BACE Chromatography Techniques 3

Question 1

What is a chromatogram?

Accepted Answer

A plot of detector signal versus elution volume or time

Answer

A map of the column's pore structure

Answer

A table of fraction absorbance values

Answer

A diagram of the chromatography apparatus

Question 2

Which of the following best describes 'gradient elution' in ion exchange chromatography?

Accepted Answer

Progressively increasing salt concentration in the elution buffer

Answer

Loading the sample at increasing flow rates

Answer

Decreasing column temperature during the run

Answer

Collecting fractions at fixed time intervals

Question 3

What is the function of a guard column in HPLC?

Accepted Answer

To protect the analytical column from particulates and contaminants

Answer

To increase the resolution of the main column

Answer

To pre-concentrate the sample before injection

Answer

To remove air bubbles from the mobile phase

Question 4

In thin layer chromatography (TLC), the Rf value is calculated as:

Accepted Answer

Distance traveled by spot / distance traveled by solvent

Answer

Distance traveled by solvent / distance traveled by spot

Answer

Distance from origin to spot / total plate length

Answer

Spot intensity / background intensity

Question 5

When performing protein purification by chromatography, SDS-PAGE is typically run on collected fractions in order to:

Accepted Answer

Confirm the presence and purity of the target protein

Answer

Determine the ionic strength of each fraction

Answer

Measure the total volume of each fraction

Answer

Calculate the pH of the eluate

Question 6

Which buffer property is most critical to control when performing ion exchange chromatography?

Accepted Answer

pH and ionic strength

Answer

Temperature

Answer

Viscosity and density

Answer

Color and turbidity

Question 7

After an affinity chromatography purification step, the column is often regenerated by:

Accepted Answer

Flushing with a regeneration solution to remove residual bound material, then re-equilibrating

Answer

Storing it dry at room temperature

Answer

Autoclaving the column at 121°C

Answer

Reversing the flow direction permanently