View the full transcript and gain access to JoVE Science Education videos
Q1: What temperature and pressure does an autoclave use to sterilize materials?
Autoclaves sterilize materials using pressurized steam at 121 degrees Celsius and at least 15 p.s.i. pressure. After a minimum of 30 minutes at these extreme conditions, the steam dehydrates and kills microorganisms present in the loaded materials, making autoclaving an economical decontamination method for laboratories.
Q2: Which materials are safe to autoclave in the laboratory?
Compatible autoclave materials include pyrex, borosilicate glass, stainless steel, polypropylene, and polycarbonate. Pipette tips, boxes, and paper in autoclave-compatible bags are also safe. Never autoclave items that melt, burn, are explosive, or contain liquids that evaporate, toxic chemicals, or radioactive substances.
Q3: Why do liquids require different autoclave settings than solids?
Liquids require longer autoclave cycles than solids to safely exhaust steam and prevent flash boiling. Larger volumes of liquid materials also take longer to reach the correct temperature throughout. Proper spacing and ventilation in the secondary container ensure adequate steam circulation and uniform heating of liquid samples.
Q4: How should you prepare liquid samples before autoclaving?
Fill compatible containers about half full, never exceeding two-thirds capacity. Loosen the cap or cover loosely with aluminum foil to allow gas ventilation. Place all materials in a secondary polypropylene or stainless steel container with adequate spacing. Attach autoclave tape to monitor temperature exposure during the sterilization cycle.
Q5: What personal protective equipment is required when operating an autoclave?
Wear standard lab PPE including safety glasses, lab coats, and closed-toe shoes. Heat-resistant gloves are essential for handling hot materials. When working with liquid samples, also use an apron and face shield to protect against high temperature and pressure hazards from steam exposure.
Q6: What steps should you follow after an autoclave cycle completes?
After the cycle ends, verify pressure has returned to zero and the autoclave has cooled. Carefully open the door to release leftover steam, then allow materials to stand for 10 minutes to release hot gases. Check that autoclave tape shows black stripes, remove materials wearing appropriate PPE, log your usage, and transport items to a secure area or laminar flow hood to cool.
Q7: How do you properly load materials into an autoclave chamber?
Load liquid and dry materials separately using different autoclave cycles. Ensure materials do not touch the chamber walls to prevent melting. Maintain sufficient spacing between items to allow good heat flow and steam circulation. Close and seal the door securely before starting the cycle to maintain proper pressure and temperature conditions.