What difference does sorbent mesh size make?

Sorbent mesh size has very little effect on sorbent retention volume, provided that there are at least four or five particles across the internal diameter of the sample tube. This stems from the fundamental theory of gas–solid chromatography, and explains why Carbopack B (60/80 mesh) has the same retention performance as Carbotrap (20/40 mesh) and Carbograph 1TD (40/60 mesh).

Most thermal desorption sorbent tubes use a 100-mesh gauze to support the sorbent, which means that any sorbent with a mesh size or 80 or greater should be supported within the tube. When changing from one mesh size to another, it is important to consider the difference in impedance and ensure that sampling and desorb flows are verified.