Tissue Culture Nosepiece by Drummond Scientific Co.

• The Drummond Tissue Culture Nosepiece eliminates the possibility of cross-contamination due to over-pipetting. It incorporates a dual hydrophilic 0.8 µm, hydrophobic 0.8 µm filter which prevents further use once contaminated by fluid. This double membrane filter provides a barrier to particles as small as 0.1 µm. Each kit contains all necessary parts including four filters. 
• Extra filters may be ordered separately 
• The Tissue Culture Nosepiece has been certified to meet or exceed USP Class VI - 121° plastics tests for biosafety.

Why Use a Drummond Self-Locking Filter in Your Pipet-Aid?
In order to provide a fail-safe, one-time check valve for Pipet-Aid pipettors, Drummond pioneered the use of a “self-locking” dual layer filter composed of one hydrophobic membrane and one hydrophilic membrane located in the nosepiece. With a dual layer membrane, when the filter is challenged with an aqueous solution, the hydrophobic layer prevents liquid from entering the handle and the wetted hydrophilic layer restricts the flow of air which locks the Pipet-Aid from further use.

The most effective safety measure to prevent contamination is the cotton or fiber plug in each pipet. Even if a sterile filter is installed in a Pipet-Aid, the first time an aerosol comes in contact with the bottom membrane, the filter is rendered forever non-sterile. The only thing that prevents this from happening is the plug in the pipet itself which prevents aerosols from leaving the pipet and prevents them from entering. Drummond "self-locking" filters are supplied nonsterile because we believe there is no effective and practical method to maintain sterility in these devices.