1 . Centrifuge
A centrifuge is a machine designed to separate heavy material from light material. When the substance is a very fine solid in a solution, separating parts of the mixture can be more difficult than a solid. In our case, we will use a centrifuge to separate DNA from a liquid so we can focus just on the DNA. A centrifuge works by spinning the substance at high speed. You have probably seen the trick where you fill a bucket of water about halfway full, spin it around, and watch as the water stays in the bucket. The water is pushed against the bottom of the bucket by what is colloquially known as centrifugal force. Though not a real force, but a reaction to the centripetal force, centrifugal force pushes against the bottom of the bucket. This causes the particles in the solution to clump at the bottom of the tube. That solid clump is called a pellet, and the solution above it is called the supernatant .
2 . A laboratory centrifuge
A laboratory centrifuge is a piece of laboratory equipment, driven by a motor, which spins liquid samples at high speed. There are various types of centrifuges, depending on the size and the sample capacity. Like all other centrifuges, laboratory centrifuges work by the sedimentation principle, where the centripetal acceleration is used to separate substances of greater and lesser density.
3 . Background
Centrifugation may present two serious hazards: mechanical failure and dispersion of aerosols. This fact sheet describes safety and maintenance procedures to minimize centrifuge hazards. If a centrifuge malfunctions while in operation, turn it off immediately and unplug. If tube breakage occurs, turn centrifuge off immediately. Leave for 30 minutes to reduce the risk of aerosols. The operator should wear proper gloves, remove debris, clean and disinfect centrifuge interior, rotors, safety cups or buckets following the manufacturer s instructions.
4 . Centrifuge Safety
Centrifuges can create aerosols and this must be considered with each use. The necessary precautions taken will depend upon what is being used. If hazardous materials such as carcinogens, highly toxic, or infectious agents will be placed in a centrifuge, then precautions must be taken to prevent an exposure of lab personnel to aerosols or liquids.
5 . The work surface must be level and firm
Do not use the centrifuge on an uneven or slanted work surface. If a spill has occurred in the centrifuge, hold breath, close the centrifuge lid, turn centrifuge off, and immediately leave the lab. Notify others to evacuate the lab, close the door, post a biohazard spill sign at the lab door. Remove any contaminated protective clothing and place in a biohazard bag. Wash hands and any exposed skin surfaces with soap and water. Seek medical attention as necessary.
6 . Balance the tubes in the rotor
If you want to run a tube with 10 mL of liquid, put another tube with 10 mL of water in the opposing hole on the rotor (see photo, below). If the liquid has a higher or lower density than water, you must balance the tubes by mass, not volume. The total mass of each tube should be as close as possible this becomes increasingly important at very high rotor speeds. Running a centrifuge with unbalanced load could permanently damage the centrifuge. It could also cause injury to you or someone else.
7 . Do not open the lid while the rotor is moving
Even though many centrifuges have a safety shutoff if the lid is opened, the only thing this does is stop powering the rotor. The rotor will still spin due to its own inertia for a while until friction slows and eventually stops it. For centrifuges with swinging bucket rotors, fasten a protective inner safety lid (if available for your model centrifuge) onto the bucket; for those with fixed angle rotors, fasten an inner safety lid to the rotor before centrifugation. Ensure that the safety lid is properly sealed and positively locked into place.
8 . If you see it wobbling or shaking pull the plug
A little vibration is normal, but excessive amounts can mean danger. FIRST, double check that you correctly balanced the tubes. If the answer is yes and the wobbling still happens, contact the manufacturer or dealer and get the unit serviced. If you bought the centrifuge from us, here s the contact info if the unit needs service or replacement. Do NOT continue to run a centrifuge that wobbles visibly when the rotor is spinning.
9 . Wear a face shield and or safety goggles
Wear a face shield and / or safety goggles if you have to work anywhere near a centrifuge that s in use. Accidents happen sometimes under the most freakish or unexpected circumstances. The rotor is spinning very rapidly and generates extreme forces. Although a physicist would tell you that centrifugal force is an illusory force , the point makes not one bit of difference to the sample as it spins in the rotor. It might as well be experiencing a real force that pulls the particles toward the bottom / outside of the tube. These illusory forces have been known to tear apart enormous flywheels in factories, for example, with disastrous consequences (read some of the compilations of machinists stories from Lindsay Publications, for instance).
10 . Do not bump jar or move the centrifuge while the rotor is spinning
Instruct all other persons in the area to stay clear of the unit while it s operating. Make sure you don t have the cord dangling from a table edge where someone could catch their foot in it and pull down the centrifuge. Start the centrifuge when the centrifuge lid should be covered only after the slow start. After separation, first turn off the centrifuge, the centrifuge stopped turning, only open the centrifuge cover and remove the samples, not with external force it to stop. centrifugation time is generally 1 to 2 minutes, during which the experimenter not to leave to do something else.