Dear listmembers,

I'm working on extraction of cellulose from tree rings for C and H isotope
analyses, and I need your help.

Can anyone explain me the difference between 90% nitric acid, fuming and 90%
nitric, red fuming.  According to the technique I'm going to utilize
(Alexander and Mitchell, 1949), I should use ''90% nitric acid (90% fuming but
not red fuming)''.  Explanations given me by representatives of technical
services (Fisher and Aldrich) are as follows:
- Nitric acid with concentration of HNO3 below 97.7% will always be red
fuming; white fuming nitric acid sould have HNO3 content greater then 97.7%
(Fisher).
- Nitric acid, red, fuming (90%) is called red fuming because it has dissolved
oxides (as N2O3) added (5-10%).  On the contrary, nitric acid (90%) without
these oxides (no more than 0.1%) is considered as nitric acid, fuming
(Aldrich).

The problem is that acids sold by both companies are listed as fuming acids in
their catalogs but supplied with documentation as red fuming acids.  Besides,
I'm not totally satisfied with the explanations given me by the technical
people (either from Fisher nor from Aldrich).

I would greatly appreciate any information concerning this matter.  Thank you
very much.  Best regards.  Anna Smirnov


Delta-Lab,
Center Géoscientifique de Québec
Complexe Scientifique, 2700 rue Einsein, C.P. 7500
Ste-Foy, (Québec),
G1V 4C7, Canada
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Ph: (418) 654-3711
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