By Anonymous on Wednesday, January 24, 2001 - 08:40 am:
Okay, I developed an isoctatic separation on a traditional 3 micron base-deactivated RP-18 150mm x 4.6mm i.d. column, looked good. The manufacturer made up three 150mm x 3mm i.d. columns for validation studies, different lots (ONE WAS THE SAME LOT AS WAS THE 4.6mm column); the flow rate was adjusted to about half to keep linear velocity/retention times the same. The resolution was actually worse on the 3mm i.d. columns. Halving the injection volume from 10ul to 5ul didn't help. The buffered mobile phase was unchanged, same reservoir. Have any others observed this or can explain this?
By tom jupille on Wednesday, February 28, 2001 - 05:46 pm:
Extra-column volume? (connecting tubing, detector cell. etc.).
If you're interested, I've got a spreadsheet that I generated for a training course a few years ago to calculate the effect of extra-column peak broadening as a function of column size and analyte k'. If you e-mail me separately I can send you a copy.
-- Tom Jupille / LC Resources
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