of reaction are controlled by extraction equilibrium. The detection limit of this method is 9. 8 × 10-7 g/L(20℃ ) and 8. 3 × 10-7 g/L (25℃). The linear range is 2~800 μg/L (20℃ ) and 1. 6~600μg/L (25℃ ) respectively. The method has been applied to the determination of trace vanadium in rock with satisfactory results.