OPTIMIZATION OF ESTRADIOL MONITORING IN RAW AND TREATED WASTEWATER SAMPLES BY RESPONSE SURFACE METHODOLOGY

Estradiol, also designed as 17- ? -estradiol, belongs to the pharmaceutical class of steroid estrogens and was included in the �Watch List� since 2013 the Directive 2013/39/EU due to its potential risk to human health and environment. The low removal efficiency of estrogens by the conventional wastewater treatment plants, becomes a major source of their release into different aquatic matrices. This work presents the optimization of an analytical methodology based on solid phase extraction and high-performance liquid chromatography using the response surface methodology to detect and quantify 17-?- Estradiol in wastewater treatment plant effluents. From a set of 10 studied solvent/mixture compositions, pure methanol was selected as the better choice to use as mobile phase composition for liquid chromatography. The solid phase extraction step was optimized using a three-level Box-Behnken experimental design with sample volume, sample pH, adsorbent drying time and solvent composition in the washing step, as the four factors to be studied. The sample volume of 500 mL, a sample pH value adjusted to a value of 2, an adsorbent drying time of 60 min and the use of 10% of methanol in the adsorbent washing step were the obtained optimized conditions. The pH value was concluded to be the more significant parameter for average recuperations of estradiol higher than 80%. The method validation was performed by monitoring 17-?-estradiol in real wastewater treatment plant samples, collected from raw affluent, secondary treatment and treated effluent. The methodology was tested successfully, and estradiol was quantified in all the three studied samples.