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Hi Hans, What do you use to stop bacterial activity? Linda Anderson At 04:27 AM 1/16/2008, you wrote: >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 ><mailto:[log in to unmask]>[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<http://www.aol.de> <http://www.aol.de>AOL.de. Linda Davis Anderson, Ph.D. 1156 High St. Institute of Marine Sciences University of California Santa Cruz, CA 95064 email: [log in to unmask] FAX: 831 459-4882 phone: 831 459-4789