Chromatography

Question 1

1. Which component in a chromatographic system carries
   the sample?

a. Stationary phase
b. Mobile phase
c. Support
d. Column

Answer 1

b. Mobile phase

Question 2

2. Which of the following is not an approach that can be
   used to improve the separation of two compounds by a
   chromatographic system?

a. Increase the degree of peak retention
b. Increase the selectivity of the system for one compound versus another
c. Increase the amount of sample that is applied
d. Increase the efficiency of the system

Answer 2

c. Increase the amount of sample that is applied

Question 3

3. In column chromatography, unknown analytes are identified as they pass through the detector. Comparison of
   the ______ of unknown analytes with that of standard
   compounds can be used for identification of the analytes.

a. separation factor
b. retention factor
c. resolution
d. plate height

Answer 3

b. retention factor

Question 4

4. Before it can be used in a separation by GC, a compound
   must:

a. be volatile or be converted into a volatile form.
b. not be volatile.
c. be water soluble.
d. be present in a large quantity in a sample.

Answer 4

a. be volatile or be converted into a volatile form.

Question 5

5. Which type of GC might use alumina particles as the stationary phase?

a. Gas-liquid chromatography
b. Gas-solid chromatography
c. Bonded phase gas chromatography
d. Capillary gas chromatography

Answer 5

b. Gas-solid chromatography

Question 6

6. Which of the following common detectors for GC can be
   used in more than one mode to either detect many compounds or examine specific analytes?

a. Nitrogen-phosphorus detector
b. Electron capture detector
c. Mass spectrometer
d. Flame ionization detector

Answer 6

c. Mass spectrometer

Question 7

7. Which of the following statements concerning LC is not
   correct?

a. HPLC is the form of LC used in most routine chemical separation or analysis methods.
b. Normal-phase chromatography uses a nonpolar
stationary phase and is one of the most popular types
of LC.
c. Cation-exchange chromatography uses negatively
charged groups as the stationary phase.
d. A porous support is used in size-exclusion chromatography

Answer 7

b. Normal-phase chromatography uses a nonpolar
stationary phase and is one of the most popular types
of LC.

Question 8

8. Some point-of-care tests use chromatography as a processing step in the assay. In point-of-care pregnancy testing, for example, the stationary phase is nitrocellulose
   paper and the hCG antigen is present in a urine sample,
   which is considered the mobile phase. The antigen in
   the mobile phase binds with an antibody in the stationary phase. This is an example of planar chromatography
   using which of the following as the separation mechanism?

a. Partition chromatography
b. Ion-exchange chromatography
c. Size-exclusion chromatography
d. Affinity chromatography

Answer 8

d. Affinity chromatography

Question 9

9. Which statement is true about the mobile phase in LC?
   a. The strength of the mobile phase is varied during
   solvent programming.
   b. A strong mobile phase gives strong retention for
   compounds on an LC column.
   c. An organic solvent is a weak mobile phase in
   reversed-phase chromatography.
   d. The mobile phase has few interactions with the
   injected compounds in LC.

Question 10

10. Which of the following statements is not true about
    planar chromatography?

a. Compounds may be identified by using their retardation factors.
b. Paper may be used as a support in this method.
c. This method is mainly used for quantitative analysis.
d. Thin-layer chromatography is one form of this
method.

Answer 10

c. This method is mainly used for quantitative analysis.