紫外光度法测定食品中的还原型维生素C

Determination of Ascorbic Acid in Food Using Ultraviolet Spectrophotometry

本文以Ｆｅ（３＋）将在２６５ｎｍ有最大紫外吸收的还原型维生素Ｃ选择性地氧化为在２６５ｎｍ无吸收的氧化型维生素Ｃ，实现对食品样品中多种紫外干扰成分的本底校正，建立了一种测定食品中还原型维生素Ｃ的新方法。还原型维生素Ｃ含量在０～３００ｕｇ／２５ｍｌ范围内符合比耳定律，ｒ＝０．９９９９５。运用本法实际测定了马铃薯、番茄等食品中的还原型维生素Ｃ的含量，回收率在９７．５～１０１．２％之间，相对标准偏差在０．７５～１．２６％之间，测定结果与２，６－二氯靛酚法基本一致。

A new background correction method for ultraviolet spectrophotometry determination of ascorbic acid in food has been reported in this paper. The procedure is based on the Fe(Ⅲ) oxidation of reduction VC with maximum absorption at 265nm to oxidize VC without absorption at 265nm. Beer's law is obeyed within the range of 0￣300μg per 25ml for ascorbic acid, regression coefficient r=0. 99995.This method has been applied to analysis of ascorbic acid in foods such as potato and tomato. The recoveries is 97. 5￣101. 2%, relative standard deviation is 0. 75～1. 26%.The analytical results agree with those by 2, 6-dichlorophenol indophenol.