TOPIC OF DISCUSSION: CENTRIFUGATION SLIDESHARE.pptx

Centrifugation is a powerful technique used in laboratories to separate components of a heterogeneous mixture based on their density. This process utilizes centrifugal force to rapidly spin samples, causing denser particles to migrate outward more quickly than lighter ones. As a result, distinct layers form within the sample tube, allowing for easy isolation and purification of target substances.

1. CENTRIFUGATION By Shubhi Jain M.Sc Biotechnology Mount Carmel College, Bangalore

2. SYNOPSIS Introduction Principle Types of centrifuge

3. CENTRIFUGATION Centrifugation is the process used to separate or concentrate materials suspended in a liquid medium. It is a process which involves the use of centrifugal force for the sedimentation of heterogeneous mixtures or substances on the basis of differential densities. Centrifugation is the process used to separate or concentrate materials suspended in a liquid medium.

4. PRINCIPLE The principle of centrifugation is to separate the particles suspended in liquid media under the influence of centrifugal field. The material to be centrifuged is placed either in test tubes or bottles in a rotor in a centrifuge, Particles differing in sizes, shapes and densities are separated as their sedimentation rate is different. The centrifugal force is generated by rotating the rotor of centrifuge at a high speed. In a solution, particles whose density is higher than that of solvent “SINKS” [sediment] and the particles that are lighter, they “FLOAT AT THE TOP” The greater the difference in the density, the faster they move. If there is no difference in the density (ISOPYNIC CONDITION), the particles stay steady. Centrifuge can separate and purify subcellular organelles, proteins, nucleic acids and several macromolecules. It is also used to separate two or more immiscible liquids from a solution.

5. TYPES OF CENTRIFUGE DESK-TOP CENTRIFUGE :- (LOW SPEED CENTRIFUGE) These are very simple and small (can be placed atop a desk and hence the name) and are least expensive. They are normally used to collect rapidly sedimenting substances such as – RED BLOOD CELLS (RBC’S), YEAST CELLS OF BULKY PRECIPITATES OF CHEMICAL REACTIONS. These are also known as ‘CLINICAL CENTRIFUGE’ since most of the clinical work is done by these models. Their maximum speed is usually : 300-500 rpm and they do not have any temperature regulatory system i.e no refrigeration equipment. Two types of rotors used are- FIXED ANGLE & SWINGING BUCKET Low speed centrifuge works on the same principle as the other centrifuge but the application is limited to the separation of simpler solutions.

6. HIGH SPEED CENTRIFUGE:- It is a device that uses centrifugal force to separate particles of different mass or densities suspended in a liquid. It can operate with a maximum speed of upto -2500 rpm providing about 90,000g centrifugal force in the process. It is usually equipped with refrigeration equipment to remove heat generated due to friction between the air and the spinning rotor. The temperature can be easily be maintained in the range (0-4 ℃ ) by means of a thermocouple. These instruments are routinely used to collect micro-organisms, cell debris, cells, large cellular organelles, precipitates of chemical reactions and immunoprecipitates . Although these centrifuges are useful in isolating subcellular organelles such as nuclei, mitochondria, lysosomes etc , they are of little use in isolating smaller organelles such as ribosomes, microsomes etc.

7. ULTRACENTRIFUGE :- The ultracentrifuge can operate at a speed upto 7,500 rpm providing centrifugal force in excess of 5,00,000g. At such a speed, the friction between air and the spinning rotor generates significant amount of heat. To eliminate this source of heating, the rotor chamber is sealed and apart from this centrifuge has a refrigeration system which can maintain the temp of the rotor between 0-4℃. Intense heat is generated due to high speed, thus the spinning chamber must be refrigerated and kept in high vaccum . To prevent the rotor from operating at speeds which exceeds its maximum rated speed, all centrifuges possess an Overspeed Device. (rotors at high speed result in explosion) It is used for both- PREPARATIVE WORK & ANALYTICAL WORK, hence it is of two types.

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