SH1011 Issue

Record: 645

Category: Column Problem
Product: SC1011
Sample:

Question
DuPont is having a problem with an SH1011 he just put in service. The column was purchased in June of 2011 with SN H104152.

For the first time ever they are seeing a grouping of peaks eluting ahead of citric acid that are causing a drifting baseline and leading to very poor reproducibility of the citric acid peak. RSD’s are as high as 50%.

There are several peaks in the grouping and it their pattern appears reproducible although they are not attempting to quantitate them.

They are only visible in the UV they do not appear in the RI implying that their concentrations are rather low. They were not able to give me detector settings on the UV or RI.

In their analytical scheme they want to quantitate citric acid so this is a problem for them. Their internal standard is pivalic acid which elutes after everything else and has good reproducibility.

The only runs they have made are with their standards and the same standard was run on an older column on a different machine and on those runs, there were no extraneous peaks visible in the UV. This, in their mind, implies the column is the source of the column and the standard is OK.

They also feel that the standard is pushing something off the column since the position of the peaks is always the same and only appear when their standard is injected.

So far the column has had about 1L of water with a 0.01N sulfuric acid (did not confirm this concentration) run through it.

Answer

 
 
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