Hi

The Dumas combustion used in an EA for N isotopes is highly oxidising.  
There should be no CO.  If CO did form, it should be converted to CO2 as 
it passes over the copper oxide in the reduction column (I've done that 
deliberately to analyse CO in the past).

CO formed in the source from CO2 will obviously coincide with the CO2 
peak, not the N2 peak.

Hil
>> From: Kieran Craven<[log in to unmask]>
>> Subject: [ISOGEOCHEM] CO formation using EA
>> To: [log in to unmask]
>> Date: Thursday, June 16, 2011, 5:29 AM
>> Dear Isogeochem,
>>
>> A couple of questions about carbon monoxide formation from
>> estuarine
>> sediment while using an EA. I had a quick trawl through the
>> archives but
>> didn't come across anything on these.
>>
>> If CO results from incomplete combusion of a sample can its
>> effects be
>> picked up? Would CO travel at the same speed as N2 and
>> affect both %N and
>> d15N, or is it a slower moving molecule and crop up
>> elsewhere?
>>
>> These questions arise from running silver capsules
>> (following acid fuming to
>> remove IC) at a temperature of 1020C with a 3sec O2 pulse.
>> Some of the acid
>> fumed samples have higher %N than non-acidified samples
>> (acid fumed blank
>> samples show no contamination, and there doesn't appear to
>> be any memory
>> effects). d15N values don't massively differ between fumed
>> and non-acidified
>> samples.
>>
>> Thanks in advance for any
>> comments/suggestions/insights/musings/nods in
>> right direction.
>>
>> Cheers,
>>
>> Kieran
>>
>>
>> Kieran Craven
>> Postgraduate Researcher
>> Department of Geology
>> Museum Building
>> Trinity College
>> Dublin 2
>> Ireland
>>
>> Tel: +353 (0)1 896 1363
>> Email: [log in to unmask]
>>

-- 
Hilary Stuart-Williams PhD
Research Officer - Stable Isotopes
Research School of Biology
Robertson Building (46)
Sullivan's Creek Road
The Australian National University
Acton, Canberra
Australia ACT 2601
------------------------
Office 61 02 6125 2099
Fax 61 02 6125 4919