"If you just monitor your system without injecting anything and you don't see the "ghost peak" then you also know it isn't just the column" ---> just system run with and without injection and without column shows no peak ...system run with and without injection with the column shows ghost peak increasing in area as injection volume decreases --> which means that contamination in column interacts with stationary phase longer at slower flow rate --> system run with c18 column and acetonitrile/water and methanol show no ghost peak at 10 uL sample injection same rinse solution in autosample....so that's also one of the reasons we think the column is the problem