Sulfide-Doped Magnetic Carbon Nanotubes Developed as Adsorbent for Uptake of Tetracycline and Cefixime from Wastewater.

In this study, a magnetic solid-phase extraction method was developed based on multi-wall carbon nanotubes decorated by magnetic nanoparticles (Fe3O4) and cadmium sulfide nanoparticles (Fe3O4@MWCNT-CdS) for trace extraction of cefixime and tetracycline antibiotics from urine and drug company wastewater. The adsorbent features were characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), and energy dispersive X-ray analysis (EDX). Various effective parameters on the sorption and desorption cycle, such as sorption time, the mass of adsorbent, pH, salt addition, and material ratio, were investigated and optimized. The data were evaluated using isotherm models, and experimental data were well-fitted to both Langmuir (R2 = 0.975) and Freundlich (R2 = 0.985) models. Moreover, kinetic of reaction was agreement with pseudo-second-order (R2 = 0.999) as compared pseudo-first-order (R2 = 0.760). The maximum adsorption capacity for tetracycline and cefixime was achieved at 116.27 and 105.26 mg·g-1, respectively. Hence, the prepared adsorbent can be used as an alternative material for enhanced determination of pharmaceutical substances in biological fluids.

Lanthanum doped magnetic polyaniline for removal of phosphate ions from water.

Herein, magnetic polyaniline was modified with lanthanum nanoparticles (MPANI@La) as adsorbent, aiming to the treatment of high phosphate-containing aquatic solutions. High valent lanthanum doped with polyaniline was a promising adsorbent to uptake phosphate ions with possible electrostatic interaction and cation exchange process. The functional groups, composition, surface morphology, and magnetic property of the adsorbent were investigated using Fourier Transform-Infrared Spectroscopy (FTIR), Energy Dispersive X-ray (EDX), Scanning Electron Microscopic (SEM), and Vibrating Sample Magnetometer (VSM), respectively. During the experimental process, MPANI@La has removed phosphate ions from water >90%, with 80 mg adsorbent, and shaking for 150 min at room temperature. In this regard, the process was fitted with the Pseudo-second-order kinetic model (R2 > 0.999) and the Langmuir isotherm (R2 > 0.99). The proposed nanoparticles provided an appropriate adsorption capacity (qm) of 45.24 mg.g-1 at pH 4 for phosphate ions. Besides, the adsorbent can be used with an efficiency of 92.49% up to three times that reduced to 52.89% after ten times. In addition, the adsorption process was justified by thermodynamics which confirmed the proposed adsorption mechanism. Hence, the models were provided surface adsorption, monolayer pattern, and the physical mechanism of the phosphate removal process using MPANI@La. Hence the proposed adsorbent can be used as an alternative adsorbent in environmental water remediation.

Solid-Phase Extraction of Active Compounds from Natural Products by Molecularly Imprinted Polymers: Synthesis and Extraction Parameters.

Molecularly imprinted polymers (MIPs) are synthetic polymers with a predetermined selectivity for a particular analyte or group of structurally related compounds, making them ideal materials for separation processes. Hence, in sample preparation, MIPs are chosen as an excellent material to provide selectivity. Moreover, its use in solid-phase extraction, also referred to as molecular imprinted solid phase extraction (MISPE), is well regarded. In recent years, many papers have been published addressing the utilization of MIPs or MISPE as sorbents in natural product applications, such as synthesis. This review describes the synthesis and characterization of MIPs as a tool in natural product applications.

Magnetic nanoparticles assisted dispersive liquid-liquid microextraction of chloramphenicol in water samples.

This work describes the development of a new methodology based on magnetic nanoparticles assisted dispersive liquid-liquid microextraction (DLLME-MNPs) for preconcentration and extraction of chloramphenicol (CAP) antibiotic residues in water. The approach is based on the use of decanoic acid as the extraction solvent followed by the application of MNPs to magnetically retrieve the extraction solvent containing the extracted CAP. The coated MNPs were then desorbed with methanol, and the clean extract was analysed using ultraviolet-visible spectrophotometry. Several important parameters, such as the amount of decanoic acid, extraction time, stirring rate, amount of MNPs, type of desorption solvent, salt addition and sample pH, were evaluated and optimized. Optimum parameters were as follows: amount of decanoic acid: 200 mg; extraction time: 10 min; stirring rate: 800 rpm; amount of MNPs: 60 mg; desorption solvent: methanol; salt: 10%; and sample pH, 8. Under the optimum conditions, the method demonstrated acceptable linearity (R 2 = 0.9933) over a concentration range of 50-1000 µg l-1. Limit of detection and limit of quantification were 16.5 and 50.0 µg l-1, respectively. Good analyte recovery (91-92.7%) and acceptable precision with good relative standard deviations (0.45-6.29%, n = 3) were obtained. The method was successfully applied to tap water and lake water samples. The proposed method is rapid, simple, reliable and environmentally friendly for the detection of CAP.

Solid-phase microextraction based on an agarose-chitosan-multiwalled carbon nanotube composite film combined with HPLC-UV for the determination of nonsteroidal anti-inflammatory drugs in aqueous samples.

We describe the preparation, characterization, and application of a composite film adsorbent based on blended agarose-chitosan-multiwalled carbon nanotubes for the preconcentration of selected nonsteroidal anti-inflammatory drugs in aqueous samples before determination by high performance liquid chromatography with ultraviolet detection. The composite film showed a high surface area (4.0258 m2 /g) and strong hydrogen bonding between the multiwalled carbon nanotubes and agarose/chitosan matrix, which prevent adsorbent deactivation and ensure long-term stability. Several parameters, such as sample pH, addition of salt, extraction time, desorption solvent, and concentration of multiwalled carbon nanotubes in the composite film were optimized using a one-factor-at-time approach. The optimum extraction conditions obtained were as follows: isopropanol as conditioning solvent, 10 mL of sample solution at pH 2, extraction time of 30 min, stirring speed of 600 rpm, 100 µL of isopropanol as desorption solvent, desorption time of 5 min under ultrasonication, and 0.4% w/v of composite film. Under the optimized conditions, the calibration curve showed good linearity in the range of 1-500 ng/mL (r2  = 0.997-0.999), and good limits of detection (0.89-8.05 ng/mL) were obtained with good relative standard deviations of < 4.59% (n = 3) for the determination of naproxen, diclofenac sodium salt, and mefenamic acid drugs.

Rapid Determination of Non-steroidal Anti-inflammatory Drugs in Aquatic Matrices by Two-phase Micro-electrodriven Membrane Extraction Combined with Liquid Chromatography.

Two-phase micro-electrodriven membrane extraction (EME) procedure for the pre-concentration of selected non-steroidal anti-inflammatory drugs (NSAIDs) in aquatic matrices was investigated. Agarose film was used as interface between donor and acceptor phase in EME which allowed for selective extraction of the analytes prior to high performance liquid chromatography-ultraviolet detection. Charged analytes were transported from basic aqueous sample solution through agarose film into 1-octanol as an acceptor phase at 9 V potential. Response surface methodology in conjunction with the central composite design showed good correlations between extraction time and applied voltage (R2 > 0.9358). Under optimized extraction conditions, the method showed good linearity in the concentration range of 0.5-500 µg L-1 with coefficients of determination, r2≥ 0.9942 and good limits of detection (0.14-0.42 µg L-1) and limits of quantification (0.52-1.21 µg L-1). The results also showed high enrichment factors (62-86) and good relative recoveries (72-114%) with acceptable reproducibilities (RSDs ≤ 7.5% n = 3). The method was successfully applied to the determination of NSAIDs from tap water and river water samples. The proposed method proved to be rapid, simple and requires low voltage and minute amounts of organic solvent, thus environmentally friendly.

Magnetic micro-solid-phase extraction based on magnetite-MCM-41 with gas chromatography-mass spectrometry for the determination of antidepressant drugs in biological fluids.

A new facile magnetic micro-solid-phase extraction coupled to gas chromatography and mass spectrometry detection was developed for the extraction and determination of selected antidepressant drugs in biological fluids using magnetite-MCM-41 as adsorbent. The synthesized sorbent was characterized by several spectroscopic techniques. The maximum extraction efficiency for extraction of 500 µg/L antidepressant drugs from aqueous solution was obtained with 15 mg of magnetite-MCM-41 at pH 12. The analyte was desorbed using 100 µL of acetonitrile prior to gas chromatography determination. This method was rapid in which the adsorption procedure was completed in 60 s. Under the optimized conditions using 15 mL of antidepressant drugs sample, the calibration curve showed good linearity in the range of 0.05-500 µg/L (r2  = 0.996-0.999). Good limits of detection (0.008-0.010 µg/L) were obtained for the analytes with good relative standard deviations of <8.0% (n = 5) for the determination of 0.1, 5.0, and 500.0 µg/L of antidepressant drugs. This method was successfully applied to the determination of amitriptyline and chlorpromazine in plasma and urine samples. The recoveries of spiked plasma and urine samples were in the range of 86.1-115.4%. Results indicate that magnetite micro-solid-phase extraction with gas chromatography and mass spectrometry is a convenient, fast, and economical method for the extraction and determination of amitriptyline and chlorpromazine in biological samples.

Ionic liquid-impregnated agarose film two-phase micro-electrodriven membrane extraction (IL-AF-µ-EME) for the analysis of antidepressants in water samples.

The aim of this study was to investigate and apply supported ionic liquid membrane (SILM) in two-phase micro-electrodriven membrane extraction combined with high performance liquid chromatography-ultraviolet detection (HPLC-UV) for pre-concentration and determination of three selected antidepressant drugs in water samples. A thin agarose film impregnated with 1-hexyl-3-methylimidazolium hexafluorophosphate, [C6MIM] [PF6], was prepared and used as supported ionic liquid membrane between aqueous sample solution and acceptor phase for extraction of imipramine, amitriptyline and chlorpromazine. Under the optimized extraction conditions, the method provided good linearity in the range of 1.0-1000µgL-1, good coefficients of determination (r2=0.9974-0.9992) and low limits of detection (0.1-0.4µgL-1). The method showed high enrichment factors in the range of 110-150 and high relative recoveries in the range of 88.2-111.4% and 90.9-107.0%, for river water and tap water samples, respectively with RSDs of ≤7.6 (n=3). This method was successfully applied to the determination of the drugs in river and tap water samples. It is envisaged that the SILM improved the perm-selectivity by providing a pathway for targeted analytes which resulted in rapid extraction with high degree of selectivity and high enrichment factor.

Agarose-chitosan-C18 film micro-solid phase extraction combined with high performance liquid chromatography for the determination of phenanthrene and pyrene in chrysanthemum tea samples.

Agarose-chitosan-immobilized octadecylsilyl-silica (C18) film micro-solid phase extraction (µSPE) was developed and applied for the determination of phenanthrene (PHE) and pyrene (PYR) in chrysanthemum tea samples using high performance liquid chromatography-ultraviolet detection (HPLC-UV). The film of blended agarose and chitosan allows good dispersion of C18, prevents the leaching of C18 during application and enhances the film mechanical stability. Important µSPE parameters were optimized including amount of sorbent loading, extraction time, desorption solvent and desorption time. The matrix match calibration curves showed good linearity (r⩾0.994) over a concentration range of 1-500ppb. Under the optimized conditions, the proposed method showed good limits of detection (0.549-0.673ppb), good analyte recoveries (100.8-105.99%) and good reproducibilities (RSDs⩽13.53%, n=3) with preconcentration factors of 4 and 72 for PHE and PYR, respectively.

Agarose- and alginate-based biopolymers for sample preparation: Excellent green extraction tools for this century.

Recently, there has been considerable interest in the use of miniaturized sample preparation techniques before the chromatographic monitoring of the analytes in unknown complex compositions. The use of biopolymer-based sorbents in solid-phase microextraction techniques has achieved a good reputation. A great variety of polysaccharides can be extracted from marine plants or microorganisms. Seaweeds are the major sources of polysaccharides such as alginate, agar, agarose, as well as carrageenans. Agarose and alginate (green biopolymers) have been manipulated for different microextraction approaches. The present review is focused on the classification of biopolymer and their applications in multidisciplinary research. Besides, efforts have been made to discuss the state-of-the-art of the new microextraction techniques that utilize commercial biopolymer interfaces such as agarose in liquid-phase microextraction and solid-phase microextraction.

Bis{2-[1-(benzyl-imino)-eth-yl]phenolato}palladium(II).

In the title compound, [Pd(C(15)H(14)NO)(2)], the Pd atom lies on an inversion center and is coordinated by two ligand mol-ecules through the O and N atoms in a bidentate manner, forming a slightly distorted square-planar geometry. The dihedral angle between the two benzene rings in the ligand is 76.53 (19)°. The mol-ecular packing is stablized by C-H⋯O and C-H⋯π inter-actions.