A roasters reply.

We've been vacuum roasting at 300 deg C for years. There is no need to go
higer since the object is only to remove volotile organics. Our experiments
show no isotopic shifts for either foraminifera or aragonitic carbonates.

I suspect that 200 deg C would be sufficient.

-----------------------------------------------------
Bob Fifer
Benedum Stable Isotope Laboratory
Brown University                Geological Sciences
Box 1846
Providence, RI 02912

Phone:  401-863-1698            E-mail: [log in to unmask]
Fax:    401-863-2058