Magnetic Microparticle Radioimmunoassay for the Determination of Estriol in Human Serum

In the present study, using magnetic microparticles, two ultra-sensitive and simple methods based on the traditional radio-immunoassay for the determination of estriol (E3) in serum were developed. The magnetic microparticles were used as the second-antibody separation agent and the first-antibody solid-surface. Under optimized conditions, the measurement calibration curve for E3 is in the range of 0.3–30 ng ml−1. The relative standard deviation (RSD) of the intra- and inter- of the second-antibody method is 4.3% and 8.7%, respectively. The recovery is 104%–114%, and the soundness coefficient is 0.9989; The RSD of the intra- and inter- of the first-antibody method is 4.4% and 7.6% respectively. The recovery rate is 96%–115%, and the soundness coefficient is 0.9986. These two radio-immunoassay methods using the magnetic microparticle shorten the analysis time. The accuracy and precision are good enough for clinical and environmental analysis. Compared to these two methods, using the magnetic microparticle as the first-antibody was much simpler and faster.