Headspace and high boiling point compounds

[thohry]

Hi all,

I will plan to analyze certain compounds in beer and some of them have rather high boiling point, namely Ethyl phenyl acetate , Diethyl succinate... I am not sure if these compounds can be analyzed by GC-Headspace. Anyone have ever done this or have experience on this could give me an advice.

Thanks.

[chromatographer1]

You will be surprised how much you can see from analytes you think will offer so little.

It depends greatly on how much sample you put into a vial, how hot you can heat the vial, and the active sites in your sample path.

A little research on your part is better than second hand information.

Simply make up 1mL of a 1mg/mL solution of the analytes you wish to test in water or methanol.

Add 1 microliter of the solution (1 microgram of analyte) into a vial, cap and heat it in your headspace analyzer for 10 minutes at 85°C. Transfer line at 120°C or higher if necessary.

Inject a 250 microliter loop of sample and see what you get.

Your hardware will affect your results so even if I might say 'no problem' it could be a problem for you.

Inert sample pathways and the right column are necessary requirements. Once you learn what your hardware can do then you can work on getting the proper size sample and the right levels of contamination you are required to measure.

Good luck, and let us know how it turns out.

Rod

[DSP007]

Hello
These substances are insoluble in water and can theoretically be analyzed using vapor phase from the aqueous solution.
On the same principle as the "distillation with steam. "
However, much more promising to analyze them, either from solution in the fluid, or after concentration by SPME

[Peter Apps]

I'll agree with both Rodney and DSP: they probably can be done by (equilibrium)headspace, but other methods will probably work better.

Peter

[Axar]

Hello
These substances are insoluble in water

Don't you think they can be soluble in beer?


It's very complicated question for me. If it were polar substanses, we can boost their transfer from liquid to gas by adding polar solt. According to the Gibbs phase rule there are two degrees of freedom (excepting pressure). I guess, it is concentration of analite and temperature. But we can add a new component to equlibrium, so it is an ocean of solutions!
Good luck!!!

[chromatonewbie]

You might want to investigate using a Chromatoprobe - they are good for this sort of thing.