Dear Ingeborg,

Unfortunately, you do not give enough specific details about the
equilibration device, or the type of "Hokko" rods you are using, or the type
of waters you are analyzing.

In our laboratory we use Hokko 1 phi "beads" routinely for H2-water
equilibration.  We found that washing and heating to 60 C caused the beads
to lose their hydrophobicity, so essentially they were ruined by heating.
We now only rinse the beads with distilled water and let them air dry. We
have re-used 100 g of beads for over 2 years with no loss in performance.
So there really is no "re-activation" involved.  Is overheating a
possibility in the case of your rods?

Apparently, heating does not appear to be the detrimental for the Hokko
"powder" glued on rods - Dr. Ty Coplen (and others?) will attest that powder
on rods is OK with 60 C heating. Another factor could be poisoning of the
catalyst by H2S in your waters as is documented in the literature.

Len

Dr. Leonard I. Wassenaar
Stable Isotope Hydrology and Ecology Lab
National Water Research Institute
11 Innovation Blvd.
Saskatoon, SK
S7N 3H5 Canada
tel: (306) 975-5747
fax: (306) 975-5143
email: [log in to unmask]

-----Original Message-----
From: Ingeborg Gottlieb Inacio [mailto:[log in to unmask]]
Sent: Wednesday, May 26, 1999 7:54 AM
To: [log in to unmask]
Subject: Hokko rods in equilibration unit


Our trouble began with unstable results from the equilibration device, large
standard deviations and some results totally out of range, generally shifted
to the side of very high enrichment. So we looked for contamination, changed
sample bottles etc. In the end we tried new Hokko rods - and every run was
ok.  At least for a couple of weeks. Then the trouble started again. I am
almost sure the "new" Hokko rods we bought are from the same batch as the
old
ones we hade in use for about one year.

We also asked our supplier for better Hokko rods recently made by the
manufacturer. We were suggested to run an experiment without any water at
all, with only the Hokko rods inside the sample bottles. The result is
almost
0 for both H and CO2 for all 24 samples.

Has somebody in the community any experience about how to reactivate those
Hokko rods?
And what is their function in the equilibration process?

Until now we have done as suggested after every run: Flushing with distilled
water, oven at 60 degrees overnight and until 5 minutes before next run. But
so after one year the rods don't work anymore.

I will be most grateful for any help.