Chromatography Forum

Hi,
I am planning to transfer my GCs from He to N2. Could NPD, TCD, ECD work with Nitrogen a carrier gas?

TCD and ECD can work with nitrogen, ECD should work well with it since that is normally used as the makeup gas for ECD.

The NPD here works with nitrogen, you will lose a little sensitivity versus helium but not bad.

TCD works on differential thermal conductance. You may lose a lot (in some cases, all) of your sensitivity depending upon what you use the TCD for. As James points out, the others should be fine.

The Van Deemter curve for N2 is brutal. You have to really have exceptional control over your carrier gas, and really be good at optimizing systems.

Thank you so much,
An what about Hydrogen?
Can FID,NPD, TCD, ECD work with Hydrogen carrier gas?

In most cases, anything that helium can do, hydrogen can do better. One of its biggest advantages can be seen when you look at a Van Deempter plot-it's a lot "flatter" for H2 vs. He, so you can run at much higher linear velocities without much loss in resolution, and the resolution is good over a very wide range of linear velocity.

If you are using a capillary column, the contribution of the column flow to the overall flow through the detector is not actually that significant-that's why typically use a make-up gas(aux gas) with the detector. Your FID and NPD will still need H2(and air) for "fuel", and again the small additional contribution of H2 from the column won't make a difference. You MUST have nitrogen or methane-in-argon flowing into the ECD, either as the carrier from a packed column or large bore capillary, or as the make-up gas. There again, He won't really make a difference.