Protein purification and separation can be done by all except:

D i.e. DensitometrySDS polyacrylamide gel electrophoresis is method of protein seperation & purification on the basis of molecular sizeQ. Whereas electrophoretic mobility of protein in native (non-denaturating) gel electrophoresis and 2-D gel electrophoresis depends on both charge (PI) and its mass (hydrodynamic size). Densitometry is a method to quantitate protein in tissueQ.