I think that salt effect and other problems in TC/EA isotope analysis of
brines is due to not only NaCl, but also all oxygen-containing species
dissolved in the fluid (i.e.: borate, silica, bicarbonate, phosphate and
organic acids....and other polyprotic acids included in alkalinity
parameter. These compounds, in particular organic acids, are ubiquitous in
brines and formation waters associated with oil reservoirs).
Empirical and ad-hoc corrections could resolve salt effects problems for
inorganic species (...if you have correctly analyzed the chemical
composition of the fluid)....but organic species???
You could 'by-pass' this problems with this configuration:
azeotropic distillation of the brine ----> TC/EA-IRMS analysis of the
Hope this help.
Dipartimento di Scienze della Terra - UniversitÓ di Parma
(Earth Sciences Department - University of Parma)
Parco Area delle Scienze 157a
43100 Parma, ITALY
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----- Original Message -----
From: "Christopher Romanek" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, December 08, 2004 3:46 PM
Subject: Re: [ISOGEOCHEM] hypersaline samples
> Dear list members,
> When I ran pure deionized tap water (DITAP) and DITAP with enough NACl
> to reach an ionic strength of 0.7 I got different D/H results on my
> TC/EA, presumably due to a salt effect during pyrolysis. I had to
> change out and clean the glassy carbon tube after running the salty
> solns in order to get reasonable D/H values for DITAP again. Anybody
> else notice similar or different effects?
> Chris Romanek
> Stable Isotope Lab
> Savannah River Ecology Lab
> >>> [log in to unmask] 12/08/04 07:19AM >>>
> Dear List members.
> I have been sending hyper saline water samples for deuterium and
> analysis. The lab uses pyrolisis method (Finnigan Delta Plus XL ion
> mass spectrometer and Thermochemical Conversion Elemental Analyzer
> peripheral to analysis these samples. I have been using these results
> correcting for the salt effect.
> Lately, I was told that measurements are usually difficult in
> sample because of the saturation of salts is attained and therefore
> isotopic effects become more complex as the exchange rate between CO2
> water slow down considerably.
> I'm bit confused, can someone explain to me how the pyrolisis method
> work on
> hypersaline samples.
> Thanks in advance for any help.