Which factors can increase the retention time
A longer retention time may be caused by back pressure developing during analysis. The following factors may increase the retention time of analyte (drug molecule):
- Pump has not been cleaned satisfactorily
- Unfiltered buffer used
- High buffer capacity was used with solvent (methanol and/or acetonitrile)
- Guard column blockage
- Unfiltered dissolution sample was injected
Retention time of the drug can be increased (right hand graph) if back pressure develops during HPLC sample analysis