Practice question

Sephadex G-50 fractionates molecules within 1,500-30,000 Da range. Molecules above 30 kDa are fully excluded, cannot enter dextran pores, eluting at void volume first. Smaller molecules penetrate to varying extents; intermediate sizes partially included elute next, while very small molecules fully included elute last. Therefore progression from high to low molecular weight from early to late fractions defines correct order. Confusing small-to-large would invert physical principle. Recognizing large-to-small order aids in planning preparative separations, such as separating proteins from peptides, or removing salts, ensuring collection of desired size class in expected fractions.