Capillary electrophoresis

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

μ i 0 ： electrophoretic mobility μ i 0 和 (q, η, r i ) 有關 Electroosmotic flow (EOF) (3) (4) μ eo ： electroosmotic mobility (cm 2 /Vs) (5) (6) ξ ： zeta potential (V) 和 pH 值, ionic strength 有關 η ： viscosity of double layer ~ η (bulk)

 =  r    / 

+ - n EOF -+ + n - Net 毛細管電泳的向量圖

Effective Mobility and Apparent Mobility

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

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

(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

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

代入 (24) EOF 存在 (23) (24) (25) (26) EOF 和 electrophoretic 反方向則 μ eo ↑ R s ↑ Best Resolution 分離時間很長

(22) 式 R s =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 1.After the polarity & viscosity of the mobile phase EOF & electrophoretic mobility changed 2. 增加 solubility of analyte 3. reduce zeta potential

Reversal of EOF Using a Cationic Surfactant

Micellar Electrokinetic Chromatography fraction of analyte in aqueous phase fraction of analyte in micelle migration velocity (V s ) ： t R, t 0, t mc ： migration time of analyte, aqueous phase, and micelle k’ ： capacity factor n mc ： no. of analyte molecules incorporated into the micelle n aq ： no. of analyte molecules in aqueous phase (1) (2) (3) (6) (5) (7) (4)

(5)(6)(7) 代入 (4) (micelle 停在 capillary) << t 0 =∞ 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 (8) (10) (9)

Resolution t mc →∞ 兩式相等 t mc →∞ 固定相 (11)

Effect of the capacity factor t 0 /t mc =0 t mc =∞ conventional chromatography large capacitybetter resolution lead to in MEKC large k’ unfavor (11) 式最後一項 →0 optimum k’ 和 t 0 /t mc 有關 將 (12) 式微分 (12) (13)

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

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

Chiral Capillary Electrophoresis (CCE)

Separation Mode: Capillary Gel Electrophoresis (CGE)

CGE: Protein Size Separation Using SDS Linear Polymer Solutions

Separation Mode: Capillary Isoelectric Focusing (CIEF)

Detection: Direct UV Detection

Detection: Indirect UV Detection

Lab-on-a-chip or CE on chip

Photograph of the microdevice with attached transfer capillary

 -TAS concept: Miniture-Total Chemical Analysis system.