Stir bar sorptive-dispersive microextraction by a poly(methacrylic acid-co-ethylene glycol dimethacrylate)-based magnetic sorbent for the determination of tricyclic antidepressants and their main active metabolites in human urine

A poly(methacrylic acid-co-ethylene glycol dimethacrylate)-based magnetic sorbent was used for the rapid and sensitive determination of tricyclic antidepressants and their main active metabolites in human urine. This material was characterized by magnetism measurements, zeta potential, scanning electron microscopy, nitrogen adsorption–desorption isotherms, and thermogravimetric analysis. The proposed analytical method is based on stir bar sorptive-dispersive microextraction (SBSDME) followed by liquid chromatography–tandem mass spectrometry. The main parameters involved in the extraction step were optimized by using the response surface methodology as a multivariate optimization method, whereas a univariate approach was employed to study the desorption parameters. Under the optimized conditions, the proposed method was properly validated showing good linearity (at least up to 50 ng mL−1) and enrichment factors (13–22), limits of detection and quantification in the low ng L−1 range (1.4–7.0 ng L−1), and good intra- and inter-day repeatability (relative standard deviations below 15%). Matrix effects were observed for the direct analysis of urine samples, but they were negligible when a 1:1 v/v dilution with deionized water was performed. Finally, the method was successfully applied to human urine samples from three volunteers, one of them consuming a prescribed drug for depression that tested positive for clomipramine and its main active metabolite. Quantitative relative recoveries (80–113%) were obtained by external calibration. The present work expands the applicability of the SBSDME to new analytes and new types of magnetic sorbents. Graphical abstract

Poly(4-vinylphenol) coated magnetic nanoparticles based dispersive solid-phase microextraction of the determination of mercury(II) in water

<p>The development of magnetic sorbent for dispersive solid-phase micro-extraction (DmSPE) often requires lengthy multi-step reactions. This research revealed a simplified method for preparing magnetic sorbent for the DmSPE using poly(4-vinylphenol) (PVP). The magnetic sorbent (PVP@MNP) was prepared by coating PVP on magnetic particles (MNP). The characterization and formation of PVP@MNP were confirmed using infrared spectroscopy, scanning electron microscope, and energy-dispersive X-ray spectroscopy. The primary goal of this study is to develop a sensitive DmSPE method to analyze Hg2+ in water using PVP@MNP as a magnetic sorbent. The preparation of PVP@MNP was performed in a simple coating method at room temperature. Briefly, the PVP@MNP was prepared by sonicating the mixture of MNP and PVP. This sorbent was then used as a magnetic sorbent for the extraction of Hg2+ from water. The developed PVP@MNP based DmSPE reached a low method of detection limit (0.01 μg L-1) and limit of quantification (0.04 μg L-1). This method also showed a wide linearity range (100 - 2000 µg L-1) with a good correlation factor under optimized conditions. The developed method showed good recovery (72-90%) with good intraday and interday precision. This study also showed that the developed DmSPE method was effectively used to determine Hg2+ in drinking water, mineral water, and surface water. The result also demonstrated that PVP@MNP is reusable.</p>

Phosphorylation of Guar Gum/Magnetite/Chitosan Nanocomposites for Uranium (VI) Sorption and Antibacterial Applications

The development of new materials is needed to address the environmental challenges of wastewater treatment. The phosphorylation of guar gum combined with its association to chitosan allows preparing an efficient sorbent for the removal of U(VI) from slightly acidic solutions. The incorporation of magnetite nanoparticles enhances solid/liquid. Functional groups are characterized by FTIR spectroscopy while textural properties are qualified by N2 adsorption. The optimum pH is close to 4 (deprotonation of amine and phosphonate groups). Uptake kinetics are fast (60 min of contact), fitted by a pseudo-first order rate equation. Maximum sorption capacities are close to 1.28 and 1.16 mmol U g−1 (non-magnetic and magnetic, respectively), while the sorption isotherms are fitted by Langmuir equation. Uranyl desorption (using 0.2 M HCl solutions) is achieved within 20–30 min; the sorbents can be recycled for at least five cycles (5–6% loss in sorption performance, complete desorption). In multi-component solutions, the sorbents show marked preference for U(VI) and Nd(III) over alkali-earth metals and Si(IV). The zone of exclusion method shows that magnetic sorbent has antibacterial effects against both Gram+ and Gram- bacteria, contrary to non-magnetic material (only Gram+ bacteria). The magnetic composite is highly promising as antimicrobial support and for recovery of valuable metals.