Abstract: A method of determining the glycosylated fraction of a protein in a sample includes the steps of examining the sample to determine the total quantity of protein in the sample (READ 1), removing the glycosylated fraction of the protein, and then reexamining the sample to measure the glycosylated fraction of the protein (READ 2). The glycosylated fraction of the protein may then be calculated by the formula (READ 1-READ 2)/READ .times.100. The glycosylated fraction of the protein is removed by inserting a cartridge containing a binder into the sample, or by urging the sample through a cartridge containing a binder. Both of the cartridge assemblies preferably include a flow through body, a support material disposed in the body, and a binder material attached to the support wherein the binder has an affinity for the glycosylated fraction of the protein.