Liquid chromatography with fluorometric detection of unconjugated estriol in serum of pregnant women.

We describe a fluorometric liquid chromatographic assay for the measurement of unconjugated estriol in the serum of pregnant women. Estriol is extracted into methylene chloride/propanol-2 from serum by use of a Clin-Elut extraction column, the extract evaporated, and the residue redissolved in mobile phase. An aliquot is injected onto the liquid chromatograph and the estriol is separated on a reversed-phase octyl column with a mobile phase consisting of acetonitrile/phosphate buffer (23:77, v/v). The effluent is monitored by fluorescence detection. The proposed method offers good reproducibility (CV less than 7%), sensitivity (less than 0.5 micrograms/l), and accuracy. Of many drugs and steroids tested, only 16,17-epiestriol interferes with the estriol analysis.