Preconcentration of trace elements from water samples on a minicolumn of yeast (Yamadazyma spartinae) immobilized TiO2 nanoparticles for determination by ICP-AES

A trace element preconcentration procedure is described utilizing a minicolumn of yeast (Yamadazyma spartinae) immobilized TiO₂ nanoparticles for determination of Cr, Cu, Fe, Mn, Ni and Zn from water samples by inductively coupled plasma atomic emission spectrometry. The elements were quantitatively retained on the column between pH 6 and 8. Elution was made with 5% (v/v) HNO₃ solution. Recoveries ranged from 98 ± 2 (Cr) to 100 ± 4 (Zn) for preconcentration of 50 mL multielement solution (50 μg L⁻¹). The column made up of 100 mg sorbent (yeast immobilized TiO₂ NP) offers a capacity to preconcentrate up to 500 mL of sample solution to achieve an enrichment factor of 250 with 2 mL of 5% (v/v) HNO₃ eluent. The detection limits obtained from preconcentration of 50 mL blank solutions (5%, v/v, HNO₃, n = 11) were 0.17, 0.45, 0.25, 0.15, 0.33 and 0.10 μg L⁻¹ for Cr, Cu, Fe, Mn, Ni and Zn, respectively. Relative standard deviation (RSD) for five replicate analyses was better than 5%. The retention of the elements was not affected from up to 500 μg L⁻¹ Na⁺ and K⁺ (as chlorides), 100 μg L⁻¹ Ca²⁺ (as nitrate) and 50 μg L⁻¹ Mg²⁺ (as sulfate). The method was validated by analysis of freshwater standard reference material (SRM 1643e) and applied to the determination of the elements from tap water and lake water samples.     

Electrochemical signal modulation in homogeneous solutions using the formation of an inclusion complex between ferrocene and β-cyclodextrin on a DNA scaffold

Two DNA conjugates modified with ferrocene and β-cyclodextrin were prepared as a pair of probes that work cooperatively for DNA sensing, in which the electrochemical signal of ferrocene on one probe was significantly "quenched" by the formation of an inclusion complex with β-cyclodextrin of the other probe on the DNA templates.     

Light gasoil of catalytic cracking: A quantitative description of the physical properties by joint use of chromato-mass-spectrometry and molecular dynamics

In the present work, the composition and relative density of light gasoil of catalytic cracking (LGCC) were studied using chromato-mass-spectrometry and its key physical properties were numerically simulated using molecular dynamics. We have studied the distribution of hydrocarbon compounds over narrow fractions of LGCC. We have applied the ASTM D2892-11a standard distillation to find the component composition of LGCC and its narrow fractions obtained from a mixture of West Siberian oils. Molecular dynamics simulations were performed using the GROMOS96 54a7 force field for the ensemble of constant number of particles (N), pressure (P) and temperature (T) (NPT) ensemble under the constant temperature and constant pressure conditions. The topologies of the structures under study were generated by the automated topology builder (ATB) service. Both the chromatographic mass spectrometry experiments and molecular dynamics simulations indicate the contents of aromatic hydrocarbons in LGCC from the mixture of West Siberian oils up to 80 wt%.     

The Synthesis of Hexaphenylcyclotriphosphazene in Improved Yield

The reaction between phenylmagnesium bromide and hexachlorocyclotriphophazene (N ₃ P ₃ Cl ₆ ) ( 1 ) was reinvestigated for the synthesis of hexaphenylcyclotriphosphazene (N ₃ P ₃ Ph ₆ ) ( 2 ) in high yield. The reaction is complete within two weeks at room temperature using toluene as solvent. When the reactants (PhMgBr and N ₃ P ₃ Cl ₆ ) were employed in a 6:1, 36:1 and 72:1 molar ratio, compound 2 was obtained in 2.6%, 14%, and 33.4% yield, respectively. The formation of N ₃ P ₃ Cl ₆ ( 2 ) during the reaction was followed by thin-layer chromatography. Compound 2 was characterized by elemental analysis, IR, UV-VIS, ¹ H, ¹³ C, and ³¹ P NMR spectroscopy as well as by mass spectrometry.     

Assessment of matrix-dependent analyte stability and volatility during open-vessel sample dissolution for arsenic, cadmium, mercury and selenium

A sensitive method for the determination of estradiol is presented that is based on an electrode modified with multi-walled carbon nanotubes (MWNTs) along with an ionic liquid. The resulting electrode showed more sensitive voltammetric response to estradiol than other electrodes modified with MWNTs. The peak current for estradiol is linearly related to concentration over two decades, and the limit of detection is 5 nM. The method was applied to the determination of estradiol in rabbit blood serum and in environmental waters. The recoveries were 95.3–104.0% and 97.0–104.7%, respectively.     

Molybdenum tetracarbonyl complexes with linear chain polyether‐containing Schiff base ligands and their reactivity in the polymerization of methyl methacrylate

Mo(CO)₆ was reacted with the Schiff base ligand obtained by condensation reaction of 2‐acetyl‐ or benzoylpyridine with poly(propylene glycol)bis(2‐aminopropyl ether) to obtain polymeric, dinuclear metal tetracarbonyl compounds. The long‐chain Schiff base complexes are highly soluble even in non‐polar solvents such as petroleum ether, diethyl ether and n‐hexane. These complexes, as free‐radical initiators, afforded methyl methacrylate polymerization in chlorinated solvents. Copyright © 2005 John Wiley & Sons, Ltd.     

C-Totally real pseudo-parallel submanifolds of Sasakian space forms

Let be (2n + 1)-dimensional Sasakian space form of constant ϕ-sectional curvature (c) and M ⁿ be an ⁿ -dimensional C-totally real, minimal submanifold of . We prove that if M ⁿ is pseudo-parallel and , then M ⁿ is totally geodesic.     

A novel palladium nanoparticles-polyproline-modified graphite electrode and its application for determination of curcumin

A novel-modified electrode has been developed, by electrodeposition of palladium nanoparticles (PdNps) on polypyroline film-coated (Poly(Pr)) graphite electrode. The modified electrode (PdNps/Poly(Pr)/GE) was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) techniques. SEM proved that the palladium nanoparticles were uniform distributed with an average particle diameter of 20–45 nm. A higher catalytic activity was obtained for curcumin oxidation using this new modified electrode (PdNps/Poly(Pr)/GE). The square wave voltammogram of curcumin in pH 2 phosphate buffer exhibited an anodic peak at 0.504 V. This oxidation peak current was found to be linearly related to curcumin concentrations in the ranges of 5.0?×?10^?9 to 1.0?×?10^?7 M with a detection limit of 1.2?×?10^?9 M. This novel-modified electrode showed excellent sensitivity, compared with the existing reports about determination of curcumin.     

Fabrication of SPR Nanosensor Using Gold Nanoparticles and Self-Assembled Monolayer Technique for Detection of Cu2+ in an Aqueous Solution

In this work, we investigated the fabrication of surface plasmon resonance (SPR) nanosensor using gold nanoparticles (AuNPs) chemisorbed onto self assembled monolayer of 10-(3-amino phenoxy) decane-1-thiol on gold substrate. The fabrication process of SPR nanosensor was characterized using different techniques such as infrared reflection-absorption spectra (IRRAS), xX-ray photoelectron spectroscopy (XPS), and atomic force microscope (AFM). The fabricated SPR nanosensor was used for detection of Cu²⁺ in an aqueous solution using surface plasmon resonance refractometer. The results confirm the fabrication of new SPR nanosensor. The fabricated SPR nanosensor showed a good activity toward the detection of Cu²⁺. The detection of Cu²⁺ in an aqueous solution using the fabricated SPR nansensor was enhanced in the presence of gold nanoparticles.