可见分光光度法测定阿司匹林中水杨酸含量的探究

研究了用分光光度法快速、准确测定阿司匹林（ASP）中水杨酸（SA）含量的方法。以FeCl3为显色剂，通过测含杂质的阿司匹林溶液的吸光度来测定其中SA含量，考虑了pH、温度、反应时间、显色剂用量等因素对络合物生成量及稳定性的影响，确定了最适宜的测定条件，并绘制了标准工作曲线。结果表明，在pH值=3的CH3COOH—CH3COONa缓冲溶液中，Fe3＋与SA生成较稳定的络合物，络合比为1：1，常温下10min即可络合完全，该络合物的最大吸收波长为512nm。该定量方法测量误差在2．5％以内。

Study on Quantitative Determination of Salicylic Acid in Aspirin with Spectrophotometry

To discuss the rapid and accurate method for determination of salicylic acid in aspirin based on spectrophotometer technology. A violet complex was obtained when Fe3＋ and salicylic acid were mixed together in proper conditions . By measuring the absorbance of aspirin solution in which salicylic acid as the impurity, and FeCl3 added as a colour developing agent, the quantity of salicylic acid in aspirin was determined. The conditions affecting the formation and stability of the complex were studied, such as pH, temperature, reaction time, the consumption of Fe3＋ Under perfect conditions, the standard curve was achieved. The final results showed that in buffer solution of CH3COOH - CH3COONa, in which the pH value was 3, Fe3＋ and salicylic acid produce a considerably stable complex by the ratio 1 ： 1 , and the reaction favorably finished within 10 minutes at room temperature. The wavelength of maximum absorption of the complex was 512 nm . The relative error of this determination was about 2.5% .