SDS-PAGE electrophoresis is used to verify the purity of a protein product. Some of the limitations of this method are:
· identification of a band on a protein gel is not always reliable because different polypeptides can have very similar molecular masses,
· band on a protein gel may mask the presence of more than one polypeptide, · presence of non-protein residues can affect the mobility of polypeptide and thus cause an error.