ITSP SmartSPE, PFAS-free UCT Enviro-Clean WAX, 10 mg, These SmartSPE cartridges are manufactured with Polypropylene/Silicone septa to eliminate PTFE from interfering with PFAS related compounds. Also review our list of 11 mm snap caps with Polypropylene/Silicone septa and 11 mm Polypropylene Snap Cap Vials.