Preconcentration of selected cephalosporins using waste PET-derived UIO-66 as an adsorbent before HPLC-DAD quantification

Abstract

In this work, a method for the extraction, preconcentration and determination of five different cephalosporin antibiotics in various water samples using ultrasound-assisted dispersive solid-phase extraction (UA-DSPE) and high-performance liquid chromatography coupled with diode-array detection (HPLC-DAD) was developed. The waste PET-derived UIO-66 was prepared and used as an adsorbent. The prepared adsorbent was characterised using Fourier transform infrared spectroscopy, X-ray diffraction, high-resolution scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. The large surface area, pore volume, and microporous nature of the material were necessary to ensure there were abundant active sorption sites for the cephalosporin antibiotics (cefoperazone, ceftriaxone, cephalothin, cefaclor and cefoxitin). The factors affecting the UA-DSPE method were optimised using a central composite design. Under optimised conditions, wide linearity ranging from 0.1–700 µg/L with the determination coefficients greater than 0.99. The limits of detection and quantification were in the range of 0.026–0.096 μg/L and 0.09–0.32 μg/L, respectively. The intraday and interday spiked recoveries were 71.4–99.3 % and 72.6–99.1 %, respectively, with the relative standard deviation values less than 6 %. The UA-DSPE/HPLC-DAD method was successfully applied to real environmental samples such as wastewater and surface water. The adsorptive performance of the waste PET-derived UIO-66 material was investigated using a series of adsorption experiments. The adsorption isotherms and kinetics indicated that the Langmuir isotherm and pseudo-second-order kinetic models explained the adsorption process. The maximum adsorption capacities for the target analytes using waste PET-derived UIO-66 ranged from 68.3–106 mg/g. These results demonstrated that the waste PET-derived UIO-66 material could be used as a sustainable adsorbent for the adsorptive removal of cephalosporin antibiotics from waster.