POLAROGRAPHIC ENZYME-IMMUNOASSAY FOR TRACE HEPATITIS-B SURFACE-ANTIGEN

A polarographic enzyme-immunoassay for Hepatitis B Surface Antigen(HBs Ag) has been established, in which horseradish peroxidase(HRP) is used as the labeled enzyme, o-phenylenediamine(OPD) as the substrate, and the enzyme-generated product,2,2'-diaminoazobenzene (DAA), is detected by linear-potential scan polarography. Under optimal conditions, the second derivative current of DAA is linear with the concentration of H BsAg from 0.1 to 5 ng/mL. The correlation coefficient(r) is 0.9994. Th e detection limit is 0.05ng/mL and the relative standard deviation is 6.7%(8 replicates). The sensitivity of the assay is about 20-fold high er than that of ELISA. The assay has been successfully applied for min ute determination of HBsAg in both human serum and the negative contro l serum from ELISA kits. Copyright (C) 1996 by Marcel Dekker, Inc.