十二烷基硫酸钠微乳色谱体系中pH值对其电渗流行为与微结构的影响

The Effect of pH Value on Electroosmotic Flow Behavior and Microstructures in the Sodium Dodecyl Sulfate Microemulsion Chromatography System

以十二烷基硫酸钠(SDS)/正己烷/正丁醇/硼砂微乳液为毛细管电色谱运行研究体系,以甲醇峰为微乳体系电渗流峰(EOF),考察不同pH值条件下微乳体系电渗流出峰时间(tEOF)和变化趋势。以微乳液滴粒径和ζ电位考察pH值对SDS缓冲溶液微乳体系微结构的影响,用微乳体系的电导值分析pH值条件下微乳液滴与氢氧根离子之间的相互作用。结果表明,微乳体系tEOF随着pH的增大而减小;微乳液滴的粒径随pH值的升高呈减小趋势,ζ电位绝对值呈增大趋势,而在pH值8.5～9.5处因微乳粒子排布趋于有序定向化出现例外。微乳体系的电导行为在所研究的pH值范围内变化不大,呈现良好的抗酸、碱性能。

With sodium dodecyl sulfate（SDS）/n-hexane/n-butanol/tetraborate microemulsion as running buffer in capillary electrophoresis chromatography,the variation of electroosmotic flow（EOF） in different pH conditions have been discussed with the methanol peak as the EOF in this microemulsion system.The effect of pH value on the microstructure of the microemulsion system by determining particle sizes and zeta potential of microdroplets was studied,and effect of pH value on the interaction between micro droplets was evaluated by considering the conductivity value.Results showed that tEOF of microemulsion decreased as the pH increased because of the combined action of hydroxyl ionization,hydrogen bond and the electrostatic repelling force between the polar groups.The particle sizes tended to decrease as pH increased.The absolute value of zeta potential of microdroplets increased as pH increased,while a weak decrease of zeta potential was observed in the pH region of 8.5~9.5 resulting from the orderly and directional arrangement of the microdroplets.The conductivity value of microemulsion hardly changed and presented good resistence to acid and alkaline in the tested pH range.