Criteria of purity of organic compounds

The purity of an organic compound can be determined by ascertaining its some physical constants such as m.p., b.p., defined gravity, refractive index and viscosity. In common practice, sharp m.p. (in case of solids) and boiling point (in case of liquids) are employed as criteria for purity as their determination is feasible in the laboratory. A pure organic solid has a specific and sharp melting point, when an impure element has a lower and indefinite melting point.