EPA Vials. MilliporeSigma. these vials are assembled with the following materials: Type 1 borosilicate glass, PTFE/silicone septa, and a polypropylene cap. The vials are available in either clear or amber glass. All of the vials are packaged with an open top cap and a tan/white PTFE/silicone septa. The 40 mL EPA vials .