All,

I've been writing to this list a lot lately. The mass spectrometer is 
finally behaving properly and I am finally trying to fix a problem 
that appeared just as everything else went crazy.

When I run carbonate samples using our Gas Bench, typically it takes 
about 300 seconds for the carbon dioxide sample peak to come out. 
This has been the case for more than a year. Then, literally 
overnight, this changed to about 400 seconds. Nothing on the Gasbench 
was changed during the intervening night.

Since then, I've adjusted the GC temperature, which only changes the 
elution times by a few 10's of seconds at most. I've also adjusted 
the Helium carrier pressure, which makes the peaks come out at the 
right time, but the flow is so rapid that my sample peaks diminish 
far too quickly for an adequate analysis.

What am I missing?

Thanks,

~Penny

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                       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

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Office: 209b Hutchison Hall               Lab: 209 Hutchison Hall
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