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In this paper, we will introduce an enzyme‐free solid‐state electrochemiluminescent (ECL) sensor for ultrasensitive detection of Hydrogen peroxide (H2O2), as a significant molecule in many fundamental biological processes. It was fabricated based on the electro immobilization of poly (Luminol/Aniline) (PLA) nanocomposite on the surface of electrochemically reduced Graphene oxide (ERGO)/CeO2 /GCE modified electrode. We applied electrochemical technique as a controllable, rapid and simple method for the electro copolymerization of Luminol and Aniline and also the electrochemical reduction of graphene oxide (GO). The oxygen functional groups in ERGO were mostly eliminated. The properties of the ERGO/CeO2 /PLA modified electrode were also studied by FE‐SEM, Cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS) methods. Under the optimal conditions, this proposed ECL sensor exhibits high sensitivity and wide linear dynamic range for H2O2 determination from 0.8 pmolL-1 to 8 mmolL-1 with the low detection limit of 0.36 p molL-1 (S/N=3) and RSD 1.89 %. The results demonstrate that this enzyme‐free solid‐state ECL sensor offers a promising candidate for quantification of H2O2 concentration in biological fluids such as human urineIntroduction [ABSTRACT FROM AUTHOR]

In this research, nanoporous silica (SBA-15) was physically functionalized using 2-(2-nitrobenzylideneamino) guanidine compound. This functionalized SBA-15 was utilized as a new sorbent for separation and preconcentration of some lanthanide ions. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used as a detection technique. The preconcentration factor of the method is 100 and detection limit of this technique is obtained 2.9 ng/mL for Dy3+, 1.6 ng/mL for Eu3+, 8.4 ng/mL for Nd3+, 3.8 ng/mL for Sm3+ and 2.5 ng/mL for Yb3+ ions. The time and optimum amount of the sorbent, pH effect, presence of other ions on extraction condition were also tested. The maximum capacity of 5 mg functionalized SBA-15 was found to be about 155.2 μg for Sm3+, 131.2 μg for Yb3+, 128.1 μg for Nd3+, 143.3 μg for Eu3+, 140.6 μg for Dy3+ ions. The method was successfully applied for preconcentration and determination of these lanthanides in some natural water samples. [ABSTRACT FROM AUTHOR]

In this work, all-solid-state potentiometric PVC membrane sensor was introduced for fast and simple monitoring of mercury ions in waste water samples. The all solid sate electrode is made based on a conductive composite of graphite, reduced graphene oxide, epoxy resin on a copper wire. A thin layer PVC membrane is then coated on the surface of the new conducting transducer. PVC membrane is composed of 30% PVC, 62% NPOE as plasticizer, 3% ionic liquid, and 5% Hg2+ ion imprinted polymer (IIP). The sensing element of the sensor is an artificial host which is imprinted by vinyl pyridine and a suitable cross-linker. The sensor shows a Nernstian response of 29.4±0.3 mV/decade. Dynamic linear range of the sensor is 1.0×10-8-1.0×10-3 mol/L of the mercury concentration and detection limit of 3.2×10-9 mol/L. The interference of different ionic species with the response of the electrode shows a good selectivity of the proposed sensor. The proposed sensor is successfully applied in determination of mercury ions in some waste water samples. [ABSTRACT FROM AUTHOR]

In this work, a novel electrochemical technique is presented for determination of Bentazon using a nanocomposite based sensor and Continuous Coulometric Fast Fourier transformation cyclic voltammetry (CCFFTCV). In this method, the sensor response is in coulomb and is calculated based on integrating charge changes under the current voltammogram in selected potential range. The new sensor was constructed using MWCNT mixed with ionic liquid and reduced graphene oxide on a SiC NPs modified carbon ionic liquid electrode. The experimental conditions were then optimized. The modified electrode has good electrocatalytic activity toward the oxidation of Bentazon. The presence of the nanoparticles enhanced the electrochemical signal which increased the sensitivity of the sensor. Moreover, the proposed sensor exhibits good accuracy, the response time less than 7s, with good repeatability (R.S.D value of 2.3%) and long term stability. The linear concentrations range of Bentazon was from 1-150 nM with a detection limit of 2.5±0.01×10-10 M. [ABSTRACT FROM AUTHOR]

Background and Aim: The aim of this study was to assess exposure of workers in a metal industry to nickel and lead. Materials and Methods: Extraction was done using the solid-phase extraction on Chromosorb- 102 resin to prepare, concentrate and purify biological samples of urine, hair and nails of workers working in metal industries. The variables influencing response (pH, loading flow rate, elution solvent, and amount of resins, elution volume, and sample volume) were examined and the procedure was optimized. The optimized procedure was, then, validated based on the "within-day" and "day-to-day" reproducibility experiments, using low, medium and high concentrations, leading to a satisfactory accuracy and precision. Finally, lead and nickel samples were taken from the workers and their concentrations determined voltammetrically. Results: The optimum values for the examined parameters were as follows: pH = 9, ligand concentration = 0.05%, loading flow rate = 5 ml/min, elution solvent = 2M HNO3, amount of resins = 500 mg, elution volume = 15 ml, and sample volume up to 500 ml. A good reproducibility and repeatability was obtained for the optimized method under the existing conditions. Lead and nickel could be extracted with recoveries in the range of 94-100%. On the whole, the concentrations of nickel and lead in the workers' biological samples were above the respective maximum permitted levels. Conclusion: Solid-phase extraction procedure is a fast and simple method for preconcentrating and isolating analytes from biological samples. Considering the low concentrations of the analytes and presence of confounding factors in such samples, the procedure can be very effective for their preparation. The application of the developed method indicates that trace metal ions can be effectively purified and preconcentrated from different matrices like urine, hair and nail samples to assess occupational exposures. [ABSTRACT FROM AUTHOR]

In this work, a novel Hg2+ sensitive fluorescent chemosensor is constructed. The proposed nano-chemosensor was prepared through the preparation of 3-(benzo[d]thiazol-2-yl)-7-hydroxy-2H-chromen- 2-one functionalized silica nanoparticles which has high magnetization properties (BTC-Fe3O4@SiO2). The ünal product was characterized by Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UVvisible absorption and üuorescence emission. The material was found to demonstrate selective interactions with Hg2+ ions. This interaction is most probably due to the presence of the üuorophore moiety at the surface of nanomaterial. Fluorescence measurements revealed that the emission intensity of the Hg2+-bound with the magnetic core-shell Fe3O4@SiO2 NPs increases signiücantly upon addition of various concentrations of Hg2+, while in case of other mono, di, trivalent cations no changes or weak changes in the intensities were observed. The enhancement of üuorescence is attributed to the strong covalent binding of Hg2+ ions with the binding constant value of 1.7×105/M. The sensor can be applied for analysis of mercury in environmental sample. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel and simple fluorescence enhancement method is introduced for selective pyrophosphate (PPi) sensing in an aqueous solution. The method is based on a 1:1 metal complex formation between tris(8-hydroxyquinoline-5-sulphonate) thulium(III) [Tm(QS)3] and PPi ion. The linear response covers a concentration range of 1.6 × 10−7-1.0 × 10−5 mol/L PPi and the detection limit is 2.3 × 10−8 mol/L. The association constant of Tm(QS)3-PPi complex was calculated as 2.6 × 105 mol/L. Tm(QS)3 shows a selective and sensitive fluorescence enhancement toward PPi ion in comparion with I3−, NO3−, CN−, CO32−, Br−, Cl−, F−, H2PO4− and SO42−, which is attributed to higher stability of the inorganic complex between pyrophosphate ion and Tm(QS)3. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this work, for the first time, we introduce a highly selective and sensitive praseodymium(III) microsensor. Npsila-(pyridin-2-ylmethylene)benzohydrazide (PBH) was used as a membrane-active component to prepare a highly sensitive Pr(III)-selective polymeric membrane microelectrode. The electrode exhibits a Nernstian response toward Pr(III) ions over a very wide concentration range (1.0 times 10-3 -1.0 times 10-8 M), with a detection limit of 7.0 times 10-9 M (~1 ng/ml). It has a very fast response time in the whole concentration range (~10 s). The proposed microelectrode can be used for at least six weeks without any considerable divergence in potentials. The proposed membrane sensor revealed very good selectivity toward Pr(III) ions over a wide variety of other metal ions including common alkali, alkaline earth and, specially, lanthanide ions. It could be used in the pH range of 3.0-8.5. The Pr(III) microelectrode was used as an indicator electrode for the titration of 20 ml of a 1.0 times 10-6 M Pr(III) ions with a 1.0 times 10-4 M EDTA. [ABSTRACT FROM PUBLISHER]

A Th4+ ion-selective membrane sensor was fabricated from poly (vinyl chloride) (PVC) matrix membrane containing 2-(diphenylphosphorothioyl)- N′, N′-diphenyl acetamide (DPTD) as a neutral carrier, potassium tetrakis ( p-chlorophenyl) borate (KTpClPB) as anionic excluder and o-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The effects of the membrane composition, pH and additive anionic influence on the response properties were investigated. The sensor, comprising 30% PVC, 63% solvent mediator, 4% ionophore and 3% anionic additive demonstrates the best potentiometric response characteristics. It displays Nernstian behavior (15.2 ± 0.5 mV per decade) over the concentration range 1.0 × 10−2–1.0 × 10−6 M. The detection limit of the electrode is 6.3 × 10−7 M (∼140 ng/ml). The response time of the electrode is 30 s .The sensor can be used in the pH range 3.0–9.0 for about 6 weeks. The membrane sensor was used as an indicator electrode in the potentiometric titration of Th4+ ions with EDTA. It was successfully applied to the determination of thorium ions in binary mixture. [ABSTRACT FROM AUTHOR]

The reaction of 4-chloro-1,8-naphthalic anhydride with sulfur and sodium sulfide in boiling ethanol lead to 4-mercapto-1,8-naphthalic anhydride. The condensation of a later compound with amines produced 4-mercapto-1,8-naphthalimides and with ethylenediamine and orthophenylenediamine, respectively, led to 4-mercapto-7H-imidazo[2,1-a]benz[d,e]isoquinoline-7-one and 4-mercapto-7H-imidazo[2,1a]benz[d,e]isoquinoline-7-one in good to fairly high yields. [ABSTRACT FROM AUTHOR]

Regarding the importance of nanoparticles in today’s world, and in the light of the fact that their preparation can be a rather difficult task, we focused on the applicability of a simplistic direct precipitation approach for the preparation of praseodymium tungstate nanoparticles. To maximize the effectiveness of the method, a Taguchi robust design approach was applied to optimize the reaction in terms of the operating conditions influencing its outcome and the results were monitored by characterization of the Pr2(WO4)3 nanoparticles. Among the four parameters studied we found the dimensions of the produced nanoparticles to be determined by the concentrations of Pr3+ and WO43− solutions and the reaction temperature, while the flow rate of adding the cation solutions to the anion solution was found to leave very negligible effects on the product characteristics. To confirm the effect of the optimizations on the outcomes of the reaction, SEM, TEM, EDX, XRD, FT-IR and UV-Vis structural and morphological characterizations of the products were performed, the results of which were in agreement with those statistically predicted in the optimization procedure. Furthermore, as-synthesized praseodymium tungstate nanoparticles under ultraviolet light exhibited an efficient photocatalyst property in the photocatalytic degradation of methylene blue.