Pharmacokinetic study and the extraction efficiency of bulk and precipitated ibuprofen-imprinted polymer sorbents for gas chromatography and gas chromatography-mass spectrometry ibuprofen bio-analysis

Bulk and precipitation polymerization methods were used to prepare ibuprofen-molecularly imprinted polymers. Molecularly imprinted polymer-bulk and -precipitation were synthesized in acetonitrile, likewise molecularly imprinted polymer-bulk (mixture) and molecularly imprinted polymer-precipitation (mixture) in a mixture of acetonitrile/toluene (75:25 v/v). N₂ adsorption-desorption analysis data revealed that molecularly imprinted polymer-precipitation (mixture) has the highest specific surface area (200.74 m²/g). The surface chemistry and morphology of the synthesized sorbents were investigated by Fourier-transform infrared analysis and scanning electron microscope micrographs respectively. The prepared sorbents in the mixture of solvents were used in a dispersive solid-phase extraction process for selective extraction and pre-concentration of ibuprofen from urine and human plasma samples. The detection limits were 62.91 and 7.89 ng/ml using molecularly imprinted polymer-bulk (mixture) and molecularly imprinted polymer-precipitation (mixture), respectively. Also, the sorbents showed selective behavior to extract ibuprofen in the presence of naproxen, fenoprofen, and ketoprofen. Overall, the results showed that the precipitation method in the mixture of acetonitrile/toluene resulted in the preparation of a sorbent with the highest extraction efficiency. Furthermore, a pharmacokinetic study was done. The maximum plasma concentration, the time required for maximum plasma concentration, and plasma half-life were 28.95 μg/ml, 2, and 2.39 h, respectively.     

Silica-coated magnetic NiFe2O4 nanoparticles-supported H3PW12O40; synthesis,preparation, and application as an efficient,magnetic, green catalyst for one-pot synthesis of tetrahydrobenzo[b]pyran and pyrano[2,3-c]pyrazole derivatives

Research on Chemical Intermediates - A powerful, magnetic, supported, acid catalyst, NiFe2O4@SiO2–H3PW12O40, was prepared by chemical support of Keggin (H3PW12O40) heteropolyacid (HPA) on...     

SnTCPP-modified ZnO nanorods prepared via a simple co-precipitation method: application as a new photocatalyst for photodegradation and photoreduction processes

Research on Chemical Intermediates - In this paper, ZnO nanorods were synthesized after optimizing the parameters of pH and the concentration of raw materials, reflux temperature, reflux time and...     

Synthesis,Characterization and Crystal Structures of new 1,2,4‐Triazole based Schiff‐bases and their Copper(I) Complexes

The reaction of 4‐amino‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)‐thione (AMTT, 1 ) with 4‐methoxy benzaldehyde and 3‐methoxybenzaldehyde in methanol led to the iminic derivatives 4‐(4‐methoxybenzylideneamino)‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)thione ( 2 , L1) and 4‐(3‐methoxybenzylideneamino)‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)‐thione ( 3 , L2). The reaction of the latter with [(PPh₃)₂CuCl] in methanol solution gave the first Cu^I complex of 3 , [(PPh₃)₂CuCl(L2)] ( 4 ) and in chloroform solution the complex [(PPh₃)₂CuCl(L2)]·2CHCl₃ ( 5 ). All compounds were characterized by infrared spectroscopy, elemental analyses as well as by X‐ray diffraction studies. Crystal data for 2 at ?80 °C: space group P2₁/c with a = 1351.3(3), b = 399.4(1), c = 2225.2(5) pm, β = 96.50(2)°, Z = 4, R₁ = 0.0667, for 3 at ?80 °C: space group R3c with a = b = 3020.4(2), c = 708.2(1) pm, Z = 18, R₁ = 0.0435, for 4 at ?80 °C: space group P2₁/c with a = 1427.8(1), b = 1129.0(1), c = 2622.8(2) pm, β = 97.19(1)°, Z = 4, R₁ = 0.0517 and for 5 at ?80 °C: space group with a = 1280.5(1), b = 1316.1(1), c = 1731.4(1) pm, α = 78.14(1)°, β = 86.06(1)°, γ = 64.69(1)°, Z = 2, R₁ = 0.0525.     

Simultaneous derivatization and extraction of iodine from milk samples by hollow fiber liquid-phase microextraction followed by gas chromatography-electron capture detection

A simple, low-cost and sensitive method is demonstrated for derivatization and extraction of iodine from milk samples using hollow fiber liquid-phase microextraction (HF-LPME) and gas chromatography-electron capture detection. Iodide ions are converted to iodine under acidic medium and in the presence of an oxidant. The generated iodine reacted with 3-pentanone in extraction vial to give 2-iodo-3-pentanone and was extracted into 4 μL of 1-octanol located in the lumen of a hollow fiber. Organic solvent was selected using one variable at a time optimization method and the other main factors affecting derivatization and HF-LPME procedures were evaluated using a Taguchi’s L₁₆ (4⁵) orthogonal array. Under optimal conditions, the method showed low limit of detection (0.5 ng mL^?1), wide linear range (1–2,000 ng mL^?1) with good correlation coefficient (0.9997) and acceptable relative standard deviation (4.6 %, n = 5). Finally, the developed method was successfully applied for determination of iodide in real samples including infant milk formulas and cow milk with reasonable relative recoveries (99.8–110.5 %).     

Comparison of photocatalysis degradation of 4-nitrophenol using N,S co-doped TiO2 nanoparticles synthesized by two different routes

The photocatalytic degradation of 4-nitrophenol as pollutant in aqueous solutions was investigated under visible light irradiation over two different N?CS-codoped anatase TiO₂ catalysts prepared by sol?Cgel methods using titanium isopropoxide and titanium tetrachloride as two different precursors. The catalysts were characterized by XRD, SEM, DRS, EDAX and FT-IR. The effects of various operating parameters including the initial concentration of 4-nitrophenol (2?C14?ppm), solution pH (5?C8) and kinetic reactions were studied. The optimum solution pH was at around 6. For comparison purpose, the photodegradation activity of the commercial Degussa P-25 TiO₂ catalyst has also been studied. The results indicated that photocatalytic activity of N?CS-codoped TiO₂ with titanium isopropoxide as precursor was higher than N?CS-codoped TiO₂ with titanium tetrachloride as precursor and Degussa P-25.     

Multi-wall carbon nanotubes and TiO2 as a sensor for electrocatalytic determination of epinephrinein the presence of p-chloranil as a mediator

In this work, we describe an electrochemical method using p-chloranil as a mediator and multi-wall carbon nanotube and TiO₂ as sensors for sensitive determination of epinephrine (EP) in aqueous solution at pH = 10.0. It has been found that under optimum condition (pH 10.0) in cyclic voltammetry, the oxidation of EP occurred at a potential about 171 mV less positive than that unmodified carbon nanotube paste electrode. The diffusion coefficient (D) and the kinetic parameters, such as electron transfer coefficient, (α) and heterogeneous rate constant (k _h) for EP were also determined using electrochemical approaches. The electrocatalytic currents increase linearly with the EP concentration over the range 0.6–135 μM. The detection limits for EP will be equal to 0.25 μM. The relative standard deviation percentage values for 10.0 and 15.0 μM EP were 1.7% and 1.9%, respectively. Finally, this modified electrode was also examined as a selective, simple, and precise new electrochemical sensor for the determination of EP in real sample such as urine and epinephrine injection solution.     

Hierarchical Organization of Ferrocene–Peptides

Hierarchical self‐assembly of disubstituted ferrocene (Fc)–peptide conjugates that possess Gly‐Val‐Phe and Gly‐Val‐Phe‐Phe peptide substituents leads to the formation of nano‐ and micro‐sized assemblies. Hydrogen‐bonding and hydrophobic interactions provide directionality to the assembly patterns. The self‐assembling behavior of these compounds was studied in solution by using ¹H NMR and circular dichroism (CD) spectroscopies. In the solid state, attenuated total reflectance (ATR) FTIR spectroscopy, single‐crystal X‐ray diffraction (XRD), powder X‐ray diffraction (PXRD), and scanning electron microscopy (SEM) methods were used. Spontaneous self‐assembly of Fc–peptides through intra‐ and intermolecular hydrogen‐bonding interactions induces supramolecular assemblies, which further associate and give rise to fibers, large fibrous crystals, and twisted ropes. In the case of Fc[CO‐Gly‐Val‐Phe‐OMe]₂ ( 1 ), molecules initially interact to form pleated sheets that undergo association into long fibers that form bundles and rectangular crystalline cuboids. Molecular offsets and defects, such as screw dislocations and solvent effects that occur during crystal growth, induce the formation of helical arrangements, ultimately leading to large twisted ropes. By contrast, the Fc–tetrapeptide conjugate Fc[CO‐Gly‐Val‐Phe‐Phe‐OMe]₂ ( 2 ) forms a network of nanofibers at the supramolecular level, presumably due to the additional hydrogen‐bonding and hydrophobic interactions that stem from the additional Phe residues.     

Effect of single-wall carbon nanotubes on the properties of polymeric gel electrolyte dye-sensitized solar cells

A hybrid of polymer/dispersed single-wall carbon nanotubes was utilized in networking a novel composition of gel electrolyte in dye-sensitized solar cells. The gel is composed of polyethylene glycol, polyvinyl pyrrolidone, single-wall carbon nanotubes, and I^?/I₃ ^? as electrolyte. Formation of the less conductive polyiodide species in electrolyte was prohibited by the addition of single-wall carbon nanotubes leading to the excellent photovoltaic behavior of the cell under simulated standard illumination of the fabricated device owing to the increased open circuit voltage (0.47 V). Electrochemical impedance spectroscopy was employed to quantify the charge transport resistance and the electron lifetime at the TiO₂ conduction band. Charge transport resistances at the TiO₂/dye/electrolyte interface were determined for the cells consisting of the non-gel reference and our new gel electrolytes, and it was indicated that the charge recombination between injected electrons and electron acceptors (I₃ ^?) in the redox electrolyte was remarkably retarded. Electrochemical parameters obtained by the fitting showed all of the resistances increased as compared to liquid electrolyte dye-sensitized solar cells that can be related to the increase in viscosity of the gel, which hinders the ionic transportation through the electrolyte. These results were also confirmed by the electron lifetime analyses. The characteristic peak shifted to a lower frequency in the Bode phase plot for the cell containing gel electrolyte which is an indication of a longer electron lifetime in comparison with that of the cell containing very conventional liquid electrolyte.     

Heterogenized magnetic graphene oxide-supported N6-Schiff base Cu (II) complex as an exclusive nanocatalyst for synthesis of new pyrido[2,3-d]pyrimidine-7-carbonitrile derivatives

In this article, the synthesis of a novel and highly efficient recyclable and reusable heterogeneous nanocatalyst has been reported via the functionalizing of the Fe₃O₄-magnetized graphene oxide nanosheets with the N₆-Schiff base Cu (II) complex (GO/Fe₃O₄@SPNC). The structure of this novel nanocatalyst was determined by different analytical techniques such as FTIR, FE-SEM, TEM, TGA-DTG, and VSM. The catalytic activity of the synthesized GO/Fe₃O₄@SPNC nanocatalyst was explored for the synthesis of several new 2H-pyrido[3′,2′:6,7]pyrano[2,3-d]pyrimidine-7-carbonitrile derivatives with excellent yields. All new derivatives were fully identified by various spectral (¹H NMR, ¹³C NMR, FT-IR, ESI-MS) analyses. In addition, this nanocatalyst carried out satisfactory catalytic maintenance of activity and high chemical stability in the titled reactions after seven-time of recycling without substantial loss of leaching.