Development of a colorimetric assay system of trace metals and proteins inserum using microtiter plates and sensitive reagents

A new colorimetric assay system using microtiter plates is presented for th e determination of trace metals and proteins in serum samples. The use of p olystyrene microwells with about 400-mul capacity and sensitive reagents ma de it possible to reduce the sample size and required reagent. Rapid determ ination methods for iron, copper and zinc in 20 similar to 50 mul of serum using a water-soluble pyridylazo dye were developed. Drug-bound iron e.g. s accharated ferric oxide, and transferrin-bound iron in serum were simultane ously determined using a combined system of kinetic and end-point assay. A system for serum zinc with a cationic porphyrin was three-times more sensit ive than that with the pyridylazo dye. A latex agglutination immunoassay wa s utilized for the determination of alpha2-macroglobulin and albumin in ser um. The proposed systems are sensitive, accurate, precise, simple, and rela tively inexpensive.