Chromatography Forum

hello i need to workout what type of column/ columns i need for a GC 6000 Series we need to find out what a liquid sample is and recently purchased a GC 6000 Series - column we would be doing small sample test batches of precursers identification and purity testing of low melting point solids please help all advice welcomed thanks

Basic separations are done by distillation type separations which mean a methyl silicone column, 100% or 95/5% methyl/phenyl silicone is recommended.

Remember, just because it is a liquid at room temperature or slightly higher doesn't mean it will elute , or elute well by GC.

You need to characterize your liquids-semisolids thoroughly before you inject them into a GC.

best wishes,

Rod

thanks a lot for your help we can see this is going to be quite a learning curve

Look for the presence of functional groups, like free acids, amino, thiol, and other functionalities which can cause decompositions, reactions, rearrangements, tailing, etc.

The use of TLC, NMR, UV and IR spectroscopy are all recommended.

Imagine how well dissolved NaCl in water will elute from a GC column after it is separated from the water on the column!

best wishes,

Rod

Don't take this the wrong way, but your purchase of a GC to identify liquids and low melting solids has more than a hint of CSI about it (in case you so not watch much TV; CSI is a drama about crime scene forensics - they are infamous for squirting muck into lab instruments and getting complete answers out in about 10s). As I hope that you know, identifying unknowns does not go like this, if you think that it does then you probably need to get some help with the chemistry.

Peter

Don't mean to "pile on", but GC would be one of my last choices for doing qualitative analysis for unknown liquids. As others have indicated, a multiple technique approach with a skilled chemist to assist in analysis and interpretation would be the way to proceed.