European Journal of Chemistry
ISSN / EISSN : 21532249 / 21532257
Current Publisher: European Journal of Chemistry (10.5155)
Total articles ≅ 858
Latest articles in this journal
European Journal of Chemistry, Volume 10, pp 305-316; doi:10.5155/eurjchem.10.4.305-316.1901
Abstract:Cathodic voltammetric behaviors of drospirenone and ethinylestradiol were used for the simultaneous determination of both drugs in bulk and in pharmaceutical formulation (Yasmin® tablets) without the interference of excipients. The determinations were made on hanging mercury dropping electrode using square-wave technique in a voltammetric cell containing 10 mL of 0.04 mole/L Britton-Robinson. After every aliquot addition, the solution was stirred for 10 s at 1000 rpm, rested for 10 s then square wave voltammetry mode was ramped from +100 to -1700 mV with scan rate of 100 mV/s, pulse amplitude of 50 mV and measurement time of 5 ms. Several factors such as pH, type of supporting electrolyte, pulse amplitude and scan rate were studied to optimize the condition for voltammetric determination of these drugs. With optimized experimental parameters, a good linearity was obtained for both drugs over a range of 1.36×10-6 to 1.91×10-7 mole/L and 6.75×10-8 to 6.07×10-7 mol/L of drospirenone and ethinylestradiol, respectively. Characterization of the proposed method was done according to International Conference on Harmonization, Q2B: Validation of Analytical procedures. The proposed method was statistically compared with the reference method and the results revealed no significant difference regarding accuracy and precision.
European Journal of Chemistry, Volume 10, pp 273-280; doi:10.5155/eurjchem.10.4.273-280.1885
Abstract:All-solid state potentiometric ion selective electrodes have the merits of being portable, small and suitable for small volume samples. Herein, disposable home-made screen printed polymeric ion selective electrode (SPE) is developed for determination of oxymetazoline (OXM) in pharmaceutical nasal drops and drug substance. Ion selective electrodes with optimal potentiometric response were achieved by careful selection of the ion exchanger and plasticizer. A screen printed electrode utilizing oxymetazoline-tetraphenyl borate (OXM-TPB) as an ion exchanger and dibutyl phthalate (DBP) as a plasticizer exhibited a Nernstian slope of 59.5±0.5 mV/decade (n=3) over the concentration range from 1×10-5 to 1×10-2 M OXM (r = 0.9999) with a detection limit of 5.0×10-6 M. The electrode is useful over a wide pH range from 4.0 to 8.0. The electrode showed a high selectivity for OXM against several common interfering ions. The potential interference from benzalkonium chloride was easily eliminated by treatment the sample with KI. Comparable potentiometric characteristics including linearity, detection limit, pH range and selectivity pattern were obtained with a carbon paste electrode (CPE) comprising same ion exchanger and plasticizer. The electrodes were successfully used for the assay of OXM in the drug substance and in the dosage form in presence of benzalkonium chloride with high accuracy (±2%) and precision (%RSD ˂2.5). The proposed method is simple, accurate and precise.
European Journal of Chemistry, Volume 10, pp 281-294; doi:10.5155/eurjchem.10.4.281-294.1844
Abstract:The present study describes, the X-ray single crystal analysis of 4-((2-chloro-6-methoxyquinolin-3-yl)methyl)-2-phenyl-2H-1,2,4-triazol-3(4H)-one (TMQ). The crystal data for C19H15ClN4O2: monoclinic, space group P21/n (no. 14), a = 7.3314(15) Å, b = 12.459(3) Å, c = 18.948(4) Å, β = 98.322(9)°, V = 1712.5(6) Å3, Z = 4, T = 296.15 K, μ(MoKα) = 0.245 mm-1, Dcalc = 1.423 g/cm3, 5082 reflections measured (3.926° ≤ 2Θ ≤ 38.556°), 1428 unique (Rint = 0.0545, Rsigma = 0.0574) which were used in all calculations. The final R1 was 0.0423 (I >2σ(I)) and wR2 was 0.1145 (all data). The Density functional theory optimized molecular geometries in TMQ agree closely with those obtained from crystallographic studies. The Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energy levels and energy gap were calculated by experimental (UV absorption & Cyclic voltammetry) and theoretical studies in two different solvents. The natural bond orbital analysis was performed to understand the molecular interaction on the basis of stability of molecule arising from hyper-conjugative interaction and charge delocalization. Hirshfeld surface and their related fingerprint plots enabled the identification of significant intermolecular interaction. The molecular electrostatic potential analysis provides the visual image of the chemically active sites and comparable reaction of atoms.
European Journal of Chemistry, Volume 10, pp 295-304; doi:10.5155/eurjchem.10.4.295-304.1886
Abstract:A lingo-cellulosic material Jute Stick Powder was used as a biosorbent to remove Pb(II) ions from aqueous solution and the biosorption behavior was investigated as a function of pH, metal ion concentration, adsorbent dosages and agitation time. Sorption binding sites present in JSP was assessed by Infrared spectroscopy (IR) and Scanning Electron Micrograph (SEM). The determined experimental data were fitted to some common kinetic and equilibrium models. Langmuir isotherm and pseudo-second-order kinetic model gave better fit to experimental data. The study revealed that spontaneous ion-exchange and complexation process involved in the adsorption mechanism. When the repeated adsorption-desorption cycles were performed, JSP kept its adsorptive efficiency even after three cycles of reuse.
European Journal of Chemistry, Volume 10, pp 336-344; doi:10.5155/eurjchem.10.4.336-344.1852
Abstract:A highly sensitive and stable solid-state electrochemiluminescence (ECL) sensor was developed based on tris(2,2’-bipyridyl)ruthenium(II) (Ru(bpy)32+) integrating with 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) functionalized graphene. Ru(bpy)32+ is incorporated with the ABTS functionalized graphene based on not only the π-π stacking but also electrostatic interactions. Coupled with capillary electrophoresis (CE), this ECL sensor was used to detect tyramine and 5-hydroxytryptamine (5-HT) based on their quenching effects for the Ru(bpy)32+/tripropylamine (TPA) system. The quenching mechanism was illustrated and the conditions for CE separation and ECL detection were optimized. Based on an S/N = 3, the limit of detection (LOD) for tyramine and 5-HT were 0.1 μM and 0.02 μM, respectively. The applicability of the proposed method was further illustrated in the determination of tyramine and 5-HT in human plasma samples from small intestine carcinoid patients.
European Journal of Chemistry, Volume 10, pp 317-322; doi:10.5155/eurjchem.10.4.317-322.1895
Abstract:The catalytic decomposition of H2O2 on differently pre-treated Au/CeO2 catalyst was studied by kinetic measurements at 20-50 °C. The prepared catalyst was subjected to pre-treatment by heating either in oxidative (10% O2/N2) or inert (pure N2)atmosphere at 400 °C. The different oxidation states of gold were determined by X-ray photoelectron spectroscopy measurements. The Au/CeO2 catalyst exhibited an excellent catalytic activity towards H2O2 decomposition. The catalytic activity of oxygen pre-treated sample was about twice higher than that measured for nitrogen pre-treated sample. This finding ran parallel to the amount of Aun+ as determined by XPS, indicating the role played by Aun+ species as the most active catalyst’s constituent. However, one cannot overlook the role of metallic gold in catalyzing the H2O2, decomposition showing small activity compared to that of cationic gold. The average crystallites size of metallic gold particles was found to be 7±0.5 nm independent of the pre-treatment conditions. The apparent activation energy of the catalyzed reaction was found to be 46.5 and 47.8 kJ/mol for oxygen and nitrogen pre-treatment, respectively.
European Journal of Chemistry, Volume 10, pp 403-408; doi:10.5155/eurjchem.10.4.403-408.1889
Abstract:The ab-initio DFT method (B3LYP) is applied to the study of the C-C and C-H bond cleavage reactions in acenaphthylene molecule. It is found that the C-C bond cleavage proceeds via a singlet aromatic transition state, compelled through a disrotatoric ring opening reaction. A sigmatropic H atom shift follows the transition state in some of these reactions, where the formation of a methylene -CH2,acetylenyl-, allenyl- or butadienyl moiety in the final product is possible. The calculated activation and reaction energies for the C-C ring opening are 164-236 and 52-193 kcal/mol, respectively. The calculated cleavage reaction energies for the C-H bonds are 117-122 kcal/mol and the activation energies are 147-164 kcal/mol.
European Journal of Chemistry, Volume 10, pp 345-349; doi:10.5155/eurjchem.10.4.345-349.1898
Abstract:Single crystal X-ray diffraction has established the absolute configuration of the indole alkaloids from Vinca erecta such as akuammiline-o-acyl derivative of akuammine with a 3D stable polycyclic framework. Crystal data for C24H28N2O5: orthorhombic, space group P212121 (no. 19), a = 7.349(3) Å, b = 16.099(5) Å, c = 17.323(5) Å, V = 2049.5(12) Å3, Z = 4, T = 293(2) K, μ(CuKα) = 0.789 mm-1, Dcalc = 1.376 g/cm3, 1742 reflections measured (7.496° ≤ 2Θ ≤ 119.792°), 1742 unique (Rsigma = 0.0374) which were used in all calculations. The final R1 was 0.0608 (I > 2σ(I)) and wR2 was 0.1680 (all data). The polycyclic framework of the well-known picrinine and akuammine is compared. The ether bridges located in different positions of the framework and forming five-membered cycles do not change the conformation of the polycyclic akuammiline framework. In V. erecta alkaloids, the exomethylene fragment (C18-C19=C20-C21) of the polycyclic backbone always takes on the E-condition.
European Journal of Chemistry, Volume 10, pp 381-385; doi:10.5155/eurjchem.10.4.381-385.1922
Abstract:A new enaminone was synthesized by reacting 3,5-bis-(trifluoromethyl)acetophenones and N,N-dimethylformamide dimethyl acetal and its detailed structural and crystalline properties were studied. The crystal data were found to be as C13H11F6NO, monoclinic, space group P21/c (no. 14), a = 8.1556(8) Å, b = 24.877(3) Å, c = 7.6067(7) Å, β = 116.745(6)°, V = 1378.2(3) Å3, Z = 4, T = 293(2) K, μ(MoKα) = 0.150 mm-1, Dcalc = 1.500 g/cm3, 40777 reflections measured (5.594° ≤ 2Θ ≤ 56.786°), 3413 unique (Rint = 0.1040, Rsigma = 0.0584) which were used in all calculations. The final R1 was 0.0771 (I > 2σ(I)) and wR2 was 0.2541 (all data).
European Journal of Chemistry, Volume 10, pp 350-357; doi:10.5155/eurjchem.10.4.350-357.1899
Abstract:Daclatasvir (DAC), sofosbuvir (SOF) and ribavirin (RIB) have been recently co-formulated in tablet dosage form for the treatment of Hepatitis C virus infections. In this work, the resolution and quantitation of overlapped spectral signals was achieved by both univariate and multivariate algorithms. Pure component contribution algorithm (PCCA) as a novel approach was applied along with factor based partial least squares (PLS) algorithms using both full range and synergistic intervals (siPLS). Each drug could be determined at its λmax using PCCA, while PLS and siPLS were used for multivariate determination of the three components. Good linear relationships were obtained in the ranges of 5.45-16.35, 4.40-44.00 and 5.50-35.00 µg/mL for DAC, SOF and RIB, respectively, by PCCA. The PLS and siPLS models were built for the three compounds each in the concentration range of 2.00-10.00, 10.00-20.00 and 10.00-26.00 µg/mLfor DAC, SOF and RIB, respectively. Validation of the proposed methods was ascertained according to ICH guidelines for PCCA and through the use of internal and external validation sets for PLS and SiPLS models. The three methods were successfully applied for determination of DAC, SOF and RIB in pure form and in tablets.