-------- Original Message --------
> Subject: Re: Carbob-13 spectrum of CO2
> Date: Mon, 24 Mar 2003 15:25:01 -0800
> From: "V.P.Chacko" <chacko_at_mri.jhu.edu>
> Organization: The Johns Hopkins University, School of Medicine
> To: Peter Lundberg <peter.lundberg_at_imv.liu.se>
You are in much better luck than you think!!!
It is very easy to get an NMR spectrum of dissolved CO2. Here's the
recipe, fully tested and proven:
Materials:
1. A spatula-ful ( or a "teaspoonful") of Bicarbonate of Soda (Baking
Soda will do just fine)
2. 1-2 mL distilled water (tap water will work too, you really don't
need D2O for this expt.)
3. One Broadband NMR spectrometer (any make, any field strength)
4. One 5 or 10 mm (depending on the probe) NMR tube (any quality)
Here's what you have to do:
Dissolve the bicarbonate in the H2O and transfer to the NMR tube.
Shake well, or better yet, vortex it for a few seconds, to get rid of
the extra gases.
Wipe the outside of the NMR tube with a Kleenex. Insert the tube into
a spinner and drop it into the probe, previously positioned inside the
magnet of the afore-mentioned NMR spectrometer.
Tune the probe to C13 frequency and take one NMR spectrum with NA = 1,
using nothing but "one pulse". You don't need decoupling in this case.
Voila, you got the NMR spectrum of CO2!!
You don't even need to shim, or lock the spectrometer, if the
spectrometer has recently been used with the probe in use. You see, in
aqueous solution, (at NTP!!) CO2 is in equilibrium with HCO3(-), the
bicarbonate ion.
This is so easy you will be amazed at how easy it is. You will even ask
yourself, "why didn't I think of it"!!
chacko
Peter Lundberg wrote:
>> Hi all,
>>
>> no it's no bad joke.
>> A few weeks ago I got a request for the C-13 spectrum
>> of carbon dioxide. Like you I thought this is a confusion and maybe
>> the IR sectrum was wanted.
>> But:
>>
>>> Dear Rainer
>>> Thank you for the e-mail you sent to my colleague Anita Lockyer
>>> regarding NMR for CO2. It is indeed the C-13 spectrum that we require.
>>> I realise this will not show much but we need a copy to submit as part
>>> of an EUdata package for the Biocidal Products Directive.
>>
>>
>> I have no idea, where to find a C-13 spectrum of carbon
>> dioxide. Do you have an idea?
>
>
> Hi Rainer,
>
> As long as they don't ask you for a 12C NMR spectrum, there is at least
> a chance...
>
> What is the aqueous solubility of CO2(g) compared to say H2(g) or N2(g)?
> The latter two are relatively easy to observe (in aqueous solution) in
> NMR spectra. CO2 is probably much more difficult due to its lower
> receptivity, but I believe it should be fairly soluble in water. If a
> spectrum of 13C enriched sodium carbonate is acceptable, the detection
> would be a lot easier. Low temperature would probably be favourable in
> order to observe dissolved CO2.
>
> 73, Peter
Received on Mon Mar 24 2003 - 17:34:01 MST