I pre-slit chromatography vial septa with PP caps Sigma-Aijiren Chromatography Vials, Caps, Septa & Inserts, Tubes, 31/7/2020 · Pre-slit septa is ideal for automatic sampleing because Septa is kept sealed between Vials and Caps, and pre-slit processing makes it easy to puncture the sample feeder's injection into HPLC Vials for sampling.