beginrag is correct, vacutainers are completely sterile. The company I work for does the sterilization of these for some companies.
Obviously though once you touch them and open them they are not sterile, but there shouldn't be any contaminants.
10G - Low Tech Planted [ Chocolate Neos, MTS, Tracked Nerite / Anubias Nana, Windelov Java Fern, Water Wisteria, Dwarf Sag ]29G
- Non Planted Native Tank [ Creek Chub, Yellowfin Shiners, MTS / Water Wisteria ]