Determination of Gallic Acid in Chinese Herbal Medicine with Flow Injection Chemiluminescence Method
The rapid and easy flow injection chemiluminescence method was established to measure the content of gallic acid in the chinese herbal medicines. It was based on the enhanceed chemiluminescent emitted during the oxidation of gallic acid by producing of hydroxy free radical with chemical reaction between Fe3+ and H2O2 solution in HCl medium condition in the presence of rhodmine 6G as energy transfer in chemiluminescence system,in which various factors influenced the chemiluminescence system were investigated carefully. The possible mechanism of the proposed method was also studied preliminarily. The results showed that 0.18 mol/L hydrochloric acid solution,ferric chloride concentration of 0.04 mol/L,hydrogen peroxide 1.0 mol/L,and 1.0×10-4 mol/L rhodamine 6G solution was the chemical composition of the optimal chemiluminescence system. The detection limit is 3×10-6 g/L (3σ),the linear range of determination was from 1.0×10-5-1×10-2 g/L and 0.01-1.0 g/L,r=0.9984 and 0.9947,the relative standard deviation was 3.8%(1×10-4 g/L,n=11). This method is proved to be of high sensitivity,low detection limit,simple operation and inexpensive devices. The recommended method has been successfully used for the analysis of gallic acid in chinese herbal medicine of gallnut and medicine terminalia fruit.