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

Synthesis and Characterization of Glycidyl Esters of Acrylic and Methacrylic Acids for NIPU Coatings

Glycidyl acrylate (GA) and Glycidylmethacrylate (GMA) are the reaction products of the epichlorohydrin (ECH) with acrylic acid (AA) and methacrylic acid (MAA) respectively. These monomers were synthesized via two different routes i.e. direct reaction of AA and MAA with ECH and second by reaction of AA and MAA with Sodium hydroxide to form sodium salt of the acid followed by reacting with ECH. The polymerization inhibitor used was tert-butyl hydroquinone (TBHQ) and catalysts used were triethylamine (TEA) and quaternary ammonium salt. Experimental results show that first route is suitable for synthesizing GA and second route is suitable for synthesis of GMA. The catalysts also have drastic effect on the conversion to the respective glycidyl esters. The study of the effect of catalyst and polymerization inhibitor has been carried out via both routes.

Cyclization Reactions Involving 2-Aminoarenetellurols and Derivatives of α,β-Unsaturated Carboxylic Acids

The reductive cyclization of arenetellurols carrying α,β-unsaturated amide functionalities in the ortho position was investigated. Conceptually, such compounds can form 1,3-tellurazoles without the involvement of the unsaturation in the ring closure, they can form 1,4-tellurazinone derivatives, or they can undergo ring closure to 1,5-tellurazepinones. Amides derived from acrylic and methacrylic acid generated 1,5-tellurazepinones while 2-cinnamylamidobenzenetellurol cyclized to a 1,3-tellurazole derivative. In contrast, the reaction of acetylenedicarboxylic acid and its derivatives with 2-aminoarenetellurols generated 1,4-tellurazepinones, including a derivative of novel tricyclic naphtho [1, 4]tellurazinone. A comparison with analogous reactions of sulfur congeners indicates that their chemistry is a good predictor for the products obtained from 2-aminoarenetellurols. Selected compounds were characterized by X-ray crystallography. The present work offers access to previously unexplored organotellurium heterocycles.

Interações químicas entre monômero e molécula molde em polímeros com impressão molecular, o EGDMA: 2-VP (4: 1) - estudo de caso MIP lumefantrina

Molecularly Imprinted Polymers (MIP) are synthetic materials used as a tool to enhance the selectivity in different analytical approaches, such as solid-phase extraction, chromatography, and sensing devices. Knowing the mechanism involved in the interaction between the template and monomer is essential for a further successful application. However, studies on this topic are scarce. This work evaluates the involved mechanisms in the template-monomer interaction for a lumefantrine MIP system, an antimalarial drug. Field-emission gun scanning electron microscopy, thermal analysis, X-ray diffraction, and density functional theory were applied to determine the mechanism involved in two MIPs obtained in different conditions. A new parameter, named Molecularly Imprinting Factor (MIF), was proposed to evaluate the contribution of specific interactions in the sorption of the analyte by the MIP structure. MIF allows direct insights into specific binding, non-specific contributions, interaction nature, behavior predictability, system acid-base behavior, pre-screening pairs capability, and binding site affinities evaluation. Two interaction types were observed, covalent and non-covalent, when methacrylic acid and 2-vinyl pyridine were used as monomers, respectively. Therefore, the use of methacrylic acid formed a sorbent inappropriate for solid-phase extraction since the binding is not reversible. On the other hand, 2-vinyl pyridine-lumefantrine binding was reversible, and MIF = 0.59 (59.02% of specific site sorption) indicates that the predominant mechanism in the sorption is specific.

Selective adsorption of cationic dye utilizing poly(methacrylic acid-co-ethylene dimethacrylate) monolith from wastewater

In this study, poly(methacrylic acid-co-ethylene dimethacrylate (poly(MAA-co-EDMA)) monolith was prepared for the selective adsorption of acidic dye, namely methylene blue (MB), from wastewater. The fabrication of the monolith was carried out by photoinitiation polymerization by irradiating a mixture of methacrylic acid (MAA), ethylene dimethacrylate (EDMA), porogenic solvents and an initiator. Batch adsorption assays were performed to examine the impact of monolith dosage and initial dye concentration on the adsorption capacity and efficiency of the monolith towards MB dye molecules. This adsorption kinetic study revealed that MB adsorption on the monolith followed pseudo-second-order model and equilibrium adsorption behavior was best modeled by Langmuir adsorption isotherm indicating a monolayer adsorption with a maximum adsorption capacity of 50.00 mg g-1. Owing to the presence of negative binding sites on the monolith surface, cationic MB molecules are selectively adsorbed from MB/methyl orange (MO) mixture with an adsorption efficiency of 99.54% at equilibrium time. Moreover, the MB adsorbed monolith was regenerated up to four cycles and the percentage removal efficiency of MB on the monolith dropped to 67.64 % after the fourth cycle. Finally, the monolith effectively adsorbed MB from the tap water in presence of competing ions and the maximum adsorptive capacity obtained was 47.62 mg g-1 with 84.5% adsorption efficiency. Hence, poly(MAA-co- EDMA) monolith is an adequate sorbent for the treatment of cationic dyes in the presence of other dyes and competing ions from wastewater.