VICI Jour offers two types of low-pressure fittings for 1/4-28 flat-bottomed fitting details:
Flangeless connections utilize several ferrule designs. The ferrule grips the tubing as the fitting is tightened, without significantly reducing the tubing ID.
Flanged tube end fittings are held onto polymeric tubing by a flange pressed onto the port with a nut and polypropylene washer. The washer protects the flange, yet never comes in contact with the mobile phase.
More information on Properties of Polymers
See AlsoEasy-flange kit