藻酸双酯钠与天青A相互作用机理的研究与应用

藻酸双酯钠(ASD)与天青A(AA)反应可使天青A溶液褪色，最大褪色波长位于608 nm。应用光谱法研究了ASD与AA的作用机理，考察了反应体系中pH和AA/ASD摩尔比对ASD与AA相互作用的影响。通过理论模型测得AA与ASD最大结合数N=168，结合常数K=3.25×106。根据ASD-AA褪色体系建立了新的ASD测定方法，检测限为0.009 μg·mL-1,ASD的浓度在1～10 μg ·mL-1范围内遵守郎伯-比尔定律。该褪色体系操作简便，有较好的稳定性、选择性与准确度。据此直接测定了片剂中ASD的含量，得到满意结果。

Study on the Interaction between Alginic Sodium Diester and Azur A and the Application

The interaction of alginic sodium diester (ASD) and azur A (AA) was studied by absorption spectra. The influence of pH and the molar ratio of AA/ASD on the spectra was investigated. The maximum binding number (N = 168) and the binding equilibrium constant (K = 3.25 x 10(6)) of the alginic sodium diester and azur A were obtained by the theoretical model. The new method for the determination of ASD was developed by the formation of ASD-AA ion-association complex that caused the fading of the AA. The detection limit is 0.009 microg x mL(-1). The method has the advantages of simplicity, stable system, good accuracy and selectivity, and was applied to the determination of alginic sodium diester in tablets with satisfactory results.