to the water equilibration people,
 
just a reminder, the isotope equilibration between H20 and H2 happens in the vapor phase , so if there is no H2S in the vapor (depending on the pH of the liquid ) then there is no poisoning of the catalyst surface. But if you do have H2S in the vapor phase the catalyst will be inactive with time. And a second reminder: the equilibration occurs on the catalyst surface the catalyst has to be temperature controlled . some people place the catalyst well above the liquid phase at the top of a bottle where the temperature might be different by a few tenth of a centigrade compared to the temperaturecontrolled liquid and therefore they get different fractionation results. and a third thing: do not stop bacterial activity with HgCl2 this ruins the catalyst
 
Hans Friedrichsen
 
for
 
MS Analysentechnik (producer of the catalyst sticks)



-----Ursprüngliche Mitteilung-----
Von: Jonathan Wynn <[log in to unmask]>
An: [log in to unmask]
Verschickt: Di., 15. Jan. 2008, 19:15
Thema: [ISOGEOCHEM] poisoning of D/H platinum rods/Hokko Beads by dissolved sulfide, and copper pre-treatment

Hi All,
 
I've read in the ISOGEOCHEM archives that the Platinum catalyst used in D/H analyses of H2O by equilibration can be "poisoned" by dissolved sulfides. Does anyone have experience to estimate a sulfide concentration above which this effect should be considered significant? I've also read about pre-treatment with copper to avoid this problem. Does anyone have a reference or advice for a standard pre-treatment?
 
Thanks,
 
Jonathan Wynn
Department of Geology
University of South Florida
4202 E Fowler Ave, SCA 528
Tampa, FL 33620
Tel. +1 (813) 974-9369
Lab. +1 (813) 974-5278
Fax. +1 (813) 974-2654
[log in to unmask]
http://shell.cas.usf.edu/~jwynn

---

Bei AOL gibt's jetzt kostenlos eMail für alle! Was es sonst noch umsonst bei AOL gibt, finden Sie hier heraus AOL.de.