Solid phase ELISA for serum ferritin

We describe a solid-phase enzyme immunoassay for human serum ferritin, with the use of polyethylene glycol to shorten the reaction. The amount of bound enzyme-antibody conjugate used as a second site antibody is proportional to the ferritin titre in the assay. This method is fast, and the reagents are stable for many months at 4 degrees C. The lowest detectable concentration was 5 micrograms/l. Interassay coefficients of variation were 9.3 and 12.2%, respectively, at ferritin concentrations of 100 micrograms/l and 200 micrograms/l. The data also show that polyethylene glycol accelerates antigen-antibody complex formation in the solid phase. An assay may be completed in 5 h.