Abstract: A TEST TUBE SOLID PHASE SECONDARY ANTIBODY TECHNIQUE AND ITS APPLICATION IN RIA FOR β-HCG Hao Xiuhua; Chen Panzao; Li Zhenjia（Biochemistry Research Lab. of Chinese PLA General Hospital, Beijing 100853）ABSTRACT A simple and sensitive assay ofβ-HCG can be performed by solid phase RIA using secondary anti-body linked to test tubes． Its sensitivity is less than 4 mIU/ml and the working range is 4—160mIU／ml． Statistical corrclation between the present assay and conventional liquid－ phase RIA ofβ－HCG is satisfactory（r=0．9942）.The method might take the place of conventional liquid-phase RIAfor β-HCG.Key words choriogonadotropin radioimmunoassay test tube solid phase secondary antibody