Synthesis and comparison of four magnetic sorbents for dispersive micro-solid-phase extraction of antidiabetic drugs in urine and water samples

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.

A thin biofilm of chitosan as a sorptive phase in the rotating disk sorptive extraction of triclosan and methyl triclosan from water samples

The features and nature of the sorptive phase may be the stage that determines the scope of microextraction techniques. In search of new alternatives, materials of natural origin have recently been explored to establish greener analytical strategies. Based on that search, this research proposes the use of chitosan as a sorptive phase, which was assessed in the rotating disk sorptive extraction of emerging contaminants from aqueous systems. Chitosan is a biopolymer of animal origin that is usually found in the shells of crustaceans. The main characteristic of this material is the presence of a high number of nitrogenous groups, which gives it high reactivity, but its main disadvantage is associated with its high swelling capacity. In this research, chitosan was crosslinked with a low concentration of glutaraldehyde to form thin films that were easily immobilized on the surface of the rotating disk. The main advantage of this modification is the considerable decrease in the swelling capacity, which prevents loss and rupture of the sorbent during high rotation of the disk. In addition, it not only improved the physical characteristics of chitosan but also increased its extraction capacity. With regard to its use as a sorptive phase, all the variables associated with the microextraction of the analytes were studied, and optimal variables were found to be: pH 4, 20% NaCl (salting out effect), 30-45 min as equilibrium time and elution of analytes with a mixture of methanol:ethyl acetate (1:1). Validation of the methodology for the determination of methyl triclosan and triclosan was carried out, and relative recoveries between 89 and 96% and relative standard deviations less than 14% were found. The detection limits were 0.11 and 0.20 μg L^-1, respectively. Through its application in real samples (natural and residual waters), triclosan was quantified between 0.7 and 1.3 μg L^-1. Finally, the "green" properties of the phase were evaluated, demonstrating that it is reusable for at least three cycles and biodegradable. Compared to its efficiency with a commercial phase (in this case, the styrene divinyl benzene phase), the proposed biosorbent provided a similar and even higher sorptive capacity (depending on the analyte).