I-screw cap engu-9mm yenziwe ngezinto ezisezingeni eliphezulu, ihlinzeka ngokuqina okuhle kakhulu nokumelana namakhemikhali. Ukucutshungulwa kwayo okunembayo kuvumela ukuvaleka okulula nokuphumelelayo, okuqinisekisa ukuvalwa okuthembekile kwezitsha ze-HPLC. I-septa, eyenziwe ngezinto eziyisipesheli, inikeza ukungabi nalutho okuphelele nokuhambisana namasampula anhlobonhlobo, iqinisekisa imiphumela enembile nephindaphindekayo ekuhlaziyweni kwe-HPLC.