Chromatography Forum

hi,

needed to run GC on compounds as listed below

DMAC( dimethylacetamide)
DEG (diethylene glycol)
PPG( Polypropylene Glycol)

all the compounds are high in boiling point, which i believe that changing the form or derivitised it into a low boiling point compound is necessary. Can anyone kindly advise on how shld i go abt changing its form?

Thanks all in advance,

PPG by GC?

Nope. Don't think so.

The other two are no problem as a thin film Carbowax capillary can and will handle them well.

You may need to use GPC to analyze any polymer. Do you have this available?

Anything else in the mix we should be informed about?

best wishes,

Rod

PPG by GC?

Nope. Don't think so.

The other two are no problem as a thin film Carbowax capillary can and will handle them well.

You may need to use GPC to analyze any polymer. Do you have this available?

Anything else in the mix we should be informed about?

best wishes,

Rod

Rod, thx for your advice.
Made a mistake, shld be polyethylene glycol, but I guess it's not feasible too since it's a polymer and am using a carbowax column.
As for GPC, any idea when can I get more information on this instrument, as I haven't use it at all before.
May I also know if glycerine is suitable for direct GC injection as well?

Once again, thanks all!

GPC is gel permeation chromatography and if you search LC archives you will find a lot of information. Also if you check the normal commercial sites for LC columns you will find the info you seek. My company is one of several who sell LC columns. You need to find one for the molecular weight range of your polymer.

Glycerine is derivatized before analysis by GC. BSA or MSTFA or Sweeley reagent are all options.

You will be making a Trimethylsilyl ether derivative, in this case a tri-TMS ether. The proton from each of the hydroxyl groups is replaced with a TMS group. This analysis is done on a 100% or 95% methyl-5% Phenyl silicone column.

You could probably make acetate esters of the DEG and glycerine if you prefer that derivative instead. I would use a 50% phenyl-50% methyl silicone type phase or something more polar in order to get good peak shape.

Feel free to call Supelco technical service if you need more assistance. It is free of charge.

best wishes,

Rod

lingo

You need no derivatisation for GC analysis of diethylene glycol. I was using an Innowax column. It worked fine.
I also managed to elute low molecular mass PEG from a GC column. As I remember it was PEG 400 or sth with lower molecular mass. There was no derivatisation and peaks were well saparated but I don't remember the column. It was several years ago.

Regards