if must...and i do IF MUST!!!
afer loading the liquid, put the needle on spare syringe and power squeez it down wih alcohol. a couple of times, 5-6 cc, 1 cc at the time, and the last time you put the cap back on the needle and getthe alcohol in it as the cap is closed.
again THIS IS ONLY IF YOU MUST!!!! for whatever unexplainable reason it may be.. i cant think of any, but i worked on a cruise ship in my youth and only had limited needles, was recomended to this way by crew dr.
and every time before use practice power flushing for a couple of cc .. but do have to have designated syringe and needle... (for storing )

and then just use the needle to load... and put it back on the storing designated syrienge

AGAIN NOT THE SAFEST WAY, YET THE SAFEST OUT OF NOT SAFE PRACTICES....