Dear list memebers !

Anyone out there experiencing the same problems ? As the quartz
reactor tubes for the reduction and oxidation reactors of my
elemental analyzer quite easily break upon removal of catalysts, I
turned to stainless steel tubes. I used one of these to
contain the reduction catalysts, the oxidation one was still made of
quartz.
The carbon and nitrogen contents as well as the carbon isotopic
results were quite fine, very reproducible and correct. However, the
delta15N values were false showing numbers being 50 to 80 permille
versus atm-air too high. This problem did not dissapear upon
analysing 250 samples with the same reactor, but immediately vanished
when switching back to the quartz tubes.
Are there possibilities to deactivate the steel column ? Are there
steel qualities, which don't give rise to such problems ?
 Please help, otherwise I'll have to return the tubes back to the
producer. Thanks in advance,

Wolfgang
Dr. Wolfgang Wanek
Department of Chemical Physiology of Plants
Institute of Plant Physiology
University of Vienna
Althanstraáe 14
A-1091 Vienna, Austria

Tel: + 431 31336 1426
Fax: + 431 31336 776
Email: [log in to unmask]