Hi Mathieu
NaOH can easily pick up some carbonate during storage.
I used to prepare carbonate-free NaOH by adding a small quantity of BaCl2 to
a NaOH solution. One can judge the degree of contamination by the cloudiness
in the bottle. Allow the precipitate to settle and use the supernatent
solution to add to the sample
I hope this helps
Siep
AS TALMA
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-----Original Message-----
From: Mathieu Daėron [mailto:[log in to unmask]]
Sent: Wednesday, 18 May, 2016 11:40
Subject: DIC precipitation by addition of barium hydroxide
Dear all,
A traditional method to precipitate DIC from aqueous solutions in the lab or
in the field is to induce supersaturation with respect to BaCO3 by adding
concentrated BaCl2 followed by NaOH (e.g., Beck et al, 2005,
<https://dx.doi.org/10.1016/j.gca.2005.02.003>). However, using this method
I've occasionally had issues with incorporation of Na and/or Cl in the
precipitates.
Alternatively, I've considered the possibility of simply adding Ba(OH)2 (or
Ca(OH)2, if I'm not worried about CaCO3 polymorphs). Does anybody have an
idea why this might not work equally well?
Thanks,
- Mathieu
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