Determination of Human Serum Ceruloplasmin Based on Its Ferroxidase Activity

Abstract

This paper reports a simple and sensitive method for the determination of ceruloplasmin in human serum based on its ferroxidase activity. In acetate buffer solution (pH 6.5), iron (Fe²⁺) was rapidly oxidated to Fe³⁺ by ceruloplasmin. The addition of trichloroacetic acid solution stopped the reaction from deproteinization, but the remaining Fe²⁺ in the reaction mixture was stable for about 2h. The remaining Fe²⁺ was chelated with 2-nitroso-5-(N-propyl-N-sulfopropylamino)phenol as a specific reagent for Fe²⁺. The chelated compound developed a color that has a peak absorbance at 745nm upon addition of ammonium acetate solution. The method was suitable for the determination of ceruloplasmin at concentrations up to 100mg/dl. The within-run precision, or coefficient variation, was 3.25%. Close correlation was found between this method and other methods currently available.