Dispersive micro solid phase extraction of glibenclamide from plasma, urine, and wastewater using a magnetic molecularly imprinted polymer followed by its determination by a high-performance liquid chromatography-photodiode array detector.

The present study describes the development of a simple and selective analytical method for dispersive micro solid phase extraction and determination of glibenclamide (GLB) using magnetic molecularly imprinted polymer (MMIP) as a sorbent. MMIP was fabricated by the non-covalent method on the surface of silicated Fe3O4 and had a high affinity for glibenclamide; dual monomers, itaconic acid and allylamine, were used for this. Polymerization was achieved by the precipitation method in the presence of glibenclamide as the template and ethylene glycol dimethacrylate as the cross-linker. The morphology and structural properties of the MMIP were characterized by different analytical methods. To achieve maximum extraction efficiency, influencing parameters were optimized. The linearity range was 1-2000 and 12-2000 µg L-1 by high-performance liquid chromatography-photodiode array detector (HPLC-PDA) and UV-vis spectroscopy, respectively. The detection and quantification limits with UV-vis and HPLC-PDA analyses were 4 and 12 µg L-1 and 0.3 and 1 µg L-1, respectively. Under optimized conditions, recovery of glibenclamide spiked in plasma, human urine, and wastewater was between 89.4 and 102.9% at the concentration levels of 25, 250, and 500 µg L-1; relative standard deviations were below 3.7% by HPLC-PDA. The developed method has a favorable pre-concentration factor of 140.0. Equilibrium data and sorption isotherms fitted well with the Langmuir model. A maximum sorption capacity of 24.260 mg g-1 was acquired based on the Langmuir model. The synthesized sorbent with high selectivity was used to separate GLB from complex biological systems and wastewater before measurement with UV-vis or HPLC-PDA.

Synthesis of magnetic molecular imprinted polymer with a new functional monomer for dispersive micro solid phase extraction of captopril from wastewater and biological samples and determination by UV-Vis spectrophotometry.

A magnetic molecularly imprinted polymer (MMIP) was fabricated for captopril by surface polymerization of Fe3O4@SiO2 nanoparticles using a new functional monomer of N-(allylcarbamothioyl)-2-chlorobenzamide. It was then employed as a selective nanosorbent for dispersive magnetic micro solid phase extraction (DM-µ-SPE) of captopril from biological and wastewater samples. To characterize the physicochemical properties of the MMIP, different analytical methods such as the vibrating sample magnetometer, field emission scanning electron microscopy, Brunauer-Emmett-Teller, and Fourier transform infrared spectroscopy were utilized. To gain the maximum extraction recovery of captopril, the influence of various operating conditions was investigated and experimental settings optimized. After the extraction step, the concentration of captopril was measured by UV-Vis spectrophotometer at 245 nm. The assessments demonstrated that the MMIP provides higher extraction efficiency in comparison to magnetic non-imprinted polymer, suggesting the establishment of selective recognition binding sites at the MMIP surface. The method depicted desirable figures of merit of a low detection limit of 0.16 µg L-1, a limit of quantification of 0.50 µg L-1, a linear dynamic range of 0.50-22.0 µg L-1, and an acceptable preconcentration factor of 333. The magnetic MIP was successfully employed for preconcentration and extraction of trace amounts of captopril in real samples, such as human blood serum, urine, and wastewater samples, with recoveries in the range 95.7 to 102.6% and relative standard deviations < 5%.

Nanoraspberry-like copper/ reduced graphene oxide as new modifier for simultaneous determination of benzenediols isomers and nitrite.

In this study, immobilized nanoraspberry-like copper on the reduced graphene oxide (NRCu-rGO) was synthesized and used for modification of glassy carbon electrode (GCE) for selective and sensitive simultaneous determination of benzenediols isomers; hydroquinone (HQ), catechol (CC), resorcinol (RS) as well as nitrite (NO2-). A detailed investigation such as field emission scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction as well as electrochemistry methods such as cyclic voltammetry, electrochemical impedance spectroscopy, differential pulse voltammetry (DPVs) and chronoamperometry are performed in order to elucidate the preparation process and properties of the NRCu-rGO/GCE. DPVs peak currents increased linearly with the analytes concentrations within the ranges of 0.13-131.5 µM for HQ, CC, RS and 0.3-131.5 µM for NO2- with a detection limits 49, 52, 60 and 100 nM for HQ, CC, RS and NO2-, respectively. The proposed modified electrode was successfully used for simultaneous determination of HQ, CC, RS and NO2- in real samples.