A novel 4-(2-pyridylazo) resorcinol functionalised magnetic nanosorbent for selective extraction of Cu(II) and Pb(II) ions from food and water samples

Determination of furfurals in baby food samples after extraction by a novel functionalized magnetic porous carbon

Herein, a novel polypyrrole-polyaniline functionalized magnetic porous carbon (MPC@PPy-PANI) composite material was fabricated and utilized for the separation/extraction of furfurals from baby food and dry milk samples. In this way, magnetite@silica nanoparticles were first synthesized, and then a magnetic metal–organic framework (MMIL-101(Fe)) was prepared. After that, the MMIL-101(Fe) was pyrolyzed in a neutral atmosphere to obtain MPC. Ultimately, the MPC was functionalized with a co-polymer of aniline–pyrrole via oxidation polymerization. The synthesis of MPC@PPy-PANI was confirmed with FT-IR spectroscopy, SEM, TEM, VSM, and XRD techniques. Furfural and hydroxymethyl furfural were selected as the model analytes, which were separated/quantified on an HPLC-UV instrument. The LODs, LOQs, and linear dynamic ranges (LDRs) were in the range of 0.3–0.7 μg kg⁻¹, 1.0–2.5 μg kg⁻¹, and 1.0–600 μg kg⁻¹, respectively. Repeatability of the method was studied as an RSD parameter, and was located in the range of 5.5–6.8% (within-day, n = 5) and 8.2–9.4% (between-day, n = 3 days). The applicability of the proposed method was established by analyzing several baby food and dry milk samples. The relative recovery (RR%) and repeatability were located in the range of 86–111% and 3.3–10.1%, respectively, showing excellent accuracy and precision of the method.

Herein, a novel polypyrrole-polyaniline functionalized magnetic porous carbon (MPC@PPy- PANI) composite material was fabricated and utilized for the separation/extraction of furfurals from baby food and dry milk samples.

Extraction and preconcentration of Ni(ii), Pb(ii), and Cd(ii) ions using a nanocomposite of the type Fe3O4@SiO2@polypyrrole-polyaniline

In this study, the application of Fe₃O₄@SiO₂@polypyrrole-polyaniline magnetic nanocomposite was studied for Ni(ii), Cd(ii), and Pb(ii) ions preconcentration extraction. In this regard, the silica layer prevents the Fe₃O₄ nanoparticles (NPs) from aggregating over a broad pH range value and simultaneously improves chemical stability and hydrophilicity. By using a Box-Behnken design, the effect of various parameters affecting the preconcentration was studied. FAAS was employed to quantify the eluted analytes. The detection limits are 0.09, 1.1, and 0.3 ng mL^-1 for Ni(ii), Cd(ii) and Pb(ii), ions, respectively. The relative standard deviations (RSDs%) were calculated for determining the method's precision, lower than 7.5%. The capacities of sorption are 75, 84, and 98 mg g^-1, respectively. With the usage of a certified reference material, the developed method was validated. After that, the validated method was employed to rapidly extract trace target ions from food samples and gave satisfactory results.

Lead Assays with Smartphone Detection Using a Monolithic Rod with 4-(2-Pyridylazo) Resorcinol

A monolithic rod of polyurethane foam-[4-(2-pyridylazo) resorcinol] (PUF-PAR) as a simple chemical sensor for lead assays with smartphone detection and image processing was developed. With readily available simple apparatus such as a plastic cup and a stirrer rod, the monolithic PUF rod was synthesized in a glass tube. The monolithic PUF-PAR rod could be directly loaded by standard/sample solution without sample preparation. A one-shot image in G/B value from a profile plot in ImageJ for a sample with triplicate results via a single standard calibration approach was obtained. A linear single standard calibration was: [G/B value] = -0.038[µg Pb2+] + 2.827, R2 = 0.95 for 10-30 µg Pb2+ with a limit of quantitation (LOQ) of 33 µg L-1. The precision was lower than 15% RSD. The proposed method was tested by an assay for Pb2+ contents in drinking water samples from Bangkok. The results obtained by the proposed method agree with those of ICP-OES and with 100-120% recovery, demonstrating that the method is useful for screening on-site water monitoring.

Synthesis and characterization of a novel magnetic porous carbon coated with poly(p-phenylenediamine) and its application for furfural preconcentration and determination in baby food and dry milk powder samples

The aim of the current research is to develop a MSPE method for the determination of furfural in baby food and dry milk samples. In this regard, a novel magnetic porous carbon composite coated with poly(p-phenylenediamine) was fabricated, characterized, and then applied to the preconcentration/extraction of furfurals from baby food and dry milk powder samples. Initially, magnetic nanoparticles (Fe₃O₄) were synthesized, and then coated with a metal–organic framework layer named MIL-101(Fe). Afterward, the magnetic MIL-101(Fe) was subjected to calcination under a nitrogen atmosphere and magnetic porous carbon was achieved. Finally, a layer of poly(p-phenylenediamine) was coated on the magnetic porous carbon. The structure of the nanocomposite was investigated with various methods, including FT-IR spectroscopy, electron microcopies (SEM and TEM), VSM, and XRD. The fabricated nanocomposite was applied in magnetic solid-phase extraction of furfural and hydroxymethyl furfural and their determination with liquid chromatography. The effect of experimental variables was explored by using an experimental design approach. The LODs and linear range for the target furfurals were 1.0–2.0 μg kg⁻¹ and 3.0–500 μg kg⁻¹, respectively. The method's repeatability was explored using RSD values and was found to be in the range of 5.2–6.4% (one-day, n = 5) and 9.1–10.8% (day to day, n = 3). Eventually, this new method was employed for the extraction/quantification of target compounds in baby food and dry milk powder samples.

In this research, a novel magnetic porous carbon composite coated with poly(p-phenylenediamine) was fabricated, characterized, and then applied to the preconcentration/extraction of furfurals from baby food and dry milk powder samples.

Efficient Removal of Cr(VI) Ions by a Novel Magnetic 4-Vinyl Pyridine Grafted Ni3Si2O5(OH)4 Multiwalled Nanotube

The contamination of water systems by heavy metals greatly threatens human health and ecological safety. An efficient adsorbent is critical for the removal of these contaminants. In this work, magnetic Ni3Si2O5(OH)4 nanotubes (NTs) have been synthesized via in situ hydrothermal reduction and further functionalized by grafting poly(4-vinyl pyridine) (P4VP) brushes on its surface via atom transfer radical polymerization. Characterizations by Fourier transform infrared, X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, and X-ray photoelectron spectroscopy proved that P4VP was successfully grafted on the surface of magnetic Ni3Si2O5(OH)4 NTs. The resultant Ni3Si2O5(OH)4-g-P4VP NTs are efficient nanosorbents for removing Cr(VI) anions from water. The Cr(VI) adsorption capacity of Ni3Si2O5(OH)4-g-P4VP NTs reaches 1.49 mmol/g at a pH of 3. The pseudo-second-order kinetic model and the Freundlich isothermal model are suitable to describe the adsorption process. The analysis using Weber-Morris and Boyd models indicates that both intraparticle diffusion and external film diffusion affect the Cr(VI) adsorption process. The adsorption enthalpy is estimated to be 18.37 kJ/mol. More than 90% of the Cr(VI) adsorption capacity of the Ni3Si2O5(OH)4-g-P4VP NTs remains after eight adsorption and desorption cycles.

Synthesis and application of a novel magnetic metal-organic framework nanocomposite for determination of Cd, Pb, and Zn in baby food samples

This work describes the synthesis and application of a novel magnetic metal-organic framework (MOF) [(Fe3O4-2,5-dimercapto-1,3,4-thiadiazole)/Cu3(benzene-1,3,5-tricarboxylate)2] to preconcentrate trace amounts of Cd(II), Pb(II), and Zn(II) ions. A Box–Behnken design was used to find the parameters affecting the preconcentration procedure through response surface methodology. Three variables including sorption time, amount of the magnetic sorbent, and sample pH were selected as affecting factors in the sorption step, and four parameters including type, volume, concentration of the eluent, and elution time were selected in the elution step for the optimization study. These values were 33 mg, 11 min, 5.7 EDTA, 4.3 mL, 0.64 mol L–l EDTA solution, 16 min, for amount of the magnetic sorbent, sorption time, sample pH, type, volume, and concentration of the eluent, and elution time, respectively. Following the sorption and elution steps, the ions were quantified by FAAS. The limits of detection were 0.10, 0.15, and 0.75 ng mL−1 for Cd(II), Zn(II), and Pb(II) ions, respectively. The relative standard deviations (RSD) of the method were less than 8.3% for five separate batch experiments in the determination of 25 μg L−1 of Cd(II), Zn(II), and Pb(II) ions. The sorption capacity of the magnetic MOF nanocomposite was 155 mg g−1 for Cd(II), 173 mg g−1 for Pb(II), and 190 mg g−1 for Zn(II). Finally, the magnetic MOF nanocomposite was successfully applied to rapidly extract trace amounts of heavy metal ions in baby food samples.