[Estradiol Reference Standard (Control 931) of National Institute of Health Sciences].

The raw material for estradiol was examined for preparation of the "National Institute of Health Sciences (NIHS) Estradiol Reference Standard (Control 931)". Analytical data obtained were as follows: melting point, 179.0 degrees C; infrared spectrum, the same as that of the present NIHS Estradiol Reference Standard; optical rotation, -alpha-20D = +80.4 degrees; thin-layer chromatography, no impurity was detected; high-performance liquid chromatography (HPLC), a trace amount of two impurities were detected; loss on drying, 0.24%; assay, 100.4% by UV spectrophotometry and 101.2% by HPLC. Based on the above results, the raw material was authorized as the NIHS Estradiol Reference Standard (Control 931).