Simultaneous determination of eight estrogens and their metabolites in serum using liquid chromatography with electrochemical detection.

The liquid chromatography (LC) with electrochemical detection allows to determine, evaluate and validate the level of estrogens and their metabolites in serum. The method is fast and sensitive, and the hormones can be determined simultaneously, from one serum sample. The proposed method was successfully applied to the determination of following estrogens: estrone (E(1)), 17beta-estradiol (E(2)), estriol (E(3)) and following catecholestrogens: 2-hydroxyestradiol (2-OHE(2)), 4-hydroxyestradiol (4-OHE(2)), 4-hydroxyestrone (4-OHE(1)), 2-methoxyestradiol (2-MOE(2)) and 2-methoxyestrone (2-MOE(1)). The method of LC with electrochemical detection (LC/EC) was applied for the determination of catecholestrogens in serum sample taken from pregnant women. Estrogens and catecholestrogens were extracted from 1 mL of serum by applying diethyl ether under the specified conditions. The parameters of the procedure included using a specific mobile phase, applying the column Symmetry C18 (5 microm, 3.0 mm x 150 mm), equipping the applied electrochemical detector with the working glassy-carbon electrode, as well as applying the reference electrode Ag/AgCl. The calibration studies on this study were performed, and a good analytical performance for E(1), E(2), E(3), 2-OHE(2), 4-OHE(2), 4-OHE(1), 2-MOE(2) and 2-MOE(1) was attained, along with low limits of detection (LOD of 0.18-0.30 ng/mL), satisfactory limit of quantification (LOQ of 0.23-0.92 ng/mL) and excellent linear dynamic range (0.6-8.0 ng/mL). In conclusion, the presented methodology is the sensitive method of the simultaneous measurement of eight estrogens and their metabolites from one sample of blood and it might be clinically applied for testing serum of pregnant women, as well as for further studies on estrogens and their metabolites.