AAA AccQT. question?
Freedy, James [OBI] (Jfreedy@obius.jnj.com)
Fri, 15 Oct 1999 07:33:52 -0400
Good Day,
I have been successfully using the AccQTag chemistry and system, for
amino acid analysis. I am monitoring by both UV and fluorescence and have
determined LOD and LOQ for my specific application. As well I have
determined a dynamic range of linearity for this application and both
precision and accuracy have been demonstrated.
My question is; why after approximately 18 chromatographic runs do I
lose my retention times for the amino acids?(They slide off the back end of
the chromatogram.) Is it strictly a column conditioning phenomenon or is
there more to it than that? I have been able to bring the chromatography
back to the original optimized state twice by just re-starting the system as
described in the manual(5min, 60%acn/40%water, 9min, 100%buffer, AccQT
eluent A). My third attempt at a re-start, as in the manual, was not
successful, I had to wash the column more extensively with acn and water
before I could generate the original chromatography. I would appreciate any
input, because of the time savings in not having to work it all out on my
own. Either on-line or off will do, but on-line may benefit others as well.
Thanks in advance.
James G. Freedy
Ortho Biotech, Inc.
jfreedy@OBIUS.JNJ.com