Dear all,

It was published quite some time ago (Tsuji et al., 1975) that for the Dumas
type combustion, as is used in the EA systems:
"....it is supposed that nitrogen oxides, formed during the combustion,
retain on the surface of the reduced Cu ...". No source of this statement is
given, however.
If this is true for Cu(/CuO) filled reactors, is the same memory found for
other fillings (e.g. Co3O4, Cr2O3 ± Ag ± Co3O4, WO3 on Al)? If there is a
significant difference in memory effect for one of these other materials
compared with the classical CU/CuO filling, then there is a good argument to
swap to that other material. I am curious about your reactions.

About Bill's message - makes sense to hear more about that, and how to solve
this problem. If indeed some of the commercial provided programs are leading
to wrong calculations for these enriched samples, it is important to be
reported. Might be a simple change in parameters in the program cures such
mis-calculations??? Is the Isodat software meant (suitable) for enriched
samples anyway?
Probably a matter Willi can give us some more expertise....

Reference:
Tsuji, O., M. Masugi, and Y. Kosai, 1975, An instrumental method for
nitrogen-15 and total nitrogen by combined system of mass spectrometer and
automatic nitrogen analyzer.: Anal. Biochem., v. 65, p. 19-25.

Berst wishes,
Pier.
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Dr. Pier A. de Groot
Economic Geology Research Unit
University of the Witwatersrand
Private Bag 3
2050 Johannesburg
South Africa
Tel. +27 11 717 6582  Fax. +27 11 339 1697
E-mail: [log in to unmask]

WEB-site on "Handbook of Stable Isotope Analytical Techniques (2 volumes)":
http://www.icon.co.za/~pagroot/index.html, or if finding problems:
http://www.icon.co.za/~pagroot/index_1.html
last update: August 15, 2000
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