Hi Francois, and Brian,
Without wishing to split hairs, strictly chemically speaking neither side here is correct.
Setups that convert organics into H2 for 2H stable isotope analysis at temperatures below 1350 C have usually done so under reductive conditions, using a reducing agent as reactor filling, which is not the same as pyrolysis.
However, setups that convert organics at temperatures above 1350 C don't exactly perform pyrolytic reactions either. Thermolysis would be a more apt term, which is why some manufacturers have gone away from using the term pyrolysis and have adopted the term high-temperature conversion instead.
Pyrolysis is often described (or defined) as a special case of thermolysis. In fact, it would be counterproductive to our needs if the organic molecules we'd like to analyse isotopically would be decomposed by pyrolysis since pyrolysis can result in very complex mixtures of breakdown products, not just simple molecules such as H2 and CO. For example, pyrolysis of amino acid can yield complex polycyclic heteroaromatics; pyrolysis of glutamic acid yields 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole and 2-amino-dipyrido[1,2-a:3',2'-d]imidazole, both highly potent carcinogenic and mutagenic compounds.
I think if we all adopt the term high temperature conversion and move away from pyrolysis, we keep our noses clean chemically speaking and do all sides in the instrument development race justice.
"Facts do not cease to exist because they are ignored."
Aldous Huxley, "Proper Studies", 1927
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From: Stable Isotope Geochemistry on behalf of Francois Fourel
Sent: Fri 16/07/2010 14:27
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] Flash EA CO analysis
Hello Trina and Brian,
I would be very careful with final statements as this one Brian.
Farquhar et al 1997; Koziet et al 1997, Bréas et al 1998, Saurer et al
1998, Kornexl et al 1999, Revesz and Böhlke 2002, Lécuyer et al
2007...amongst others have published EA pyrolysis data which did not
come from a FlashHT or a TCEA . Plus if you read carefully those papers
you will discover as well that some of those data have been generated at
temperatures different from the one you indicate.
UMR CNRS 5125 PEPS
Université Claude Bernard Lyon 1
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B Jones a écrit :
> Pyrolysis is only possible on the FlashHT or TC/EA as 1380 to 1450C is
> required (ie requires a high teperature furnace).
> Brian Jones
> On Sat, Jul 3, 2010 at 1:28 AM, TRINA BOSE <[log in to unmask]
> <mailto:[log in to unmask]>> wrote:
> Can you please give reference for the exact configuration of the
> Pyrolysis reactor as
> such is not available in the Flash EA manual I have, only the
> combustion reactor
> configuration is available.
> On Fri, 2 Jul 2010 10:35:27 +0100, Jon Davies wrote
> > Dear Trina,
> > I'm not sure that it is feasible to obtain reliable 13C and 18O
> data off
> > one run.
> > The Flash reactor column for oxygen analysis contains carbon
> > (nickelised) to ensure the complete conversion of sample oxygen
> into CO.
> > So while the 18O data in the produced CO will be purely from the
> > oxygen, the 13C data will be a mix of sample carbon + reactor
> > carbon.
> > I believe that you will need to carry out two analyses -
> firstly using
> > a pyrolysis reactor for the 18O measurement and secondly using a
> > combustion reactor to produce CO2 for the 13C measurement.
> > Regards
> > Jon Davies
> > Technical Manager
> > Elemental Microanalysis Ltd.
> > Okehampton Business Park,
> > Exeter Rd. Okehampton,
> > Devon EX20 1UB UK
> > Tel +44 (0)1837 54446
> > Fax +44 (0)1837 54544
> > www.microanalysis.co.uk <http://www.microanalysis.co.uk/>
> > -----Original Message-----
> > From: Stable Isotope Geochemistry
> [mailto:[log in to unmask] <mailto:[log in to unmask]>] On
> > Behalf Of TRINA BOSE
> > Sent: 02 July 2010 09:30
> > To: [log in to unmask] <mailto:[log in to unmask]>
> > Subject: [ISOGEOCHEM] Flash EA CO analysis
> > Hi All
> > I would like to Analyze Carbon Monoxide extracted from wood samples
> > using a flash EA.
> > For this, I am confused about the Reactor Column
> > Configuration.Basically, I want to
> > measure carbon and oxygen isotopic compositions from the wood sample
> > during the same
> > run, i.e. by producing CO using its own Carbon and oxygen.
> Please help.
> > sincerely
> > Trina Bose
> > Research Fellow
> > Indian Institute of Tropical Meteorology
> > Dr. Homi Bhabha Road, Pashan, Pune-411008
> > Ph.: 020 25904430
> Trina Bose
> Research Fellow
> Indian Institute of Tropical Meteorology
> Dr. Homi Bhabha Road, Pashan, Pune-411008
> Ph.: 020 25904430
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