Ready-to-use buffer solution for the preparation of protein samples to be separated in SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Loading Buffer Blue (2X) contains Bromophenol Blue as a tracking dye to monitor the sample during the electrophoretic run. Loading Buffer Blue (2X) contains 0.5M Tris-HCl (pH 6.8), 4.4% (w/v) SDS, 20% (v/v) glycerol, 2% (v/v) 2-mercaptoethanol, and bromophenol blue in distilled/deionized water.