D. Polyacrylamide gel electrophoresis (PAGE) It has a high molecular sieving effect and so separation is very efficient. In agar gel electrophoresis, serum components are separated into 5 fractions; while in PAGE serum will show more than 20 different bands. The amount of cross linking and thereby the pore size can be controlled. Another common variant is the SDS-PAGE electrophoresis. Here proteins are boiled for 1-2 minutes with a denaturing agent, sodium dodecyl sulphate (SDS) (Fig. 54.2). The negative charges of SDS will cover the protein molecules, making them strongly negative. Then the separation of molecules will depend mainly on their molecular size. SDS-PAGE is therefore commonly used for molecular weight determination as well as for assessing the purity of proteins.Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 600