Highly selective solid phase extraction of clonazepam from water using a urea modified MOF prior to HPLC analysis

The presence of pharmaceutical pollutants, such as clonazepam (CZP), in aquatic environments poses significant risks to ecosystems and human health. This study introduces a novel solid-phase extraction (SPE) method utilizing a urea-modified metal-organic framework (MIL-101(Fe)-Urea) for the selective preconcentration and quantification of CZP in environmental water samples, then analyzed by high performance liquid chromatography analysis. The MIL-101(Fe)-Urea adsorbent was synthesized through a post-synthetic modification approach and characterized using FTIR, PXRD, SEM, BET, and EDX techniques. Key extraction parameters, including pH, adsorbent dosage, extraction/desorption times, and sample volume, were optimized to achieve maximum adsorption efficiency. Under optimal conditions, the method demonstrated excellent linearity (R² = 0.997) within a concentration range of 20-1500 µg L^-1, with a low detection limit (LOD = 0.030 µg L^-1), high recovery rates (94.9-99.0%), and a relative standard deviation of 1.4%. The developed method was successfully applied to real environmental water samples, confirming its practicality for environmental monitoring. This study highlights the potential of MIL-101(Fe)-Urea as an advanced adsorbent for the analysis of pharmaceutical contaminants, contributing to the development of efficient and environmentally friendly analytical techniques for water quality assessment.