Automated assay of ceruloplasmin by kinetic analysis of o-dianisidine oxidation

Automated procedures for the kinetic assay of serum ceruloplasmin activity using a bichromatic and a centrifugal analyzer are described. The method is based on the oxidase activity of ceruloplasmin at pH 5.0 with o-dianisidine as substrate. Enzyme activity is reported in I.U./l, based on the molar absorption coefficient of o-dianisidine consumed. The substrate is stable and is not subject to non-enzymatic oxidation. Comparison with a manual reference end-point assay using the same substrate indicates good correlation of the bichromatic and centrifugal methods. The analytical precision is comparable to the manual assay for both methods.