流动注射不可逆双安培法测定水杨酸的研究

Flow Injection Irreversible Biamperometric Determionation of Salicylic Acid

基于不可逆电对的双安培检测原理，利用水杨酸在铂电极上的氧化和高锰酸钾在另一铂电极上的还原构建双安培检测新体系，建立了在外加电压为-0．3V条件下流动注射双安培法直接测定乙酰水杨酸片剂中微量水杨酸的新方法。结果在-0．3V外加电压下，0．05mol／L硫酸载液中，测得水杨酸的响应电流与其浓度在8．00×10^-6～4．00×10^-4mol／L范围内呈线性关系（r=0．9985，n=7），检出限为2．00×10^-6mol／L，连续测定1．00×10^-4mol／L的水杨酸溶液13次，电流值RSD为2．36％，进样频率为80样／h。该方法具有较高的选择性和灵敏度，样品处理方法简单快速，适于在线分析。

A flow-injection irreversible biamperometric method for the determination of microamount salicylic acid in acetyl-salicylic acid table is described. The proposed method is based on the elctrochemical oxidation of salicylic acid at one platinum electrode and the reduction of permanganate at another to form an irreversible biamperometric detection. Under the external potential difference of -0.3V, in the 0.05mol/L sulfuric acid, salicylic acid can be determined over the range from 8.00 × 10^-6 mol/L to 4.00 × 10^-4 mol/L with a sampling frequency of 80 samples per hour. The detection limit for salicylic acid is 2.00 ×10^-6mol/L and the relative standard deviation （RSD） for 13 reduplicate determinations of 1.00× 10^-4 mol/L salicylic acid is 2.36%. The method is simple, rapid with highly sensitive and selectivity, and is suitable for the on-line analysis.