Chromatography Forum

Hi everyone

I am working flavour compounds (acetaldehyde , acetoin, 2-butanone, diacetyl). I do get a nice separation with standards values of 100ppm or more. But when I dilute them 10 times, I cannot pick them anymore.Can someone help me for this matter.I played around with the split . I inject 1.5 ml (headspace GC);DB-5 column
Could anyone help me for this matter
Thank you anisame

Anisame,
These compounds are likely to be very sensitive to chromatographic problems like active sites - they are also subject to degradation.
eg acetaldehyde forms paraldehyde very rapidly.
I think you need to give more information such as:

injector conditions?
oven temperatures and ramp?
detector conditions?
model of headspace sampler?
split ratios?
matrix?
transfer line deactivated/inert?

before you can get a good answer to your question.
Hope someone can help
WK

Hello,

what kind of head space have you ? I recently see an head space injector of Perkin Elmer which trap the sample in activate carbon, concentrate it and after few cycle of headspacing realese the sample in the column. This technique can increase the sensitivity of your analyse. An other question: what kind of detector do you use ? You could also inject a non sensitive compound at a concentration of 10 ppm and see if you can detect it.
A simple solution consist to visit the site www.agilent.com and check the right column for your application, even you can choose an other column brand.

Sorry for my bad english, i usually speak french

Davide

Salut moi aussi suis francophone
Je te laisse mon email on peut partager nos experiences si tu veux
ledoeuff.cedric@rcc.ch