When using an Elemental Anlayzer (Carlo Erba) to measure natural abundance
15N I seem to find that the age of the magnesium perchlorate can affect the
results.  If I get poor results, replacing the magnesium perchlorate seems
to solve the problem, but eventually this doesn't seem to work.  Then I
switch to a new previously unopened bottle of magnesium perchorate, and
this again seem to solve the problem.  It is as though the magnesium
perchlorate gradually deteriorates in the bottle after it has been opened a
few times.

Has anyone else experienced this?

I recall someone telling me that they used a small amount of P2O5 after the
Magnesium perchlorate in the water trap, and that this would take out
additional water.  Has anyone tried this and does it affect 15N or 13C
analysis?

Thanks in advance,

Paul Brooks.



Paul D. Brooks.

Dept. ESPM-Ecosystem Sci.,
151 Hilgard Hall, MC 3110,
UC Berkeley, Ca. 94720-3110.

phone (510)642-3155
FAX   (510)643-5098 (to Att. Paul Brooks)