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Cryogenic Vial Safety

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Cryopreservation refers to the storage of biological samples at low temperatures (-196°C), typically in a dewar filled with liquid nitrogen.

What are the hazards?

Liquid nitrogen hazards include severe frostbite1 and asphyxiation from liquid nitrogen evaporating in an enclosed area.2 Liquid nitrogen can also leak slowly into improperly sealed cryogenic vials over time. During vial thawing, the liquid nitrogen evaporates and expands at a ratio of 1:696 (liquid:gas), which can result in an over-pressurized vial that can rupture. Injury to personnel can occur from flying debris, as well as from exposure to the potentially biohazardous contents of the vial.3

How can I protect myself?

Complete Stanford University health and safety training for Cryogenic Liquids & Dry Ice. Contact EH&S at (650) 723-0448 to request training. Researchers must also complete laboratory specific Tier III training.

Wear proper personal protective equipment (PPE) when handling liquid nitrogen. This includes:

  • Thermally insulated gloves
  • Face shield and ANSI z87.1 safety glasses
  • Lab coat in conjunction with proper street clothes (including long pants and closed toe shoes)

Cryogenic Vial Selection

Use vials rated for cryogenic use that have a silicone O-ring. Vials with internally threaded caps are preferable.

Vials must be made of polypropylene and NOT be made of glass.

How do I store this?

Avoid liquid phase storage of vials within cryogenic dewars. Liquid nitrogen that leaks into the vials may cause vial over pressurization during thawing.

If liquid phase storage is necessary, use cryogenic heat shrink tubing to fully encase the cryogenic vial.

Special problems and procedures

Cryogenic Sample Thawing

  • Always wear proper PPE described previously.
  • Thaw the vial in a thick walled container (i.e. desiccator with lid) or within a fume hood or biosafety cabinet.
  • Remove the contents of the vial when completely thawed. Discard the vial – do not reuse.

Reference

  1. Roblin et al. (1997) Burns 23 (7/8): 638-40
  2. Tabata et al For. Sci. Int. 1995)
  3. Occupational Health and Safety Unit, University College London, Hazards of Liquid Nitrogen Cryovials, 2006
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