Mechanistic Study on Analyte Focusing by Dynamic pH Junction in Capillary Electrophoresis Using Computer Simulation

详细信息    查看全文

• 作者：Jong-Bok Kim ; Philip Britz-McKibbin ; Takeshi Hirokawa ; and Shigeru Terabe
• 刊名：Analytical Chemistry
• 出版年：2003
• 出版时间：August 15, 2003
• 年：2003
• 卷：75
• 期：16
• 页码：3986 - 3993
• 全文大小：140K
• 年卷期：v.75,no.16(August 15, 2003)
• ISSN：1520-6882

文摘

Dynamic pH junction is an on-line preconcentrationmethod in capillary electrophoresis (CE) based on electrokinetic focusing of weakly ionic analytes with in largesample volumes in a multisection electrolyte system. Inthis report, experiments and computer simulations wereperformed to gain a better insight of the analyte focusingmechanism when a dynamic pH junction was used. Acomputer program, SIMUL, was used to simulate theband-narrowing process of a group for phenol derivativesunder optimized buffer conditions, which were comparedwith experimental results. Computer simulations revealedthe formation of a sharp moving pH boundary within thesample zone causing efficient focusing of long plugs ofweakly acidic analytes based on their pK_a. These studiesoffered useful information for understanding the band-narrowing process by control of the depth and lifetime ofthe moving pH boundary as a function of analyte pK_a,sample pH, and injection length. The change in pH of thesample within the capillary was also estimated by measuring the absorbances of an analyte at two different wavelengths. Optimization of analyte focusing resulted inenhanced detection responses of about 60-450-fold interms of peak heights for some phenol derivatives' relationto conventional injections. Dynamic pH junction represents a novel approach to control band dispersion (peakwidth) and selectivity (mobility) of specific analytes forhigh-resolution CE separations.