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isoelutropic mobile phase
Posted: Wed Sep 26, 2007 3:50 pm
by olivia
Hi, can anyone tell me what the equation is to convert the organic modifier in the mobile phase from methanol to acetonitrile and keep the retention time the same
Thanks
Liv
Posted: Wed Sep 26, 2007 8:41 pm
by tom jupille
I don't think I've actually seen the equation, but the nomogram has been around for decades:
It's only an approximation in any case (obviously, details will depend on stationary phase and analyte).
Posted: Wed Sep 26, 2007 9:11 pm
by Uwe Neue
Unfortunately, it depends on the column, and the analytes. A reasonable rule of thumb is MeCN = 0.25 MeOH^2 + 0.65 MeOH (MeCN and MeOH in volume fractions).