Question

What are the advantages and disadvantages of thin-layer chromatography, adsorption column chromatography, and gas chromatography techniques? (advantages and disadvantages for each type)

Answer 1

Advantages of thin layer chromatography ----

1. Less equipment is required.
2. Very little time for separation is required.
3. It is more sensitive.
4. The lower detection limit of analytical sample in TLC is approximately one decimal lower than that is paper chromatography and very small quantities of sample is sufficient for analysis.
5. Spraying with corrosive agents for identification is also permitted which is not possible in paper chromatography as cellulose gets destroyed.

Disadvantages of thin layer chromatography ------

1. In this method the plate length is limited and hence separation takes place only upto certain length.

2. The separation takes place in an open system or in open condition and hence there are chances that sample may be affected by the humidity and temperature.

Advantages of gas chromatography ------

1. This method has a high resolution power compared to other methods.

2. This method has high sensitivity when used with thermal detectors.

3. This technique gives relatively good accuracy and precision.

4. Separation and analysis of sample very quickly.

5. Sample with less quantity is also separated.

Disadvantages of gas chromatography ----

1. Only volatile samples or the sample which can be made volatile are separated by this method.

2. During injection of the gaseous sample proper attention is required.

3. The sample of gas which is about to inject must be thermally stable so that it does not get degraded when heated.

Advantages of adsorption column chromatography -----

1. Retain and separate some compounds that cannot be separated by other methods.

Disadvantages of adsorption chromatography -----

1. Very strong retention of some solutes.

2. May cause catalytic changes in solutes.

3. Solid support may have a range of chemical and physical environments, non symmetric peaks and variable retention times.