Indirect determination of Vc with flame atomic absorption spectrometry

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 mu g . 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 mu g . 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 is 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.