R. Frew,

If the sucrose is 1% C-13, this is roughly the natural abundance level for
delta C-13. No problem!

However, if the sucrose is 99% C-13 and is added to regular sucrose to 1%, then
the sucrose is roughly 2% C-13 (ratio 2/98 = 0.0200408) and your permill
value vs PDB CO2 is about + 800 o/oo. This might work, but you need to check
the linearity in this range with regular and labeled sucrose. Also, talk to
your colleague again to verify what he/she is doing and which case or other
situation(s) is(are) involved.

Glen Martin
>Dear All
>
>I am setting up a lab with a single irms equipped for dual inlet and
>continuous flow work via an elemental analyser (Carlo Erba). My
>interests are environmental samples at natural abundances.
>I have been approached by a physical education student wanting to do
>a metabolism study using artificially enrich sucrose (around 1% 13C).
>The analyses would be of blood  glucose and breath samples.
>
>My question is, is this type of work compatible with natural
>abundance work? My training in trace analysis of metals in seawater
>has made me paranoid about contamination. Is there a concern here?
>
>I would greatly appreciate hearing your thoughts/experiences.
>
>regards
>
>Russell Frew
>**********************************************************
>Dr Russell Frew                   [log in to unmask]
>Department of Chemistry
>University of Otago                      ph  64-3-479-7913
>P.O. Box 56                             fax  64-3-479-7906
>Dunedin, New Zealand
>**********************************************************
>
>