Topics - Column Temperature

Column Temperature Column temperature is probably the most important operating variable in the practice of gas chromatography. Temperature can also effect elution time in liquid chromatography, but the effect is often far less pronounced. Temperature is more often used in liquid chromatography to provide subtle control of selectivity rather than elution time. In contrast, management of column temperature is very important in controlling elution time in gas chromatography. The two major factors that control elution time in gas chromatography are flow rate and column temperature. Although solute elution rate increases linearly with flow rate, elution rate increases approximately exponentially with column temperature and, thus, is far more effective in eluting strongly retained solutes. Column temperature programming is widely used for analyzing solute mixtures that either have a wide boiling point range or a wide molecular weight range. Flow programming is far less frequently used. In temperature programming, the column temperature is continually increased during the elution of the sample. The programming profile can be any type, but it is usual to increase the temperature linearly with time. This results in the rate of solute elution increasing approximately exponentially with time. All contemporary gas chromatographs are fitted with temperature programming facilities and ovens with very precise temperature control