I'm actually using a multi-collector inductively-coupled-plasma mass spectrometer, which means that the very expensive vacuum leak is by design -- sample is introduced in a plasma chamber at atmospheric pressure, which has been pumped down to 10-9 mbar by the time you get to the analyser end of the machine! Which at least means that doesn't need troubleshooting (except when the analyser ends up overpressured, but having cocked that up yesterday morning it was at least a fairly straightforward fix...).
We run on argon rather than helium; this means that Hilarity Ensues, because our argon supplies contain trace quantities of mercury... which exhibit isobaric interference with several of the elements I'm actually trying to measure. So in addition to monitoring stable isotopes of lead and thallium, I have to simultaneously monitor 202Hg so I can apply a correction factor for the 204Hg interference with 204Pb...
Compression fittings are, similarly happily, Not My Problem. :-) But I did, when swapping cones over, end up having the replace the graphite ring that provides a seal and good conduction, it having very comprehensively stuck to the cone that was seated on it...
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We run on argon rather than helium; this means that Hilarity Ensues, because our argon supplies contain trace quantities of mercury... which exhibit isobaric interference with several of the elements I'm actually trying to measure. So in addition to monitoring stable isotopes of lead and thallium, I have to simultaneously monitor 202Hg so I can apply a correction factor for the 204Hg interference with 204Pb...
Compression fittings are, similarly happily, Not My Problem. :-) But I did, when swapping cones over, end up having the replace the graphite ring that provides a seal and good conduction, it having very comprehensively stuck to the cone that was seated on it...