Aerosols are an issue with centrifugation as well, says Dr. Rieger: “The centrifuges' rotors have aerosol-tight lids, which must only be opened under the clean bench.”
Do-it-yourself cleaning and autoclaving capability
“Once a year, the entire laboratory and all tools and devices are cleaned, wipe disinfected, and fumigated with hydrogen peroxide,” explains BioRisk manager Rieger. In this context, the maintenance and calibration of the pipettes is also carried out by an external maintenance service. The surfaces of the pipettes are wipe disinfected after each use. “We always work with filter tips and our staff are very experienced, so it is very rare for a pipette to be contaminated in the BSL-4 laboratory. However, as we do not have running water in this laboratory, we cannot rinse the pipettes,” says Rieger. Nevertheless, once a pipette is contaminated, it needs to be cleaned. Since any exchange with the environment has to be limited to the absolute minimum in laboratories of the highest safety level, contaminated pipettes are replaced and stored for the annual review. If this is not feasible, they would have to be discharged via the autoclave or fumigation with hydrogen peroxide, then thoroughly cleaned and rinsed, before being reintroduced to the lab.
In other laboratories, it is advantageous if pipettes can be thoroughly cleaned by the users. To meet this specification, a pipette must meet a number of requirements: The lower part of pipettes should be easily removable and cleanable by rinsing on the inside and with thorough cleaning of the whole pipette. This is especially important when using electronic pipettes, as there is no standard yet. The pipette has to be resistant to common cleaning agents and DNA/RNA cleaning solutions.
If sterility is an issue, the pipette must be autoclavable without dismounting. When using Eppendorf electronic pipettes, the lower part is removable and autoclavable to inactivate microorganisms that entered the pipette cone. If a pipette gets damaged in a BSL-4 laboratory, there are three possible solutions, depending on the damage: Repair by the users, repair by the maintenance service in the annual review, or destruction.