多元校正流动注射电位滴定法同时测定苯甲酸和山梨酸

Simultaneous Determination of Benzoic Acid and Sorbic Acid by Potentiometric Titration Coupled with Multivariate Calibration Using a Flow Injection Technique

将流动注射应用于酸碱电位滴定分析,建立了一种可同时测定混合有机酸的电位滴定新方法。在该方法中,用氢氧化钠与氯化钾的混合溶液作为滴定剂,在流通池中同时插入pH指示电极和氯离子指示电极,在滴定过程中的任一滴定点,流出液的pH值和酸碱的混合比例可由两个电极的电位测定值同时获得,从而可应用多元校正法由相应的滴定曲线求得混合酸中每一种组分的含量。该方法不仅免去了体积和时间读数,而且减少了试剂和样品的消耗量,分析速度快。应用该方法对混合样品中的苯甲酸和水杨酸进行同时测定,其相对标准偏差分别为0.19%～0.37%,回收率分别为97.3%～102.6%。

A new potentiometric titration method coupled with multivariate calibration using a flow injection technique for the simultaneous determination of mixed organic acids has been developed. In this method, the titrant is a mixture of sodium hydroxide and potassium chloride, both pH indicating electrode and chloridion indicating electrode are inserted in the flow cell. In a process of titration, both the pH value and the volume ratio of the flowed acid and alkali solution at each titration point can be obtained simultaneously from the two electrodes, and then the concentration of each component in the mixture can be obtained from the titration curves by multivariate calibration method. The method is free of volumetric and time measurements, and reduces the consumption of reagent and sample. The method is also very quick in analysis rapidity. The method has been applied to the simultaneous determination of benzoic acid and sorbic acid in mixture samples with the relative standard deviation of 0.19%-0.37% and the recovery of 97.3%-102.6%.