Print

Print


Hi David,

How fast will your sample gas flow through the cryo trap?

CH4 is notoriously difficult to trap, even with liquid N2 it has to be slowed down e.g. by filling the trap with zeolites or similar. So, depending on your set-up you could easily use liquid N2 to trap CO2 while still letting through CH4.

What you need to watch is that trapping CO2 at whatever temperature will also trap any traces of humidity present in the gas phase above your cultures.

Depending on the diameter of your trap and amount of moisture, frozen water accumulating at the top of the trap (about level with the cryo liquid) might block your trap.

Best,

Wolfram

Sent from my BlackBerry 10 smartphone.
  Original Message
From: Denhaan, David
Sent: Thursday, 26 May 2016 16:08
To: [log in to unmask]
Reply To: Stable Isotope Geochemistry
Subject: Re: [ISOGEOCHEM] Using Precon for CH4 and CO2 separation


Wolfram,

Thanks for the reply. I was going to use liquid nitrogen for the CO2 trapping.  Is that too cold?  Is calculating the trapping capacity of the liquid nitrogen trap as easy as calculating the volume of tube and using PV=nRT and perhaps cutting it by 50% since I don't want to block the flow?  And you're comfortable that trapping of CO2 is thorough enough not to affect the CH4 analysis?

Thanks,

David

David DenHaan
Laboratory Technician
National Laboratory for Agriculture and the Environment
Ames, IA

-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Wolfram Meier-Augenstein (aps)
Sent: Thursday, May 26, 2016 9:39 AM
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] Using Precon for CH4 and CO2 separation

Hi David,

What you propose doing should work.  You could use a methanol/liquid N2 mix (-98C) to be sure to trap CO2 without it breaking through if you feel dry ice/acetone (-78C) might be cutting it too finely.

Best,

Wolfram
________________________________
From: Stable Isotope Geochemistry <[log in to unmask]> on behalf of Denhaan, David <[log in to unmask]>
Sent: 26 May 2016 15:20
To: [log in to unmask]
Subject: [ISOGEOCHEM] Using Precon for CH4 and CO2 separation

Dear List,

I'm trying to analyze CH4 and CO2 from the headspace of a bacterial culture with a labeled acetate substrate.  Depending on the enrichment in CO2 and methane evolved I should be able to show which bacteria are active.  I have a Precon hooked up to the gasbench GC and a Delta V.  I 'm hoping to trap the CO2 from the headspace on the manual trap this would let the CH4 pass through to be combusted and measured.  When that's done I would raise the manual trap and measure the CO2.  Is this a sound approach?  I'm worried about how much CO2 can be trapped on the manual trap and how complete the trapping is.  If CO2 comes through the manual trap I won't be able to distinguish it from the CH4.

Thanks,

David

David DenHaan
Laboratory Technician
National Laboratory for Agriculture and the Environment Ames, IA





This electronic message contains information generated by the USDA solely for the intended recipients. Any unauthorized interception of this message or the use or disclosure of the information it contains may violate the law and subject the violator to civil or criminal penalties. If you believe you have received this message in error, please notify the sender and delete the email immediately.

________________________________
This email has been scanned for spam and viruses by Proofpoint Essentials. Click here<https://eu1.proofpointessentials.com/index01.php?mod_id=11&mod_option=logitem&mail_id=zLc3Ycu4uchx&rid=22280648&report=1> to report this email as spam.


________________________________

Robert Gordon University is the top university for graduate jobs in the UK HESA July 2015


Robert Gordon University, a Scottish charity registered under charity number SC 013781.

This e-mail and any attachment is for authorised use by the intended recipient(s) only. It may contain proprietary material, confidential information and/or be subject to legal privilege. It should not be copied, disclosed to, retained or used by, any other party. If you are not an intended recipient then please promptly delete this e-mail and any attachment and all copies and inform the sender. Please note that any views or opinions presented in this email are solely those of the author and do not necessarily represent those of Robert Gordon University. Thank you.

----------

This email has been scanned for spam and viruses by Proofpoint Essentials. Visit the following link to report this email as spam:
https://eu1.proofpointessentials.com/index01.php?mod_id=11&mod_option=logitem&mail_id=r7g-niHP3VJc&rid=22280648&report=1