High-performance liquid chromatography combined with electrochemical detection was applied for the determination of estriol in human urine obtained during pregnancy. Estrogens were extracted with ether, chromatographed on a reversed-phase C-18 column with a mobile phase of methanol-water-perchloric acid mixture, and detected electrochemically at 1.1 V vs. Ag/AgCl. The minimum detectable quantity of estriol was 10 ng. Within-run precision was better than 3% for the whole procedure.
