- Decontamination—Any process for removing and/or killing microorganisms. The same term is also used for removing or neutralizing hazardous chemicals and radioactive materials.
- Disinfection—A physical or chemical means of killing microorganisms, but not necessarily spores.
- Sterilization—A process that kills and/or removes all classes of microorganisms and spores.
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Pipette cleaning
Cleaning requirements depend on the pipette used and the liquid. The chemical compatibility of the pipette should be checked prior to cleaning. When necessary, protective clothing, goggles, and disposable gloves should be worn.
Table 1. Cleaning guidelines for Thermo Scientific manual pipettes. See instructions for use for Electronic Pipettes guidelines.
| Pipetted liquids | Cleaning guidelines |
|---|---|
| Aqueous solutions and buffers | Open the pipette, rinse the contaminated parts thoroughly with distilled water, and allow to dry. |
| Acids and alkalis | It is advisable to clean the tip cone and lower part of the tip ejector with distilled water more frequently if acids or alkalis are handled. Clean as described in “Aqueous solutions and buffers.” |
| Organic solvents | Immerse the contaminated parts in a detergent solution such as Deconex® 12 Basic. Rinse thoroughly with distilled water and allow to dry. |
| Radioactive solutions | Open the pipette and place the contaminated parts in a strong detergent or cleaning solution. Rinse several times with distilled water and allow to dry. Decontamination should always be followed by confirming that radioactivity has been reduced to an acceptable level. All used cleaning materials are radioactive waste and must be disposed of according to regulations. |
| Proteins | Open the pipette, immerse the parts in a detergent solution, such as Deconex® 12 Basic. Rinse well with distilled water and allow to dry. |
| DNA, RNA |
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| DNase, RNase |
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| Viruses, mycoplasma, bacteria, and fungi | Ultraviolet (UV) radiation is a practical method for inactivating viruses, mycoplasma, bacteria, and fungi. If the inner parts of the pipette are exposed to UV light, make sure the pison and O-rings are sufficiently lubricated. |
Before assembling the pipette, wipe the piston with 70% ethanol and lubricate with the lubricant that is provided with the pipette. When removing RNase, use a freshly opened ethanol bottle and prepare 70% ethanol in DEPC treated water.
Pipette sterilization
Autoclaving is the simplest sterilization method if all pipette parts tolerate extreme heat. Pipettes should be autoclaved according to the manufacturer's instructions. To achieve sterility, a holding time of at least 20 minutes at 121°C (252°F) is required.
- Fully autoclavable: Finnpipette F2 and Digital manual pipettes
- Autoclavable tip cones: F1-ClipTip, Finnpipette F1, F3, and Novus pipettes (see Instructions for Use).
All Thermo Scientific manual pipettes can be sterilized with STERRAD® and ethylene oxide treatments. The pipette should be disassembled before the sterilization treatment.
Chemical disinfection and sterilization
Chemical disinfectants or sterilants are used to decontaminate surfaces and equipment if autoclaving is not possible or practical. The choice of a chemical disinfectant or sterilant depends on the microorganisms of concern. Also, the chemical compatibility of the materials should be taken into account. Examples of chemical disinfectants or sterilants are listed in Table 2.
If the lower tip cone and the tip ejector of a pipette have to be chemically decontaminated, the pipette should be disassembled according to the Instructions for Use.
Table 2. Examples of chemical disinfectants and sterilants
| Disinfection time (at 20°C/68°F) | Sterilization time (at 20°C/68°F) | |
|---|---|---|
| Hydrogen peroxide (7.5%) | 30 minutes | 6 hours |
| Glutaraldehyde (2.5%) | 20–90 minutes | 10 hours |
| Sodium hypochlorite (5%) | 20 minutes | N/A |
| Ethanol (70%) | 10–30 minutes | N/A |
