抗坏血酸的双安培流动注射分析

Flow Injection Biamperometric Determination of Ascorbic Acid

将流动注射双安培法应用于两种物质的不可逆电对体系。在两电极电位差即外加电压为零时，使用经过在0．01mol/LNaOH溶液中1．5V恒电位预处理的双铂丝电极，基于Vc的氧化和溶解氧的还原，拟定了流动注射双安培法测定Vc的新方法。Vc氧化电流与其浓度在1×10^(-5)mol/L－2×10^(-3)mol/L范围内呈线性关系，检测限为8×10^(－6)mol/L；两铂电极经预处理后，灵敏度增加4~6倍；连续进样24次，电流值RSD=1．58％。用本方法测定了Vc片剂和柑桔中Vc的含量，得到满意结果。

Flow injection biamperometry was used for the system consist of two irreversible couples.Employing two identical activated platinum wire electrodes with 0. 0 V potetial difference, a flow injection biamperometry for the determination of ascorbic acid was established based on the oxidation of ascorbic acid and reduction of dissolved oxygen. Under the chosen measuring conditions, the cell current is proportional to the concentration of ascorbic acid over the range of 1× 10^(-5)mol/L~ 2 ×10^(-3) mol/L.The detection limit is 8 ×10^(-6) mol/L. Using the activated electrods the sensitivity and reproducibility can be improved. The current sensitivity is 4 ~ 6 times higher than that on unactirated electrode. The RSD of 24 successive samplingr is 1. 58%. The procedure has been used for the determination of ascorbic acid in vitamin C tablet and orange juice.