Direct radioimmunoassay of estradiol-17 beta in defatted bovine milk

A radioimmunoassay was developed for rapid determination of estradiol-17 beta concentrations in unextracted defatted bovine milk. The assay was dependent on the use of a highly specific anti-estradiol-17 beta antiserum. Application of a formula to correct for the interference associated with individual milk samples and use of appropriate assay blanks facilitated interpolation on a buffer standard curve. The assay offered a high degree of sensitivity (0.6pg/ml milk) and a precision (within-assay coefficient of variation: 0.196; between-assay CV:0.191) comparable with contemporary extraction methods.