Factors Affecting Resolution in Gas Chromatography

GC is a chromatographic separation technique in which a gas (e.g. nitrogen, heli) is used as the mobile phase. Gas chromatography is one of the most accepted techniques for separating and analyzing analytes, due to its high precision, reproducibility, resolution, speed, and low detection range. GC can be useful for the separation of any volatile compound, so it is useful in the separation of many organic and inorganic compounds.

Here are the factors that affect GC resolution.

Column temperature:

The extremely high column temperature is the result of low RT and poor analyte separation, since all components are mostly in the gas phase. However, the analytes require interaction with the stationary phase to separate.

The boiling point of compounds is often associated with their polarity. If the boiling point of compost is low, the higher the vapor pressure, the shorter the retention time, because the compost will spend more time in the gas phase.

The concentration and volume of the solution show:

Usually the tops have an asymmetrical shape. If the concentration and volume of the sample solution are too high, there is tailing of the peaks, which is the reason for poor separation. The detectors used in the GC are extremely sensitive and do not require a lot of hardware to give a detectable signal. For example, flame ionization detector (FID), mass spectrometer (MS), electrolytic conductivity detector (ELCD), flame photometric detector (FPD), photoionization detector (PID), etc.

Carrier gas flow:

A higher flow rate shortens the retention time, but poor separation will also be observed. Since the molecules have little or no time to interact with the stationary phase, they are simply pushed through the column by the carrier gas.

The polarity of the stationary phase in the column and the polarity of the components:

If the polarity of the compound and the stationary phase are the same, the RT of the component will increase due to the strong interaction with the stationary phase. As a result, polar molecules have a longer retention time when a polar stationary phase is used and a shorter retention time when a non-polar polar stationary phase is used.

Column length used:

If you use a longer column length, the retention time of the components will increase proportionally to the column length and a significant broadening peak will be observed. Separation is generally improved when long columns are used in the analysis.


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