With compound specific isotope analysis in mind, I would like to know from
anybody who has tried CF-mode D/H measurements with a Geo2020 in a
GC-Pyr-IRMS configuration, where helium is the carrier gas and thus ends
up in the ion source. The detail I'd like to hear this community's opinion
on whether the interference from the "low-energy" tail of the mass-4 He+
peak underneath the mass-3 DH+ peak is very system dependent. Both the GVI
Micromass and Thermo Finnigan systems have a special method in place to
rid off this tail. Is it possible that the beam optics of the core Geo2020
system effectively separates any remnant of the 4He+ peak from the DH+
peak and therefore does not need an additional trick ? Did anybody try to
replace the He by another noble gas to carry analyte through the various
capillaries and plumbing ? I have to make a judgment call on an upgrade
plan, and thus would greatly appreciate your thoughts.