<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2900.2912" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=Arial size=4>I have recently come across a problem the
answer to which I cannot find in the Archives.</FONT></DIV>
<DIV><FONT face=Arial size=4>The problem is this: If I run the same sample in
the AUC at the same temperature and speed over the course of 5 days, I get a
distribution of s values that has a spread of plus or minus <0.4%. The sample
is quite stable and shows no suggestion of degradation between days 1 and 4 but
a small peak (< 2% of the total) shows up on day 5. The perplexing thing is
that there are systematic differences between cells 1, 2 and 3. The s
values in cell 1 are always highest, the s values in cell 2 are lowest and the s
values in cell 3 intermediate. The differences are small. Cell 1 s values are
about 0.4% less than those of cell 1. </FONT></DIV>
<DIV><FONT face=Arial size=4>The samples in the three cells are the same; they
were taken from the same batch. The buffer is the same. </FONT></DIV>
<DIV><FONT face=Arial size=4>The problem has only become evident recently. It
was not present two years ago but I cannot state unequivocally when it first
started to occur.</FONT></DIV>
<DIV><FONT face=Arial size=4>Has anyone suggestions as to cause and what might
be done to correct the problem?</FONT></DIV>
<DIV><FONT face=Arial size=4></FONT> </DIV>
<DIV><FONT face=Arial size=4>thanks for any help you can give</FONT></DIV>
<DIV><FONT face=Arial size=4>jack (kornblatt)</FONT></DIV></BODY></HTML>