Investigation of five metal–organic frameworks as sorbents in the syringe filter-SPE method for determination of metronidazole and cephalexin in water samples

Abstract

In this study, we evaluated the preparation and utilization of NH₂-MIL-101(Al) and NH₂-MIL-101(Cr) as two efficient adsorbents for the extraction of metronidazole and cephalexin in water samples using the syringe filter-SPE method. The synthesized MOF was placed inside a syringe filter to extract the target antibiotics from the water solution following their quantification by high-performance liquid chromatography (HPLC). Various characterization methods such as SEM, FTIR, XRD, TGA, and BET were used to assess and confirm the synthesis of the studied MOFs. The comparison of the adsorption capability of the synthesized MOFs revealed that NH₂-MIL-101(Al) had the greatest adsorption capability. The experimental factors affecting the extraction efficiency such as sample volume and pH, and the type and volume of the adsorption solvent were thoroughly studied and optimized. Under the optimal conditions, the detection limits were calculated to be in the range of 0.5 to 10.0 μg L⁻¹, and a linear range between 2.0 and 800 μg L⁻¹ was obtained. Very good repeatability with RSD values ranging between 3.2% and 5.3% was achieved. The calculated relative recovery ranged from 95% to 104% at the spiked levels of 60–150.0 μg L⁻¹.