Centrifuge, Centrifuges & Centrifugation
Centrifuges for research, clinical trials, routine pathology, blood separation with, for example, Vacutainers in the main lab or at a collection centre. We will gladly install and train your staff onsite. Fronine supply, instal and service these Eppendorf Centrifuges:
Fronine Laboratory Supplies offer a wide range of Eppendorf centrifuges for nearly every market. With adaptors from 0.2 ml tubes through to 400ml flasks, Fronine Lab Supplies can provide a centrifuge suited to your precise requirements.
The smallest capacity centrifuge offers a fixed angle rotor for 12 X 1.5/2.0 ml tubes, with adaptors for 0.2ml, 0.4ml & 0.5ml microtubes. All rotors are autoclavable. Max RPM of 14,500 and max G’s of 14,000.
Next size up is a centrifuge with a 24-place rotor for 1.5ml or 2.0ml tubes and same adaptors for microtubes with the standard rotor. Special rotor for Aerosol tight centrifugation available. Max G’s of 16,100. A larger brother centrifuge is available with adjustable ramp rates and standard 30 place rotor. A special fixed angle Hi G PCR rotor for 24 x 1.5/2.0ml tubes at 25000 G’s is available for a very economical price.
A very reliable and flexible centrifuge with a small footprint is available with the capacity of spinning tubes from 1.1ml to 85ml, all with aerosol tight caps. Fixed angle or swing out, swing bucket rotor options for these centrifuges, as a refrigerated and now heated model is sold. In fact most of our centrifuges are available as refrigerated. A 30 x 15ml Falcon Tube rotor is an option, along with 90ml square buckets for even greater capacity.
The larger general purpose centrifuge should feature the options of refrigeration, fast cool function, at set RPM, automatic rotor recognition, motorized lid latch, imbalance cut-off, fulfill all current safety standards; speed, rcf and radius correction values correction values can be entered by the user; values can be changes during centrifugation; temperature range of -9 to 40 degrees centigrade [on refrigerated models]; stand-by refrigeration; speed can be set from 200 rpm to maximum speed in increments of 10rpm; selectable program memory for up to 34 individual user programs; 10 acceleration and 10 braking ramps for sensitive samples. Tube, deepwell plates, microplate, microtitre and PCR plate adaptors / buckets are available as well as tube adaptors for tubes between the sizes of 1.5ml and 400ml flasks. Now new buckets also allow our range of centrifuges to spin microscope slides and cell culture flasks! Fixed angle and swing out rotors, fully autoclavable are available too.
All Fronine supplied Eppendorf Centrifuges come with a two year warranty, fully supported by Fronine's factory-trained service department.
A brief history of the Centrifuge
Centrifuges similar to our bench top centrifuges have been in use since the mid-1800’s. These centrifuges were capable of speed of about 3000 rpm. The early ones were hand driven; after 1912, the centrifuges were electrically driven. First applications were non-biological, such as separation of milk and collection of precipitates.
Miescher (1872) attempted to separate macromolecules – credited with the discovery of nucleic acids.
The development of the ultracentrifuge is generally credited to Svedberg who worked in the 1920’s and 1930’s. Svedberg coined the term “ultracentrifuge.” Svedberg was a colloid chemist - he studied the structure of proteins (at that time all proteins were considered to be colloids). His group used the ultracentrifuges to determine the MW and subunit structure of hemoglobin, studies which changed the ideas concerning the structure of proteins. Svedberg’s group developed a number of ultracentrifuges. Some of the early models were capable of reaching 900,000xg, but the rotors were very small. For routine work they used larger rotors which could reach 260,000xg.
The first commercial ultracentrifuge was produced in 1940 by SPINCO.
Types of Centrifuges
- Desk top clinical centrifuges. The maximum speed of most desk model centrifuges is below 3000 rpm and all of them operate at ambient temperature.
- Highspeed centrifuges are those operating up to speeds of 20,000 to 25,000 rpm.
- The ultracentrifuge has the ability to attain centrifugal forces in excess of 5000xg (75,000, r=8cm). The development of the ultracentrifuge permitted the fractionation of subcellular organelles previously observed only in electron micrograph; this in turn permitted assay of their enzymatic constituents, providing insights into structure-function relationships. The contemporary ultracentrifuges consist of four principal parts: drive and speed control, temperature control, vacuum system and rotors.
- Drive and speed control. The drive shaft itself is only about 3/16 in in diameter. The samll diameter of the shaft allows it to flex during rotation, thus accommodating a small degree of rotor imbala ce without vibration or spindle damage. An overspeed system was developed to prevent operation of a rotor above its maximum rated speed. Such operation results in the rotor being torn apart or exploding. It is for this reason that the rotor chamber is always enclosed in heavy armor plate capable of containing any such explosion. The over speed system consists of (1) a ring of alternating reflecting and non-reflecting surfaces attached to the bottom of the rotor., (2) a small but intense point source of light, and (3) a photocell. The passing of reflecting and nonreflecting surfaces throught the light beam as a consequence of rotor rotation chaps the light and establishes a pulsing signal in the photocell output circuitry. The frequency of this signal, which is a function of the speed of rotation, is compared to a standard reference signal. If the rotor-generated signal frequency surpasses that of the reference, the instrument is automatically shut down.
- Temperature control in highspeed instruments involves placing a thermocouple in the rotor chamber, and monitoring only the rotor chamber temperature. In the case of an ultracentrifuge and infrared radiometric sensor placed beneath the rotor continuously monitors the rotor temperature directly, ensuring more accurate and responsive temperature control.
- Vacuum System. At speeds below 15,000 to 20,000 rpm only small amounts of heat are generated by friction between air and the spinning rotor. At greater speeds, however, air friction is significant and becomes severe above 40,000 rpm. To eliminate this source of heating, the rotor chamber is sealed and evacuated by two pumping systems operating in tandem. The first system is a mechanical vacuum pump similar to those in normal laboratory use, which can establish a vacuum down to 100 to 50u. Once the pressure in the chamber has decreased below 250u, a water-cooled diffusion pump is also brought into operation. Using both pumps it is possible to attain and hold vacuums of 1 to 2 u. As would be expected, temperature control is significantly improved when the rotor chamber is evacuated.
- Rotors - A large variety of rotors are available for use in modern ultracentrifuges, and fall into two classes: angle and swinging bucket. Both types are constructed from either aluminum alloys for low to moderate speeds or titanium for highspeed operation. Angle rotors consist of a solid piece of metal with 6 to 12 holes machined at an angle between 20o and 45 o. These rotors are most often used for applications involving total sedimentation or “pelleting” of a constituent. Swinging bucket rotors consists of a rotor from which hang three to six free moving buckets. These buckets hang vertically when the rotor is at rest and swing 90 o to a horizontal position, under the influence of centrifugal force, as the rotor attains a speed of 200 to 800 rpm. This type of rotor was designed principally for incomplete sedimentation of a sample through some sort of gradient. In this position material sedimented to different areas of the tube appearing as bands running across the tube rather than at an angle as in an angle rotor.