Single drop microextraction or solid phase microextraction-gas chromatography-mass spectrometry for the determination of iodine in pharmaceuticals, iodized salt, milk powder and vegetables involving conversion into 4-iodo-N,N-dimethylaniline

A rapid sequence of oxidation and iodination using 2-iodosobenzoate as an oxidizing agent and N,N-dimethylaniline as an iodine scavenger at pH 6.4, when 4-iodo-N,N-dimethylaniline is formed, has been used for the determination of iodide by GC-MS. Solid phase microextraction (SPME) and single drop microextraction (SDME) have been used for the extraction of the iodo-derivative and their relative efficiencies compared. Pharmaceutical samples were subjected to solid phase extraction (SPE) for cleanup and the eluate analyzed for iodide. Iodate in salt samples was reduced to iodide with ascorbic acid. Milk powder and dried vegetables were wet combusted with peroxydisulfate to liberate covalently bound iodine as iodate which was reduced before derivatization. A rectilinear calibration graph was obtained for 0.1 microg-10 mg l(-1) iodide by both extraction methods, the correlation coefficient and limit of detection (LOD) were 0.9995 and 25 ng l(-1) iodide by SPME method, and 0.9998 and 10 ng l(-1) iodide by SDME method, respectively. SDME appeared to be more efficient technique than SPME for the present system. From the pooled data, the average recovery of spiked iodide to real samples was 100.7% (range 96.5-107.0%) with an average R.S.D. of 3.1% (range 2.6-4.5%).     

Three-dimensional structure determination of N-(p-Tolyl)-dodecylsulfonamide from powder diffraction data and validation of structure using solid-state NMR spectroscopy

The three-dimensional structure, conformation, and packing of molecules in the solid state are crucial components used in the optimization of many technologically useful materials properties. Single-crystal X-ray diffraction is the traditional and most effective method of determining 3-D structures in the solid state. Obtaining single crystals that are sufficiently large and free of imperfections is often laborious, time-consuming, and, occasionally, impossible. The feasibility of an integrated approach to the determination and verification of a complete three-dimensional structure for a medium-sized organic molecule without using single crystals is demonstrated for the case of an organic stabilizer compound N-(p-tolyl)-dodecylsulfonamide. The approach uses a combination of powder XRD data, several computational packages involving Monte Carlo simulations and ab initio quantum mechanical calculations, and experimental solid-state NMR chemical shifts. Structure elucidation of N-(p-tolyl)-dodecylsulfonamide revealed that the Bravais lattice is monoclinic, with cell dimensions of a = 38.773 A, b = 5.507 A, c = 9.509 A, and beta = 86.35 degrees, and a space group of P21/c.     

Analysis of the factorization method for elliptic differential equations

This paper presents a numerical analysis of the method of factorization for elliptic boundary value problems. A second-order elliptic boundary value problem is transformed into a decoupled system of first-order initial value problems. This elaborates the decoupled system’s occupying operator, the solution of the problem, and the affine part of the operator. The solution of the problem is thus obtained by solving the factorized system using the finite-element method. A comparative study is made with the help of an example that illustrates many of its properties.     

Nanoporous morphology of alumina films prepared by sol–gel dip coating method on alumina substrate

Nanoporous crack free alumina thin films were fabricated in two phases gamma (??) and alpha (??) by sol?Cgel dip coating method. The thickness of the mesoporous films was increased with binder by varying its concentration, and with increasing the number of coating. The porosity, pore size, surface area and phase were controlled by sintering temperature. Interconnected pore structure of 8?C15?nm diameter were successfully prepared by repeating the deposition several times. FESEM, BET, AFM and XRD techniques were employed for the microstructural characterization.     

Characterization of ion transport property in hot-press cast solid polymer electrolyte (SPE) films: [PEO: Zn(CF3SO3)2]

Characterization of ion transport property in dry solid polymer electrolyte (SPE) films: [PEO: Zn(CF₃SO₃)₂] in different salt wt% ratio has been reported. SPE films have been prepared by a hot-press casting procedure. Salt concentration dependent conductivity study at room temperature identified SPE film: [90PEO: 10 Zn(CF₃SO₃)₂] as optimum conducting composition (OCC) with σ _rt ~ 1.09 × 10⁻⁶ S/cm which is approximately three orders of magnitude higher than that of pure PEO host (σ _rt ~ 3.20 × 10⁻⁹ S/cm). The reason attributed for σ _rt enhancement has been the increase in degree of amorphous phase in polymeric host after salt complexation. This has been confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and polarized optical microscopy (POM) analysis. To evaluate the usefulness of SPE OCC film in all-solid-state-battery applications, ion transport property has been characterized in terms of basic ionic parameters viz. ionic conductivity (σ) and total ionic (t _ion)/cation (t ₊) transport numbers. Mechanism of ion transport has been explained by temperature dependent conductivity measurements and the activation energy (E _a) has been computed by least square linear fitting of “log σ − 1/T” Arrhenius plot.

     

Cation complexation with p-tert-butylcalix[5]arene pentacarboxylic acid derivative: an allosteric regulation of the first metal ion for stepwise extraction of the second ion

A calix[5]arene based solvent extraction reagent 3, appending carboxylic acid groups at the lower rim, has been developed and its complexation behavior towards some transition metal ions has been studied. The host 3 can selectively and quantitatively extract Pb(II) ions above pH 1.8 while other divalent ions such as Cu(II), Zn(II), Co(II), Ni(II) are extracted quantitatively only above pH 3.0. The outstanding Pb(II) selectivity of 3 comes from the size fit complementarity effect of the Pb(II) ion in the calix[5]arene cavity. One molecule of 3 extracts two Pb(II) ions in a stepwise manner. The first Pb(II) ion is extracted into the deep cavity of the calix[5]arene defined by phenoxy oxygen atoms. The first complexed Pb(II) ion acts as a template to bring the host into a cone conformation and induces a positive allosteric effect for the extraction of the second Pb(II) ion at an oxygen rich coordinating site composed of carboxyl groups. Both the Pb(II) ions are extracted through an ion exchange mechanism and the electroneutral complex in the organic phase is formed by the release of an equivalent number of hydrogen ions into aqueous solution. The loaded Pb(II) is easily back-extracted from Pb(II)-complexed 3 using dilute acid solution.     

An Efficient Route for the Synthesis of 3-(4-Bromophenyl)-2-Phenyl-3,4-Dihydro-2H-Benzo[E][,32,]Oxazaphosphinine,its P-Chalcogenides and Metal Complexes

Abstract

2-[(4-bromophenylamino)-methyl]-phenol (1) gave substantially pure 3-(4-bromophenyl)-2-phenyl-3,4-dihydro-2H-benzo[e][1,3,2]- oxazaphosphinine (2) on cyclization with phenyldichlorophosphine in toluene at 0 °C. Reaction of 2 with H₂O₂ in dichloromethane gave selectively 3. P-chalcogenides (4 and 5) were prepared by reacting 2 with elemental S and Se powder in toluene, whereas the tungsten pentacarbonyl complex 6 was prepared by reacting 2 with [W(CO)₅(CH₃CN)] in tetrahydrofuran at 25 °C.

Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional figures.     

Graft Copolymers from Natural Polymers Using Free Radical Polymerization

The present research work deals with the surface modification of natural cellulosic polymers to develop novel materials for different applications. Natural cellulose-graft-poly (methyl acrylate) copolymers were prepared using the free radical induced graft copolymerization technique. Different reaction parameters were optimized to achieve the highest percentage of grafting of natural cellulose-graft-poly (methyl acrylate) copolymers. The natural cellulose graft copolymers were characterized by FT-IR, SEM, TGA, and physicochemical studies. For the evaluation of swelling and the physicochemical mechanism, swelling and chemical resistance studies were carried out in different solvents as well as chemicals.     

Mechanoluminescence by impulsive deformation of γ-irradiated Er-doped CaF2 crystals

An impulsive technique has been used for mechanoluminescence (ML) measurements in γ-irradiated Er doped CaF₂ crystals. When the ML is excited impulsively by the impact of moving piston on to γ-irradiated CaF₂:Er crystals, two peaks are observed in ML intensity with time and it is seen that the peak intensities of first and second peaks (I_m1 and I_m2) increase with increasing impact velocity. However the time corresponding to first and second peaks (t_m1 and t_m2) shifts towards shorter time values with increasing impact velocity. It is also seen that the total ML intensity I_Total initially increases with the impact velocity and then it attains a saturation value for higher values of the impact velocity. We have presented a theoretical explanation for the observed results.     

Metal complexes of biological active 2-aminothiazole derived ligands

The most imperative outcomes of extensive sterdies (synthesis, spectral, structural characterization and biological applications) of metal complexes with thiazole derived ligands are reviewed. A large number of coordination compounds are known but still there is a need of new compounds to develop various efforts in different fields for biomedical applications. The synthesis of Schiff base ligands is very important, and it has recently drawn the attention of numerous research groups, making this area constantly evolve. Authors are also synthesizing some novel biologically potent ligands and their unique complexes and complexes found more biological active agents than that of ligands against bacteria, fungi and herbs. Highlights: Schiff bases and their metal chelates catalyze reactions; Schiff bases derived from sulfane thiadiazole show toxicities against insects; Schiff bases of thiadiazole have good plant regulator activity; Phenyl ring attached to the thiazole group showed interesting structure activity.