CE

Question 1

CE Instrument

Answer 1

1. Outlet
2. Inlet
3. sample
4. power supply
5. capillary
6. detector and computer

Question 2

CE vs LC

Answer 2

• no eddy diffusion
• flat velocity profile
• higher efficiency and resolution

Question 3

Controlling EOF

Answer 3

1. pH

determines ionisation of silanols

2. Coating
   - permanent

constant EOF

• dynamic

reversible, and variable EOF

Question 4

Electrophoretic Mobility and Velocity

Answer 4

Question 5

apparent velocity

Answer 5

Question 6

Electrophoretic mobility from times

Answer 6

Question 7

EOF velocity

Answer 7

Question 8

Co vs Counter EOF

Answer 8

co:

EOF and mobility aligned. Detected before EOF.

Counter:

EOF and mobility opposite. Detected after EOF

Question 9

CZE Separation Media

Answer 9

Background Electrolyte

contains co and counter ions for EOF

and buffered

Question 10

CZE separation

Answer 10

separates by electrophoretic mobility

Question 11

CZE analytes

Answer 11

Ions

Question 12

CZE disadvantages

Answer 12

Cannot separate neutral (migrate together)

Question 13

Detection methods

Answer 13

1. Photometric

direct or indirect

2. Conductivity

differences in conductivity

3. MS

Question 14

Co ions for indirect

Answer 14

1. strong absorbance
2. mobility close to analytes average

phthalic acid, p-hydroxybenzoic, chromate

Question 15

Why Buffer

Answer 15

reproducibility

smoother signal

tolerance to sample pH

Question 16

Electromigration Dispersion

Answer 16

Occurs whe conductivity lower in BGE

analytes move faster in BGE

causes tailing or fronting

Question 17

Minimise EMD

Answer 17

1. maximise electrolyte concentration in BGE
2. minimise injected analyte concentration

Question 18

Poor sensitivity UV

Answer 18

Because of beers law

1. short path length
   - bubble cell, right angle, multi reflection cell
2. limited sample amounts

stack analyte

Question 19

Field Enhancement Stacking

Answer 19

analyte has lower conductivity than BGE

analyte moves faster in band

and stacks at interface

allows for longer injection, high sample amounts, increased sensitivity

typically prepared in water

Question 20

CE-MS

Answer 20

offline detection

Advantages:

• high sensitivity
• qualitative and quantitative

Disadvantages

• expensive
• limit BGE/buffer choice

Question 21

Electrokinetic chromatography details

Answer 21

• allows for separation of neutrals
• charged micelles have own migration time
• partition between BGE and micelles by hydrophobicity
• analytes that partition more towards micelles migrate closer to micelles
• analytes that partition more towards micelles migrate closer to EOF

Question 22

EKC separation media

Answer 22

BGE and psuedo stationary phase/micelles

Question 23

EKC retention calc

Answer 23

Normal and

Reverse

k = 1/(tr/tmc - 1)

Question 24

Neutral effective velocity

Answer 24

Question 25

Retention factors EKC

Answer 25

hydrophobicity of analyte concentration of micelles structure of micelles pH additives e.g. ion pair

Question 26

Chiral EKC separation media

Answer 26

chiral pseudo stationary phase cyclodextrin

Question 27

chiral EKC Separation mechanism

Answer 27

effective velocity (retention and mobility)

Question 28

chiral EKC analytes

Answer 28

small or large organic enantiomers

Question 29

Chiral EKC Applications

Answer 29

purification impurity determination enantiomer excess

Question 30

chiral EKC advantages

Answer 30

Higher efficiency that LC faster equilibration cheaper phased added to buffer rather than a column can combine with other CE modes

Question 31

Enantiomer Excess

Answer 31

Question 32

Affinity Capillary Electrophoresis Details

Answer 32

Determination of binding constants of receptor and ligand

Question 33

ACE media

Answer 33

BGE with ligand or receptor

Question 34

ACE separation

Answer 34

ligand binds to receptor creating complex and altering migration time increasing conc forms more complex and observed time is closer to complex time than receptor time gradient of change is proportional to binding constant

Question 35

ACE limitations

Answer 35

- time consuming - multiple experiments - specialised - assumptions (conc, equil, wall, field)

Question 36

ACE advantages

Answer 36

- small sample size - binding stoichiometry - does need pure ligand

Question 37

ACE analytes

Answer 37

receptor and ligand

Question 38

Capillary Isotachopohoresis (cITP)

Answer 38

concentrates ions into bands

Question 39

cITP media

Answer 39

Leading and terminating electrolyte

Question 40

cITP separation

Answer 40

inject sample between LE and TE LE \> sample \> TE separates into mobility blocks

Question 41

cITP advantages

Answer 41

concentration of analyte blocks controlled by concentration of leading electrolyte

Question 42

cITP limits

Answer 42

- conc changes affect migration times - hard to quantify - not good for analytical

Question 43

cITP analytes

Answer 43

ions

Question 44

Capillary ioselectric focussing (cIEF)

Answer 44

separates zwitterions based on isoelectric point i.e. pH where no charge

Question 45

cIEF Media

Answer 45

anolyte catholyte acid at the anode base at the cathode

Question 46

cIEF Separation

Answer 46

anolyte/catholyte creates pH gradient analytes migrate till reach isoelectric point creates bands that can be eluted by pressure

Question 47

cIEF analytes

Answer 47

zwitterions/ampholytes

Question 48

cIEF applications

Answer 48

separating ampholytes determining isoelectric point

Question 49

Capillary Gel Electrophoresis (CGE)

Answer 49

separate large molecules by size through seiving with gel

Question 50

CGE media

Answer 50

gel/soluble polymer

Question 51

CGE advantages

Answer 51

faster more efficient than traditional replacable gel automation quantitation

Question 52

CGE applications

Answer 52

DNA sequencing molecular weight determination determination of agrregates

Question 53

Capillary Electrochromatography (CEC)

Answer 53

chromatographic phase/column embedded in capillary. Combines electrophoresis and chromatography

Question 54

CEC columns

Answer 54

packed monolithic open tubular microfabricated

Question 55

CEC separation

Answer 55

effective mobility | (electrophoresis and retention)

Question 56

CEC advantages

Answer 56

can separate anions, cations and neutrals in one run better efficiency than LC

Question 57

Stacking MEKC

Answer 57

sweeping sample prepared without micelles analyte migrates to interface of band and BGE leading to sharper peaks

Question 58

oxidation at anode

Answer 58

2 H₂O(l) → O₂(g) + 4 H+(aq) + 4e− becomes acidic

Question 59

Reduction at cathode

Answer 59

2 H+(aq) + 2e− → H₂(g) becomes basic

Question 60

u_ep units

Answer 60

cm² / V min

Question 61

CZE method

Answer 61

1. Know analytes 2. choose BGE to ionise 3. apply suitable voltage - avoid joule heating 4. organic solvents - alter selectivity/solubility 5. coatings - alter EOF