A lab centrifuge is a device that uses centrifugal force to separate particles from a solution, according to the size, shape, viscosity, and density of the medium.
Particles in a solution that has a higher density than the solvent sink (and are known as sediment). In contrast, lighter particles float to the top. The greater the difference in density, the faster the particles move. If there is no difference, the particles stay steady in the solution. When separating particles from a solution where there is little difference in density, rather than using gravity, you can use centrifugal force.
Why is this important in biotechnology? Centrifuges can be used in various laboratories to separate fluids, gases, or liquids based on density, as well as cell, organelle, virus, protein, and nucleic acid purification.
Furthermore, it is commonly used in PCR to ensure a number of things. For instance, it ensures reactants, like the PCR master mix, are located at the bottom of the wells, rather than the sides, after mixing. This results in proper concentrations and improved yields.
This type of centrifuge is used to collect small amounts of material that rapidly settle to sediment, such as erythrocytes, yeast cells, etc. A small benchtop centrifuge has a maximum relative centrifugal field of 3,000 to 7,000 x gravity (g). As the name suggests, this instrument can fit on your benchtop.
There are many benchtop models available, such as high-speed, microcentrifuge, clinical, and cell washer models. The clinical benchtop models and cell washers typically operate at lower speeds and are best suited to diagnostic applications, including washing debris from red blood cells.
Similar to the benchtop models, mini centrifuges are used in a wide variety of labs. In general, these models are designed to spin down microcentrifuge or PCR tubes and are designed to be compact, affordable, and efficient.
Things to consider when acquiring a mini centrifuge include the max RPM/RCF (revolutions per minute and relative centrifugal force), tube capacity, and the model’s cooling functionality if working with temperature-sensitive samples.
A microcentrifuge is used for spinning a variety of samples at high speed. Spinning samples quickly results in the pelleting of nucleic acids or proteins from solution, as well as microfiltration of small aqueous samples.
Furthermore, these models can spin your samples without the need for a technician to be nearby, thanks to automated features. Repeated samples can be treated in the same manner, meaning your samples can be introduced to the machine by various lab technicians, but their treatment will remain the same.
This specialized centrifuge is designed to accommodate microplates for PCR. In general, microplate centrifuges offer stable, high-speed centrifugation for 3-second cycle times. It is compact by design and includes automated features that provide both vibration and noise control.
These models are ideal for high- or medium-throughput applications and are capable of rapid customizable acceleration and deceleration, which minimizes the required cycle time.
These centrifuges have a refrigerated rotor chamber. They also have the option to change rotor chambers for another size. Their maximum speed is 6,500 g. They are used to collect substances that rapidly sediment, such as chloroplasts, nuclei, and erythrocytes.
This kind of centrifuge reaches speeds of about 60,000 g. As such, it is used to collect proteins precipitated by ammonium sulfate, cellular debris, micro-organisms, and larger cellular organelles.
These devices are also a type of high-speed centrifuge and offer an array of features. Let’s review the two most common types.
This type of ultracentrifuge produces a relative centrifugal force of about 600,000 g. The chamber is refrigerated, sealed, and evacuated. An ultracentrifuge can determine the shape and mass of macromolecules, separate lipoprotein fractions from plasma, assist in ligand binding kinetic studies, and more.
This type of ultracentrifuge can operate at 500,000 g. Analytical ultracentrifuges are available with three kinds of optical systems. These include a light absorption system, the Schlieren system, and the Rayleigh interferometric system. The Schlieren and Rayleigh systems are used to detect changes in the refractive index of the solution.
There are different types of rotors for centrifuge machines, which influence what the centrifuge does and how much it costs.
Also referred to as swinging bucket rotors, these rotors have buckets that start in a vertical position. During acceleration, the buckets swing to a horizontal position so that during centrifugation the tube and the solution in the tube are aligned perpendicular to the axis of rotation and parallel to the centrifugal field. The tube returns to its original position as the rotor decelerates.
Generally, swing bucket rotors support two separation types —rate-zonal and isopycnic. For rate-zonal separations, swing buckets are preferred because the distance between the outside of the meniscus and the outside of the bottom of the tube is long enough for adequate separation to occur.
Fixed-angle rotors hold tubes at a constant fixed angle, generally anywhere between 14° and 40° to the vertical. The centrifugal field forces particles to move radially outward and have only a short distance to travel before they collide with the outer wall of the centrifuge tube. As a result, a region of high concentration is formed that has a greater density than the surrounding medium. The precipitate sinks and collects as a small compact pellet at the outermost point of the tube.
Because of this, they are often used for pellet applications to either pellet particles from a suspension and remove the extra debris or to collect. When deciding to use a fixed angle rotor, consider the K factor. The K Factor indicates how efficiently the rotor can pellet at maximum speed. The lower the K-factor, the higher the pelleting efficiency.
These rotors are considered zero-angle fixed-angle rotors where the tubes are aligned vertically in the body of the rotors all the time. These are highly specialized pieces of equipment that are generally used to band DNA in cesium chloride. These rotors have low K factors, which is useful if the particle only needs to move a short distance until it pellets.
Elutriator rotors are a type of continuous flow rotator that feature recesses to hold a cone-shaped separation chamber. The point of the cone points away from the axis of rotation. It is counterbalanced by a bypass chamber on the opposite side of the rotor, which also provides a fluid outlet.
Zonal rotors can either be a continuous flow type or a batch type. The batch type is more widely used than the continuous flow option. The batch rotor is designed to minimize the wall effect encountered in a swinging bucket and fixed-angle rotors and to increase the sample size.
Handle all rotors with care to prevent scratching. Wash with deionized water and dry thoroughly to prevent corrosion. Store in a clean and dry environment. Do not submerge swing-bucket rotors in water because they are difficult to dry.
Centrifuge equipment pricing varies depending on the brand, make and model, and type. Top manufacturers include Thermo Fisher, Eppendorf, Sigma, and Ohaus. Price ranges for each type are:
As you can see, benchtop units are low-cost compared to more specialized models; however, they may not be the best choice for your lab. Consider your research needs when deciding on the best prices for a centrifuge. Ultimately, you need to ensure that you’re acquiring an instrument that can handle of your requirements.
If you need to get the bells and whistles, it will add to the total costs. However, if your research requires specific add-ons, then it’s a necessary cost. For example, it’s possible to get refrigeration on many types of centrifuges.
These units tend to fall into the higher end of the spectrum, but acquiring a lab centrifuge that provides it is often critical. Lastly, you can customize and buy additional rotors, but customizing the lab centrifuge configuration adds to your final costs.
When it comes to buying a lab centrifuge, you could end up investing a rather large amount of your working capital upfront, depending on the type, the number of units, add-ons, and customizations your lab needs. Though centrifuge machines are not as expensive as other types of equipment, when you’re on a budget, purchasing them may not be practical.
While there’s always the option to buy a refurbished unit, you’re still left with the cost of maintenance and repair outside of any warranty coverage that may be included. The warranties often provide limited, short-term coverage that isn’t useful in the long term.
Leasing your laboratory equipment with Excedr, on the other hand, allows you to make the most of your budget. Our leases significantly reduce the upfront costs required, and repairs and maintenance are covered for the life of your lease.
Your lease will cost a fraction of the price it costs to purchase the equipment outright while giving you the freedom and flexibility to upgrade your lab equipment at the end of your lease term. Furthermore, you can still procure the exact brand of centrifuge you want. Whether it’s Thermo Fisher Scientific, Beckman Coulter, Eppendorf, or Millipore Sigma, we’ve got you covered.
Lastly, when you lease with us, you’ll be able to save even more money because your lease payments will be tax-deductible, though you’ll need to speak with an accountant as rules and regulations vary depending on your location and industry.
Contact us today to learn more about centrifuge leases.