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Capillary electrophoresis

Capillary electrophoresis. Electrophoretic migration. (1). Z i ： charge # of component i e 0 ： elemental charge [ 1.602 ×10 -19 C ] E=V/L ( V ： applied voltage ； L ： length ). (2). r i ： stokes radius of i component η ： viscosity of the medium [Pa · S]

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Capillary electrophoresis

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  1. Capillary electrophoresis

  2. Electrophoretic migration (1) Zi：charge # of component i e0：elemental charge [ 1.602×10-19 C ] E=V/L ( V：applied voltage；L：length ) (2) ri ：stokes radius of i component η：viscosity of the medium [Pa · S] Vi0：migration velocity of i component

  3. (3) (4) μi0：electrophoretic mobility μi0和(q, η, ri)有關 Electroosmotic flow (EOF) (5) μeo：electroosmotic mobility (cm2/Vs) (6) ξ：zeta potential (V) 和pH值, ionic strength有關 η：viscosity of double layer ~ η (bulk)

  4. m = er e0x / h

  5. + + n - - EOF + n Net - 毛細管電泳的向量圖

  6. Effective Mobility and Apparent Mobility

  7. (7) (8) (9) if no EOF (10)

  8. Efficiency (11) (12) (13) (14) (15)

  9. (16) (17) (18) 對某一analyte , μ和D 是constant V固定 D愈小 N愈大 對大分子分離有利

  10. Resolution (19) (20) ：平均速度 ：平均距離 (cm) (21) (22)

  11. (23) EOF存在 (24) 代入(24) (25) (26) EOF和electrophoretic反方向則μeo↑ Rs↑ Best Resolution 分離時間很長

  12. (22)式Rs=column eff. × selectivity factor selectivity →separation factorαin chromatography • Buffer composition • Complex formation • 1. Borate complexation 2. ion pairing • 3. inclusion complex 4. metal complexation • Organic modifier • After the polarity & viscosity of the mobile phase EOF & • electrophoretic mobility changed • 2. 增加solubility of analyte • 3. reduce zeta potential

  13. Reversal of EOF Using a Cationic Surfactant

  14. Micellar Electrokinetic Chromatography k’：capacity factor nmc：no. of analyte molecules incorporated into the micelle naq ：no. of analyte molecules in aqueous phase (1) fraction of analyte in aqueous phase (2) fraction of analyte in micelle (3) (4) migration velocity (Vs)： (5) tR, t0, tmc：migration time of analyte, aqueous phase, and micelle (6) (7)

  15. (micelle停在capillary) << (5)(6)(7)代入(4) (8) (9) t0=∞ EOF is completely suppressed, in MEKC EOF is not essential. 這時分析物向正(+)移動，k’值愈大移動速率愈快 (10)

  16. Resolution (11) tmc→∞ 兩式相等tmc→∞固定相

  17. large capacity better resolution lead to Effect of the capacity factor (12) t0/tmc=0 tmc=∞ conventional chromatography in MEKC large k’ unfavor (11)式最後一項→0 optimum k’和t0/tmc有關 將(12)式微分 (13)

  18. capacity factor ：specific volume of micelle (14) k：distribution coefficient Vmc,Vaq：volumes of micelle and aqueous phases (15) (16) when (Vmc<<Vaq) << 1 (17) k’ vs conc. of surfactant Csf linear if k is constant 可調整Csf來調整k‘ RP-HPLC調整phase ratio對k‘改變小

  19. hydrophilic (ionic group) hydrophobic Effect of EOF on the resolution > > 愈小 Rs愈大 (from 11式) < 1 separation factor ← micelle (stationary phase in RP-HPLC) aqueous (mobile phase in RP-HPLC) type of surfactants：

  20. Chiral Capillary Electrophoresis (CCE)

  21. Separation Mode: Capillary Gel Electrophoresis (CGE)

  22. CGE: Protein Size Separation Using SDS LinearPolymer Solutions

  23. Separation Mode: Capillary Isoelectric Focusing (CIEF)

  24. Detection: Direct UV Detection

  25. Detection: Indirect UV Detection

  26. Lab-on-a-chip or CE on chip

  27. Photograph of the microdevice with attached transfer capillary

  28. m-TAS concept: Miniture-Total Chemical Analysis system.

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