A chemiluminescence immunoassay (CLIA) method of high sensitivity, selectivity and reproducibility for the determination of estriol (E3) in human serum was developed. The magnetic microparticles were used as the second-antibody separation agent and the first-antibody solid-surface, respectively. Under the selected conditions, the two methods with magnetic microparticles as the second-antibody separation agent and the first-antibody solid-surface respectively, showed a calibration curve for E3 both in the range of 0.6～60 ng/mL. In the first-antibody method, the CVs (coefficient of variations) of intra- and inter-assays were less than 11% and 15%, respectively. The recovery was in the range of 90%～116%, and the soundness coefficient was 0.9987. In the second-antibody method, the CVs of intra- and inter-assays were less than 8% and 10%, respectively. The recovery was in the range of 88%～118%, and the soundness coefficient was 0.9974. Compared with the traditional micro-plate CLIA method, both of the proposed methods exhibited less analysis time and labor. The proposed methods have been used to determine E3 in human serum successfully.

Key words: estriol, magnetic microparticle, chemiluminescence immunoassay, human serum