How to Choose a Lab Centrifuge
The decision to buy a laboratory centrifuge should be based on the purpose for which it is to be used, the number of samples that are to be handled in a day, type of centrifugation applications required, the centrifugal force needed to be generated and the type of rotor that will be useful for a particular application. These instruments are scalable as well as configurable, meaning microcentrifuges that handle sub-milliliter volumes to benchtop and floor-standing high throughput centrifuges are available in the market.
Benchtop centrifuges are the most versatile instruments used for laboratory work as they enable handling most applications at lower costs and reduced sample throughput. Specialized centrifuges are also available within the benchtop category. For example, a refrigerated centrifuge, hematocrit centrifuge, microcentrifuge and ultracentrifuge required for various studies in different areas like clinical, molecular biology, etc., are available to the users in modern day laboratories.
A refrigerated centrifuge finds application in the centrifugation of temperature sensitive material. It is used for routine as well as research work in auxiliary laboratories in industry, educational institutions, research centers, hospitals, biotechnology and medical laboratories, blood banks and pharmaceutical laboratories. Refrigerated centrifuges come with electronic or microprocessor controls. High volume low speed and low volume high speed benchtop models of refrigerated centrifuges are also available.
The operating parameters such as speed, time, temperature, etc., can be set with the help of soft touch keypads provided on the panel of the instrument. In order to ensure accurate speed settings for different rotors, brushless induction motors are used and some models come with a unique rotor identification facility. While over current cut off protection is provided for the motor in most models, rotor safety is ensured by incorporating lid interlock systems that do not allow the running of the centrifuge with the lid open. Further, the closed lid can be opened only when the rotor completely stops.
Refrigerated microcentrifuges are used for radio immuno assay applications and routine work in biochemical and clinical laboratories including determination of hematocrit values to assess blood loss, serum analysis and precipitate separation.
Centrifuges are cooled to prevent the heat generated because of the spinning of the rotor from affecting the samples being prepared for analysis. To understand the specifications of refrigerated centrifuges, some information about the products of primary manufacturers of centrifuges such as Eppendorf will be helpful.
The benchtop models of refrigerated centrifuges manufactured by Eppendorf have a spin speed range of 4,400 rotations per minute (RPM) to 14,000 RPM with the gravitational force ranging from 3,000 × g to 20,800 × g. The benchtop models are designed to work at 120 V and 50 – 60 Hz or 230 V and 50 Hz. The refrigerated microcentrifuges manufactured by Eppendorf are designed to achieve speeds of 13,200 RPM (16,110 × g) to 17,500 RPM (30,130 × g).
A microcentrifuge uses small sample holding tubes from 0.2 milliliter to 2.0 milliliter and can accommodate up to 96 well-plates. It is a compact centrifuge, and for specialized applications, it is designed to generate forces up to 30,000 × g. It is used for studies in the in the fields of molecular biology, biochemistry and polymer science. As the rotor spins at higher speeds, this type of centrifuge is often provided with lids for bio-containment to prevent aerosolization hazards.
A centrifuge is a work horse instrument in any modern laboratory. It is one of the earliest scientific appliances that are used for core applications such as separation of components from blood, sediment analysis, removal of particles from fluids, etc., through the application of centrifugal force. However, new applications for centrifuges have also been recognized, especially in the fields of molecular biology and biochemistry. Another development in the field of centrifugation has been the shrinking of the sample sizes. Sample sizes have come down from flasks to tubes, vials and eventually microplates.
Though traditional centrifuges were not designed to handle microplates, most manufacturers have incorporated design modifications to accommodate protocol transfer from tubes to microplates. Rotors that use specialized swing out buckets to process shallow-well microplates at low gravitational forces and tall or deep wells that are required for high speeds have been developed. Typically, the centrifuges that generate very high gravitational force have only two buckets and are designed to operate at the lowest possible frictional resistance and noise.
It is true that centrifuges are relatively simple devices to operate, but accurate control of gravitational force, rotor speeds, duration of spinning and temperature are all essential for precise analysis of the samples that are loaded into it. In the olden days, the instruments had just three knobs to control speed, time and temperature. Modern day centrifuges come with advanced touch-screen controls that enable adjustment of any parameter and recall any of the stored methods.
As far as the materials of construction of different parts of centrifuges are concerned, more of plastics and composite materials are being used in modern days. This is because the mass required for moving the shrunk sample sizes are less. The use of lightweight, strong, durable and chemically resistant carbon fibers and fiber-reinforced plastics as materials for construction of centrifuge parts have revolutionized the centrifuge market in terms of safety.
There is a constant demand for simplifying the use of centrifuges by customers. This poses the manufacturers with the challenge of presenting an interface that enables the technician operating the centrifuge to access all critical features without the need to refer to the operation manual. The users of centrifuges have also been demanding for reduction of noise generated when it is put into operation. Some degree of success has been achieved by employing brushless motors, better insulation and more effective air seal.
The food sector seems to be emerging as a strong market for centrifuges. Some of the interesting applications that are being worked out include measurement of fat content of milk, extraction of honey from honeycombs, determination of fish muscle water holding capacity, extraction of essential oils from nuts and herbs, etc., to name a few.
For all requirements of centrifuges and related parts, sample holders, etc., visit Lab Centrifuge Shop at http://labcentrifugeshop.com/ and find out the options available for you.