How long is it since this machine measured H2? Has there been source cleaning since then? Have you run the autofocus? Sometimes this bootstraps a signal from nothing.
Otherwise I think you could be describing the situation where the H2 configuration is not focussing the beams into the collectors - that is the wrong combination of HT and magnet settings - a situation I have had after replacing a mass spec computer and having to recreate the gas config. Start with HT = 2.85kV and magnet = 950 (my current XP settings) and then making say 20 step magnet adjustments, do HT scans over 100 volts or so/run the peak centre routine. Note that when you perform a magnet scan the position of the peaks does not correspond to the static magnet current required to focus the beams into the collectors.
> -----Original Message-----
> From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On
> Behalf Of Suvankar Chakraborty
> Sent: Tuesday, 17 July 2012 6:33 a.m.
> To: [log in to unmask]
> Subject: [ISOGEOCHEM] Detection of H2 with Conflo IV and Delta Plus XP
> Dear All,
> This is my first time on Isogeochem, I am Suvankar
> Chakraborty, a post doc at University of Kentucky.
> I was trying to setup a TC/EA with our Conflo IV and Delta Plus XP.
> However, when I am trying to calibrate our Delta plus XP for H2, I cannot
> see any H2 in the scan. H2 tank is connected properly with Conflo IV
> without any leak and I am getting pressure reading in the Conflo IV unit.
> I have leak tested several time. Conflow IV is properly configured for
> TC/EA (solid) using H2 reference gas. Mass 2 and 3 are supposed to be
> collected in cup 2 and 8.
> During the scan I can see peak for mass 3 but no luck with mass 2. No auto
> dilution has selected.
> If there is someone who is using the Conflo IV and using H2 gas can you
> please help me to determine the problem. Happy to receive any suggestion
> about this matter.