Determination of natural and synthetic estrogens and their conjugates in sewage sludge by pressurized liquid extraction and liquid chromatography–tandem mass spectrometry

In this study we present a pressurized liquid extraction/liquid chromatography–tandem mass spectrometry (PLE/LC–MS–MS) method to determine a group of estrogens and conjugated estrogens in sewage sludge. Parameters that affect the extraction step such as extraction solvent, temperature, pressure, static extraction time, number of cycles, purge time and flush volume have been optimized. In the LC–MS–MS system, electrospray ionization and a triple quadrupole analyzer have been used, and the multiple reaction monitoring mode has enabled low levels of target analytes to be detected. All recoveries were higher than 81% except for estrone 3-glucoronide and estradiol 17-glucoronide which were not extracted and consequently, they were not considered in the present study. The repeatability and reproducibility between days expressed as %RSD (n = 3), were lower than 6% and 9%, respectively. The method developed allowed the target analytes to be quantified at low levels of μg/kg. The limits of detection were lower than 26 μg/kg of dry weight (d.w.) of sewage sludge, except for 17α-estradiol, 17β-estradiol, 17α-ethinylestradiol and estradiol 17-acetate whose values were between 150 and 175 μg/kg (d.w.). The method was applied to determine these compounds in sewage sludge from two domestic sewage treatment plants. Estrone 3-sulfate, estradiol 3-sulfate, diethylstilbestrol, estrone and estriol were determined in some samples and estriol showed the highest value (406 μg/kg d.w.).