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1.
Ali F. Al-Ghamdi Abdulilah Dawoud Bani-Yaseen 《Russian Journal of Electrochemistry》2014,50(4):355-362
In this study a reduction square wave voltammetric method was developed and validated for the direct determination of ciprofloxacin (CIP) in pharmaceutical formulation and biological fluid using hanging mercury dropping electrode (HMDE) surface. Best results were obtained for the quantitative determination of CIP in 0.02 M Britton-Robinson buffer at pH 2.5 and at a potential of ?1300 mV vs. Ag/AgCl reference electrode. Various experimental and instrumental parameters affecting the peak current and potential of CIP electrochemical reduction were investigated and optimized. The monitored peak current was directly proportional to the concentration of CIP, where it exhibited a linear response in the range 3.0 × 10?7–2 × 10?6 M (r = 0.99). The accuracy of the proposed method was concluded based on the value of mean recovery of 98 ± 0.72 % with RSD of 0.181 % at a detection limit of 7 × 10?9 M. Possible interferences by various substances usually present in pharmaceutical formulations have been also evaluated. After validating the proposed method, the applicability of this voltammetric method was demonstrated by estimating CIP in its pharmaceutical formulation and spiked human urine, where values of mean recoveries of 97 ± 1.0% and 108.0 ± 2.0% were obtained, respectively. 相似文献
2.
Spectrofluorimetric study on the interaction between antimicrobial drug sulfamethazine and bovine serum albumin 总被引:1,自引:0,他引:1
Abdulilah Dawoud Bani-Yaseen 《Journal of luminescence》2011,131(5):1042-1047
The interaction between the antimicrobial drug sulfamethazine (STM) and bovine serum albumin (BSA) has been studied using steady state and synchronous fluorescence spectroscopy. Fluorescence emission data revealed that BSA (2×10−6 M) fluorescence was statically quenched by STM at various concentrations, which implies that STM-BSA complex has been formed. The fluorescence emission data was analyzed via applying the Stern-Volmer analysis in combination with thermodynamic investigation, where obtained results revealed that quenching is static with quenching constants of 2.371, 1.658, and 0.916×105 M−1 at 298, 304, and 310 K, respectively. Binding constants and number of binding sites at different temperatures were also determined by applying the Scatchard method, which in turn were used to construct the van't Hoff plot in order to estimate the enthalpy (ΔH) and entropy changes (ΔS) for the complexation process. An average of 1.00±0.17 was estimated for the number of sites of BSA, which indicated that STM binds to BSA with stoichiometric ratio of 1:1. The values that were estimated from the van't Hoff plot for ΔH and (ΔS) were −36.8 kJ mol−1 and −14.9 J mol−1 K−1, respectively, which indicate that the STM-BSA complex is stabilized with hydrogen bonds and van der Waals interactions. Synchronous fluorescence data was obtained at Δλ of 15 and 60 nm, where obtained results confirmed that STM binds to BSA at the tryptophan residue (Trp. 213). In addition, the distance between STM and the Trp. 213 was estimated via employing the Förster's non-radiative energy-transfer theory, and was found to be 2.73 nm, which in turn indicated that STM can bind to BSA with high probability. 相似文献
3.
Abdulilah Dawoud Bani-Yaseen Nathir F. Al-Rawashdeh Idrees Al-Momani 《Journal of inclusion phenomena and macrocyclic chemistry》2009,63(1-2):109-115
In this paper, the influence of inclusion complexation with β-cyclodextrin (β-CD) on the photostability of antazoline, xylometazoline, and naphazoline in aqueous media was investigated. The photodegradation reaction of these drugs molecules was explored using UV–vis spectrophotometery-based kinetic analysis and high performance liquid chromatography (HPLC). Quantitative evaluation of the influence of β-CD was judged based on the observed rate constant (k obs), half-life time (t 0.5) and t 0.1 of the photodegradation reaction and the peak area of the corresponding analyte after photodegradation using HPLC separation. It has been demonstrated that the photostability of these selected imidazoline-based drugs has been enhanced upon forming inclusion complexes with β-CD in aqueous media. Moreover, high consistency regarding the photostability enhancement was obtained using both techniques. Hypothetical structure for 1:1 inclusion complexes was proposed based on molecular mechanics calculations, which in turn provide an insight for the energetically preferential structure of the inclusion complexes. The results obtained demonstrate that β-CD can be utilized as photostabilizer additive for enhancing the photostability of imidazoline-derived drugs molecules. 相似文献
4.
Bani-Yaseen AD Kawaguchi T Price AK Culbertson CT Jankowiak R 《Analytical and bioanalytical chemistry》2011,399(1):519-524
Catechol estrogen-derived DNA adducts are formed as a result of the reaction of catechol estrogen metabolites (e.g., catechol
estrogen quinones) with DNA to form depurinating adducts. Developing a new methodology for the detection of various DNA adducts
is essential for medical diagnostics, and to this end, we demonstrate the applicability of on-chip capillary electrophoresis
with an integrated electrochemical system for the separation and amperometric detection of various catechol estrogen-derived
DNA adducts. A hybrid PDMS/glass microchip with in-channel amperometric detection interfaced with in situ palladium decoupler
is utilized and presented. The influence of buffer additives along with the effect of the separation voltage on the resolving
power of the microchip is discussed. Calibration plots were constructed in the range 0.4–10 μM with r
2 ≥ 0.999, and detection limits in the attomole range are reported. These results suggest that on-chip analysis is applicable
for analyzing various DNA adducts as potential biomarkers for future medical diagnostics. 相似文献
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6.
In response to recent helium atom scattering (HAS) and neutron scattering results, Monte Carlo simulations and perturbation theory calculations have been performed for D2 on MgO(0 0 1). Monte Carlo simulations predict that D2 molecules form a series of interesting structures, p(2 × 2) → p(4 × 2) → p(6 × 2), with coverages Θ = 0.5, 0.75, 0.83 respectively, and followed by a formation of a top layer of p(6 × 2) unit cell symmetry. The three types of mono-layers are stable up to 13 K, whereas the top layer still exists up to 10 K. This is in partial agreement with the neutron scattering and HAS results that report c(2 × 2), c(4 × 2) and c(6 × 2); they agree in terms of coverage and stability, but disagree in terms of symmetry. A quantum mechanical examination of the D2 molecules’ rotational motion shows the molecular axes are azimuthally delocalized and hence the simulated structures are c-type rather than p-type. These calculations also indicate that ortho-D2 and helicoptering para-D2 prefer cationic sites, while cartwheeling para-D2 prefers anionic sites. 相似文献
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8.
Jassem G. Mahdi Hanna M. Dawoud David R. Kelly 《Journal of Saudi Chemical Society》2009,13(3):291-293
The preparation of allyl chlorostannan 5 was achieved into two steps via free radical displacement of the sulphone group by tributyltin radical. The chemical structure of compound 5 was confirmed by normal spectroscopic methods, including NMR, IR and MS. The mechanism for the free radical reaction of chlorosulphone 6 with tributyltinhydride is likely to proceed via the catalysis of the trace amount of the iodoallyl chloride 4. 相似文献
9.
Mahmoud Sunjuk Bassam El-Eswed Jamal N. Dawoud Amneh Shtaiwi Monther Khanfar Mohammad El-Khateeb 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):558-575
Abstract Lithium complexes were prepared with phenylphosphinic and phenylphosphonic acids. The complexes were studied in the solid state using Fourier transform infrared spectroscopy spectroscopy and in solution (methanol) using 1H, 13C, and 31P Nuclear magnetic resonance spectroscopy (NMR) spectroscopy; the most preferred structures of the complexes were determined by density functional theory (DFT) computational method. Although methanol has a strong solvation effect on lithium ions and ligands, which causes dissociation of the complexes, significant changes of the NMR spectra of the complexes (relative to those of the free ligands) were observed. The new spectroscopic results indicate the presence of the phenylphosphinic acid tautomer (I: C6H5PH(?O)OH) rather than that of phenyl-phosphorous acid (II: C6H5P(OH)2) in deuterated methanol showing PH/PD exchange. On the other hand, tautomer I predominates in the complex with lithium without showing PH/PD exchange. The DFT calculations predict that tautomer I is the preferred structure in the case of free ligand and lithium complex. The absence of a PH/PD exchange in the complex is due to the formation of a chelating complex, rather than of a simple salt between lithium ion and the two oxygen atoms of I, which prevent tautomerization of I into II. DFT calculations support the formation of lithium chelating complexes. The lithium ion was found to affect the spectroscopic properties of phenylphosphinic acid more dramatically than those of phenylphosphonic acid. 相似文献
10.
This study focuses on the application of the carbon arc‐generated molybdenum‐ and tungsten‐based catalyst systems, MoCl5? C and WCl6? C, to effect ring‐opening metathesis polymerization (ROMP) of bicyclo[2.2.1]hept‐2‐ene (norbornene). The results are compared with those previously obtained by the electrochemically generated MoCl5? ē? Al? CH2Cl2 and WCl6? ē? Al? CH2Cl2 systems. The polymer products are characterized using 1H and 13C NMR, gel permeation chromatography, differential scanning calorimetry and thermo gravimetric analysis. According to NMR spectra analyses, the molybdenum‐based catalyst system produced polynorbornene with ca 48% cis structure whereas tungsten system produced ca 56% cis structure polynorbornene and in both cases the polynorbornene had a blocky distribution. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献