Dextran is coupled to a high strength Separopore® 4B-CL matrix. Coupling dextran to this material expands the surface area of the Separopore® beads allowing for further binding of macromolecules. Dextran-Separopore® 4B-CL is used in affinity chromatography as a protein binding site. It has been used to study Alzheimer’s disease by quantifying cerebrospinal fluid (CSF) in relation to amyloid accumulation in rat brain parenchyma.