International Journal of Spectroscopy The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. EPR Spectroscopy of Different Sol Concentration Synthesized Nanocrystalline-ZnO Thin Films Sun, 22 Nov 2015 12:33:00 +0000 Nanocrystalline zinc oxide (nc-ZnO) thin films were grown on p-type silicon substrate through spin coating by sol-gel process using different sol concentrations (10 wt.%, 15 wt.%, and 25 wt.%). These films were characterized by high resolution nondestructive X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDS) attachment, and electron paramagnetic resonance (EPR) techniques to understand variations in structural, morphological, and oxygen vacancy with respect to sol concentration. The film surface morphology changes from nanowall to nanorods on increasing sol concentration. EPR spectra revealed the systematic variation from ferromagnetic to paramagnetic nature in these nc-ZnO films. The broad EPR resonance signal arising from the strong dipolar-dipolar interactions among impurity defects present in nc-ZnO film deposited from 10 wt.% sol has been observed and a single strong narrow resonance signal pertaining to oxygen vacancies is obtained in 25 wt.% sol derived nc-ZnO film. The concentrations of impurity defects and oxygen vacancies are evaluated from EPR spectra, necessary for efficient optoelectronic devices development. Manju Arora, Rayees A. Zargar, and S. D. Khan Copyright © 2015 Manju Arora et al. All rights reserved. Raman Spectroscopy and Statistical Analysis of the Silicate Species and Group Connectivity in Cesium Silicate Glass Forming System Sun, 18 Oct 2015 06:28:44 +0000 The Raman spectra of %Cs2O-(100 − x)%SiO2 (, 22, 27, 33, and 37 mol%) glasses and melts were measured in the temperature range of 293 to 1553 K. The concentrations of the species were calculated as a function of the composition and temperature based on the deconvolution analysis of the spectra. It was found that a dynamic equilibrium among structural units in the melts with  mol% can be described by disproportionation reaction . The enthalpy of this reaction was found to be equal to 32 ± 6, 43 ± 8, 56 ± 10, and 52 ± 9 for , 27, 33, and 37 mol%, respectively. The nonideal entropy of mixing (Δ) depends on the melt temperature and increases almost linearly with increasing temperature. The , , and distributions with ranging from 0 to 55 mol% were modeled using experimental data for the concentrations of the units. Armenak Osipov, Leyla Osipova, and Rimma Zainullina Copyright © 2015 Armenak Osipov et al. All rights reserved. Secondary Metabolites of the Cuticular Abdominal Glands of Variegated Grasshopper (Zonocerus variegatus L.) Mon, 07 Sep 2015 13:48:17 +0000 Chemical compounds were extracted with petroleum ether from the cuticular abdominal glands of grasshopper (Zonocerus variegatus L.) and eleven compounds were characterised using Gas Chromatography/Mass Spectrometry (GC/MS) technique in combination with Fourier Transform-Infrared Spectroscopy (FT-IR). The compounds analysed were 2,7-dimethyloctane (3.21%), decane (5.33%), undecane (3.81%), tridecanoic acid methyl ester (4.76%), hexadecanoic acid (9.37%), 11-octadecenoic acid methyl ester (23.18%), pentadecanoic acid, 14-methyl-methyl ester (4.43%), (Z)-13-docosenoic acid (10.71%), dodecyl pentafluoropropionate (9.52%), 2-dodecyl-1,3-propanediol (6.38%), and 1,12-tridecadiene (19.30%). FT-IR analysis of the extract showed peaks at 1270.17 (C–O and C–F), 1641.48 (C=C), 2937.68 (C–H), and 3430.51 (O–H) cm−1 indicating the presence of ether, alkene, alkane, alcohol, carboxylic acid, and fluoric compounds. These compounds consisted of 32.37% ester, 31.65% hydrocarbons, 20.08% fatty acid, 9.52% halogenated ester, and 6.38% alcohol. The highest component was 11-octadecenoic acid methyl ester followed by 1,12-tridecadiene. Since behavioural bioassays were not carried out, the consideration of these compounds to be pheromone semiochemicals remains a hypothesis. O. U. Igwe and D. E. Udofia Copyright © 2015 O. U. Igwe and D. E. Udofia. All rights reserved. Application of ATR-FTIR Spectroscopy to Compare the Cell Materials of Wood Decay Fungi with Wood Mould Fungi Wed, 19 Aug 2015 12:30:18 +0000 Wood fungi create vast damage among standing trees and all types of wood materials. The objectives of this study are to (a) characterize the cell materials of two major wood decay fungi (Basidiomycota), namely, Trametes versicolor and Postia placenta, and (b) compare the cell materials of decay fungi with four wood mould fungi (Ascomycota), namely, Aureobasidium pullulans, Alternaria alternata, Cladosporium cladosporioides, and Ulocladium atrum. Fourier transform infrared (FTIR) spectroscopy is used to characterize the microbial cellular materials. The results showed that the IR bands for the fatty acid at ∼2900 cm−1 were different for the two-decay-fungi genre. Postia placenta shows more absorbance peaks at the fatty acid region. Band ratio indices for amide I and amide II from protein amino acids were higher for the mould fungi (Ascomycota) than the decay fungi (Basidiomycota). Similarly, the band ratio index calculated for the protein end methyl group was found to be higher for the mould fungi than the decay fungi. Mould fungi along with the decay fungi demonstrated a positive correlation () between amide I and amide II indices. The three-component multivariate, principal component analysis showed a strong correlation of amide and protein band indices. Barun Shankar Gupta, Bjørn Petter Jelle, and Tao Gao Copyright © 2015 Barun Shankar Gupta et al. All rights reserved. On the Molecular Modeling Analyses of Novel HIV-1 Protease Inhibitors Based on Modified Chitosan Dimer Thu, 19 Mar 2015 11:47:32 +0000 The molecular modeling studies include quantitative structure activity relationship, IR spectra, and docking calculations, occurring for novel inhibitors based on chitosan dimer which were tried as HIV protease. The inhibitors were investigated with molecular modeling calculations at different level of theories. Each compound has phenol with hydroxymethylcarbonyl (HMC) group which added to chitosan in positions 2, 3, 2′, or 3′. The geometry of studied compounds is optimized with semiempirical PM3 method. Quantitative structure activity relationship (QSAR) properties of the suggested compounds are calculated at the same level of theory. Depending on QSAR calculations, the compounds with positions 2 and 2′ are less hydrophilic. The position 2′ compound makes good docking interaction into HIV protease active site. Calculated IR spectra indicate that the interaction through hydrogen bonding through the hydrogen of OH at positions 3 and 3′ gives rise to two OH bands one for chitosan and the other for phenol and HMC group. While at position 3′ CH band starts to appear. Zarrag Al-Fifi, Noha A. Saleh, Hanan Elhaes, and Medhat Ibrahim Copyright © 2015 Zarrag Al-Fifi et al. All rights reserved. Design of Novel Metal Nanostructures for Broadband Solar Energy Conversion Tue, 03 Feb 2015 12:29:21 +0000 Solar power holds great potential as an alternative energy source, but current photovoltaic cells have much room for improvement in cost and efficiency. Our objective was to develop metal nanostructures whose surface plasmon resonance (SPR) spectra closely match the solar spectrum to enhance light absorption and scattering. We employed the finite-difference time-domain simulation method to evaluate the effect of varying key parameters. A novel nanostructure with SPR absorption matching a region of the solar spectrum (300 to 1500 nm) that contains 90% of solar energy was successfully designed. This structure consists of a large gold-silica core-shell structure with smaller gold nanoparticles and nanorods on its surface. Such complex nanostructures are promising for broad and tunable absorption spectra. In addition, we investigated the SPR of silver nanoparticle arrays, which can achieve scattering close to the solar spectrum. We demonstrated an improvement in efficiency of over 30% with optimal nanoparticle radius and periods of 75 nm and 325 nm, respectively. In combination, our studies enable high-efficiency, tunable, and cost-effective enhancement of both light absorption and scattering, which has potential applications in solar energy conversion as well as biomedical imaging. Kristine A. Zhang, David Ma, Ying-Chih Pu, and Yat Li Copyright © 2015 Kristine A. Zhang et al. All rights reserved. Effect of Moderate UVC Irradiation on Bovine Serum Albumin and Complex with Antimetabolite 5-Fluorouracil: Fluorescence Spectroscopic and Molecular Modelling Studies Sat, 31 Jan 2015 13:24:31 +0000 The interaction of antimetabolite 5-fluorouracil (5FU) with bovine serum albumin (BSA) under UVC (253.7 nm) irradiation was investigated in the present study using UV-Vis spectroscopy, steady state/time resolved fluorescence spectroscopic techniques. The stability of protein was found to be very strong when BSA gets bind to 5FU and moreover it is compared with the free BSA under UVC irradiation. From the fluorescence spectroscopic study, the stability of the complex was found to acquire 2-fold stronger than free protein. From the molecular modelling studies, we came to know the hydrogen bonds between BSA and antimetabolite 5FU are strong, up to 70.4 J/m2 under UVC irradiation. Shanmugavel Chinnathambi, Subramani Karthikeyan, Devadasan Velmurugan, Nobutaka Hanagata, Prakasarao Aruna, and Singaravelu Ganesan Copyright © 2015 Shanmugavel Chinnathambi et al. All rights reserved. Spectral Properties of Dyes with Interfragmental Charge Transfer: Solvatochromism and Solvatofluorochromism of 2-(3-Coumaroyl)-benzopyrylium Perchlorates Tue, 23 Dec 2014 00:10:03 +0000 The paper deals with the spectral properties of dyes with interfragmental charge transfer, in particular, derivatives of 2-(3-coumaroyl)benzopyrylium (CBP) perchlorates. The positions of long-wavelength absorption and emission bands, quantum yields, and lifetimes of fluorescence were measured, mostly in aprotic solvents. Regression analysis of the relationship between the spectral characteristics of CBP and the main solvent parameters (polarity, polarisability, nucleophilicity, and electrophilicity) was carried out. It was found that the characteristics of CBP depend mainly on two solvent parameters—polarity and/or nucleophilicity. An increase in these parameters results in a hypsochromic shift of absorption bands and a decrease of lifetimes and fluorescence intensity. The positions of the emission bands can demonstrate either hypsochromism or bathochromism, depending on the nature of the substituents. The solvatofluorochromic effects are not as strong as the solvatochromic ones. We believe that the spectral behaviour of CBP can be explained by cation depolarisation and by a decrease in the stability of nucleophilic complexes with solvent molecules that is associated with interfragmental charge transfer following excitation, relaxation, and radiative deactivation of the excited state. Edward V. Sanin, Alexander I. Novikov, and Alexander D. Roshal Copyright © 2014 Edward V. Sanin et al. All rights reserved. Graphical Conversion between Compliance and Modulus, Permittivity and Electric Modulus, and Impedance and Admittance Tue, 25 Nov 2014 14:46:26 +0000 Spectrometries probing relaxation and retardation phenomena, such as dielectric, mechanical, and impedance spectroscopies, often require the analyses with both susceptibilities spectra and its reciprocals (e.g., complex permittivity and electric modulus, mechanical compliance and mechanical modulus, and impedance and admittance). In the present paper, the geometric relation between and is derived and the procedure to convert into on a Cole-Cole diagram is proposed. This method helps us to relate them intuitively and yields clearer understanding on their interrelations. Moreover, it opens the new route for the geometric approach to derive many mathematical properties of spectra. The relation between peak position of spectrum and that of spectrum and the shape of spectra are discussed on the basis of this method. Masahiro Nakanishi Copyright © 2014 Masahiro Nakanishi. All rights reserved. Optical Path Length Calibration: A Standard Approach for Use in Absorption Cell-Based IR-Spectrometric Gas Analysis Thu, 17 Jul 2014 08:24:52 +0000 We employed a comparison method to determine the optical path length of gas cells which can be used in spectroscopic setup based on laser absorption spectroscopy or FTIR. The method is based on absorption spectroscopy itself. A reference gas cell, whose length is a priori known and desirably traceable to the international system of units (SI), and a gas mixture are used to calibrate the path length of a cell under test. By comparing spectra derived from pressure-dependent measurements on the two cells, the path length of the gas cell under test is determined. The method relies neither on the knowledge of the gas concentration nor on the line strength parameter of the probed transition which is very rarely traceable to the SI and of which the uncertainty is often relatively large. The method is flexible such that any infrared light source and infrared active molecule with isolated lines can be used. We elaborate on the method, substantiate the method by reporting results of this calibration procedure applied to multipass and single pass gas cells of lengths from 0.38 m to 21 m, and compare this to other methods. The relative combined uncertainty of the path length results determined using the comparison method was found to be in the ±0.4% range. Javis Anyangwe Nwaboh, Oliver Witzel, Andrea Pogány, Olav Werhahn, and Volker Ebert Copyright © 2014 Javis Anyangwe Nwaboh et al. All rights reserved. Uniform versus Nonuniform Scaling of Normal Modes Predicted by Ab Initio Calculations: A Test on 2-(2,6-Dichlorophenyl)-N-(1,3-thiazol-2yl) Acetamide Thu, 10 Jul 2014 11:44:12 +0000 A test on calculated vibrational modes of 2-(2,6-dichlorophenyl)-N-(1,3-thiazol-2yl) acetamide using ab initio density functional method has been performed. The calculated harmonic vibrational frequencies are scaled via two schemes, uniform, , and nonuniform, . Scaled vibrational modes are compared with experimental FTIR bands. A good correlation is shown between scaled frequencies with the correlation coefficient, . This clearly shows that both schemes efficiently reproduce observed spectrum. However, a close investigation of individual normal modes reveals that nonuniform scaling performs much better than uniform scaling especially in the high frequency region. Ambrish K. Srivastava, Anoop K. Pandey, Saurabh Pandey, Prakash S. Nayak, B. Narayana, B. K. Sarojini, and Neeraj Misra Copyright © 2014 Ambrish K. Srivastava et al. All rights reserved. Quantum Chemical and Spectroscopic Investigations of (Ethyl 4 hydroxy-3-((E)-(pyren-1-ylimino)methyl)benzoate) by DFT Method Wed, 09 Jul 2014 09:02:39 +0000 In the present work we have reported the optimized ground state geometry, harmonic vibrational frequencies, NMR chemical shifts, NBO analysis, and molecular electrostatic potential surface map of the title compound using DFT/B3LYP/6-311++G(2d, 2p) level of theory. We have compared our calculated results with the experimentally obtained values and found that both are in close agreement with each other. We have used the gauge-invariant atomic orbital (GIAO) approach to calculate the NMR (13C and 1H) chemical shifts using Gaussian 09 package. TD-DFT (time-dependent DFT) approach has been used to simulate the electronic spectra of the title compound in order to account for excited states. Other molecular properties such as HOMO-LUMO energies, NBO analysis, and PED distribution analysis have been studied and reported using DFT/B3LYP/6-311++G(2d, 2p) level of theory. Diwaker and Abhishek Kumar Gupta Copyright © 2014 Diwaker and Abhishek Kumar Gupta. All rights reserved. New Kinetic Spectrophotometric Method for Determination of Fexofenadine Hydrochloride in Pharmaceutical Formulations Sun, 29 Jun 2014 08:58:54 +0000 A simple and sensitive kinetic spectrophotometric method was developed for the determination of fexofenadine hydrochloride in bulk and pharmaceutical preparations. The method is based on a kinetic investigation of the oxidation reaction of fexofenadine using alkaline potassium permanganate as an oxidizing agent at room temperature. The reaction is followed spectrophotometrically by measuring the increase of absorbance owing to the formation of manganate ion at 610 nm. The initial rate and fixed time (at 15 min) methods are utilized for construction of calibration graphs. All the reaction conditions for the proposed method have been studied. The linearity range was found to be 2.5–50.0 μg mL−1 with detection limit of 0.055 μg mL−1 for both initial rate and fixed time methods. The proposed method was applied successfully for the determination of fexofenadine in pharmaceutical formulations; the percentage recoveries were 99.98–101.96%. The results obtained were compared statistically with those obtained by the official method and showed no significant differences regarding accuracy and precision. Safwan Ashour and Mouhammed Khateeb Copyright © 2014 Safwan Ashour and Mouhammed Khateeb. All rights reserved. Understanding and Control of High Temperature Oxidation Flaws of Low-Density Poly(ethylene) with Raman Spectroscopy Thu, 05 Jun 2014 08:51:53 +0000 Studies of high temperature oxidation of polyethylene are not much present in the literature though it can really be a problem especially in polymer production and processing. This study aims to detect oxidation flaws in polyethylene and to determine their impact on polymer structure and properties. Besides, we suggest a method via PLS-regression to determine the degree of flaws that can occur during polymer processing due to oxidation. Several kinds of oxidation flaws were reproduced in laboratory at 150°C in an oven operating in air and Raman spectroscopy analysis was performed on each sample. Using statistical tools as chemometrics on these spectra, we have built a Partial Least Square (PLS) model able to predict the oxidation degree of flaws. Interpretation of the model construction and further characterization tests show that oxidation can be followed with the evolution of the crystalline carbon group and of the created carbonyl functions. Finally we suggest possible mechanisms which can explain the high temperature oxidation process in LPDE, and we link them to the modification of the material properties. Marie Veitmann, Richard Jumeau, Patrice Bourson, Michel Ferriol, and François Lahure Copyright © 2014 Marie Veitmann et al. All rights reserved. Binding of the Bi (III) Complex of Naringin with β-Cyclodextrin/Calf Thymus DNA: Absorption and Fluorescence Characteristics Thu, 05 Jun 2014 07:38:26 +0000 Naringin-Bi (III) complex (Narb) was prepared and analysed by UV-Visible absorption and fluorescence measurements. The inclusion complex of Narb with β-Cyclodextrin (β-CD) was characterized by the UV-Visible absorption, Infrared, scanning dlectron microscopic, and X-ray diffractometric techniques. The stoichiometry of the inclusion complex of Narb with β-CD was 1 : 1 with a binding constant of 5.18 × 102 mol−1 dm3. The interaction of Narb with Calf Thymus DNA (ctDNA) was investigated in the presence and the absence of β-CD. The binding constants for the interaction of Narb with ctDNA in the absence and the presence of β-CD were 1.29 × 105 mol−1 dm3 and 6.89 × 104 mol−1 dm3, respectively. The Stern-Volmer constants for the interaction of Narb with ctDNA in the absence and the presence of β-CD were 1.25 × 104 mol−1 dm3 and 5.10 × 103 mol−1 dm3, respectively. The lowering of the binding affinity and the were observed for the interaction of Narb with ctDNA in the presence of β-CD. Sameena Yousuf and Israel V. Muthu Vijayan Enoch Copyright © 2014 Sameena Yousuf and Israel V. Muthu Vijayan Enoch. All rights reserved. Estimation of Tadalafil Using Derivative Spectrophotometry in Bulk Material and in Pharmaceutical Formulation Wed, 21 May 2014 12:48:14 +0000 Four simple, rapid, accurate, precise, reliable, and economical UV-spectrophotometric methods have been proposed for the determination of tadalafil in bulk and in pharmaceutical formulation. “Method A” is first order derivative UV spectrophotometry using amplitude, “method B” is first order derivative UV spectrophotometry using area under curve technique, “method C” is second order derivative UV spectrophotometry using amplitude, and “method D” is second order derivative UV spectrophotometry using area under curve technique. The developed methods have shown best results in terms of linearity, accuracy, precision, and LOD and LOQ for bulk drug and marketed formulation as well. In N,N-dimethylformamide, tadalafil showed maximum absorbance at 284 nm. For “method A” amplitude was recorded at 297 nm while for “method B” area under curve was integrated in the wavelength range of 290.60–304.40 nm. For “method C” amplitude was measured at 284 nm while for “method D” area under curve was selected in the wavelength range of 280.80–286.20 nm. For methods A and B, tadalafil obeyed Lambert-Beer’s law in the range of 05–50 μg/mL while for “methods C and D”, tadalafil obeyed Lambert-Beer’s law in the range of 20–70 μg/mL, and-for “methods A, B, C, and D” the correlation coefficients were found to be  than 0.999. Zamir G. Khan, Amod S. Patil, and Atul A. Shirkhedkar Copyright © 2014 Zamir G. Khan et al. All rights reserved. FTIR Spectroscopy Combined with Partial Least Square for Analysis of Red Fruit Oil in Ternary Mixture System Wed, 21 May 2014 09:43:55 +0000 FTIR spectroscopy is a promising method for quantification of edible oils. Three edible oils, namely, red fruit oil (RFO), corn oil (CO), and soybean oil (SO), in ternary mixture system were quantitatively analyzed using FTIR spectroscopy in combination with partial least square (PLS). FTIR spectra of edible oils in ternary mixture were subjected to several treatments including normal spectra and their derivative. Using PLS calibration, the first derivative FTIR spectra can be exploited for determination of RFO; meanwhile, the second derivative spectra were preferred for determination of CO and SO. The values obtained for the relationship between actual and FTIR predicted values of RFO, CO, and SO were 0.9863, 0.9276, and 0.9693, respectively. The root mean square error of calibration (RMSEC) values obtained were 1.59, 1.72, and 1.60% (v/v) for RFO, CO, and SO, respectively. The result showed that FTIR spectroscopy offers accurate and reliable technique for quantitative analysis of RFO, CO, and SO simultaneously in ternary mixture systems. Besides, the developed method can be extended for analysis of CO and SO as adulterants in RFO. A. Rohman, Dwi Larasati Setyaningrum, and Sugeng Riyanto Copyright © 2014 A. Rohman et al. All rights reserved. Simple Atomic Absorption Spectroscopic and Spectrophotometric Methods for Determination of Pioglitazone Hydrochloride and Carvedilol in Pharmaceutical Dosage Forms Sun, 18 May 2014 07:39:19 +0000 This study represents simple atomic absorption spectroscopic and spectrophotometric methods for determination of pioglitazone hydrochloride (PGZ-HCl) and carvedilol (CRV) based on formation of ion-pair associates between drugs and inorganic complex, bismuth(III) tetraiodide (Method A) and between drugs and organic acidic dyes, fast green and orange G (Method B). Method A is based on formation of ion-pair associate between drugs and bismuth(III) tetraiodide in acidic medium to form orange-red ion-pair associates, which can be quantitatively determined by two different procedures. The formed ion-pair associate is extracted by methylene chloride, dissolved in acetone, dried, and then decomposed by hydrochloric acid, and bismuth content is determined by direct atomic absorption spectrometric technique (Procedure 1) or extracted by methylene chloride, dissolved in acetone, and quantified spectrophotometrically at 490 nm (Procedure 2). Method B is based on formation of ion-pair associate between drugs and either fast green dye or orange G dye in acidic medium to form ion-pair associates. The formed ion-pair associate is extracted by methylene chloride and quantified spectrophotometrically at 630 nm (for fast green dye method) or 498 nm (for orange G dye method). Optimal experimental conditions have been studied. Both methods are applied for determination of the drugs in tablets without interference. Afaf A. Abdelmonem, Gamal H. Ragab, Hisham Hashem, and Eman A. Bahgat Copyright © 2014 Afaf A. Abdelmonem et al. All rights reserved. Two-Pulse Phase Modulation Based Decoupling Schemes for Removing Heteronuclear Spin Interactions in the NMR Spectroscopy of Isotropic Systems: An Analysis Using Experiments and Numerical Simulations Thu, 15 May 2014 00:00:00 +0000 Heteronuclear spin interactions in solids and anisotropic liquids can be removed by phase modulated decoupling sequences with frequency sweep, such as -TPPM and its variants. The performance of these sequences in isotropic spin systems with regard to the experimental parameters, phase angle, and decoupler offset is presented here. A comparison is made with other commonly used heteronuclear decoupling schemes in liquids, namely, WALTZ-16, GARP, and MLEV. Also, the trajectories of nuclear magnetization vector of abundant nuclei in a simple spin system during TPPM and -TPPM decoupling sequences are traced out using computer simulations. Cyril Augustine Copyright © 2014 Cyril Augustine. All rights reserved. New Simple Spectrophotometric Method for the Simultaneous Estimation of Paracetamol and Flupirtine Maleate in Pure and Pharmaceutical Dosage Form Mon, 12 May 2014 13:01:22 +0000 A new, simple, precise, accurate, reproducible, and efficient Vierordt’s method or simultaneous equation method was developed and validated for simultaneous estimation of paracetamol and flupirtine maleate in pure and pharmaceutical dosage form. The method was based on the measurement of absorbance at two wavelengths 245 nm and 344.5 nm, of paracetamol and flupiritine maleate in 0.1 N HCl correspondingly. Calibration curves of paracetamol and flupiritine maleate were found to be linear in the concentration ranges of 5–15 μg/mL and 1.53–4.61 μg/mL, respectively, with their correlation coefficient values (R2) 0.999. LOD and LOQ were 185.90 ng/mL and 563.38 ng/mL for paracetamol and 78.89 ng/mL and 239.06 ng/mL for flupiritine maleate. In the precision study, the % RSD value was found within limits (%). The percentage recovery at various concentration levels varied from 99.18 to 100.02% for paracetamol and 98.47 to 100.09% for flupiritine maleate confirming that the projected method is accurate. It could be concluded from the results obtained in the present investigation that this method for simultaneous estimation of paracetamol and flupirtine maleate in pure and tablet dosage form is simple, accurate, precise, and economical. The proposed method can be applied successfully for the simultaneous estimation of paracetamol and flupiritine maleate in pure and pharmaceutical dosage form. P. Giriraj and T. Sivakkumar Copyright © 2014 P. Giriraj and T. Sivakkumar. All rights reserved. Spectroscopic Characterization of Stability and Interaction of Pd-Ag Complexes Thu, 08 May 2014 00:00:00 +0000 Colloidal metal nanoparticles are of great interest because of their use as catalysts, photocatalysts, adsorbents, and sensors as well as their application in optical, electronic, and magnetic devices. Supported bimetallic systems represent a large part of heterogeneous catalysts which have been used in various reactions important in the chemical, petrochemical, and oil industry. Pd-Ag bimetallic nanocatalysts have become vitally important in some of the petrochemical industry’s processes like hydrogenation of C2–C5 olefins. A heat-treatment method for the preparation of well-stable Pd-Ag complexes is demonstrated using water, concentrated HCl and concentrated nitric acid as media. The stability and interaction of Pd-Ag complexes were characterized by UV-vis absorption spectroscopy. Pd-Ag bimetallic nanoparticles of spherical cubic and octahedral shape in the range of average particle size of 20–60 nm have been prepared and characterized by transmission electron microscopy (TEM). Sharad V. Lande, Nagesh Sharma, Ajay Kumar, and Raksh Vir Jasra Copyright © 2014 Sharad V. Lande et al. All rights reserved. The Application of Simple and Easy to Implement Decoupling Pulse Scheme Combinations to Effect Decoupling of Large Values with Reduced Artifacts Tue, 29 Apr 2014 12:48:16 +0000 Of the various problems in decoupling one nucleus type from another using standard decoupling pulse schemes for broadband decoupling, a particular challenge is to effect full, artifact-free decoupling when the size of the coupling constant is very large. Herein it is demonstrated that 1H decoupling of the 31P NMR spectrum of diethyl phosphonate HP(=O)(OCH2CH3)2 can be accomplished with reduced artifacts despite the large value of 693 Hz by using a combination of decoupling pulse schemes involving continuous-wave (CW) irradiation and either adiabatic-pulse decoupling (APD), MPF decoupling, or traditional composite-pulse decoupling (CPD) schemes such as WALTZ or GARP. The considered strategy is simple, efficient, and easy to implement on most instruments. The best result was attained for a combination of CW and CPD using GARP with a standard pulse width of 60 μs. Altogether, the advantages of the methodology include low power requirements, complete decoupling, tolerance of a range of large values, large bandwidth for normal-sized values, and the suppression of sidebands. Karel D. Klika Copyright © 2014 Karel D. Klika. All rights reserved. Development and Validation of a Discriminating In Vitro Dissolution Method for Oral Formulations Containing Satranidazole Thu, 24 Apr 2014 00:00:00 +0000 The development of a meaningful dissolution procedure for drug products with limited water solubility has been a challenge to the pharmaceutical industry. Satranidazole (BCS Class II drug) is a new nitroimidazole derivative with potent antiamoebic action. There is no official dissolution medium available in the literature. In the present study, parameters such as saturation solubility in different pH medium, dissolution behavior of formulations, influence of sink conditions, stability, and discriminatory effect of dissolution testing were studied for the selection of a proper dissolution medium. Results of solubility data revealed that solubility of Satranidazole decreases with an increase in pH. Satranidazole showed better sink condition in 0.1 N HCl as compared to other media. The drug and marketed formulations were stable in the dissolution media used. An agitation speed of 75 rpm showed a more discriminating drug release profile than 50 rpm. Using optimized dissolution parameters (paddle at 75 rpm, 900 mL 0.1 N HCl) greater than 80% of the label amount is released over 60 minutes. UV-spectroscopic method used was validated for the specificity, linearity, precision, robustness, and solution stability. The method was successfully applied to granular formulations and also to marketed tablets containing 300 mg Satranidazole. Harshal Ashok Pawar and Pooja Rasiklal Joshi Copyright © 2014 Harshal Ashok Pawar and Pooja Rasiklal Joshi. All rights reserved. Structural Characterization of Amadori Rearrangement Product of Glucosylated Nα-Acetyl-Lysine by Nuclear Magnetic Resonance Spectroscopy Thu, 17 Apr 2014 10:12:23 +0000 Maillard reaction is a nonenzymatic reaction between reducing sugars and free amino acid moieties, which is known as one of the most important modifications in food science. It is essential to characterize the structure of Amadori rearrangement products (ARPs) formed in the early stage of Maillard reaction. In the present study, the Nα-acetyl-lysine-glucose model had been successfully set up to produce ARP, Nα-acetyl-lysine-glucose. After HPLC purification, ARP had been identified by ESI-MS with intense [M+H]+ ion at 351 m/z and the purity of ARP was confirmed to be over 90% by the relative intensity of [M+H]+ ion. Further structural characterization of the ARP was accomplished by using nuclear magnetic resonance (NMR) spectroscopy, including 1D 1H NMR and 13C NMR, the distortionless enhancement by polarization transfer (DEPT-135) and 2D 1H-1H and 13C-1H correlation spectroscopy (COSY) and 2D nuclear overhauser enhancement spectroscopy (NOESY). The complexity of 1D 1H NMR and 13C NMR was observed due to the presence of isomers in glucose moiety of ARP. However, DEPT-135 and 2D NMR techniques provided more structural information to assign the 1H and 13C resonances of ARP. 2D NOESY had successfully confirmed the glycosylated site between 10-N in Nα-acetyl-lysine and 7′-C in glucose. Chuanjiang Li, Hui Wang, Manuel Juárez, and Eric Dongliang Ruan Copyright © 2014 Chuanjiang Li et al. All rights reserved. The Low Energy Auger Electron Spectroscopy Lines as an Index of the Ba Overlayer Order on the Ni(110) Surface Wed, 26 Mar 2014 00:00:00 +0000 We investigate the interaction of Ba with the Ni(110) surface at elevated temperatures by means of Auger electron spectroscopy and low energy electron diffraction. The results show that annealing of the substrate causes desorption and ordering of the initially amorphous overlayer, resulting in c and structures. It is observed that the induced ordering crucially affects the lineshape of the double Auger transition line Ba(73 eV)N45O23P1, establishing this line as an index of ordering of the Ba overlayer. The underlying physics of this effect is discussed. D. Vlachos, M. Kamaratos, and S. D. Foulias Copyright © 2014 D. Vlachos et al. All rights reserved. Orientation of 2,6-Dicarbethoxy-3,5-bis(pyridine-3-yl)tetrahydro-1,4-thiazine-1,1-dioxide on Silver Nanoparticles: Surface-Enhanced Raman Spectral Studies Thu, 06 Feb 2014 15:43:22 +0000 Silver nanoparticles were synthesized using solution combustion method with citric acid as fuel. The prepared silver nanoparticles exhibit fcc crystalline structure with particle size of ~50 nm. The morphology and purity of the silver nanoparticles were also studied by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray analysis (EDX). Surface-enhanced Raman scattering (SERS) spectra of 2,6-dicarbethoxy-3,5-bis(pyridine-3-yl)tetrahydro-1,4-thiazine-1,1-dioxide (DBTD) adsorbed on silver nanoparticles were investigated. Orientation of DBTD on silver nanoparticles has been inferred from normal Raman spectrum (nRs) and SERS spectral feature. The observed spectral feature evidenced that DBTD would adsorb on silver surface with tilted orientation through the lone pair electrons of C–N, C=O, S=O, and pyridine ring. The present investigation has been a model system to deduce the interaction of drugs with DNA. M. Anuratha, A. Jawahar, M. Umadevi, N. Edayadulla, V. G. Sathe, V. Meenakumari, and A. Milton Franklin Benial Copyright © 2014 M. Anuratha et al. All rights reserved. A Validated Method for the Quantitation of Ciprofloxacin Hydrochloride Using Diffuse Reflectance Infrared Fourier Transform Spectroscopy Wed, 05 Feb 2014 07:03:26 +0000 A quantitative method using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was developed and validated for the estimation of ciprofloxacin in its tablet dosage forms. The solid-state samples were prepared by dilution in dry potassium bromide and were analyzed by FTIR spectrophotometer with DRIFT sampling technique. A linear relationship for the carbonyl peak area centered around 1709 cm−1 was observed in the range of 0.3–1.5% w/w with good correlation coefficient of 0.998. The percent recovery of ciprofloxacin in three marketed tablet dosage forms was in the range of 98.76 ± 0.27. The present reported method is precise, reproducible, and eco-friendly. DRIFTS may have a potential as an alternative method for qualitative and quantitative analysis of ciprofloxacin in bulk drugs and tablet dosage forms. Bhoomendra Bhongade, Sirajunisa Talath, and Sunil Dhaneshwar Copyright © 2014 Bhoomendra Bhongade et al. All rights reserved. Development and Validation of Spectrophotometric Methods for Simultaneous Estimation of Valsartan and Hydrochlorothiazide in Tablet Dosage Form Thu, 09 Jan 2014 09:03:40 +0000 Two UV-spectrophotometric methods have been developed and validated for simultaneous estimation of valsartan and hydrochlorothiazide in a tablet dosage form. The first method employed solving of simultaneous equations based on the measurement of absorbance at two wavelengths, 249.4 nm and 272.6 nm, for valsartan and hydrochlorothiazide, respectively. The second method was absorbance ratio method, which involves formation of Q-absorbance equation at 258.4 nm (isoabsorptive point) and also at 272.6 nm ( of hydrochlorothiazide). The methods were found to be linear between the range of 5–30 µg/mL for valsartan and 4–24 μg/mL for hydrochlorothiazide using 0.1 N NaOH as solvent. The mean percentage recovery was found to be 100.20% and 100.19% for the simultaneous equation method and 98.56% and 97.96% for the absorbance ratio method, for valsartan and hydrochlorothiazide, respectively, at three different levels of standard additions. The precision (intraday, interday) of methods was found within limits (). It could be concluded from the results obtained in the present investigation that the two methods for simultaneous estimation of valsartan and hydrochlorothiazide in tablet dosage form are simple, rapid, accurate, precise and economical and can be used, successfully, in the quality control of pharmaceutical formulations and other routine laboratory analysis. Monika L. Jadhav, Manoj V. Girase, Shripad K. Tidme, and Manish S. Junagade Copyright © 2014 Monika L. Jadhav et al. All rights reserved. Sequential Spectrophotometric Method for the Simultaneous Determination of Amlodipine, Valsartan, and Hydrochlorothiazide in Coformulated Tablets Sun, 15 Dec 2013 14:24:14 +0000 A new, simple and specific spectrophotometric method was developed and validated in accordance with ICH guidelines for the simultaneous estimation of Amlodipine (AML), Valsartan (VAL), and Hydrochlorothiazide (HCT) in their ternary mixture. In this method three techniques were used, namely, direct spectrophotometry, ratio subtraction, and isoabsorptive point. Amlodipine (AML) was first determined by direct spectrophotometry and then ratio subtraction was applied to remove the AML spectrum from the mixture spectrum. Hydrochlorothiazide (HCT) could then be determined directly without interference from Valsartan (VAL) which could be determined using the isoabsorptive point theory. The calibration curve is linear over the concentration ranges of 4–32, 4–44 and 6–20 μg/mL for AML, VAL, and HCT, respectively. This method was tested by analyzing synthetic mixtures of the above drugs and was successfully applied to commercial pharmaceutical preparation of the drugs, where the standard deviation is <2 in the assay of raw materials and tablets. The method was validated according to the ICH guidelines and accuracy, precision, repeatability, and robustness were found to be within the acceptable limits. Hany W. Darwish, Said A. Hassan, Maissa Y. Salem, and Badr A. El-Zeany Copyright © 2013 Hany W. Darwish et al. All rights reserved. Intermolecular Interactions between Eosin Y and Caffeine Using 1H-NMR Spectroscopy Sun, 10 Nov 2013 12:59:02 +0000 DETECHIP has been used in testing analytes including caffeine, cocaine, and tetrahydrocannabinol (THC) from marijuana, as well as date rape and club drugs such as flunitrazepam, gamma-hydroxybutyric acid (GHB), and methamphetamine. This study investigates the intermolecular interaction between DETECHIP sensor eosin Y (DC1) and the analyte (caffeine) that is responsible for the fluorescence and color changes observed in the actual array. Using 1H-NMR, 1H-COSY, and 1H-DOSY NMR methods, a proton exchange from C-8 of caffeine to eosin Y is proposed. Macduff O. Okuom, Mark V. Wilson, Abby Jackson, and Andrea E. Holmes Copyright © 2013 Macduff O. Okuom et al. All rights reserved.