流动注射在线柱氧化-分光光度法测定抗坏血酸

Determination of ascorbic acid by flow-injection spectrophotometric method with on-line reaction column

建立了流动注射在线反应柱氧化-分光光度法测定维生素C(AA)的方法。在流动注射管路中装载吸附了Fe3+的聚合物树脂作为反应柱,当AA溶液通过反应柱时,将Fe3+还原为Fe2+,Fe2+不被吸附而进入水相与邻菲罗啉络合,用分光光度法测定被AA定量还原的Fe2+的量,从而间接测定药品中AA的含量。AA质量浓度在0.5～20.0 mg/L范围内与吸光度呈良好的线性关系,方法的检出限为0.28 mg/L,对10.0 mg/L的AA溶液平行测定6次,相对标准偏差为1.8%。样品加标回收率在99.2%～106.6%之间,采样频率为60次/h。

A novel flow-injection spectrophotometric method was proposed for the determination of ascorbic acid with on-line reaction column. The polyester resin that adsorbed Fe^3＋ was packed in the glass tubing as a mini reaction column. When a stream of a solution of ascorbic acid was merged with the mini reaction column, the ascorbic acid reacted with the Fe^3＋ , Fe^3＋was reduced to Fe^2＋ which can not be adsorbed by the resin. Then, Fe^2＋ reacted with phenanthroline to form a complex. As a result, the ascorbic acid was detected by spectrophotometry. The analytical curve was linear in the concentration range from 0. 5 mg/L to 20. 0 mg/L with a detection limit of 0. 28 mg/L, and the relative standard deviation （RSD, n = 6） was 1.8%. The recoveries varied from 99. 2% to 106. 6% ,and the analytic frequency was 60 samples per hour .