Poly(alkylene-H-phosphonate)s obtained by direct esterification and oxidation of hypophosphorous acid with ethylene glycol

This paper presents for the first time the synthesis of poly(alkylene-H-phosphonate)s by one-pot tandem reaction of hypophosphorous acid and ethylene glycol. Zirconium oxychloride was used as esterification catalyst, Nickel vinylphosphonate, Nickel sulfate, Nickel chloride hexahydrate were used as transfer hydrogenation catalyst. Nickel vinylphosphonate was synthesized in our laboratory and used for the first time as catalyst in this process. The compounds were characterized by ¹H-NMR, ¹³C-NMR and ³¹P-NMR spectroscopy. Molar masses were determined by SEC-MALLS technique and depend on the catalyst used. The obtained poly(alkylene-H-phosphonate)s have molar masses between 1.50 and 11.85 kDa, higher than those obtained by other methods mentioned in the literature.     

Voltammetric Determination of Proguanil in Malarone and Spiked Urine with a Renewable Silver Amalgam Film Electrode

Electrochemical properties of proguanil were investigated by a voltammetric method (SWV) using a renewable silver amalgam film electrode. The influence of buffer pH as well as potential amplitude, frequency, and step potential was studied. The repeatability, precision and recovery of the developed method were examined. The reduction peak current was used for proguanil voltammetric determination in the range 1×10^?7–6×10^?6 mol L^?1, LOD=2.9×10^?8 mol L^?1, LOQ=9.7×10^?8 mol L^?1. The standard addition method was used to determine proguanil in a commercial formulation (Malarone) and in spiked urine.     

Determination of Buprenorphine (BUP) with Molecularly Imprinted Polymer Zn/La3+ Metal Organic Framework on Modified Glassy Carbon Electrode (GCE)

In this study we report the Zn/La³⁺ metal organic frameworks (MOFs) were synthesized with the co-precipitation assisted microwave method. Zn/La³⁺ MOFs were used as a new nanocomposite for the design and construction of a nanosensor based on glassy carbon electrode (GCE). MOFs due to their unique and excellent physicochemical properties can be used in sensors based on glassy carbon electrode (GCE). The synergistic effect of MOFs on glassy carbon electrode increases the power of the limits of detection (LOD). In this study, a new chemical sensor was fabricated by electro polymerization to measure buprenorphine with MOFs based on molecularly imprinted polymer. Zn/La³⁺ MOFs nanostructures were identified with scanning electron microscopy (SEM), Dynamic light scattering (DLS), Transmission electron microscopy (TEM) and the Fourier-transform infrared spectroscopy (FT-IR) spectra. Buprenorphine was used as a template, pyrrole was used as a monomer, potassium ferrocyanide as an electrochemical active tracer in electropolymerization processes and the parameters affecting the sensor response were optimized. At the Zn/La³⁺ MOF/MIP electrode, the calibration curve in the linear region was obtained in the concentration range between 4 to 50 ng/ml and the detection limit was 1.08 ng/ml. In a new strategy, Zn/La³⁺ MOFs nanostructures can be introduced as new materials with high efficiency which used at chemical sensors for detection of the opiates in all over the world.     

Polyelectrolyte multilayers as stationary phases for open tubular ion chromatography

Polyelectrolyte multilayers deposited on the wall of fused silica capillaries were used as stationary phases in open tubular ion chromatography. The multilayers were formed by flushing the capillaries with solutions of polyanions and polycations such as polydiallyldimethylammonium chloride and dextran sulphate. Columns with several bi-layers were constructed and used in low pressure non-suppressed open tubular ion chromatography of common inorganic anions (F⁻, Cl⁻, NO₃⁻) and cations (Li⁺, Na⁺, NH₄⁺, K⁺, Cs⁺) with contactless conductometric detection. Using sodium benzoate and tartaric acid eluents the separations were typically achieved in less than 35 min with separation efficiencies between 2000 and 9000 theoretical plates. A bi-functional column was prepared that contains both anionic and cationic functional groups and was used for simultaneous separation of anions and cations.     

Radiochemical measurement of <Superscript>237</Superscript>Np in a solution of mixed radionuclides: Experiences in chemical separation and alpha-spectrometry

A radiochemical procedure is described for the measurement of 0.1 Bq ²³⁷Np in a solution containing similar activity concentrations of Th, U, Pu and Am as well as activity concentrations of ⁶⁰Co, ⁹⁰Sr and ¹³⁷Cs one hundred times higher. A tracer of ²³⁹Np (milked from ²⁴³Am) was used as an isotopic spike for chemical yield determination. The relationship between gamma-counting geometries for ampoule (liquid) and NdF₃ (solid) ²³⁹Np sources was established so that Np chemical yields could be measured by a comparative method. Efficiencies of alpha-spectrometers for ²³⁷Np in NdF₃ sources were measured by a bootstrap technique. Two sets of experiments were designed and used to test out the procedure.     

Determination of the number of unpaired electrons in metal-complexes. A comparison between the Evans’ method and susceptometer results

1,4,8,11-Tetraazacyclotetradecane (cyclam) is widely known as an ideal ligand for chelating heavy metal ions such as Ni²⁺ and Cu²⁺. In this work, the consequences of chelation on the preference for high spin or low spin configuration were investigated for Fe³⁺, Ni²⁺, Cu²⁺ and Cr³⁺. Two methods were used to determine the number of unpaired electrons in the complex. First the dependence of magnetic susceptibility change of the crystalline powder as a function of temperature increase was measured. In the second case, the Evans’ method was used to obtain information about the number of unpaired electrons in the dissolved complexes. In some cases, such as Fe³⁺ and Ni²⁺, a discrepancy between the results obtained with the two methods was noticed. The results are influenced by the geometry of the complex, the aggregation state and the dimensions of the ions.     

Anion-exchange and solvent extraction studies on the separation of radioiodine with particular reference to the production of 123I via proton irradiation of 123Te metal target

The separation of radioiodine was investigated using two wet chemical procedures, namely anion-exchange and solvent extraction. Some factors affecting the separation, such as HCl, NaOH and tetrabutyl ammonium bromide (TBAB) concentrations, used solvents ethyl acetate, benzene and carbon tetrachloride and different quaternary ammonium salts were studied. For each procedure the optimum conditions were deduced. The separation of ¹²³I was effected from proton-irradiated ¹²³Te target under the optimized conditions of the two procedures. The yield of ¹²³I obtained using the Dowex 21k anion-exchanger and tetrabutyl ammonium bromide solution as eluting agent was 88±3%; the radionuclidic purity was high and the time needed was 60 minutes. In solvent extraction process using TBAB in ethyl acetate as the extracting agent, the yield of ¹²³I was low (47±3%), the radionuclidic purity was not as good as in the anion-exchange method, and the time needed was 150 minutes. Therefore, the anionexchange method is preferable. A comparison of this wet chemical method of separation of ¹²³I with the commonly used dry distillation method is given. The wet method appears to be more suitable when a ¹²³Te metal target is used.     

Sodium meta-vanadate as volumetric reagent: Iodine monochloride method

In hydrochloric acid medium sodium meta-vanadate was used as a volumetric reagent for the determination of copper, zinc, cobalt, mercury, and lead. Cu⁺², Zn⁺² and Co⁺²were precipitated as complex mercurythiocyanates, Hg⁺² as mercuric zinc thiocyanate and Pb⁺² as Iodide. The thiocyanates were dissolved in concentrated hydrochloric acid and titrated against standard sodium meta-vanadate solution in the presence of iodine monochloride as a pie.oxidizer and catalyst. In titration of the iodide against the meta-vanadate. it was not necessary to add iodine monochloride to the titrant because it is formed during the titration. Chloroform was used as an indicator. It was pink owing to the liberation of iodine during the titration and became pale yellow at the end-point because of the formation of iodine monochlonde.     

Natural and fallout radionuclide concentrations in the environment of Islamabad

A study on the concentration of natural and fallout radionuclides in environmental samples collected from different localities of Islamabad was performed. For the determination of gamma-emitters such as ²³⁸U, ²³²Th, ⁴⁰K and ¹³⁷Cs high purity germanium (HPGe) detector was used while for the analysis of ⁹⁰Sr, a beta-emitter, liquid scintillation counting system was used. The indoor absorbed dose rate was measured by a CaF₂ : Dy thermoluminescence detector. Other radiation parameters were also determined to evaluate the radiation hazard. All the results were well within the permissible limits showing that there is no radiation hazard in the environment of Islamabad.     

Use of radiometric emanation method in the characterization of anthropogenic glass analogue for vitrification of nuclear waste

Anthropogenic analogues can be used as one of the sources of information about long-term behaviour of engineered barriers, used for geological disposal of radioactive waste. The radiometric emanation method, based on the measurement of radon release from the solid samples, was used in the study of the alteration of anthropogenic glass analogues for radioactive vitrified waste. The samples were labeled at their surface by a solution containing ²²⁸Th and ²²⁴Ra,serving as source of ²²⁰Rn nuclides. The radon ²²⁰Rn nuclides were introduced in the uranium glass samples due to the recoil energy of the α-decay of ²²⁸Th and ²²⁴Ra nuclides. The man-made uranium glass samples from a locality in the Czech Republic were used. The measurement, based on the release of radon atoms from the samples, was applied to characterize the radon diffusion permeability and microstructure changes of weathered and non-weathered uranium glass samples during heat treatments. The radon diffusion characteristics and microstructure stability of the uranium glass analogue samples were evaluated by using a mathematical model.     

Investigation of hydrodynamic behaviour of a pilot-scale trickle bed reactor packed with hydrophobic and hydrophilic packings using radiotracer technique

A radiotracer study was carried out in a trickle bed reactor (TBR) independently filled with two different types of packing i.e., hydrophobic and hydrophilic. The study was aimed at to estimate liquid holdup and investigate the dispersion characteristics of liquid phase with both types of packing at different operating conditions. Water and H₂ gas were used as aqueous and gas phase, respectively. The liquid and gas flow rates used ranged from 0.83?×?10^?7?C16.67?×?10^?7?m³/s and 0?C3.33?×?10^?4?m³ (std)/s, respectively. Residence time distribution (RTD) of liquid phase was measured using ⁸²Br as radiotracer and about 10?MBq activity was used in each run. Mean residence time (MRT) and holdup of liquid phase were estimated from the measured RTD data. An axial dispersion with exchange model was used to simulate the measured RTD curves and model parameters (Peclet number and MRT) were obtained. At higher liquid flow rates, the TBR behaves as a plug flow reactor, whereas at lower liquid flow rates, the flow was found to be highly dispersed. The results of investigation indicated that the dispersion of liquid phase is higher in case of hydrophobic packing, whereas holdup is higher in case of hydrophilic packing.     

Control of Thickness of PEDOT Electrodeposits on Glass/ITO Electrodes from Organic Solutions and its Use as Anode in Organic Solar Cells

Poly-ethylendioxythiophene (PEDOT) was electropolymerized from the monomer EDOT in acetonitrile (ACN) containing Bu₄N⁺ClO₄^-, BF₄^- or PF₆^- ions as supporting electrolyte. The electrode used was transparent electrodes (Glass/ITO) in order to generate the anode of an organic solar cell (OSC). Potentiodynamic and potentiostatic electropolymerization techniques were used to make the conducting polymer deposits (E-PEDOT), which were obtained as a thin film onto the ITO surface. It was possible to control the thickness of the electrodeposited films in the range of 15 to 200 nm measured by AFM. With the thinner films (until 100 nm), it was observed that its absorbance at 700 nm was linearly dependent with their thickness and it was possible to obtain an equation that was used to measure the films thickness of future experiments. The E-PEDOT films were successfully used for constructing OSC's and the efficiency values found were equivalent or slightly superior to those found with the classical PEDOT:PSS anode.     

Effervescence-assisted dispersive liquid-liquid microextraction based on deep eutectic solvent for preconcentration and FAAS determination of copper in aqueous samples

A new effervescence-assisted dispersive liquid-liquid microextraction, EA-DLLME, technique was developed for preconcentration and flame atomic absorption spectrometric determination of copper in aqueous samples. Effervescence assistance and DES combination for metal ion extraction was used for the first time. In the presented study, six different effervescence powders were examined to achieve maximum extraction efficiency. In addition, 1,5 diphenyl carbazide was used as complexing agent and DES prepared by mixing choline chloride and phenol was used as extraction solvent. The effect of several parameters such as pH, concentration of complexing agent, composition and volume of DES, amount of THF, composition and amount of effervescent agent were examined. Performed experiments showed that optimum pH was 6.0, the best effervesce powder composition was NaH₂PO₄:Na₂CO₃ with 2 × 10^?3:1 × 10^?3 molar ratio and the amount of effervesce powder was 0.4 g. Under optimum conditions enhancement factor, limit of detection and limit of quantification were calculated as 78, 2.9 and 9.7 μg L^?1, respectively. In addition, to prove precision of the method intra-day relative standard deviations were calculated for 10 and 50 μg L^?1 Cu²⁺ concentrations and found as 2.1% and 1.3%, respectively. The proposed method showed good linearity within the range of 10.0–100 μg L^?1. Finally, proposed method was successfully applied to determination of copper traces in aqueous samples.     

Radiochemical studies of the sorption behavior of strontium and barium

The sorption behavior of strontium and barium on kaolinite, bentonite and chlorite-illite mixed clay was studied by radioanalytical techniques using the batch method.⁹⁰Sr (29.1 y) and¹³³Ba (10.5 y) were used as radiotracers. Characterization of the solid matrices was done by FTIR and XRD spectrometries and specific surface area measurements. Synthetic groundwater was used as the aqueous phase. The variation of the distribution ratioR _d, as a function of metal ion loading was examined. The sorption isotherms were fitted to various isotherm models. The sorption energies were calculated to be in the range of 8–10 kJ/mol suggesting an ion exchange type of sorption mechanism. In detailed experiments, chlorite-illite mixed clay was first presaturated with K⁺, Sr²⁺, Ca²⁺ and Al³⁺ ions, respectively, prior to sorption studies with Ba²⁺ ions. The results of Ca²⁺ pretreated chlorite-illite were very similar to those of natural chlorite-illite, suggesting that the Ba²⁺ ion exchanges primarily with the Ca²⁺ ion on the clay minerals.     

Analysis for catecholamines and related compounds based on luminescence at room temperature and at 77 k

The luminescence characteristics of 34 catecholamines and related compounds at room temperature and at 77 K are reported. Neutral, basic and acidic mixtures were used as solvents. Limits of detection, linear ranges and analytical precision were determined for each case. Analytically useful luminescence was obtained at 77 K. In neutral and acidic solutions, both fluorescence and phosphorescence could be used qualitatively and quantitatively; in basic solutions, the phosphorescence was valuable at concentrations as low as 10⁶–10^-9 M, depending on the compound.     

Quantitative Determination of Fluconazole by Infrared Spectrophotometry

Abstract

The purpose of the study was the quantitative determination of fluconazole by IR spectrophotometry which was realized by the application of the KBr disc technique. In this study dehydrocholic acid was used as internal standard.

The absorption bands at 960 and 675 cm^?1 were chosen for fluconazole and 1705 cm^?1 for dehydrocholic acid. The concentration range between 0.4–1.6% w/w in KBr disc showed compliance with Beer's law.

Besides IR spectroscopy, UV spectroscopy and HPLC methods were also used In the quantitative determinations. In the UV spectroscopy method the absorbance value at 261 nm in MeOH was used for fluconazole. In quantitative determinations which were performed by using HPLC, ketoconazole was the internal standard. Different regression equations were applied for each method in order to complete the quantitative determination. In UV spectroscopy and HPLC methods, relative standards were found as 0.74, 1.04% and in IR spectroscopy (675, 960 cm^?1) relative standards were found as 1.1 and 1.51%, respectively.     

Homogeneous electrocatalytic oxidation of captopril by iodide and its application to pharmaceutical analysis

Potassium iodide was used as a homogeneous electrocatalyst for the oxidation of captopril. Cyclic voltammetry and chronoamperometry were used in kinetic studies. The diffusion coefficient and catalytic rate constant were calculated to be 4.94?×?10^?5?cm²?s^?1 and 1.87?×?10³?M^?1?s^?1, respectively. Linear sweep voltammetry was applied to quantitative determination of captopril; a linear calibration curve was obtained in the range of 4.0?C500???M of captopril with a limit of detection of 0.84???M and a sensitivity of 0.035 A?M^?1. The method was applied to the determination of the drug in its tablets and validation methods showed that the results were quite satisfactory.     

Luminescent organo‐polysiloxanes containing complexed lanthanide ions

In this study, a type of polysiloxane with the ester as the functional side group was prepared via a hydrosilylation reaction. The functionalized polysiloxane was then allowed to complex with Tb³⁺ and Eu³⁺ ions. Fourier transform infrared, ultraviolet absorption spectra and ¹H‐NMR, ¹³C‐NMR and ²⁹Si‐NMR spectra were used to confirm the modification. Differential scanning calorimetry and thermal gravity analysis were used to study the polysiloxane's thermal properties. The complexes' luminescence spectra were recorded, and narrow‐width green and red emissions were achieved. Copyright © 2009 John Wiley & Sons, Ltd.     

Preparation, quality control and stability of 131I-Lanreotide

Summary Lanreotide, a synthetic octapeptide analog of a native hormone somatostatin, was labeled with ¹³¹I, the most widely used therapeutic and easily available radionuclide. Radioiodination of Lanreotide was carried out by Chloramine-T and Iodogen methods. Chloramine-T and Iodogen were used as oxidizing agents to form an electrophilic iodine species, which then labeled the tyrosine of Lanreotide. The maximum radiolabeling yield was ~80%. Chloramine-T was found more suitable than the Iodogen method, because nearly 25% of the initial iodine activity was lost/adsorbed on the Iodogen coating. Thin layer and high performance liquid chromatographies were used for monitoring the reaction of ¹³¹I with Lanreotide, the stability and purity of ¹³¹I-Lanreotide.     

Labeling of atenolol with radioactive iodine-125 using <Emphasis Type="Italic">N</Emphasis>-bromosuccinimide and hydrogen peroxide as oxidizing agents

An adopted method for the preparation of high radiochemical purity ¹²⁵I-atenolol was investigated. Direct radioiodination of atenolol was carried out using N-bromosuccinamide or hydrogen peroxide as an oxidizing agent. The reaction proceeds well within 30 min at room temperature (25 ± 1 °C) and afforded a radiochemical yield up to 97% as pure as ¹²⁵I-atenolol. Different chromatographic techniques (electrophoresis, TLC and HPLC) were used to determine the radiochemical yield and purity of the labeled product. Biodistribution studies were carried out in normal Albino Swiss mice and the results indicate that ¹²⁵I-atenolol can be used safely as myocardial imaging agent.