The diluent washes the tubing between each sample, Gas Chromatography (GC) Blue Screw Cap with Bonded PTFE/Silicone Slit Septa (pk/100). Results of Using Re-washed Vials and Closures - Chromatography . Autosampler, Closures, Contamination, Used Vials, Vial Cleaning, Vials. Introduction 8-425 cap and attached to new 8-425 vials filled with.