微乳毛细管电动色谱微乳粒径电化学测定方法研究

以二茂铁(Fc)作为电化学探针,采用循环伏安法测定了微乳毛细管电动色谱中常用水包油型微乳体系十二烷基硫酸钠(SDS)/正丁醇/正辛烷在不同配比下的扩散系数,并通过扩散系数推算微乳粒径的变化规律。研究表明,随着表面活性剂SDS浓度增加,粒径减小;随着正丁醇的增加,粒径减小;正辛烷的量对粒径影响不大。使用动态激光光散射法对实验结果进行验证,发现当电活性物质Fc全部溶于油相中时,两种方法测定结果基本相符;但随着正丁醇浓度增大,粒径是增大的。Fc在微乳液滴油核外的溶解度增大,导致测量误差增大。

Studies on Droplet Size of Microemulsion in Microemulsion Electrokinetic Chromatography with Electrochemical Determination

The diffusion coefficients of microemulsion droplet, using ferrocene as the electrochemical probe in SDS/n-butanol/n-octane oil-in-water microemulsion system, were measured by the cyclic voltammetry, and the size of microemulsion droplet was then calculated from the diffusion coefficients. The effects of the composition of microemulsion on the droplet size were investigated. The results from cyclic voltammetic experiment showed that increasing amount of surfactant or cosurfanctant would result in a decreased droplet size, while in low concentration, the oil phase had little effect. However, dynamic laser light scattering (DLS) experiments showed that the droplet size had an increasing trend as increase of cosurfactant concentration. With the increase of n-butanol concentration, ferrocene existed in both oil core and outer of the droplet, which led to the inaccurate results in electrochemical determination.