GOM wrote:Hi Joe
I am flying blind on my reply because I don't have experience of Porapak Q solvent tubes and others might
However
a) Obviously different sorbents will have different selectivities
b) you say that wish to do solvent rather than thermal desorption - solvent extraction will add another layer of selectivity
c) My experience of sealed sorbent tubes is that they are pre-conditioned.
However if you look on the link that you provided
* Limited shelf-life; contact SKC for more information
‡ Tubes are chemically conditioned before shipping; use within 30 days or recondition. Restocking fee applies.
§ Each tube has a flow direction arrow and unique number.
• Limited shelf-life; refrigerator/freezer storage may be required. Contact SKC for more information.Their comments may be just to cover their backside with those disclaimers. If sealed in glass (as I have had with charcoal tubes) I don't really see a problem. Have you tried contacting them?
d) there is some information here that might be useful
https://www.ncbi.nlm.nih.gov/pubmed/15974063 I don't have access to the full paper
http://link.springer.com/article/10.1007/BF02276852e) it might be worth checking out searching under the equivalent Chromosorb Century series of adsorbents - I can't remember the Porapak Q equivalent.
f) It might be worth contacting Markes International for more information although they are more thermal desorption.
Being pragmatic - at the end of the day, because of my understanding of Porapak Q's limited selectivity, just dump them.
I fully appreciate not wanting to waste a free gift but my concern is that it may cause you to divert time that you don't really have.
If it was that good you would find far more references.
If you really wish to go down this route consider charcoal or Tenax
Regards
Ralph
Hi Ralph,
Thanks for such a detailed response, it is much appreciated. I will address the points you have listed sequentially:
a) I am aware that different sorbents have different selectivities, but the colleague I have acquired the Porapak Q tubes from used them for analysing plant volatiles, etc. This is the kind of work my lab wants to move into, as it compliments the entomological work we do. I have found a paper that seems demonstrate this application quite well:
https://www.ncbi.nlm.nih.gov/pubmed/12033802.
b) Ideally TD would be the preferable method of desorption, but I don't believe these tubes are compatible with the TD unit as I have to cut the sorbent tubes to open them. I don't have a suitable tool for cutting glass so will be resorting to scoring the tubes with glass and snapping them. The stainless steel tubes that I currently use with the TD unit do contain tenax.
c) I had briefly looked on the manufacturer's website and noticed that the tubes are preconditioned. However, they were manufactured and packaged in 2010, so would most likely need to be reconditioned - how one would go about this I have no idea.
d) Thanks for the paper links, I had seen the chemical weapons one previously as I have been researching biofumigation of potato cyst nematodes in potato crops using mustard - allyl isothiocyanates seem to reduce populations substantially.
With regards to you being able to access papers, there is a way to access any published scientific article. I'm not sure how you feel about publishers, but this website does not benefit them:
http://sci-hub.cc. All you need to do is copy and paste the URL of the paper into the search bar and you should have instant access to the paper.
e) It appears that Chromosorb 102 is interchangeable with Porapak Q. I'm still not certain as to whether this is suitable to my labs needs as the Chromosorb website doesn't make it very clear...when I say website I actually mean this document:
http://www.advancedminerals.com/pdf/Chromosorb_century_polymer_supports.pdf f) Markes International are the manufacturer's of the TD unit we currently have, although I'm not sure how much help they'd be willing to give me on an item they don't manufacture.
Thanks again Ralph!
Cheers,
Joe
EDIT: I have also found these papers:
1)
http://link.springer.com/article/10.1023/A:10224428181962)
https://www.jstor.org/stable/3547045?seq=1#page_scan_tab_contents