And need I say, after effecting the repair, you can re-process the affected results with a defined integration window for N2 that excludes the ref gas injections?
Yes, that usually means a damaged / old VG-GVF003 ferrule (that’s where the valve plunger seats).
You’ll probably have to replace the ferrule and the capillary attached to it.
Refer to the Isoprime’s Reference Injector Manual. It is pretty straightforward.
Rodrigo Nascimento Maia
Laboratory Technical Supervisor
SIIAF - Stable Isotopes and Instrumental Analysis Facility
Fundação da Faculdade de Ciências de Lisboa
Universidade de Lisboa
T: +351 21 7500619 (direct) ; internal: 22119
SIIAF – Stable Isotopes and Instrumental Analysis Facility
Faculdade de Ciências de Lisboa – Departamento de Biologia Vegetal
Edifício C2 – Sala 2.1.16
1749 016 Lisboa
This is aimed at all the IsoPrime users who’ve experienced the dreaded type mismatch error. I’ve been running dual gas CN runs and the other night things started to go haywire. Carbon values are dead on, but nitrogen results started to experience type mismatch errors (7 in a run of 100). When I looked at the chromatograms, the ref gas peak is either not there or is very jagged; as a consequence, MassLynx thinks the ref gas peak is actually a sample peak.
I’ve done a bunch of nitrogen stability runs and the chromatograms are not pretty (I can email a copy to anyone interested off list). Carbon stability runs are nice, flat and smooth. Based on my search of the archives, it looks like the nitrogen ref gas valve is sticking. Has anyone taken one of them apart? Air pressure is fine, and since carbon is stable, I don’t think it’s a dirty source.
Any advice would be greatly appreciated!
IRMS Laboratory Manager
Boston University Stable Isotope Laboratory
Department of Biology
5 Cummington St.
Boston, MA 02215
Email: [log in to unmask]
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