Laboratory Supplies: Taking Care of Your Plasticware (Part II)

In part II, we continue with how to maintain specific laboratory supplies. Here, we cover sterilizing plastics and special materials that you use with your plastic labware. Note these tips:

Sterilizing Plastics

Miniature Vials with Hinged Caps, 29.6 mL

Miniature Vials with Hinged Caps, 29.6 mL

Autoclaving: Certain chemicals that have no appreciable effects on plastics at room temperature may cause deterioration at autoclave temperatures and therefore must be removed. To avoid baking these contaminants onto the surface of the plastic, carefully clean all items and rinse thoroughly with distilled water before autoclaving.

Because of differences in heat transfer between plastics and inorganic materials, the contents of plastic containers may take longer to reach sterilization temperatures (typically 121°C). Thus, longer autoclaving cycles may be necessary for liquid contents. Cycle lengths can be determined only by experience with specific liquids and containers. Do not autoclave containers (except those made of fluoropolymers) containing detergent or wetting solutions.

Note: Before autoclaving, just set cap or closure on top of the container without engaging threads.

Polypropylene (PP), polypropylene copolymer (PPCO), polymethylpentene (PMP), ETFE, FEP, and PFA can be autoclaved repeatedly at 121°C/15 psi. Cycle length should be at least 15 minutes at 121°C to ensure sterility.

Polysulfone (PSF) and polycarbonate (PC) are autoclavable, but can be weakened by repeated autoclaving. If autoclaved repeatedly, PSF will eventually fail under high-stress applications. After repeated autoclaving, PC shows some loss of mechanical strength and may not function well under high-stress applications such as centrifugation. Limit PSF and PC autoclave cycles to 20 minutes at 121°C.

Polystyrene (PS), polyvinyl chloride (PVC), nylon, acrylic, low-density polyethylene (LDPE), and high-density polyethylene (HDPE) labware and polyurethane tubing are not autoclavable under any conditions. Note: Some transparent plastics may absorb minute amounts of water vapor and appear cloudy after autoclaving. The clouding will disappear as the plastic dries.

Gas Sterilization: Ethylene oxide, formaldehyde can be gas sterilized. Allow an appropriate aeration time suited to the particular application before using the item.

Chemical Disinfectants: In general, formalin, iodophors, quaternary ammonium compounds and benzalkonium chloride can be subjected to commonly used disinfectants. There may be some surface attack (crazing) when using a more chemically aggressive disinfectant for a prolonged time on the less chemical resistant plastics (acrylic, PS, PC, PVC).

Dry Heat: Recommended only for ECTFE, ETFE, FEP, and PFA, PMP, PSF, and TFE.

Microwaving: In general, all plastics allow transmission of microwaves. Among commonly used plastics, PMP and PSF are most transparent to microwaves; we recommend their use when the chemical and temperature resistance of PMP and PSF are compatible with the material to be heated. Use fluoropolymers when heating such aggressive chemicals as acids or solvents; proper ventilation is essential. Note: Closure threads must be completely disengaged before heating bottles or containers in a microwave oven.

Hazardous Matter

For Labware Contaminated with Infectious or Toxic Materials, autoclaving is the preferred method for sterilization. However, any method of chemical or heat sterilization compatible with the plastic can be used. Liquid waste that contains biohazardous materials must be decontaminated before disposal.

For Labware Contaminated with Both Biohazardous and Radioactive Material, first sterilize the labware, then remove the radioactive material. Methods for removing radioactive material depend on the isotope used, its quantity, half-life, material, and solubility. For routine decontamination of noninfectious/nontoxic labware, first soak in a decontaminant/cleaner for 24 hours at room temperature. Follow this with several rinsings in distilled water. To accelerate decontamination, increase the cleaner concentration and solution temperature. Always dispose of radioactive wastes and effluents properly.

Trace Level Cleaning

For Most Trace Metal Analyses, plastic is generally less contaminated than glass or other materials. However, plastic does contain trace levels of certain metals. To minimize potential low-level contamination, remove or leach these metals from plastic by soaking in 1N HCl and rinsing in distilled water. For more precise work, use HCl, followed by soaking in 1N HNO3 and rinsing in distilled water. Soaking time can vary according to individual needs, but plastics should not be soaked longer than 8 hours. Caution: Concentrated nitric acid is a strong oxidizing agent and will embrittle many plastics.

To Remove Trace Organics that contribute to trace metal absorption, clean plastic surfaces with alcohol, alkalies, alcoholic alkalies, or chloroform. A final rinse of 1N HCl also minimizes absorption of trace elements.

See our selection of laboratory supplies and consumables.

Reprinted with permission from Thermo Fisher Scientific

1 Comment on "Laboratory Supplies: Taking Care of Your Plasticware (Part II)"

  1. Autoclave is needed by many things. One that is definitely where we are for the sterilization of medical equipment in a hospital. It aims to prevent the infection from microorganisms that cause disease.

    Additionally, usually used also for the agriculture industry in the manufacture of tissue culture. And also for mushroom farmers.

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