Introduction
      •  particles or cells in a liquid suspension, will settle at the bottom 
         of tube due to gravity (1x g) during long period to time. 
      •  However, the length of time required for such separations is 
         impractical.
      •  Other particles which are very small in size, will not separate at 
         all 
      •  So, high centrifugal force though method called centrifugation 
         must be used in these cases.  
        Simply, 
  Centrifugation >>>>> Increasing the 
      effect of gravity
      Sedimentation
      •  Is the motion of molecules in solutions or, particles in 
         suspensions, in response to an external force such as gravity, 
         centrifugal force or electric force. 
      •  Centrifugation increase the rate of sedimentation by spinning 
         the samples and creating a centrifugal force acts on particles in 
         an instrument called a centrifuge. 
         The rate of sedimentation depends on: 
         1. Properties of molecules: size, shape, density
         2. Properties of solvent or gradient material: density, viscosity, 
            temperature
         3. Interaction between solute molecules and solvent or gradient 
            material
                            Centrifugation
      Theoretical  bases of centrifugation:
      •   When suspension is rotated at certain speed or Revolution Per 
         Minute (RPM) centrifugal force causes the particles to move 
         away from the axis of rotation. 
      •  The force on particles is called relative central force (RFC)
      Relative centrifugal force:
      •  Relative centrifugal force (RCF) is the measurement of the 
         force applied to a sample within a centrifuge. 
      •  Centrifugal force is measured as X g  gravity. 
      •  An RCF of 500Xg indicates that the centrifugal force applied 
         is 500 times greater than earth gravitational force
      •  This can be calculated from the speed (RPM) and the 
         rotational radius (cm) using the following calculation.