Hi, Paul:

Charcoal made in SKC Inc. is sealed in a glass tube. One tube is enough to
treat about 4ml of water. It is very convenient and effective. The address is:
334 Valley View Road, Eighty Four, Pennsylvania 15330.

Good luck.

Dachun Zhang
Isotope Lab
ZymaX

Paul Brooks wrote:

> First I would like to thank all of you who replied on the storage of IAEA
> standards.  The information was very useful.
>
> We are using FM Gas Bench for 18O equilibrations with 0.2% CO2 in
> Helium.  This method usually works very well.  Unfortunately we have a
> batch of water extracted from grass leaves that report results that make no
> sense.  It appears that some of them actually generated CO2, while other
> took it out of the atmosphere!  Running them twice made no difference and
> yet other samples and standards in the run analyzed very well.
>
> It has been suggested that this is probably due to contamination from
> organic volatiles in the sample, and that we should add some activated
> charcoal to each sample, shake them and then re-equilibrate them.  I am not
> familiar with this method.  Has anyone else ever used this and do they have
> a reference and suggestions as to the type of carbon?
>
> Thanks in advance,
>
> Paul.
>
> Paul D. Brooks,
> Dept. ESPM-ES,
> 147 Higard Hall MC 3110,
> UC Berkeley, Ca. 94720-3110.
>
> phone (510)643-1748,
> FAX (510)643-5098.