I did the annual maintenance of my HPLC 1200.
All tests are passed (pressure, leak, intensity).
I installed a new column to do the calibration of the HPLC and analyzed a standard to check the retention time.
The standard Tr is shifted from 0.7 min respect to normal Tr. I tested a second new column (from the same batch) and Tr is shifted from 0.7 min here again.
I tested an old column (with 1800 injections) changed in June 2019 and Tr is good.
In July, I had the same problem with 2 columns from the same batch: one had a shift of 0.4 min and the the other of 0.7 min) and I had to use the one with a 0.4 min shift since that time.
What protocole do you recommend to condition the new column ? I do 100% methanol for one hour.
Is there a drift due to zorbax columns fabrication ?
Before I change tubing and filters, what would you recommend to test ?
Many thanks for your help
