Conclusions:

The conclusions that have been drawn from the rate theory of van Deemter are of practical interest and could be used to get better column efficiency.

i) Particle diameter: Column efficiency is improved through the use of small and uniform particle size. Supports that provide the highest efficiency are diatomaceous earth category along with 100 - 120 mesh range.

ii) Flow rate: For maximum efficiency, a column must be operated at the optimum flow rate. This is found through a plot of H against the flow rate. The minimum H determines the optimum linear gas velocity or a flow rate to be used. Within practice, operating at flow rates slightly higher than optimum will reduce the analysis time and not materially affect the H.

iii) Carrier gas: The detector employed commonly dictates the choice of carrier gas. Therefore for the high efficiency, a high molecular weight gas should be the choice. While rapid analysis time is needs and high efficiency is not essential, a low molecular weight carrier gas like as helium or hydrogen would be preferred.

iv) Type of liquid phase: A low viscosity, low vapor pressure solvent along with good absolute solubility for the sample should be used. To acquire a separation, it must also exhibit a differential solubility.

v) Amount of liquid phase: Low liquid loadings (thin film) 1 % - 10 % have the benefits of fast analysis and lower temperature operation. Low liquid loadings, therefore, decrease the sample capacity and might needs highly inactive solid supports.

vi) Pressure: A majority of practical gas chromatographers work at an outlet pressure of one atmosphere so in which operation at optimum flow rate fixes the inlet pressure. Therefore, best efficiency is acquired at low inlet-to-outlet pressure ratios.

vii) Temperature: The resolution could commonly be improved through lowering the column temperature. The practical problem along with low temperature results in long analysis time. The Lowering temperatures also decreases decomposition of the compounds but might increase adsorption. Simultaneous reduction of liquid loading and temperature is commonly beneficial. The limit to this is the increased exposure of active sites on the solid support and the required for sensitive detector.

viii) Column diameter: Capillary and preparative column experiments denoted in which efficiency is improved along with decreasing internal diameter.