Pipette decontamination
  • 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 liquidsCleaning guidelines
Aqueous solutions and buffersOpen the pipette, rinse the contaminated parts thoroughly with distilled water, and allow to dry.
Acids and alkalisIt 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 solventsImmerse the contaminated parts in a detergent solution such as Deconex® 12 Basic. Rinse thoroughly with distilled water and allow to dry.
Radioactive solutionsOpen 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.
ProteinsOpen 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
  • DNA can be eliminated by immersing pipette parts in at least 3% (w/v) sodium hypochlorite for at least 15 minutes (2,3). Rinse well with distilled water and allow to dry.
  • Treat the pipette parts with Thermo Scientific DNA AWAY Surface Decontaminates according to instructions.
  • Exposure to ultraviolet for 30–60 minutes will further reduce but not completely eliminate DNA contamination on the pipette surface (4).
  • No special treatment is required to remove RNA because it degrades rapidly and is sensitive to ubiquitous RNases.
DNase, RNase
  • RNase can be removed by first cleaning the pipette with a detergent solution, followed by thoroughly rinsing with water and then 95% ethanol to speed the drying process. Pipette parts are then soaked in a 3% hydrogen peroxide solution for 10 minutes. Finally, the parts are rinsed thoroughly with DEPC-treated water (5) and allowed to dry.
  • Treat the pipette parts with Thermo Scientific RNase AWAY Surface Decontaminates according to instructions.
  • DNase can be destroyed by autoclaving (15 min., 121°C/250°F)
Viruses, mycoplasma, bacteria, and fungiUltraviolet (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 minutes6 hours
Glutaraldehyde (2.5%)20–90 minutes10 hours
Sodium hypochlorite (5%)20 minutesN/A
Ethanol (70%)10–30 minutesN/A

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