Changing Mobile Phase Without Interrupting the Flow

The method for the titer assay that we want to run is a bind and elute assay, we have to change the mobile phase once we bind the mAb to the column in BLC-20P HPLC. How we use a gradient system to change the mobile phase in BLC-20P HPLC under full pressure with an isocratic system without depressurizing the system or interrupting the mobile phase flow?

Equipment: Buck Scientific BLC-20P HPLC