Stable Isotope Geochemistry


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Zheng-Hua Li <[log in to unmask]>
Reply To:
Stable Isotope Geochemistry <[log in to unmask]>
Wed, 11 Feb 2004 20:05:01 -0500
text/plain (66 lines)
Dear Germán,
Have you tried to restart the software? We had some crazy peaks with the NT
system a while ago, I simply turned the software off, then restarted it,
everything was back to the normal. Based on your story described above, it
seems to me that there is nothing to do with  EA and ConFlo. The He flow is
fine, and no CO2, H2O, O2 signal when you inlet N2 means no leakage. So, it
seems the problem comes either from the MS or the computer. Since you still
can get the peaks (no matter how crazy they are!), that means the filament is
good. If the RESTART doesn’t work, I might need to blame the MS. Go ahead shut
off the SGE valve to see what will happen. If the problem still shows up, Then
the MS is wrong.

Please let us know if you are still crazy!

Hope it helps,

Good luck,


Zheng-Hua Li
306 G&G Building
Dept. of Earth and Planetary Sciences
University of Tennessee, Knoxville, TN 37996
Tel: 865-974-9622
Fax: 865-974-2368

>===== Original Message From Stable Isotope Geochemistry
<[log in to unmask]> =====
>We have a problem with our Conflo-III system, which is attached to a
>Delta Plus XL. When we turn on any of the reference gases (CO2 or N2),
>we get a large signal (>14 volts).  My first thought was that the
>pressure was too high. We decreased the pressure using the gauge in the
>Conflo unit, but there was no luck. We checked the pistons and the
>distances of the capillaries inside the open split glass cell when they
>are on and off, and all of them looked ok.  I also thought that we were
>not getting any or low flow of helium. We measured the flow of the
>helium stream entering the open split glass cell and it was what is
>expected (~2 ml/min).  We even disconnected the EA to see if somehow the
>problem was with the EA, but we still see the same problem.  What makes
>this problem so particular is that when we turn on the CO2 reference gas
>we only get a large signal on mass 44. Masses 28, 40, or 18 only show a
>slight increase. When we turn on the N2 reference gas we only get a
>large signal (>14 volts) on mass 28, not on any other mass.  I ran out
>of ideas, so I would  really appreciate any help.
>Germán Mora
>Assistant Professor
>Depart. of Geol. & Atmosph. Sci.
>Iowa State University
>Ames, IA 50011-3212
>Phone: 515-294-7586
>Fax:   515-294-6049
>E-mail: [log in to unmask]