Huge tailing during SEC HPLC on 1260/1290 but not 1100 machines?

I'm running SEC HPLC and getting these very long broad tails consistently - the peak doesn't broaden, but it also does not return to baseline except as a very gradual slope. The issue seems to get worse the longer the machine has been running (see below), and switching from steel to PEEK tubing and swapping out different flow cells has not helped. What's most unusual is that the problem only happens on our 1260/1290 series hplcs - the exact same sample, method, buffer, and column on a much older 1100 series does not give any issues.

 

Blue line is the first run, teal line is the exact same sample after 2 more repeat injections.

 

Does anyone have any idea what's causing this? And why the older series instrument doesn't have the same issue? We are using an advancebio SEC.

Parents
  • There are several possible causes of tailing.  Firstly, it's likely the flow cell volumes in each detector are different. The standard cell for the G1315 is 13ul, while the standard cells in the G4212 and G7117 are just  1ul so this is not an apples to apples comparison.   Also look at the type of capillaries used in the systems and see if there is any difference in the internal diameter, and length. Larger capillaries and longer lengths mean greater dead volume and dispersion effects. Replace green tubing with Red tubing.

    There might also be effects due to Silanol interactions, or contamination on the column. Clean column or replace. 

     

    -Howard

Reply
  • There are several possible causes of tailing.  Firstly, it's likely the flow cell volumes in each detector are different. The standard cell for the G1315 is 13ul, while the standard cells in the G4212 and G7117 are just  1ul so this is not an apples to apples comparison.   Also look at the type of capillaries used in the systems and see if there is any difference in the internal diameter, and length. Larger capillaries and longer lengths mean greater dead volume and dispersion effects. Replace green tubing with Red tubing.

    There might also be effects due to Silanol interactions, or contamination on the column. Clean column or replace. 

     

    -Howard

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