Hi all. I have a curious problem. I've been doing headspace analyses 
for d18O of water samples using the Gasbench in continuous flow mode 
on our Delta plus XP.

A few samples yielded negligible peaks. I re-ran them, and still no 
measurable peaks. I decided to check the pH and have found that the 
samples that won't run are all at about pH 12. Presumably, the CO2 
gas that I'm flushing with is going into solution in the water rather 
than remaining a gas in the headspace and exchanging oxygen like good 
gasses should.

I think I need to neutralize the waters, but I'm not sure how to do 
it without affecting the oxygen values of the water.

Has anyone else dealt with this problem? What did you do about it? If 
need be, I could run the oxygen analyses using our TC/EA, but since 
I've run all the other samples in this set by headspace 
equilibration, I'd like to run them all this way.

Thanks,

~Penny

*******************************************************************
                       Dr. Pennilyn Higgins
                        Research Associate

                             "SIREAL"
   Stable Isotope Ratios in the Environment Analytical Laboratory

         Department of Earth and Environmental Sciences
         University of Rochester
         227 Hutchison Hall
         Rochester, NY 14627

                    [log in to unmask]

Office: 209b Hutchison Hall               Lab: 209 Hutchison Hall
Voice : (585) 275-0601              Outer lab: (585) 273-1405
FAX   : (585) 244-5689              Inner lab: (585) 273-1397

           http://www.earth.rochester.edu/SIREAL/index.html
*******************************************************************