We have been using Hayesep-Q for plant volatile collection by dynamic air entrainment, with variable results in terms of impurities and recovery levels. I wonder if colleagues have had better experiences with Tenax or other adsorbents (for solvent elution).
A few suggestions:
Poropak Q is a good material for collection of plant volatiles.
Regarding impurities: - connect your 'air' source to an activated charcoal column and confirm the eluting 'air' or any gas you tend to use is clean of impurities (you chould check this with a blank run in GC-MS of the elluting gas).
It is a good idea to treat the (inner surface of) glassware with trimethylsillyl chloride to block the -OH groups on the inner surfaces of your glass apparatus to avoid loosing the plant volatiles (which tend to stick to the Si-OH surface of the glass).
Ideally, remove the poropak Q or Hayesep-Q and do a head space sampling instead of using a solvent, since solvents also also carry some impurities. Otherwise, run a solvent blank to confirm which impurities come from the solvent.
Good luck in your efforts
Thank you. Indeed, volatile adsorption to glass be an issue. The problem for silylating the inner wall is that the collection jar is rather large, 35 cm heigth x 25 cm diam, in order to fit the plants. So, it seems difficult to dip it in a silylating solution. I use these cylinders with a base and top made of PTFE. Regards.
Dear Andrez,
You do not need to dip! Instead, rinse the flask with the silylating solution. I mostly used 5 litres' RB flasks for my work on plant volatiles collections (more than 12 years back) and used have 50 mL of the silylating solution for complete rinsing. Avoid plastic/PTFE/rubber and related type of material (as well as tubings) which tend to include impurities in volatile collections. Make sure that the apparatus is completely glass from the part where you get a clean gas to the part after volatile collection (poropakQ) location. Maximise use of ground joints all thru'. This is the best way of avoiding impurities. Good luck
I was using Tenax. Its advantage is thermodesorbtion, so you can pack the trap once and usr it many times. I"ve used glass pipette 10 ml, filled with tena[ while gently nocked against the table. After passing the air with volatiles, they should be washed with hexane or another solvent. To desorb the residuals, just heat the trap (about 200 C, but it is better to check, I did it 20 years ago) while passing argon or nitrogen througt the trap.
Thank you for all your replies. I have been using Hayesep, the substitute product after SuperQ was discontinued, and now I am waiting to get Tenax, and planning to do filters with both adsorbents. It seems to me that Hayesep is good for retaining some compounds, but others just go through it. I have no means for thermal desorption, so will keep using solvents. I will sylanize both the collection tubes and the filters and glass wool, as suggested.
Respected sir
i have just planned work on collection of volatile compounds..can anyone suggest me where i can get this air entrainment apppratus...please extremly needed
It seems to me that you can't really buy it. You need to get glassware according to the plants you will be sampling, and teflon parts/tubing. In my case, I purchased large glass tubes, 25 cm diameter and 40 cm length, and had custom-designed teflon lids made, which have a circled groove to fit the glass tube. The lower lid opens in half to fit the plant. Entrance and exit for air are simply grooved in the teflon lids as threads to screw the appropiate fittings. For fittings I am using brass, but teflon would be better, you would need someone to make these from solid teflon tubes, using a lathe. For air you need teflon tubing.
Dear researchers,
I'm also trying to sample volatiles but from Pine trees. I wonder if Tenax and Super-Q are also good for tree volatile sample. Any idea?
It depends on which compounds you are searching for.... Tenex and some its relatives can be great for lower molecular weight compounds from trees. SuperQ and Porapak work, too. But don't rule out activated charcoal for the really small molecules. Also, your airflow and timing of flow to reduce break through can really help get good results. We use large teflon sleeves wrapped around jeffrey pine trees and sealed with a very large adjustable hose clamp. Then we used all teflon in and outflow tubing and accessories.
http://www.sigmaaldrich.com/catalog/product/supelco/20331?lang=en®ion=CO
Hello,
What is the safest way to ship Haysep Q filters, without compromising the volatiles trapped? I understand temperature change can affect the volatiles.
Thanks in advance for your feedback.
How you will pack the Poropak-Q in the glass tube with glass wool or non-absorbent cotton at both end?????. for purifying air, carbon powder or granulated carbon, which one is best???
It is possible to buy pre-packed Poropak that is supplied in sealed tubes. This means that you can pretty much guarantee that there is no moisture or other contaminant in the sorbent. Packing you own can be fiddly and result in opened jars of Poropak hanging around, unless you order the exact amount you need When you need to use the pre-packed tubes you use a tubing cutter to remove both ends. Take a look at our Forestry paper that details the supplier and method. We used tubes containing two amounts of Poropak, which are a small amount of sorbent followed by an inert gap and then the main quantity. This enhances retention, by reducing bleed-through. If you do decide to make your own then clean glass wool is an option for sealing the material into the tubes. We used the same type of tubes as inlets, but these contained carbon to clean the air. At the start of a collection we always ran a background air check by collecting the air around the trees to see if there were any pollutants. We also washed the carbon tubes in solvent and analysed the washings. Hope this helps.
Hi any one has made volatile collection filter in lab themselves instead of buying. can you please share with me the protocol or method.
Tenax®-GR Adsorbent Resin for Trapping Volatiles is good. We used it for host plant volatile collection.
I am currently using a very cheap, high-throughput method using PDMS tubing pieces, as outlined by Kallenbach et al. (2014) [doi: 10.1111/tpj.12523], I am in the process of comparing recovery against tenax and poropak, but you can read up on the method in the paper mentioned above to see if it might work for you.