Optimization of temperature-controlled ionic liquid homogenous liquid phase microextraction followed by high performance liquid chromatography for analysis of diclofenac and mefenamic acid in urine sample

In this work, a temperature-controlled ionic liquid homogeneous liquid phase microextraction (TCIL-HLPME) technique followed by HPLC–UV was applied for preconcentration and determination of diclofenac (DIC) and mefenamic acid (MEF) in urine samples. 1-butyl-3-methylimidazolium hexafluorophosphate ([C₄mim][PF₆]) was used as the optimum extraction solvent. Experimental design and response surface methodology was used for the optimization process. Firstly, a screening step, using Plackett-Burman design, was carried out to find the significant factors on the extraction efficiency and subsequently, a central composite design (CCD) was employed to find the optimum values of these parameters. The optimal conditions were obtained as extraction solvent volume of 105 µL; sample pH of 2.0, extraction time of 6 min, centrifugation time of 5 min; heating time of 2 min; heating temperature of 50 °C and 20 % of NaCl. Under optimized conditions, the preconcentration factors of 82 and 60 were obtained for DIC and MEF, respectively. The detections limits of 20 and 30 ng mL^?1 were achieved for DIC and MEF by the proposed method, respectively. The calibration curves were linear in the range of 40–1000 and 60–1000 ng mL^?1 for DIC and MEF, respectively. The intra- and inter-assay precisions (RSD %, n = 3) were in the range of 3.5–4.4 % and 7.3–8.0 % at the concentration level of 100 ng mL^?1, respectively. The validated method was successfully applied for the analysis of target analytes in some urine samples.     

Red water treatment by photodegradation process in presence of modified TiO<Subscript>2</Subscript> nanoparticles and validation of treatment efficiency by MLR technique

An active photocatalyst under sunlight irradiation was proposed for treatment of red water of TNT production process. The nanoparticles of TiO₂/S_0.05,Zn_0.05 were prepared by the sol–gel method and were verified by XRD pattern, TEM image, EDXS analysis, BET analysis and DRS spectra. The proposed photocatalyst showed the surface area of 146 m² g^?1, anatase and rutile phases and band-gap energy of 2.92 eV. The prepared nanoparticles were used as photocatalyst in treatment of red water under UV lamp and sun irradiations. The photodegradation process was optimized in conditions of 5 g L^?1 of photocatalyst, irradiation time of 4 h and dilution times of 1000 of real samples. The treatment efficiency of 76 and 69 % and rate constants of 0.368 and 0.319 h^?1 were obtained under UV and sun irradiations, respectively. The multiple linear regression as a statistic technique was used for study of validation and verification of four factors of mole fraction of S dopant, the irradiation intensity of UV lamp, the dose of photocatalyst and dilution times on samples as predictor’s on the treatment efficiency of red water as the response variable. The output of MLR showed the obtained P values <0.05 in confidence level of 95 % for all of the variables. Thus, the null hypothesis is rejected, and a meaningful addition is observed in the model because changes in the predictor’s value are related to changes in the response variable.     

First reported correlation between the calculated gas-phase proton macroaffinities of some metal complexes with their measured formation constants in solution: Zn(II) complexes of a series of tripodal aliphatic tetraamines

A theoretical study on the first protonation step of a series of metal complexes with the general formula {M(N[(CH2)nNH2][(CH2)mNH2][(CH2)pNH2])2+} (n = m = p = 2, tren; n = 3, m = p = 2, pee; n = m = 3, p = 2, ppe; n = m = p = 3, tpt; n = 2, m = 3, p = 4, epb; and n = m = 3, p = 4, ppb; and M = Zn2+) was reported using both the Hartree-Fock and DFT (B3LYP) levels of theory. For the first time, two kinds of our recently published definitions for gas-phase proton affinities of polybasic ligands, proton microaffinity and proton macroaffinity, were extended to their metal complexes. There is a good correlation between the calculated gas-phase proton macroaffinities and the corresponding formation constants in solution.     

Numerical analysis of effect of nanofluid and fin distribution density on thermal and hydraulic performance of a heat sink with drop-shaped micropin fins

Journal of Thermal Analysis and Calorimetry - In the present study, the effect of nanofluid and distribution density of fin on thermal–hydraulic performance of a heat sink with drop-shaped...     

Synthesis of new TCH/Ni‐based nanocomposite supported on SBA‐15 and its catalytic application for preparation of benzimidazole and perimidine derivatives

A stable nickel‐decorated SBA‐15 nanocomposite (Ni/TCH@SBA‐15) was synthesized through surface modification of silica nanoparticles with 3‐chloropropyltriethoxysilane (CPTES) and thiocarbohydrazide (TCH) followed by metal–ligand coordination with Ni (II). The structure of this organometallic nanocomposite was characterized by Fourier transform‐infrared, field emission‐scanning electron microscopy, EDAX, transmission electron microscopy, atomic absorption spectroscopy and N₂ adsorption–desorption (Brunauer–Emmett–Teller) techniques. The catalytic performance of Ni/TCH@SBA‐15 (NNTS‐15) was determined for the synthesis of 2‐aryl‐substituted benzimidazoles and 2,3‐dihydroperimidines. The excellent yields within shorter reaction times, simplicity of catalytic methods, non‐toxicity and clean reactions, mild reaction conditions and easy work‐up procedure are the important merits of these synthetic protocols. Moreover, the Ni (II) bonded to the SBA‐15 surface was stable under the catalytic reaction conditions resulting in its efficient recycling and reuse.     

Efficient synthesis of new functionalized 2-(alkylamino)-3-nitro-4-(aryl)-4H-benzo[g]chromene-5,10-dione

Molecular Diversity - Structurally diverse benzo[g]chromenes were conveniently synthesized by one-pot, multi-component reaction of N-alkyl-1-(methylthio)-2-nitroethenamine (derived from the...     

Proton transfer process in synthesis of 3-acetyl-4-(substituted ethylenyl)coumarins and chromeno[3,4-c]pyridines

The triphenylphosphine mediated reactions of electron-deficient carbon-carbon triple bonds with 3-acetylcoumarins in dichloromethane afford functionalized 3-acetyl-4-(substituted ethylenyl)coumarins. Also, triphenylphosphine-catalyzed three-component cascade annulation reactions of 3-acetylcoumarins, activated acetylenic compounds, and hydrazines or amines provide a straightforward access to 3,5-dihydro-2H-chromeno[3,4-c]pyridine-1,2-dicarboxylates. In these strategies, the main step to the target products is proton transfer process. All products were obtained in good to high yields.