Hi, you want your samples to evaporate when you run them on GC. So, you ramp the temp to provide a range of temperatures for your compounds to evaporate and be detected. It depends on what your compounds of interest or objectives are.

Hi Varoon. I agree that column temperature will help vaporize the individual components of the mixture. But how does the program of increasing temp from suppose, 35 to 200 at 20 C/min make a difference when compared with maintaining a constant temp of 200 C? Will this kind of program allows low boiling component to elute early and delay the elution of high boiling component, thereby separating them more efficiently?

Also, I'd like to understand the significance of parameters like input flow rate, input gas volume, pressure, column length, carrier gas, column specs, temperature program, composition etc. over analysis. Each parameter above should have its own significance and can very well provide a handle to improvise the analysis. Please suggest any reference if possible. Thank You.

Increasing the temperature causes the compound to interact less with the stationary phase, akin to increasing the concentration of the "strong" solvent in column chromatography. By increasing the temperature in a ramp, compounds that would otherwise elute later now move through the column faster. This reduces the total run time when a mixture of compounds is run through the column than have very different elution times in a column.

The oven program is very important to separate the different components depending n their boiling points and interaction with the stationary phase. If the oven program is kept constant, the least volatile components take a very long time to elute and if the oven temperature is maintained at a high temperature throughout the run, the resolution between the peaks would not be sufficient especially for analysis including a wide variety of components.

Hope this help,

very good answers..your answers really helped me a lot