SI-50 application and Shodex catalog

Record: 858

Category: Column Problem
Product: SI-90 4E
Sample:

Question
The pressure was just over 900psi. I have probably only had about 50 injections in this column, even though I’ve had it for about a year. I honestly can’t remember what the system pressure was back when I first set up the IC. I’m wondering if trying to run the benzoic acid may have interfered. Should I try the wash for hydrophobic contaminants in this case?

Answer
Yes, I would use the regeneration conditions for the hydrophobic contaminants to see if you can remove any benzoic acid that may be interacting with the packing material.

The pressure does not seem to be the issue. The benzoic acid may be interacting with the packing material and taking up the active sites. In this case the anions may take longer to elute because there are less active sites for the anions to interact with during analysis. Again, did the change in retention times occur gradually or suddenly?

 
 
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