Chromatography Forum

Hi,

We have a very low dose fomulation that uses ethanol:propylene glycol:H2O=5:45:50 as vehicle and hope to directly inject this formulation into HPLC without diluting. Although I am worried about the viscosity of the Propylene glycol the pressure looks OK while shooting it directly into HPLC, I've tried filtering samples (0.45um nylon, PTFE, GHP) before injection but all have interference peaks, so can I not filter the sample because the pressure didn't seem to increase at all?

Thanks.

Can you post the name of the sought-for analyte, that would help.

A polar column will retain somewhat the propylene glycol and ethanol, may give un-interfered peak for you. With nonpolar column, those will elute quickly.