Katayama H, Ishihama Y, Asakawa N
Department of Analytical Chemistry, Analytical Research Laboratories, Eisai Co., Ltd., Ibaraki, Japan.
Anal Chem. 1998 Jun 1;70(11):2254-60. doi: 10.1021/ac9708755.
A stable modification of the inner wall of a fused silica capillary was established by a simple coating procedure, successive multiple ionic-polymer layer (SMIL) coating. An anionic polymer was tightly fixed to the capillary wall by the SMIL coating, in which a cationic polymer was sandwiched between the anionic polymer and the uncoated fused silica capillary by noncovalent bonding. The SMIL-coated capillary showed a long lifetime. The endurance of the SMIL-coated capillary was more than 100 runs, and it was also tolerant to organic solvents, 1 M NaOH, and a surfactant. The coating efficiency did not depend on capillary sources, and the relative standard deviation of capillary-to-capillary reproducibility was less than 1%. In this study, dextran sulfate (DS) was used as the anionic polymer, and Polybrene was used as the cationic polymer for SMIL modification. The DS-modified capillary (SMIL-DS capillary) exhibited a pH-independent electroosmotic flow (EOF) from anode to cathode in the pH range of 2-11. The SMIL-DS capillary showed good performance for acidic protein analyses under physiological conditions (pH 7.4). Also, the presence of EOF under acidic conditions permitted new applications. Simultaneous separations of cationic, anionic, and neutral amino acids were achieved by capillary zone electrophoresis, and separations of cresol isomers were achieved by micellar electrokinetic chromatography under the acidic conditions. The SMIL-DS capillary was also useful for fast and precise determination of the pKa of acidic functional groups.
通过一种简单的涂层方法——连续多层离子聚合物层（SMIL）涂层，实现了对熔融石英毛细管内壁的稳定改性。通过SMIL涂层将阴离子聚合物紧密固定在毛细管内壁上，其中阳离子聚合物通过非共价键夹在阴离子聚合物和未涂层的熔融石英毛细管之间。SMIL涂层毛细管具有较长的使用寿命。SMIL涂层毛细管的耐用性超过100次运行，并且还耐有机溶剂、1 M NaOH和表面活性剂。涂层效率不依赖于毛细管来源，毛细管间重现性的相对标准偏差小于1%。在本研究中，硫酸葡聚糖（DS）用作阴离子聚合物，聚凝胺用作SMIL改性的阳离子聚合物。DS改性毛细管（SMIL-DS毛细管）在2-11的pH范围内表现出从阳极到阴极的pH无关电渗流（EOF）。SMIL-DS毛细管在生理条件（pH 7.4）下对酸性蛋白质分析表现出良好的性能。此外，酸性条件下EOF的存在允许新的应用。通过毛细管区带电泳实现了阳离子、阴离子和中性氨基酸的同时分离，在酸性条件下通过胶束电动色谱实现了甲酚异构体的分离。SMIL-DS毛细管也可用于快速、精确地测定酸性官能团的pKa。
