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Silica vs Wax Column
Posted: Tue Jan 04, 2011 7:48 pm
by 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.
Re: Silica vs Wax Column
Posted: Wed Jan 05, 2011 12:26 am
by 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.
Re: Silica vs Wax Column
Posted: Wed Jan 05, 2011 8:46 am
by 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