Rebecca Hood wrote:

> Dear all
>
> Does anyone have a simple method for azeotrophic distillation of
> water
> from plants, is this the best method known to us ?.... is there a good
>
> fully explained
> procedure somewhere with diagrams etc.
>
> Also is anyone doing micro litre 18O or 3H analysis of water samples
> on
> a contract basis, if so how much per sample? and what are the
> constraints in terms of salts and contaminants?
>
> Thanks for your help in advance.
>
> Dr. Rebecca Hood
>
> >

   The azeotropic distillation was originally developed for soil water.
The paper by Araguas-Araguas et al. 1995 Journal of hydrology 168:
159-171 has an interesting discussion on the method with many good
references.  I have tried vacuum distillation and azeotropic
distillation and my opinion  is that if both methods are well done they
give equal results.  I prefer vacuum distillation because its simpler.
Another way of extracting water is by squeezing there is a paper by
White et al. in Geochimica where this method is used, I dont use this
method because the water sample often comes out quite dirty, but in
principle it works just fine. Hope this is of help, please feel free to
contact me in case you have any other questions.  Leo