Oct 26, 2021 · Clear VOA Vials with 0.125 in. Low Bleed Septa Ultra Low bleed septum is low in free-siloxanes making it ideal for soil analysis by EPA Method 5035. Siloxane peaks originating from the silicone septa during in-vial heated purge and trap procedures like EPA Method 5035 can cause interference with detecting target analytes of similar retention times.