Facile synthesis of new magnetic sorbent based on MOF-on-MOF for simultaneous extraction and determination of three benzodiazepines in various environmental water samples using dispersive micro solid-phase extraction and HPLC

An efficient and facile sample preparation method based on dispersive micro solid-phase extraction (D mu SPE) was presented to extract three benzodiazepines (BZDs), including clobazam, clonazepam, and oxcarbazepine, in real water samples. A Hybrid core-shell MOFs (MIL-100(Fe)@MIL-53(Fe)) was synthesized as the main component of the D mu SPE sorbent using chemical and hydrothermal methods and magnetized with Fe3O4 nanoparticles using the sol-gel technique. The ability of the sorbent to extract BZDs was compared with each sorbent component. Factors that affected the method were optimized using one factor at a time and design of experiment strategy (a definitive screening design and a central composite design). The method presents wide linearity of 0.1-276, 0.2-368, and 0.1-314 ng mL-1 for determining clobazam, clonazepam, and oxcarbazepine with the determination coefficients (R2) higher than 0.9923, respectively. LODs for the determination of clobazam, clonazepam, and oxcarbazepine were 0.03, 0.06, and 0.03 ng mL-1. The method shows the intra-day and inter-day RSDs lower than 2.5 and 3.0 %, and preconcentration factors higher than 817 for determining BZDs, respectively. Besides, analysis of environmental water samples with the method for measuring BZDs with the recoveries of 92.5-97.6 % and relative standard deviations of 3.1-4.3 % indicated the method has a good ability to analyze real samples, especially environmental water samples.