methanol to Acetonitrile gradient

[coquim]

HI people!...i really wanna know if would be possible to do a gradient method from methanol to Acetonitrile keep the same concentration of bufffer (i´m using tetrabuthylammonium and phosphate). For example, starting with 85% buffer 15%MeOh, and a certain time have 85% Buffer 15% Acetonitr....Have someone used to something like this?
Thanks in advance for all!

[tom jupille]

Sure. Just put your 85/15 buffer/MeOH in the "A" reservoir and 85/15 buffer/ACN in the "B" reservoir and program 0 - 100% B. (If you want to maintain isoelutropic conditions, however, you will probably have to fudge the ACN and MeOH concentrations).

The only scenario where I can visualize this being useful is the specific case where early-eluting peaks are better separated with MeOH and late-eluters better separated with ACN. Most people would use this as a last resort if other variables like temperature, pH, or column chemistry proved inadequate.

[coquim]

thanks for your answer T.J. i appreciate.
i must say that i finaly solve the separation modifying Ph and tº avoiding the gradient method...