GOM wrote:Hi Joe
From wikipeadia
Wood vinegar = The principal components of pyroligneous acid are acetic acid, acetone and methanol. It was once used as a commercial source for acetic acid. In addition, the vinegar often contains 80-90% water along with some 200 organic compounds.
So in answer to your query, yes, SPME into the headspace or into the liquid would work and I would suggest a polar column e.g. Innowax. A good general purpose fibre for this would be a DVB/ carboxen fibre
see
http://www.sigmaaldrich.com/technical-d ... ibers.htmlOthers may have a better experience/ recommendations on this
BUT, from experience (e.g. have you got a hammer? - when what they really needed was a screwdriver - true example) it is easy to get mislead on a query that pre supposes a particular approach -in this case SPME
Do you have any more details on the target analytes and the purpose of the analysis? It may be helpful for others to formulate a better reply
Regards
Ralph
Hi Ralph,
I hope you're keeping well?
Wikipedia was also my first port of call when I was approached with this query, and when I saw 80-90 % water I had some reservations as I was told to keep samples containing water away from the GC-MS at all costs.
It would be great to be in a position to purchase a non-polar column for this analysis, but as my colleague only wants to analyse it out of curiosity I can only run the sample on the non-polar HP5-MS column I currently have installed. Similarly I don't really want to spend money on new SPME fibres so I only have 75 um Carboxen/polydimethylsiloxane at my disposal.
I suppose I did ask a bit of a pointed question there!
The purpose of the analysis is just to scope out the chemical components that make up the wood vinegar, so there are no target analytes particularly.
Cheers,
Joe
PeterApps wrote:
Hi Joe
You'll get a chromatogram using SPME - whether it tells you what you need to know about the vinegar is not guaranteed, whether it's the best method is another question.
How are the mites doing ?
Peter
Hi Peter,
I hope you're keeping well?
I suspect it isn't the best method, but the analysis is just a preliminary investigation to see get a general idea as to what compounds make up the wood vinegar.
The mites are doing very well, thank you. I haven't replied to the other thread recently as I have been focussing on undertaking some of the behavioural assays using silica extracts from a number of different mite species. Once I have the behavioural data, I intend to pursue the GC-MS work further. I actually found a modified version of your pipette tip idea for filtering the silica gel from my solvent after extraction:
https://www.agilent.com/en-us/products/sample-preparation/sample-preparation-methods/filtration/selectionguide. These syringe filters fit onto the end of a leur lock hamilton syringe, so I can use a wide gauge needle to suck up my sample then swap over the tip and then push down the plunger to filter my sample. It seems to work relatively well and provides no contamination when compared to the centrifuging technique. I hope to be able to update everyone once I have finished the work!
Cheers,
Joe