<P> In biochemistry, dialysis is the process of separating molecules in solution by the difference in their rates of diffusion through a semipermeable membrane, such as dialysis tubing . </P> <P> Dialysis is a common laboratory technique that operates on the same principle as medical dialysis . In the context of life science research, the most common application of dialysis is for the removal of unwanted small molecules such as salts, reducing agents, or dyes from larger macromolecules such as proteins, DNA, or polysaccharides . Dialysis is also commonly used for buffer exchange and drug binding studies . </P> <P> Diffusion is the random, thermal movement of molecules in solution (Brownian motion) that leads to the net movement of molecules from an area of higher concentration to a lower concentration until equilibrium is reached . In dialysis, a sample and a buffer solution (called the dialysate) are separated by a semi-permeable membrane that causes differential diffusion patterns, thereby permitting the separation of molecules in both the sample and dialysate . </P>

Where do we need to use the principle of dialysis