Aspiration of media into a collection flask under vacuum is one of the most commonly performed laboratory procedures. It is important to protect the house vacuum from liquids and aerosols that might contaminate the system. Use a hydrophobic filter and in-line disinfectant flasks to protect your vacuum system from potential contamination.

Effective decontamination and house vacuum protection is simple following these instructions:

• Before aspiration, add decontamination solution at the recommended concentration to the collection flask. For example – add undiluted bleach to fill 10% of the final volume of the collection flask (100 mL undiluted bleach added to a 1 L collection flask).

Bleach is an effective decontaminant for cell culture media with the added advantage that its strong oxidizing properties will turn the phenol red indicator in the media from pink to yellow/clear.  Aspiration flasks containing pink liquid indicate insufficient bleach concentration and should be topped off with fresh bleach until a yellow/clear color is achieved prior to additional aspiration or disposal.  If the collection flask is maintained for more than one day, be advised that the disinfectant qualities of bleach degrade after 24 hours. Therefore, additional bleach must be added to the collection flask daily. 

• Label the collection flask “biohazard” to identify its contents.
• Overflow collection vessel, HEPA in-line filter, and secondary containment/spill tray need to be installed to provide adequate protection.

Modified from: www.cdc.gov/biosafety/publications/bmbl5/BMBL5_appendixA.pdf