Measurement of serum unconjugated estriol and estradiol by high-performance liquid chromatography

Measurement of Estriol (E3) and estradiol (E2) within 22 min by high-performance liquid chromatography (HPLC) was achieved in this study, and the values were compared with those of a radioimmunoassay (RIA). A totally computerized HPLC method was developed for measuring unconjugated E3 (u-E3) and E2 (u-E2) in the sera of pregnant women. The serum samples were injected directly into the apparatus and transferred to a pretreatment column where the estrogens were absorbed while hydrophilic components such as proteins and carbohydrates were excluded. The estrogens were then passed through another separation column containing a new type of polymer gel. The mobile phase consisted of an acetonitrile-water mixture, and separation was achieved by means of a reversed-phase procedure. The eluate was monitored for fluorescence. All procedures were monitored and controlled with a built-in microcomputer. Serum samples from 97 normal pregnant women at 20-41 wk gestation were simultaneously assayed by HPLC and RIA. The correlations obtained by HPLC and RIA were as follows: u-E3, y = 0.905x - 0.385, with a coefficient of correlation of r = 0.912; for u-E2, y = 0.964x + 5.024, with a coefficient of correlation of r = 0.841 (y, RIA value; x, HPLC value). The quick measurement of u-E3 and u-E2 by HPLC can be a useful method for evaluating fetoplacental function.