Three-phase carrier-mediated hollow fiber microextraction based on deep eutectic solvent followed by HPLC–UV for determination of raloxifene and ethinylestradiol in pharmaceutical wastewater treatment plants

Abstract

Endangering of the aquatic organisms and humans health by entrance of the pharmaceuticals in hydrosphere is becoming an important growing problem in the world. Effluents from wastewater treatment plants (WWTPs) are considered one of the main disposal pathways and incoming load of different pharmaceuticals in hydrosphere. In the present work, a new carrier-mediated hollow fiber liquid phase microextraction (CM-HFLPME) based on deep eutectic solvent (DES) was combined with HPLC–UV and applied for determination of ethinylestradiol (EE) and raloxifene (RLX) in pharmaceutical wastewater samples. The target analytes were extracted from 17 mL of the basic solution with pH 11 into an organic phase, as the supported liquid membrane (SLM) impregnated in the pores of a hollow fiber, and then back-extracted into the acceptor phase locating into the lumen of the hollow fiber. SLM consisted of n-octanol containing N,N,N-cetyltrimethyl ammonium bromide (CTAB), as the carrier, and the acceptor phase contained a mixture of DES and HCl. The important factors including sample pH, extraction time, HCl concentration and CTAB amount were optimized using a central composite design (CCD). Under the optimized conditions, preconcentration factors of RLX and EE were found to be 86 and 53, respectively. The limits of detections (LODs), based on 3S/N, were found to be 5.0 ng/mL for RLX and 10 ng/mL for EE, respectively. The calibration curves of RLX and EE were linear within the ranges of 20–5000 ng/mL (r2 = 0.9980) and 30–5000 ng/mL (r2 = 0.9985), respectively. Relative standard deviation (RSD%) of RLX and EE, based on three replicates at the concentration of 100 ng/mL, was calculated 1.7% and 2.6%, respectively. Finally, the feasibility of the proposed method was successfully confirmed by extraction and determination of RLX and EE in pharmaceutical wastewaters.