The application of centrifugal force in a controlled manner is the basis of the separation method known as centrifugation. A high speed centrifuge is a machine, which is typically powered by an electric motor, that rotates an object, such as a rotor, around a stationary axis. This movement is what gives the high speed refrigerated centrifuge its name.
The operates according to the principle of sedimentation, which states that substances will separate according to their density when subjected to the influence of gravitational force (g-force). There are numerous methods of separation, such as pelleting, isopycnic separation, ultrafiltration, density gradient separation, phase separation, and phase separation.
The most common use for centrifuges is pelletizing of various materials
In this step, the particles are collected into a concentrated pellet at the base of the tube and are separated from the remaining solution, which is referred to as the supernatant
In the process of phase separation, chemicals are extracted from a matrix or an aqueous medium and then placed into a solvent (for further investigation at the chemical or molecular biological level)
The use of a membrane is central to the process of ultrafiltration, which cleans, separates, and concentrates macromolecules
When performing isopycnic centrifugation, a self-generating density gradient that was established through equilibrium sedimentation is used as the driving force
This method concentrates on matching the characteristics of the surrounding solution with those of the analysis
In centrifugation protocols, the relative centrifugal force, also known as rcf, and the degree of acceleration, measured in multiples of g and referred to as g-force, are typically specified
When working with rotational speed, such as revolutions per minute (rpm), there is room for some degree of imprecision
The most common application for vertical rotors is in ultracentrifugation for isopycnic separations, more specifically for the banding of DNA in cesium chloride. Vertical rotors are fairly specialized pieces of equipment. Because the density range of the solution has the same density as the particle of interest in this type of separation, the particles will orient themselves within this portion of the gradient. Isopycnic separations are not dependent on the pathlength of the gradient; rather, they are dependent on the run time, which must be long enough to allow the particles to orient themselves at the correct position within the gradient. Vertical rotors typically have K factors in the range of 5–25, which indicates that the particle needs to travel only a short distance to pellet (or in this case, form a band). As a result, run time is minimized. When it has been established that a vertical rotor is suitable for the application carried out by the end-user, the volume and speed of the process become the deciding factors for which rotor to implement.
Rotor care
Maintenance of the rotors in the correct manner is mandatory for ensuring both their safety and their longevity. Regular maintenance of the rotors can save both time and money, as well as significantly extend the rotors' useful lives, in addition to lowering the risk of accidents. The steps outlined below make up a straightforward and efficient approach to rotor maintenance.
Rinse
Rinsing the rotor with water after each use to remove any residual sample or dirt, followed by a thorough drying, yields dramatic results in rotor longevity. This is true regardless of whether the rotor in question is made of carbon fiber, aluminum, or titanium. It may be necessary to use a gentle detergent along with a soft cloth or brush in order to remove debris that has become firmly embedded on the rotor. When attempting to free lodged debris, you should never use any tools made of metal. After being rinsed or washed, the rotors must undergo a thorough drying process before being used again.
Purge of germs
When working with substances that could potentially cause infection, it is best practice to perform a disinfection step after each use. The major laboratory supply companies carry a wide variety of disinfection products for your convenience. It is essential to select the appropriate cleaning agent for the rotor material. This is due to the fact that different rotor materials require different kinds of disinfection products. Bleach, for instance, may be utilized on carbon fiber rotors but may not be utilized on aluminum rotors. Reviewing the provided literature is beneficial because all rotor manufacturers provide guidelines regarding the acceptable active ingredients that can be found in a disinfecting agent.
Sterilize
- Because autoclaving can be done with any type of rotor, including those made of aluminum, titanium, or carbon fiber, it is by far the most common and straightforward method of sterilization
- When autoclaving is not an option, users should consult the manufacturer's guidelines to determine which active disinfecting ingredients can be used on the rotor without risk of damaging it
