To start work in different modes of HPLC, a simple switching procedure is recommended.
A simple 30 minute procedure allows switching from one mode to another.

Procedure:

A – Moving from Reversed Phase to Normal Phase HPLC; pump 100% methanol for 15 minutes at 1 mL / minute flow rate, followed by 15 minutes 100% methylene chloride. The column is ready to be equilibrated with mobile phase for NP-HPLC.

B – Moving from Normal Phase to Reversed Phase HPLC; pump 100% methylene chloride for 15 minutes at 1 mL / minute flow rate, followed by 15 minutes 100% methanol. The column is ready to be equilibrated with mobile phase for RP-HPLC.