Capillary Electrophoresis

Question 1

What does CE stand for?

Answer 1

Capillary Electrophoresis

Question 2

What is the name of the positive side of the electric field? The negative? What direction does the electric field flow?

Answer 2

Anode (+) attracts anions (-) and Cathode (-) attracts cations (+). Flow towards the cathode.

Question 3

Why CE?

Answer 3

Higher resolution (due to less diffusion), faster seperation (due to high voltage), simpilicty (due to it being gel free) and accurate (due to HPLC detection)

Question 4

Post-column VS On-column detection

Answer 4

Post column detection uses fluorescence lasers and would have high sensitivity due to no light scattering. But it is not commercially available.

On-column, what we have available, uses absorbance with a UV lamp. Low sensitivity due to light scattering.

Question 5

What does EOF stand for?

Answer 5

Electoosmotic flow

Question 6

What factors can chance electroosmotic flow?

Answer 6

EOF Increased by increased pH, increased temperature, decreased buffer conc.

EOF decreased by addition of organic modifier, surfactant or polymers.

Question 7

What factor determines the time for an analyte to go through a capillary?

Answer 7

The mass to charge ratio.

Positively charged (cations) will move faster than anions.

Small cations move faster than large cations.

Large anions move faster than small anions.

Question 8

What does MEKC stand for?

Answer 8

Capillary Micellar Electrokinetic chromatography

Question 9

Steps in determining Kd from CE

Answer 9

1. Measure the migration time of a target at different concentrations of a ligand in the buffer solution.
2. Plot the velocity of the target VS the concentration of the ligand. Will be an S curve.
3. Find the [ligand] when at 50% of the velocity change.