分光光度法测定微量表面活性剂在油/水体系中的分配系数

Determination of partition coefficient of trace anionic surfactants in oil/water systems with visible spectrophotometry

测定微量阴离子表面活性剂浓度的分光光度法被推广到测定油相中的微量阴离子表面活性剂浓度,进而用于表面活性剂在油/水体系中分配系数的测定。两种情形下氯仿层的吸光度只取决于测量体系中自由阳离子表面活性剂的浓度,因此可用单一阳离子的标准曲线作工作方程。用该法测定油相和水相中的阴离子表面活性剂浓度,工作方程斜率不同,测量下限分别可达2 5×10-5mol·L-1和1×10-6mol·L-1。

The spectrophotometric method for determining trace anionic surfactant concentration in alkaline aqueous solution is extended to determine anionic surfactant concentration in oil phase and is successfully applied to determine partition coefficient of trace surfactants in oil/water systems.It is found that in both cases that the concentration of surfactant in oil or aqueous solution is to be determined,the absorbance of chloroform layer depends only on the free cationic surfactant concentration in measuring system.The absorbance-concentration corelation of a single cationic surfactant,therefore,can be worked out as operatinge equations.For the determination of surfactant concentrations in both the oil and aqueous solutions,the operating equations show different slope and the minimum concentrations detectable can be as low as 5×10^(-5) mol·L^(-1) and (1×(10^(-6)) mol·L^(-1)),respectively.