In one aspect, the invention provides methods for protein sample preparation for electrophoretic separation. The method comprises a step of providing a protein sample in solution, adding a chaotrope to the protein sample, adding a surfactant to the protein sample, wherein the final concentration of the surfactant in the solution is less than critical micelle concentration of the surfactant. In another aspect, the invention also provides methods of electrophoretic separation of protein samples that includes the protein sample preparation method as described herein. In yet another aspect, the invention provides a loading buffer solution composition for protein sample preparation that includes a surfactant in solution at a final concentration that is less than critical micelle concentration of the surfactant, and; a chaotrope.