Peak Splitting & Poor peak shape using VanGuard

I am seeing peak splitting or poor asymmetry when using a Vanguard column but not when it is removed. On another UPLC the peak shape is good and as expected. It seems likely to be due to dead volume in the fitting between the column guard and active column preheater. Has anyone had similar experience or could recommend better fittings?

Separation conditions: Cortecs C18 2.1 x 50 mm 1.6um Column, Vanguard Cortecs C18 2.1 x 5mm, Mobile phase: 45:45:10 0.2% H3PO4:MeCN:MeOH


  • Hi dmurray648 - This article from the knowledge base has some helpful tips for finding the cause of splitting peaks.  Maybe it will help!

    Good Luck!
  • If every peak (if more than 1) has deformed/split peaks that's the sign of a mechanical issue either with a connection or even potentially a defect with the VanGuard PreColumn.  As referenced earlier the knowledge base has good tip on troubleshooting this issue. If multiple VanGuard PreColumns don't improve the peak shape/give the same poor results, that would point to a connection issue; re-setting the ferrule/fitting on the inlet tubing/preheater is the first action I'd take.  Also it would be recommended to confirm that the pre-heater is "on" on both systems.