Suvankar, Do you have a good mass calibration and tuning for HD? For all of my XPs I have had to do a manual calibration. It is rather different from setting the instrument up for a gas like CO2 or N2. If you need more information on a HD calibration please let me know. Cheers, Ben Benjamin Harlow Manager, Stable Isotope Core Laboratory Washington State University School of Biological Sciences 367 Eastlick Pullman, WA 99164-4236 Office: 509-335-6161 Lab: 509-335-6154 Fax: 509-335-3184 Laboratory for Biotechnology and Bioanalysis (LBB2) Stable Isotope Core http://www.isotopes.wsu.edu<http://www.isotopes.wsu.edu/> From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Mihai Lefticariu Sent: Monday, July 16, 2012 1:21 PM To: [log in to unmask] Subject: Re: [ISOGEOCHEM] Detection of H2 with Conflo IV and Delta Plus XP Suvankar, Check the position of the needle (SGE) valve you use for the TCEA on the IRMS, maybe it helps. Cheers. Mihai Lefticariu (Southern Illinois University Carbondale) On Mon, Jul 16, 2012 at 1:33 PM, Suvankar Chakraborty <[log in to unmask]<mailto:[log in to unmask]>> wrote: 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.