Magnetic chitosan-zeolite composite as an adsorbent in ultrasound-assisted magnetic solid phase extraction of tetracyclines in water samples

An ultrasound-assisted magnetic solid-phase extraction method was developed to pre-concentrate tetracyclines (TCs) in wastewater and river water. The magnetic chitosan-zeolite composite was used as an adsorbent. The morphological and structural properties of the adsorbent were characterised by various analytical techniques. The factors affecting the ultrasound-assisted magnetic solid-phase extraction method were optimised using a central composite design. A high performance liquid chromatography equipped with a photodiode array detector was used to quantify TCs in wastewater and river water samples. Under optimised parameters, the developed analytical approach gave acceptable linearity (LOQ-400 µg L⁻¹) with correlation coefficients exceeding 0.993, while the detection and quantitation limits ranged from 0.05–0.67 and 0.14–2.03 µg L⁻¹, respectively. Attained recoveries were 90–101%, with intraday and interday precision expressed as the relative standard deviation (%RSD) below 5%. Even though the target analytes (tetracycline, oxytetracycline and oxytetracycline) were not detected in environmental samples, the synthesised adsorbent was suitable for the isolation of TCs in a complex matrix resulting in an accurate, precise, rapid and sensitive analytical method.