聚合物-盐-水析相体系液-固萃取动力学光度法测定痕量钴

Determination of Trace Cobalt by Catalytic Kinetic Spectrophotometry of Liquid-solid Extraction Based on Polymer-salt-water Phase Separation System

关键词:  液-固体系析相萃取技术  催化动力学光度法  钴的测定

Key words:  liquid-solid extraction  catalytickinetic spectrophotometry  determination of cobalt

摘要:

将析相萃取技术与催化动力学光度法相结合,建立了一个测定痕量钴的聚合物-盐-水体系析相萃取-催化动力学光度法。在Na₂HPO₄-NaOH缓冲溶液中,Co²⁺可灵敏催化过氧化氢氧化苯芴酮褪色反应,用聚乙烯吡咯烷酮-硫酸铵-水的非有机溶剂萃取体系萃取出未被氧化的指示物苯芴酮与水相中的氧化剂分离,从而可终止该反应并通过测量有机相的吸光度显著提高分析的灵敏度。钴浓度在0 μg/L~0.03μg/L范围内与ΔA呈线性关系,检测限为3.4×10^-5 μg/L。该方法灵敏度高,选择性好,用于直接测定水样中超痕量钴,结果满意。

Abstract:

A catalytic kinetic spectrophotometry for determining trace cobalt is developed in combination with liquid-solid extraction of phase separation system of polyvinylpyrrolidone ammonium sulfate-water. It is based on the sensitively catalysis effect of Co²⁺ on the decoloring reaction of phenylfluorone by hydrogen peroxide in the buffer solution of Na₂HPO₄-NaOH. The liquid-solid extraction system can be used to stop the reaction by separation of phenylfluorone into organic phase from water phase. The sensitivity can be improved by determining the absorbance of phenylfluorone in organic phase. The linear range of the determination is 0 to 0.03 μg/L, and the detection limit is 3.4×10^-5 μg/L. The method is highly sensitive and selective, and has been applied to determination of trace cobalt(Ⅱ) in natural water with satisfactory results.