Dear All,
 
I have been measuring carbon and nitrogen isotope ratios using my Delta Plus IRMS (Thermo) interfaced with a Flash elemetal analyser (EA1112) through Conflo III.  Recently, I noticed an unique problem.  The two reference gas injections used to give me a std dev. better than 0.06 permill. But now, the std dev are pretty bad.  I tried tightening the capillery ferules at the Conflow interface.  The areas of masses 44, 45 and 46 are not very bad, they are not exactly same!  Can this small change in area cause a huge shift in std dev of the isotope measurements?  Has anyone encountered a similar problem?  Please can you suggest a solution to this?
 
Thanks and regards,
Shesha 

Dr. M.S. Sheshshayee
Associate Professor
Department of Crop Physiology
University of Agricultural Sciences
GKVK Campus, Bangalore 560 065
INDIA

Ph(W): +91-80-2362 0737
Ph(H): +91-80-2363 6414
Mobile: 93425 90578



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