Fibronectin is also called cold-insoluble globulin. The antigen used for immunization has been isolated from pooled human citrate plasma. For the quantitation of fibronectin, citrate, heparin or EDTA-plasma should be used. Serum is not suited as the amount of fibronectin left in serum after the blood coagulation, is variable. Nephelometry, turbidimetry and rocket immunoelectrophoresis are the recommended quantitative methods for fibronectin. Single radial immunodiffusion tends to give erroneous results. If plasma samples have been frozen, they must be thawed at 37 °C before performing quantitative analysis. More details on quantitation of fibronectin are found in references 1 and 2.