Sequential competitive enzyme immunoassay for human chorionic gonadotropin.

In the previous report, we had developed a simultaneous competitive enzyme immunoassay for hCG, using sheep red blood cells as the solid phase. The serum sample was not checked because of serum interference. In this report we have developed sequential competitive enzyme immunoassay. The sequential method is preferred because serum interference is removed and silicone rods are used as the solid phase instead of sheep red blood cells, which would be easily washed away in that procedure. The working range of this procedure is from 0.5 mIU/ml to 200 mIU/ml. That value for serum hCG correlates well with that by RIA (n = 0.904) Coefficients of variation are satisfied (14.2%: within assay and 15.2%: between assay).