间接原子吸收法测定维生素C的含量

Indirect Determination of Vc with Flame Atomic Absorption Spectrometry

利用银离子可被维生素C还原为银沉淀的原理,建立了原子吸收法间接测定维生素C含量的方法。实验中考察了温度、时间、Ag^＋用量对反应的影响,选取反应在室温下进行,反应时间为35 min,氧化剂用量为1.0μg·mL^-1Ag^＋溶液2.0 mL。同时优化了测定银的最佳原子吸收条件。建立的方法易于操作,检出限小于1.0μg·mL^-1相对标准偏差为2.04%,线性范围宽,不受样品颜色干扰且其他共存物质干扰也较小,弥补了其他分析维生素C的方法的一些不足,样品测定结果和药典中的碘量法一致,该法的回收率为99.30%-106.06%,结果较为满意。绘制了两种标准曲线,其中绘制以银为标准的工作曲线更简便,而以维生素C为标准的工作曲线相比更准确。

In the present paper,a new method for indirect determination of Vc by atomic absorption spectrometry is proposed,based on the reducing properties of Ag^＋.The effects of temperature,reaction time and use level of Ag^＋ on the experiment were studied.Room-temperature and reaction time of 35 minutes were chosen.The oxidant amount is 2.0 mL solution of Ag^＋（1.0 μg·mL^-1）.Meanwhile the AAS working conditions for Ag determination were optimized.The proposed method allows the determination of Vc in a wide range with a relative standard deviation of 2.04%,and the detection limit is less than 1 μg·mL^-1.The method cannot be disturbed by the colour of sample.The interference of coexistent substance is also weak.Other methods for determining Vc could be remedied by this method.Two kinds of standard curves were plotted,standard working curve of sliver and standard working curve of Vc.The former is easier,while the latter is more accurate and could be applied flexibly according to the physical circumstances.This method i s easy to control and has been applied to the determination of ascorbic acid in pharmaceutical preparations and orange juice.The recovery ratio of this method is 99.30%-106.06%.The results obtained in the analysis agreed well with the iodimetry in pharmacopeia.