Hi Karyne,

I don't know of any selective temperature methods. Normally we
would extract inorganic-N from the soil sample using 2MKCl and
measure inorganic-N concentration on the filtered extracts. At the
same time, combust another subsample for total-N and by
difference calculate the organic-N content of the soil. If you're
particuarly intersted in nitrite content then check Stevens R J and
Laughlin R J 1995 (Nitrite transformations during soil extraction
with potassium chloride. Soil Science Society of America
Journal 59:933-938) who discuss pH effects on nitrite.

Tim.

> Dear Isogeochemers,
>
> Has anyone used EA-IRMS to determine total, organic and inorganic N
> contents in soils?
>
> If I combust the whole soil/sediment at 1000C furnace temp, I will get
> total N, but is there a certain temperature that will only combust
> organic N, so I can do simple arithmetic to calculate the inorganic N
> (Total N -Organic N =Inorganic N)?
>
> Has anyone got any other 'quick' methods for doing this type of
> separation.
>
> Thanks in anticipation
>
> Karyne
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Dr Karyne Rogers
> Stable Isotope Laboratory Team Leader
> Institute of Geological and Nuclear Sciences
> PO Box 31-312
> Lower Hutt
> New Zealand
>
> tel +644-5704636
> fax +644-5704657
> email [log in to unmask]
> Web Site: http://www.gns.cri.nz
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Dr Tim Clough,
Research Scientist,
Soil, Plant and Ecological Sciences Division,
Soil and Physical Sciences Group,
P O Box 84,
Lincoln University,
Canterbury,
New Zealand.

Phone: (64) (3) 325 2811
Fax:  (64) (3) 325 3607