Direct radioimmunoassay for diethylstilbestrol in serum.

A radioimmunoassay method for the measurement of diethylstilbestrol directly on 50 microliters of human serum was established using a tritium-labeled radioligand and a double antibody as a separation reagent. The assay was sensitive (less than 0.17 micrograms/L), reproducible (intra-assay and interassay coefficient of variation values, 8.14% and 8.25%, respectively), and accurate (recovery up to 95%). Factors influencing the assay are identified and discussed.