Surface imprinting polymerization for synthesis of a molecularly imprinted polymer and its application in ultrasound-assisted dispersive solid-phase microextraction of selected tetracycline antibiotics in wastewater

The presence of pharmaceutical pollutants in the environment has detrimental effects on the water system which consequently impacts the aquatic and terrestrial life. These pharmaceutical residues exist in trace amounts which require sensitive sample preparation methods for their detection. In this work, surface imprinting polymerization was utilized to successfully synthesize a magnetic metal–organic framework-molecularly imprinted polymer (Fe₃O₄@MIL-101(Cr)@MIP) for use as a selective sorbent for the isolation of selected antibiotics in aqueous environments based on the ultrasound-assisted dispersive technique. A variety of analytical methods and techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and Brunauer–Emmett–Teller were used to characterize the structural and morphological features of the synthesized Fe₃O₄@MIL-101(Cr)@MIP. The synthesized Fe₃O₄@MIL-101(Cr)@MIP was then employed as a selective adsorbent in the ultrasound-assisted dispersive molecularly imprinted solid-phase micro-extraction method developed for the extraction and preconcentration of oxytetracycline and chlortetracycline as model antibiotics in wastewater prior to their analysis with high-performance liquid chromatography–diode array detector. Using a multivariate optimization method, important factors such as sample pH, the mass of the adsorbent, eluent volume and elution time were optimized. The analytical method gave the quantification limits of 0.11 µg L⁻¹ and 0.13 µg L⁻¹ for oxytetracycline and chlortetracycline, respectively. The recoveries obtained for oxytetracycline and chlortetracycline, after spiking wastewater samples ranged from 78 to 99%, with relative standard deviations not exceeding 5%. These findings suggested an acceptable analytical method that could be routinely applied for the determination of these drugs in wastewater.