Determination of estrogens in environmental water samples by LC/MS/MS

An analytical method for the simultaneous determination of estrogens (17beta-estradiol, 17alpha-estradiol, estrone, ethinylestradiol) by liquid chromatography/tandem mass spectrometry (LC/MS/MS), following sample pretreatment by solid-phase extraction using a C-18 cartridge, back extraction from the water phase with ethyl acetate and cleaned up using NH2 cartridge, has been developed. It has been observed that the main fragment negative ions with electrosplay ionization (ESI) were deprotonated molecules, [M - H](-), for each compound, as follows: 17beta-estradiol and 17alpha-estradiol, m/z 271; estrone, m/z 269; ethinylestradiol, m/z 295. The product ion, m/z 145, was obtained from all compounds using a collision energy of 50 eV. The detection limits of four compounds ranged from 0.1 ng/ml to 0.5 ng/ml. Good linearity (r greater than or equal to 0.998) of the calibration curve was obtained in the concentration range from 0.5 ng/ml to 100 ng/ml for all compounds. The present method has been successfully applied to the determination of estrogens in environmental water samples, such as river water and the discharge of sewage treatment plants.