Dear Listmembers
We have had a recent spate of Cu reduction tubes becoming blocked by
some reaction taking place within the copper oxide which is forming as
the copper becomes oxidised. The system is a Carlo Erba EA attached to
a Europa geo 20/20 running in continuous flow mode. the reduction
furnace runs at 600 C.
Instead of the usual granular copper oxide replacing the granular
copper we get a black shiny (viterfied) plug of solid copper oxide
which blocks the He flow  and in bad cases fractures the silica tubing
of the reduction column.
There seems to be little pattern as to when it happens and is just as
likely towards the end of the life of a reduction column as a few hours
after a column change. The vast majority of samples that we process are
collagen.
Has anyone else had similar experiences? any thoughts on possible
causes such as excess water in the combustion products?


Dr. Peter Ditchfield
Stable Isotope Laboratory Manager
Research Laboratory for Archaeology
University of Oxford
6 Keble Road, Oxford, OX1 3QJ, UK
tel:01865-283647
fax:01865-273932