Abstract: DEVELOPMENT OF RADIOIMMUNOASSAY KIT FOR ATRIAL NATRIURETIC FACTOR IN PLASMASu Jingxian Hou Huiren(Department of Isotope, China Institute of Atomic Energy, Beijing 102413)ABSTRACTA specific radioimmunoassay (RIA) kit for Atrial Natriuretic Factor(ANF) is developed and applied to the measurment of human plasma. ANF is iodinated according to the method of ChT and purified by sephadex G50. The specific activity of 125IANF is more than 10 MBq/μg, the radiochemical purity is more than 90% and the excessive antibody binding is (78-81)%. The kit has a set of stable lyophization standards. The range of detection is from 65 pmol/L to 3 250 pmol/L. The assay method is simple and quick with the following characteristics: the average recovery in human plasma is (93.4-115)%, the intra and inter coefficients of variation are (3.2-4.5)% and (3.1-6.2)%, respectively, the nonspecific binding is (1.9-4.4)%, the detection limit is 17 pmol/L and the correlation coefficient of high value plasma dilution is 0.999 2-0.999 8. The content of ANF in 97 healthy adults is 122.0±24.8 pmol/L.Key words atrial natriuretic factor(ANF) radioimmunoassay(RIA) kit