right now I am measuring enriched samples (up to 2 atom % 15N) on my NC2500
with Delta Plus. I have a blank of about 10 mV and I noticed that my blank
is also getting enriched during a run, up to a few hundred permil. The
first blanks at the start of a run have normal values. When I check the
source of the blank is comes mostly from the autosampler ( by moving the
autosampler without tin cup and with O2 injection off).
Allthough blank corrections are minor, I am a bit surprised that my blank
is getting enriched.
Does anyone have the same experience?
Richard van Logtestijn