Chromatography Forum

Hope everyone are keeping well in these strange times.

I am trying to develop a multiple headspace extraction method to measure caffeine in solids such as ground coffee.

Is there anyone out there doing MHE on an Agilent 7697A system as I would welcome any advice as to possible settings as part of the headspace parameters.

So far on one occasion I ran 5 extractions from a caffeine standard and got the expected results with the peak area of the caffeine decreasing according to the predicted Ln relationship. Since then I have run into problems and can't get things to work even when using the same conditions

Typically if I do 5 extractions from the same vial I only get peaks on the 5th run. If I do 3 extractions from the same vial I only get peaks on the 3rd run etc.

I have tried changing some of the settings in the headspace parameters such as the flow settings but without success partly as I am not totally sure of what each parameter does. I have spoken to Agilent but as this is quite an uncommon way of doing things they aren't too familiar with what I am trying to do.

Anyone able to help with some suggestions
Thanks
Kevin

Good luck with that one. Over the years I've tried to get caffeine by GC with headspace SPME and nothing I've tried has worked reliably. I must admit, when the first things I tried didn't work right away, I gave up pretty easily. The GC would've been a backup method to what we normally use (HPLC).

Ditto on SPME GCMS for caffeine here - thought we might have nailed it down for a second using a C13 caffeine internal standard (which cost a bit), but Nah - back to HPLC

With a melting point of 235C I wouldn't think headspace would be a good method for Caffeine. It is very easy to extract with Dichloromethane or Ethyl Acetate though.