Micelle-Mediated Extraction and Flame Atomic Absorption Spectrometric Method for Determination of Trace Cobalt Ions in Beverage Samples

A new method has been developed for preconcentration of cobalt at trace levels in beverage samples using calcon carboxylic acid as chelating agent and cetyl pyridinium chloride as an auxiliary ligand and entrapped into Triton X-114 prior to its determination by flame atomic absorption spectrometry (FAAS). The main parameters affecting cloud point extraction (CPE) efficiency such as pH, concentration of the complexing agent, cationic and nonionic surfactant concentration, salt effect, the equilibrium time, and temperature were investigated and optimized. After optimization of the CPE conditions, a preconcentration factor of 60, an enhancement factor of 106, and a detection limit of 0.20 μg L⁻¹ by (R ² = 0.9978) were obtained from a calibration curve constructed in the range of 0.7–100 μg L⁻¹. The proposed preconcentration procedure was successfully applied to the determination of cobalt ions in some real samples including natural drinking water, tap water, and beer and wine samples. The accuracy and validity of the proposed CPE/FAAS method was tested by means of five repeated analysis of reference standard materials (TM-253, a low level fortified water standard for trace elements). A good agreement between analytical results (28.8 and 28.5 μg L⁻¹ with calibration curve and standard addition curve method, respectively) and certified value (27.9 μg L⁻¹) for Co (p < 0.05) were obtained and verified by means of calibration curve and standard addition curve method using CPE procedure.     

A novel potentiometric pH electrode based on sulfated natural Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> and analytical application in food samples

A novel solid state potentiometric pH electrode based on sulfated natural Fe₃O₄ silicone was fabricated. The optimum potentiometric performances such as Nernstian response, response time, selectivity, life-time and reproducibility of pH electrodes were investigated by using a computer-controlled potentiometric device. Moreover, the potentiometric performance of the solid state pH electrodes was studied with different mixtures sulfated natural Fe₃O₄, silicone and graphite powder. The best potentiometric behavior of proposed pH electrode was obtained with a composition of 20% (w/w) sulfated natural Fe₃O₄, 40% (w/w) graphite powder and 40% (w/w) silicone. The sub-Nernstian response for pH electrode was exhibited with a slope of 30.8?±?1.4 mV/pH (r?=?0.9963) from pH 2 to pH 12. In addition, the dynamic response time was found as 10 s in acidic medium and further the proposed pH electrode can be used for at least 1 year without any significant slope of the pH–potential curve. The selectivity coefficient of pH electrode was interpreted according to fixed interference method in the presences of Na⁺, Li⁺, K⁺, NH₄⁺, SO₄^2?, CH₃COO^? and NO₃^? ions. The reproducibility of pH electrode was calculated in pH 4 and pH 6 phosphate buffers and it was found as 0.24 RSD (%) and 0.27 RSD (%) respectively. The proposed pH electrode was used to determine of pH in acid?bases titration compared with glass pH electrode and is highly stable in corrosive systems including HF solution. Terminally, the pH value was successfully determined in some soft drinks and milk samples by proposed solid state pH electrode at 95% confidence level with satisfactory agreement compared with glass pH electrode.     

Mycoflora of hazelnut (Corylus avellana L.) and aflatoxin content in hazelnut kernels artificially infected with Aspergillus parasiticus

In this research, 30 hazelnut samples were used to determine their internal mould populations and their aflatoxin contents. The results showed that Aspergillus was the most common genus in the experimental samples (96.6% of all samples). Thirty-one% of isolates were classified as Aspergillus flavus and none of the samples contained aflatoxins. In the second part of the experiment, the kernels were inoculated with conidia of Aspergillus parasiticus and incubated at three different humidified conditions and two different temperatures for 45 days. Aflatoxin contents of the samples kept in 98% relative humidity and at 28 degrees C were higher (904.6 micrograms/kg) than that of the other samples. On the other hand, no aflatoxin was detected in the control samples that were not inoculated but kept at the same conditions.     

Charge transfer and delocalization studies from Kβ-to-Kα intensity ratios in CoxCu1−x alloys

Kβ-to-Kα X-ray intensity ratios of Co and Cu have been measured in pure metals and in alloys of Co_xCu_1−x (x = 0.8, 0.7, 0.6, 0.5, 0.4, 0.3 and 0.2) following excitation by 22.69 keV X-rays from a ¹⁰⁹Cd radioactive point source. The valence-electronic configurations of these metals were determined by corporation of measured Kβ-to-Kα X-ray intensity ratios with the results of multiconfiguration Dirac–Fock (MCDF) calculation for various valence-electronic configurations. Valance electronic configurations of Co and Cu in alloys indicate significant differences with respect to the pure metals. Our analysis indicates that these differences arise from delocalization and/or charge transfer phenomena in alloys. Namely the observed change of the valence-electronic configurations of metals in alloys can be explained with the transfer of 3d electrons from one element to the other element and/or the rearrangement of electrons between 3d and 4s, 4p states of individual metal atoms.     

Learning differential diagnosis of erythemato-squamous diseases using voting feature intervals

A new classification algorithm, called VFI5 (for Voting Feature Intervals), is developed and applied to problem of differential diagnosis of erythemato-squamous diseases. The domain contains records of patients with known diagnosis. Given a training set of such records, the VFI5 classifier learns how to differentiate a new case in the domain. VFI5 represents a concept in the form of feature intervals on each feature dimension separately. classification in the VFI5 algorithm is based on a real-valued voting. Each feature equally participates in the voting process and the class that receives the maximum amount of votes is declared to be the predicted class. The performance of the VFI5 classifier is evaluated empirically in terms of classification accuracy and running time.     

Selective separation and concentration of Pd(II) from Fe(III), Co(II), Ni(II), and Cu(II) ions using thiourea‐formaldehyde resin

Thiourea‐formaldehyde (TUF), a well‐known chelating resin, has been synthesized and it was used in the adsorption, selective separation, and concentration of Pd(II) ions from Fe(III), Co(II) Ni(II), and Cu(II) base metal ions. The composition of the synthesized resin was determined by elemental analysis. The effect of initial acidity/pH and the adsorption capacity for Pd(II) ions were studied by batch technique. The adsorption and separation of Pd(II) were then examined by column technique. FTIR spectra and SEM/EDS analysis were also recorded before and after the adsorption of Pd(II). The optimum pH was found to be 4 for the adsorption. The adsorption data fitted well to the Langmuir isotherm. The maximum adsorption capacity of the TUF resin for Pd(II) ions was found to be 31.85 mg g⁻¹ (0.300 mmol g⁻¹). Chelating mechanism was effective in the adsorption. Pd(II) ions could be separated efficiently from Fe(III), Cu(II), Ni(II), and Co(II) ions using TUF resin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Palladium-PEPPSI-NHC Complexes Bearing Imidazolidin-2-Ylidene Ligand: Efficient Precatalysts for the Direct C5-Arylation of N-Methylpyrrole-2-Carboxaldehyde

Catalysis Letters - The Pd-catalyzed direct arylation of pyrroles is an important research field for organic synthesis and catalysis chemistry. However, imidazolidin-2-ylidene based Pd-NHC...     

Flexible poly(styrene-ethylene-butadiene-styrene) hybrid nanofibers for bioengineering and water filtration applications

Among the thermoplastic elastomers that play important roles in the polymer industry due to their superior properties, styrene-based species and polyurethane block copolymers are of great interest. Poly(styrene-ethylene-butadiene-styrene) (SEBS) as a triblock copolymer seems to have the potential to meet many demands in different applications due to various industrial requirements where durability, biocompatibility, breaking elongation, and interfacial adhesion are important. In this study, the SEBS triblock copolymer was functionalized with natural (Satureja hortensis, SH) and synthetic (nanopowder, TiO₂) agents to obtain composite nanofibers by electrospinning and electrospraying methods for use in biomedical and water filtration applications. The results were compared with thermoplastic polyurethane (TPU) composite nanofibers, which are commonly used in these fields. Here, functionalized SEBS nanofibers exhibited antibacterial effect while at the same time improving cell viability. In addition, because of successful water filtration by using the SEBS composite nanofibers, the material may have a good potential to be used comparably to TPU for the application.