For several reasons, there is interest to replace helium for a different carrier gas in gas chromatography. Hydrogen is the obvious choice, but there is a concern on safety and reactivity. It is also possible to use nitrogen, but this is often not considered because it has a low optimal flow and velocity.
By using method translation and chromatogram modeling it became clear that the loss of efficiency using nitrogen could be perfectly compensated by using a smaller ID capillary of a shorter length. By replacing a 30m x 0.25 for a 20m x 0.15mm, it is demonstrated that separations under nitrogen are exactly the same as obtained with Helium, in the same analysis time, while using exact the same conditions for oven programming. Even the inlet pressures are very close.
The only price that has to be paid, is a loss in loadability, which means that this concept will not work for every application, but for many, it will. Besides the guaranteed availability, using nitrogen offers a big advantage in the cost and consumption volume of carrier gas, meaning cost per analysis will also benefit significantly.
Presenting author:
Jaap de Zeeuw
Restek Corporation, weerhaan 9, 4336 KT, Middelburg, The Netherlands
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Authors:
Jaap de Zeeuw - Restek Corporation, weerhaan 9, 4336 KT, Middelburg, The Netherlands
Jack Cochran - Restek Corporation, weerhaan 9, 4336 KT, Middelburg, The Netherlands
