Martin,

We use dual inlet IRMS here.
We prepare our atmospheric nitrogen standard offline using a pyrex/quartz
prepline, similar to that in the 1975 paper by
Charles Kreitler. We run the air sample first through a quartz copper oxide
furnace at 700 degrees C, then through a pyrex
copper oven at 400 degrees C. Our comparisons during an interlaboratory study
was very good.

Glen  Martin
Water Sciences Laboratory
103 NRH, East Campus
University of Nebraska
Lincoln, NE 68583-0844
voice: 402-472-8210
FAX:   402-472-9599