I have a TC-EA system based on the Hekatech furnace with glassy carbon tube
in ceramic tube design. It used to work fine. Now I have severe tailing
of the CO peak which I have been unable to cure. I'm out of ideas as to
what to try next.
Here are some things I have already tried.
1. The tailing is similar whether I try organic (eg sucrose) or inorganic
(eg silver nitrate) samples.
2. Changing the reactor temperature between 1200 and 1400 has no effect
3. Baking the molecular sieve GC column did not help
4. Reassembing the reactor numerous times including replacing the glassy
carbon tube and filling (130 mm GC 'chips' sieved to 2.5-3.5 mm + 5mm
layer nickelized carbon) had no effect.
5. Increasing the spring loading on the glassy carbon tube did not help -
the theory here was that the balance of gas flow through the inner and
outer tubes was incorrect and that more spring pressure would increase the
flow through the inner tube.
6. The system is leak tight and has a low background and blank.
What really gets me is that nothing I have tried so far had any effect -
any ideas most welcome
UC Davis Stable Isotope Facility
Department of Agronomy
3112 Plant & Environmental Sciences Bldg.
Davis, CA 95616
phone 530 754 7517
fax 530 752 4361