Silica vs Wax Column

[RedMello06]

I am trying to detect propylene glycol in fuels. As of right now the PG is eluting a min into the fuels retention zone (its a broad section). The boiling points are similar but as the fuels are not polar at all and the PG very polar would a change in column help? We are currently using a 30m fused silica column.

[Consumer Products Guy]

When we assay for propylene glycol in consumer products (not fuels) we use trimethylsilyl derivatization and a non-polar column.

We've also done some glycols directly on 624 columns, such as Rtx-624.

[Peter Apps]

The important thing about the column is not that it is fused silica, but what is coated on the inside; the stationary phase. Since you seem to have a boiling point separation (or lack of) at the moment you are probably using a non-polar phase. A polar phase will retain the glycol more in relation to the non-polar constituents, this may or may not give you the separation that you need. Have a look on the column manufacturers' web sites, and ask them for advice.

Keep in mind that underivatized glycols are susceptible to adsorbtion, so peaks are often bady tailed.

Peter