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Sample records for absorption spectrophotometric studies

  1. Studies on atomic absorption spectrophotometric analysis of hexavalent chromium in waste water by solvent extraction

    Atomic absorption spectrophotometric(AAS) determination of hexavalent chromium [Cr(VI)] in a waste water was studied. Cr(VI) was extracted with p-xylene from the wastewater, in the way of ion pair formation with anion exchanger aliquat-336(tri-caprylmethyl ammonium chloride). 100ml waste water, after organic materials were extracted out with toluene, was acidified with conc. HCl adjusting the medium to pH 0.5 and 20ml of p-xylene containing 0.01M aliguat-336 was used to extract Cr(VI) from the acidified solution. The absorbance of chromium was measured with air-acetylene flame at 357.9nm. Standard addition method was used in the determining concentration of Cr(VI) extracted. No interference has been found in the extraction of Cr(VI) by the Al(III), Fe(III) and Cr(III) ion presented. However, Fe(II) decreased the absorbance of Cr(VI), due to the fact Fe(II) reduces Cr(VI) to Cr(III). The contained organic material was removed prior to extracting process, since it may reduced the absorbance of Cr(VI). The recovery of added Cr(VI) was over 96%, which seems to be promising and the relative standard deviation was 3.95%. (Author)

  2. Determination of spectrophotometric absorptivity by analytical ultracentrifugation

    M Senthilraja

    2011-01-01

    Full Text Available Rapid determination of the absorptivity for a recombinant IgG monoclonal antibody using the Beckman equipped with both Raleigh interference and UV absorbance optical systems. The analytical ultracentrifuge data for determining spectrophotometric absorptivities is compared to experimental data from quantitative amino acid analysis and an enzymatic digestion method.

  3. Novel atomic absorption spectrometric and rapid spectrophotometric methods for the quantitation of paracetamol in saliva: Application to pharmacokinetic studies

    Issa M

    2008-01-01

    Full Text Available A novel atomic absorption spectrometric method and two highly sensitive spectrophotometric methods were developed for the determination of paracetamol. These techniques based on the oxidation of paracetamol by iron (III (method I; oxidation of p-aminophenol after the hydrolysis of paracetamol (method II. Iron (II then reacts with potassium ferricyanide to form Prussian blue color with a maximum absorbance at 700 nm. The atomic absorption method was accomplished by extracting the excess iron (III in method II and aspirates the aqueous layer into air-acetylene flame to measure the absorbance of iron (II at 302.1 nm. The reactions have been spectrometrically evaluated to attain optimum experimental conditions. Linear responses were exhibited over the ranges 1.0-10, 0.2-2.0 and 0.1-1.0 µg/ml for method I, method II and atomic absorption spectrometric method, respectively. A high sensitivity is recorded for the proposed methods I and II and atomic absorption spectrometric method value indicate: 0.05, 0.022 and 0.012 µg/ml, respectively. The limit of quantitation of paracetamol by method II and atomic absorption spectrometric method were 0.20 and 0.10 µg/ml. Method II and the atomic absorption spectrometric method were applied to demonstrate a pharmacokinetic study by means of salivary samples in normal volunteers who received 1.0 g paracetamol. Intra and inter-day precision did not exceed 6.9%.

  4. Spectrofluorimetric, Atomic Absorption Spectrometric and Spectrophotometric Determination of Some Fluoroquinolones

    Hesham Salem

    2005-01-01

    Simple, accurate, sensitive and selective spectrofluorimetric, atomic absorption spectrometric and spectrophotometric methods are described for the quantitative determination of ten fluoroquinolones (amifloxacin, ciprofloxacin hydrochloride, difloxacin hydrochloride, enoxacin, enrofloxacin, lomefloxacin hydrochloride, levofloxacin, norfloxacin, ofloxacin and pefloxacin mesylate). The first method was a spectrofluorimetric method in which samples of the studied drugs in 0.1 N H2SO4 showed nati...

  5. SPECTROPHOTOMETRIC, ATOMIC ABSORPTION AND CONDUCTOMETRIC ANALYSIS OF TRAMADOL HYDROCHLORIDE

    Sara M. Anis

    2011-09-01

    Full Text Available Six simple and sensitive spectroscopic and conductometric procedures (A-F were developed for the determination of tramadol hydrochloride. Methods A, B and C are based on the reaction of cobalt (II thiocyanate with tramadol to form a stable ternary complex, which could be measured by spectrophotometric (method A, atomic absorption (method B or conductometric (method C procedures. Methods D and E depend on the reaction of molybdenum thiocyanate with tramadol to form a stable ternary complex, measured by spectrophotometric means (method D or by atomic absorption procedures (method E, while method F depends on the formation of an ion pair complex between the studied drug and bromothymol blue which is extractable into methylene chloride. Tramadol hydrochloride could be assayed in the range of 80-560 and 40-–220 μg ml-1, 1-15 mg ml-1 and 2.5-22.5, 1.25-11.25 and 5-22 μg ml-1 using methods A,B,C,D,E and F, respectively. Various experimental conditions were studied. The results obtained showed good recoveries. The proposed procedures were applied successfully to the analysis of tramadol in its pharmaceutical preparations and the results were favorably comparable with the official method.

  6. Spectrofluorimetric, Atomic Absorption Spectrometric and Spectrophotometric Determination of Some Fluoroquinolones

    Hesham Salem

    2005-01-01

    Full Text Available Simple, accurate, sensitive and selective spectrofluorimetric, atomic absorption spectrometric and spectrophotometric methods are described for the quantitative determination of ten fluoroquinolones (amifloxacin, ciprofloxacin hydrochloride, difloxacin hydrochloride, enoxacin, enrofloxacin, lomefloxacin hydrochloride, levofloxacin, norfloxacin, ofloxacin and pefloxacin mesylate. The first method was a spectrofluorimetric method in which samples of the studied drugs in 0.1 N H2SO4 showed native fluorescence at 450 nm when excitation was at 290 nm. The calibration graph was rectilinear from 0.3-1.4 μg mL-1 (method I. Cobalt sulphate was used for precipitation of the ion associates formed from the reaction with the cited drugs. The formation and solubility of the solid complexes at the optimum conditions of pH and ionic strength values have been studied. The method depends on direct determination of the ions in the precipitate or indirect determination of the ions in the filtrate by atomic absorption spectroscopy. The optimum conditions for precipitation were carefully studied. Rectilinear calibration graphs were obtained in the range of 3-30 μg mL-1 for each of the investigated drugs. The molar ratios of the formed chelats were determined by Job's method and their association constants were also calculated (method II. Ammonium vanadate was used for the spectrophotometric determination of the selected fluoroquinolones by oxidation in sulphuric acid medium resulting in the development of a greenish blue colour measured at 766 nm which was attributed to the vanadium (IV produced by reduction of vanadium (V by the selected drugs. The optimum conditions for heating time, reagent concentration and sulphuric acid concentration were carefully studied. The accuracy and precision of the proposed method was confirmed by estimating five or six replicates within Beer's law limits were obtained in the range 10-40 μg mL-1 for each of the investigated drugs

  7. A method optimization study for atomic absorption spectrophotometric determination of total zinc in insulin using direct aspiration technique

    Sadia Ata

    2015-03-01

    Full Text Available A sensitive, reliable and relative fast method has been developed for the determination of total zinc in insulin by atomic absorption spectrophotometer. This designed study was used to optimize the procedures for the existing methods. Spectrograms of both standard and sample solutions of zinc were recorded by measuring the absorbance at 213.9 nm for determination of total zinc. System suitability parameters were evaluated and were found to be within the limits. Linearity was evaluated through graphical representation of concentration versus absorbance. Repeatability (intra-day and intermediate precision (inter-day were assessed by analyzing working standard solutions. Accuracy and robustness were experimented from the standard procedures. The percentage recovery of zinc was found to be 99.8%, relative standard deviation RSD 1.13%, linearity of determination LOD 0.0032 μg/mL, and limit of quantization LOQ 0.0120 μg/mL. This developed and proposed method was then validated in terms of accuracy, precision, linearity and robustness which can be successfully used for the quantization of zinc in insulin.

  8. Raman and absorption spectrophotometric studies of selected lanthanide, californium-doped lanthanide, and actinide trihalides in the solid state

    The solid-state absorption spectra of Cf(III) ions as a dopant in lanthanide trihalide hosts (LnCl3: Ln = Ce, Sm, and Y; LnBr3: Ln = Ce, Sm, Tb, and Y; LnI3: Ln = Ce and Y) have been recorded. The spectra of Cf(III) have been correlated with the various crystal structures. The phonon Raman spectra and solid-state absorption spectra of PmF3, PmCl3, PmBr3, and two crystal modifications of PmI3 have been recorded. Symmetry assignments have been made for the Raman-active bands for these trihalides and also the sesquioxide. The room-temperature absorption spectra have been correlated to crystal field effects. The symmetry assignments of the Raman-active phonon modes have been made based on polarized Raman spectra from single crystals of YF3-type orthorhombic TbF3 and PuBr3-type orthorhombic NdBr3. Raman spectra of other isostructural lanthanide compounds have been recorded and compared. Symmetry assignments for these compounds have been made by analogy to the single-crystal assignments. Raman spectra have been obtained and catalogued for a number of actinide compounds. Symmetry assignments have been made for the observed Raman-active phonon bands in this work based on the assignments made for isostructural lanthanide compounds. 29 figs., 22 tabs

  9. Absorption studies

    Absorption studies were once quite popular but hardly anyone does them these days. It is easier to estimate the blood level of the nutrient directly by radioimmunoassay (RIA). However, the information obtained by estimating the blood levels of the nutrients is not the same that can be obtained from the absorption studies. Absorption studies are primarily done to find out whether some of the essential nutrients are absorbed from the gut or not and if they are absorbed, to determine how much is being absorbed. In the advanced countries, these tests were mostly done to detect pernicious anaemia where vitamin B12 is not absorbed because of the lack of the intrinsic factor in the stomach. In the tropical countries, ''malabsorption syndrome'' is quire common. In this condition, several nutrients like fat, folic acid and vitamin B12 are not absorbed. It is possible to study absorption of these nutrients by radioisotopic absorption studies

  10. Spectrophotometric detection of diethylstilbestrol on the basis of the plasmon resonance absorption of silver nanoparticles

    2010-01-01

    In this study,a spectrophotometric detection method for diethylstilbestrol(DES)was proposed by reducing silver nitrate(AgNO3)to obtain silver nanoparticles(AgNPs)in the medium of ammonia and sodium hydroxide.It was found that the resulting AgNPs have plasmon resonance absorption(PRA)characteristic at 415 nm,and the PRA is proportional to the increase of DES concentration in the range of 4.0×10-8-1.0×10-5M with the detection limit(3σ)of 1.2×10-7M.Most of the coexisting substances at high concentrations did n...

  11. Flotation and atomic absorption spectrophotometric investigation of molybdenum

    The removal of molybdenum from an aqueous solution by the combined use of sodium diethyldithiocarbamate (Na DDTC) and oleic acid γHOL) was studied by flotation technique. The effect of variables such as Na DDTC, HOL concentrations and pH on the floatability were examined. About 98% of the molybdenum could be floated under the optimum conditions. In the investigation of molybdenum by atomic absorption spectrophotometry, Na DDTC was used to eliminate the interference effects of cations by its adding to both the sample and the standard solutions of cations. Also, the mechanism of this elimination was discussed. The interfering effects of some cations in different acid media and the phenomenal interference in presence of heteropoly atoms were explained. Moreover, the effect of multicomponent mixtures of cations was elaborated. 20 refs

  12. Spectrophotometric study of lanthanoid complexes with antipyrine and salicylic acid

    The extraction-spectrophotometric method has been used to study lanthanoid ion complexing (Pr, Nd, Ho and Er) with antipyrine (Ant) and salicylic acid (Sal). The component relationship in different-ligand compounds Ln:Aut:Sal=2:3:6 and solvate number equal to 5 are determined; molar extinction coefficients of binary and different-ligand compounds are calculated. Oscillator strengths of absorption bands corresponding to supersensitive transitions of neodymium, holmium, erbium and some most intensive praseodymium bands are calculated. The study of IR spectra of investigated compounds allows to conclude on formation of coordination bonds of the central atom with the antipyrine molecule through the oxygen of the carbonyl group as well as on carboxyl group hydrogen substitution for metal and formation of coordination bond with OH group in salicylic acid molecules

  13. Spectrophotometric study on the NGC 4922

    The results of spectrophotometric investigation of the binary galaxy NGC 4922 are presented. One of the components appears to be an elliptical galaxy with a spectrum corresponding to the spectral classes G0-G3, the other has spectral properties of low ionization Seyfert nuclei. Physical conditions and chemical abundances in this component resemble those of the Sy 2 galaxies. The mass of the Seyfert-like component within the radius of 1 kpk is nearly 0.4x108 Msub(sun). The mass of the whole system is approximately 2.2x1011 Msub(sun)

  14. A COMPARISON OF A SPECTROPHOTOMETRIC (QUERCETIN) METHOD AND AN ATOMIC-ABSORPTION METHOD FOR DETERMINATION OF TIN IN FOOD

    Engberg, Å

    1973-01-01

    Procedures for the determination of tin in food, which involve a spectrophotometric method (with the quercetin-tin complex) and an atomic-absorption method, are described. The precision of the complete methods and of the individual analytical steps required is evaluated, and the parameters that...

  15. Spectrophotometric study of ion associate of molybdotunqstophosphoric heteropoly acid with crystal violet

    The ion associates formed by molybdotungstophosphoric acid and Crystal Violet have been studied. The ratio of MTP:CV is 1:3 at P:W=1:1 and 1:4 at P:W=1:11. Conditions for the ion associate formation and flotation with butyl acetate have been found. The molar absorptivities are 2.78x105 and 4.17x105 respectively. A procedure has been developed of spectrophotometric determination of phosphorus in the presence of arsenic

  16. New method for spectrophotometric determination of quinones and barbituric acid through their reaction. A kinetic study

    Medien, H. A. A.

    1996-11-01

    A new and sensitive spectrophotometric method is described for the determination of p-benzoquinone, p-chloranil and 1.4-naphthoquinone. The method is based on the reaction between quinones and barbituric acid, by which a color is developed with maximum absorption between 485 and 555 nm in 50% methyl alcohol-water mixture. The absorption of the product obeys Beer's law within the concentration range 0.025-05 mM of orginal quinone. The kinetics of the reaction between p-benzoquinone and barbituric acid was studied in a range of methyl alcohol-water mixtures. The reaction follows overall second order kinetics, first order in each of the reactants. The rate increases with increasing dielectric constant. The method was applied for determination of barbituric acid with p-benzoquinone in the concentration range of 0.025-0.345 mM. Other barbiturates do not interfere.

  17. Determination of U and Impurities Elements in The Uranium Tetra Fluoride by Potentiometric and Atomic Absorption Spectrophotometric Methods

    The determination of u and impurities contents in the Uranium tetra fluoride (UF4)has been carried out by potentiometric titration using modified 'Davies-Gray' and atomic absorption spectrophotometric methods. Dissolution process of the powder sample using saturated Al2(SO4)3 solution introduced to determine UF4 compound content in the UF4 sample. The uranium Content in the obtained filtrate is analyzed by potentiometric. The impurities content is determined by ato-Mic absorption spectrophotometric using ammonium oxalate powder in introducing of the sample preparation. The experiment covered the observation on influence of stirring time of UF4 sample dissolution in respect to separate UF4 from its impurities in determination of uranium content. Also the effects of Ammonium Oxalate added and agitating time were observed deal with the sample preparation for the determination of Impurities content.The analysis result found that UF4 content was 96.15 ± 0.04% the relative station 0.7%. However the best impurities determination was achieved by addition of ammonium oxalate powder and 15 Minutes of agitation time at temperature of 8000C

  18. SPECTROPHOTOMETRIC STUDIES OF SANGUINARINE-Β-CYCLODEXTRIN COMPLEX FORMATION

    Veaceslav Boldescu

    2008-06-01

    Full Text Available The main aim of this study was to investigate the influence of pH and the presence of hydrophilic polymer polyvinylpyrrolidone on the formation of sanguinarine-β-cyclodextrin (SANG-β-CD inclusion complex. Spectrophotometric studies of the SANG-β-CD systems in the presence and without 0.1 % PVP at the pH 5.0 did not show any evidence of the complex formation. However, the same systems showed several obvious evidences at the pH 8.0: the hyperchromic and the hypochromic effects and the presence of the isosbestic point in the region of 200 – 210 nm. The association constants calculated by three linear methods: Benesi-Hildebrand, Scott and Scatchard, were two times higher for the systems with addition of 0.1% PVP than for the systems without it.

  19. Quasar Absorption Studies

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  20. Study of reduction of chromium (VI by calcium polysulfide using spectrophotometric method

    Batukhan Tatykaev

    2013-05-01

    Full Text Available The paper presents  the results of the study on reduction  of  Cr2O72-   to   Cr3 +  by aqueous solution of calcium polysulfide  using spectrophotometric method. Concentrations  of Cr (VI were determined on the basis of the absorption spectrum at the wavelength range 350 - 372 nm. The change of the concentration of Cr (VI during on reduction by calcium polysulfide has been shown.  The influence of pH on the rate of reducing of Cr (VI to Cr (III was considered: the rate of reducing of hexavalent chromium decreases with increasing pH. The data obtained show that recycling Cr (VI in industrial scale potentially effective at  the pH = 5.

  1. Polarographic, spectrophotometric and coulometric studies of MoO=4 in H2SO4

    This study characterizes the polarographic process of Mo O sup(=) sub(4) in H sub(2)SO sub(4) medium, determining which species is responsible by catalytic cycle. Spectrophotometric and coulometric studies are also described. (author)

  2. Novel ratio difference at coabsorptive point spectrophotometric method for determination of components with wide variation in their absorptivities

    Saad, Ahmed S.; Abo-Talib, Nisreen F.; El-Ghobashy, Mohamed R.

    2016-01-01

    Different methods have been introduced to enhance selectivity of UV-spectrophotometry thus enabling accurate determination of co-formulated components, however mixtures whose components exhibit wide variation in absorptivities has been an obstacle against application of UV-spectrophotometry. The developed ratio difference at coabsorptive point method (RDC) represents a simple effective solution for the mentioned problem, where the additive property of light absorbance enabled the consideration of the two components as multiples of the lower absorptivity component at certain wavelength (coabsorptive point), at which their total concentration multiples could be determined, whereas the other component was selectively determined by applying the ratio difference method in a single step. Mixture of perindopril arginine (PA) and amlodipine besylate (AM) figures that problem, where the low absorptivity of PA relative to AM hinders selective spectrophotometric determination of PA. The developed method successfully determined both components in the overlapped region of their spectra with accuracy 99.39 ± 1.60 and 100.51 ± 1.21, for PA and AM, respectively. The method was validated as per the USP guidelines and showed no significant difference upon statistical comparison with reported chromatographic method.

  3. Polymerization Evaluation by Spectrophotometric Measurements.

    Dunach, Jaume

    1985-01-01

    Discusses polymerization evaluation by spectrophotometric measurements by considering: (1) association degrees and molar absorptivities; (2) association degrees and equilibrium constants; and (3) absorbance and equilibrium constants. (JN)

  4. Simple and Precise UV Spectrophotometric Method Development for Estimation of Albendazole for Dissolution Study

    Vipin Kumar Agrawal

    2015-01-01

    Full Text Available Albendazole is a class II drug in biopharmaceutical classification system, so its dissolution study is very difficult because of its low solubility and difficulty during estimation of drug in bulk. The present study deals with UV spectrophotometric method development and validation for estimation of albendazole in bulk form. Albendazole is a benzimidazole derivative with an oral broad spectrum of activity against human and animal helminthes parasites. The drug obeyed the Beer’s law and showed good correlation. It showed absorption maxima at 229nm in 0.1 N HCL with 0.05% sodium lauryl sulphate (SLS. The linearity was observed between 4-20μg/ml. The method was applied for the analysis of the drug in the pure, tablet and suspension forms. The slope and intercept of the equation of the regression line are 0.009 and 0.017 respectively. Correlation coefficient was found to be 0.9996. The results of analysis were validated by recovery studies. The recovery was more than 97%. The method was found to be simple, reliable, rapid, precise, specific and reproducible and can be applied for routine analysis of albendazole in different dosage form and dissolution studies.

  5. Geomorphological and Spectrophotometric Study of Philae Landing Site A

    Pajola, M.; La Forgia, F.; Giacomini, L.; Oklay, N.; Massironi, M.; Bertini, I.; Simioni, E.; Marzari, F.; Barbieri, C.; Naletto, G.; Groussin, O.; Lazzarin, M.; Scholten, F.; Preusker, F.; Fornasier, S.; Vincent, J. B.; Sierks, H.

    2015-10-01

    5 finalists, this site has the unique value to provide detailed analysis of the multiple fractures present on its cliff and on the neighboring Hathor. Figure 1: Site A as imaged by the OSIRIS NAC camera on 6 August 2014 at 02:20:12 UT. The distance from the comet center is 117.24 km, the scale is 2.17 m/px. EPSC Abstracts Vol. 10, EPSC2015-526, 2015 European Planetary Science Congress 2015 c Author(s) 2015 EPSC European Planetary Science Congress We here present the geomorphological map coupled with the size-frequency distributions of boulders # 2 m located on the different types of terrains here identified, such as outcropping layered terrains, gravitational accumulation deposits, taluses and fine particle deposits. Gravitational slopes, derived through the 67P shape model by assuming uniform density, have been used to characterize and better interpret the various terrains. Moreover, we show the spectrophotometric properties of the area, studied through images taken by OSIRIS NAC with a scale of 50 cm/px. Albedo maps, as well as surface reflectance spectra have been obtained by taking advantage of the shape model and DTM in order to correct for the illumination and observing conditions of the terrain. This multidisciplinary analysis highlights that different types of deposits show different photometric properties.

  6. Spectrophotometric study of some metal ions using some Schiff's bases

    In this work two schiff bases namely N,N Bis(benzoyl acetone)-o-phenylene diamine (NNBBPD) and N,N Bis(benzoyl acetone)-isopropylene diamine (NNBBAID) were prepared by direct coupling of benzoyl acetone with o-phenylene and isopropylene diamine respectively. The two reagents were identified by IR spectra, thin layer chromatography (TLC) and determination of the percentage of nitrogen contents (N%). It is found that the two reagents form coloured chelates with Fe (II), Fe (III), Cu (II), U (VI), Ni (II) and Co (II). The two reagents were used for the determination of Fe (II), Fe (III) and U (VI). The formulate of these metal ion complexes were obtained using continuous variations, mole ratio and slope ratio methods. Effect of two micelles, namely sodium n-dodecyl sulphate (SDS) and hexadecyl pyridinum broinide monohydrate (HPB) on metal ion complexes were studied. It is found that both of them increase the solubility and the absorbances of the metal ion complexes with variable effects of the absorption maxima. Calibration curves for Fe (II), Fe (II) and U (VI) were obtained in optimum conditions of pH and micelles solutions. (Author)

  7. One- and two-electron reduction of aluminum and tin pyridylporphyrins. A kinetic spectrophotometric study

    Al/sup III/TPyP (TPyP = tetra-4-pyridylporphyrin), Al/sup III/TMPyP (TMPyP = tetrakis(N-methyl-4-pyridyl)porphyrin), Sn/sup IV/TMPyP, Sn/sup IV/TPP (TPP = tetraphenylporphyrin), Sn/sup IV/TPMMPyP (TPMMPyP = triphenylmono(N-methyl-4-pyridyl)porphyrin), and Sn/sup IV/TPMPyP (TPMPyP = triphenylmono-4-pridylporphyrin) were studied by steady-state and pulse radiolysis spectrophotometric techniques in neutral and alkaline aqueous and methanolic solutions. Both aluminum porphyrins (Al/sup III/P), in neutral and basic methanol, undergo one-electron reduction to form transient species which exhibit absorption maxima at 700 and 740 nm, respectively, and are thus characterized as ligand radicals (Al/sup III/P-). These species decay by disproportionation with second-order rate constants of approx.108-109. The final products depend on the nature of the porphyrin and the medium but are mainly phlorins (Al/sup III/PH2 or Al/sup III/PH-). Factors which influence the formation of final products are discussed. The tin(IV) pyridylporphyrins form one-electron-reduced species (Sn/sup IV/P-) which are stable in alkaline aqueous and methanolic solutions. These products can be further reduced to give the phlorin. In neutral or acidic solutions the 1e-reduction products disproportionate rapidly into phlorin and porphyrin. Sn/sup IV/TPP exhibits a different behavior in that the 1e-reduced species in not very long-lived and the 2e-reduction product is mainly a chlorin rather than a phorin. 20 references, 7 figures, 2 tables

  8. Simple and Precise UV Spectrophotometric Method Development for Estimation of Albendazole for Dissolution Study

    Vipin Kumar Agrawal; Shashank Chaturvedi; Amresh Gupta

    2015-01-01

    Albendazole is a class II drug in biopharmaceutical classification system, so its dissolution study is very difficult because of its low solubility and difficulty during estimation of drug in bulk. The present study deals with UV spectrophotometric method development and validation for estimation of albendazole in bulk form. Albendazole is a benzimidazole derivative with an oral broad spectrum of activity against human and animal helminthes parasites. The drug obeyed the Beer’s law and showed...

  9. Identification of phenolic antioxidants in Ipomoea mauritiana jacq. using spectrophotometric and mass spectroscopic studies

    Cheruthazhakkat Sulaiman; Sivadasan Pillai Geetha; Balachandran Indira

    2014-01-01

    Objective: Ipomoea mauritiana is used in both Ayurveda and folk medicine systems. The tuberous roots are known to be diuretic, depurative, carminative, and anthelmintic. The objective of the current study was to identify phenolic antioxidants from I . mauritiana using spectrophotometric and LC-MS analysis. Materials and Methods: An activity-guided fractionation and purification process was used to identify the antioxidative components from I . mauritiana tuber. Dried mature tubers of I. maurit...

  10. Extraction-spectrophotometric study of ternary ion-association complexes of vanadium (4) with pyrogallol and tetrazolium salts

    The systems V(4)-pyrogallol-neotetrazolium chloride and V(4)-pyrogallo-iodonitrotetrazolium chloride are studied using spectrophotometric methods. The composition of the complexes is established. Obtained results reveal that the ternary ion-association complexes are easily extracted by butanol. The optimum conditions for extraction of vanadium into n-butanol are found. Distribution constants, recovery factors, association constants and molar absorptivities ε are calculated. Molar absorptivity of the ternary complex with 2-(4-iodophenyl)-3-(4-nitrophenyl)-tetrazolium chloride (ε=8.74·103 l/mol·cm) is higher as compared to that of the complex with 2,2';5,5'-tetraphenyl-3,3'-(p-biphenyl)-ditetrazolium chloride (ε=7.30·103 l/mol·cm) and to molar absorptivities of the ternary complexes with antipyrine (ε=4.2·103 l/mol·cm) and diphenylguanidine (ε=8.0·103 l/mol·cm)

  11. EXTRACTIVE SPECTROPHOTOMETRIC STUDIES OF ACETOPHENONE 2’, 4’-DIHYDROXY THIOSEMICARBAZONE WITH IRON

    P. K. Rana

    2012-10-01

    Full Text Available Acetophenone 2’, 4’-Dihydroxy thiosemicarbazone (APDHTS as a reagent for the extractive spectrophotometric determination of Iron. The reagent APDHTS gave instantaneous and stable violet colour with Iron at pH 5.0. A linear calibration graph over the concentration range 1 ppm to 10 ppm with a 3σ limit of detection of 0.66 ppm was obtained by applying the spectrophotometric method at wavelength 370 nm. The stoichiometry of the complex is established as 1:1 (M: L by Job’s method of continuous variation and confirmed by mole ratio method. The standard deviation and the coefficient of variations are presented. The molar absorptivity and Sandal’s sensitivity of the complex is 0.4469 x 103 L mol-1cm –1 and 0.0125 µg cm-2 respectively. The results of the prescribed procedure applied for the determination of the micro amounts of Fe (III in various synthetic and standard steel samples are presented.

  12. Enhancing prediction power of chemometric models through manipulation of the fed spectrophotometric data: A comparative study.

    Saad, Ahmed S; Hamdy, Abdallah M; Salama, Fathy M; Abdelkawy, Mohamed

    2016-10-01

    Effect of data manipulation in preprocessing step proceeding construction of chemometric models was assessed. The same set of UV spectral data was used for construction of PLS and PCR models directly and after mathematically manipulation as per well known first and second derivatives of the absorption spectra, ratio spectra and first and second derivatives of the ratio spectra spectrophotometric methods, meanwhile the optimal working wavelength ranges were carefully selected for each model and the models were constructed. Unexpectedly, number of latent variables used for models' construction varied among the different methods. The prediction power of the different models was compared using a validation set of 8 mixtures prepared as per the multilevel multifactor design and results were statistically compared using two-way ANOVA test. Root mean squares error of prediction (RMSEP) was used for further comparison of the predictability among different constructed models. Although no significant difference was found between results obtained using Partial Least Squares (PLS) and Principal Component Regression (PCR) models, however, discrepancies among results was found to be attributed to the variation in the discrimination power of adopted spectrophotometric methods on spectral data. PMID:27235828

  13. Determination of trace elements in Egyptian cane sugar (Deshna Factories) by neutron activation, atomic absorption spectrophotometric and inductively coupled plasma-atomic emission spectrometric analysis

    Multielement instrumental neutron activation (INAA), inductively coupled plasma-atomic emission spectrometric (ICP-AES) and atomic absorption spectrophotometric (AAS) analyses were utilized for the determination of Ag, Al, As, Au, Ba, Be, Br, Ca, Cd, Ce, Cl, Co, Cr, Cu, Eu, Fe, Ga, Hf, K, La, Li, Lu, Mg, Mn, Na, Nb, Ni, P, Pb, Sb, Sc, Se, Sm, Sn, Sr, Ta, Th, Ti, U, V, W and Zn in sugar cane plant, raw juice, juice in different stages, syrup, deposits, molasses, A, B and C sugar, refinery 1 and 2 sugar, and in soil samples picked up from the immediate vicinity of the cane plant roots at surface, 30 and 60 cm depth, respectively. (author)

  14. Spectrophotometric and spectroscopic studies of complexation of 8-hydroxyquinoline with π acceptor metadinitrobenzene in different polar solvents

    Khan, Ishaat M.; Ahmad, Afaq

    2009-09-01

    The complexation of electron donor-acceptor complexes of 8-hydroxyquinoline (8HQ) and metadinitrobenzene (MNB) have been studied spectrophotometrically and thermodynamically in different polar solvent at room temperature. A new absorption band due to charge transfer (CT) transition is observed in the visible region. A new theoretical model has been developed which take into account the interaction between electronic subsystem of 8HQ and MNB. The results indicate the extent of charge transfer complexes (CTCs) formation to be more in less polar solvents. Stoichiometry of the complex was found to be 1:1 by straight line method and 1H NMR between donor and acceptor at the maximum absorption bands. Ionization potential ( ID) and resonance energy ( RN) were determined from the CT transition energy in different solvents. The formation constants of the complexes were determined in different polar solvents from which Δ G° formation of the complexes was estimated and also extinction coefficient of the charge transfer complex (CTC) was calculated. Oscillator strength, transition dipole strengths and maximum wavelength of the CTC ( λCT) in various solvents and IR spectra of the CTC have also been discussed. It has been observed that all parameters described above changed with change in polarity and concentration of donor.

  15. Spectrophotometric determination of boron in ammonium diuranate and interference studies

    This paper describes determination of boron in ammonium diuranate by spectrophotometry employing curcumin as a complexing agent after extraction of boron with 2-ethyl hexane 1,3 diol. Two diluents namely ethyl alcohol (EtOH) and N,N-dimethyl formamide (DMF) were investigated for the preparation of final solution. It was observed that the blank is less with DMF presumably due to higher extent of deprotonation of uncomplexed curcumin. The detection limits of method for 25 and 10 ml dilution are 20 ng and 10 ng respectively. Interference studies for several cation and anion species like Al, Cr, Mg, Ca, Fe, Mn, Mo, F, W, NO, and different amount of 10% EHD in CHCl3 are also discussed. (author)

  16. Spectrophotometric study of bio-sorption of uranium on glass grade spodumene shell powder

    Separation of uranium found in iron ore leachates was done by extraction chromatography using glass grade spodumene shellpowder (GSS) in nitric acid medium and analyzed spectrophotometrically. The influences of metal ion concentration, pH and adsorption capacity of biomass were investigated. Biosorption is a potential method of separation of heavy and trace metals from waste water and effluents from various sources. The adsorption capacities of biomass were investigated by batch experiments and column experiments. In the present study, glass grade spodumene shell powder (GSS) in acidic medium is being used as a biosorbent

  17. Spectrophotometric study of neptunium (VI) complexation by nitrate ions

    Neptunium(VI) complexation by nitrate ions was investigated by visible and near-infrared spectrophotometry, a technique suitable for observing the appearance and evolution of the species in solution. In the absence of reference spectra for Np(VI) nitrate- complexes, mathematical (factor analysis) tools were used to interpret the spectra. These chemo-metric techniques were first tested and validated on a simpler chemical system: Np(VI)complexation by the SiW11O398- anion. The test media used to investigate Np(VI) nitrate- complexes generally contain nitrate and perchlorate salts at high concentrations (high ionic strength). Media effects arising from the presence of cations, acidity or the perchlorate ion concentration are therefore significant, and no doubt account for the scattered values of the complexation constants published in the literature. The evolution of the neptunium spectra according to the parameters of the reaction medium illustrated these effects and allowed them to be quantified by a global 'perturbation constant'. In order to minimize the spectrum modifications due to media effects, the neptunium nitrate-complexes were studied at constant ionic strength in weak acidic media (2 mol.kg-1H2O) in the presence of sodium salts. The bulk formation constants and the spectrum of the NpO2(NO3)+ complex were determined for ionic strength values of 2.2, 4, 6 and 8 mol.kg-1H2O. The constants remained on the same order of magnitude regardless of the ionic strength; the thermodynamic constant β10 determined from them according to specific interaction theory is thus probably of little significance. Conversely, the bulk constants can be corrected for the effects of the perchlorate ions by taking the global 'perturbation constant' into account. (author)

  18. Flow analysis-hydride generation-gas phase derivative molecular absorption spectrophotometric determination of antimony in antileishmanial drugs

    Máximo Gallignani

    2009-01-01

    Full Text Available In the present work, the development of a method based on the coupling of flow analysis (FA, hydride generation (HG, and derivative molecular absorption spectrophotometry (D-EAM in gas phase (GP, is described in order to determine total antimony in antileishmanial products. Second derivative order (D²224nm of the absorption spectrum (190 - 300 nm is utilized as measurement criterion. Each one of the parameters involved in the development of the proposed method was examined and optimized. The utilization of the EAM in GP as detection system in a continuous mode instead of atomic absorption spectrometry represents the great potential of the analytic proposal.

  19. Synthesis and spectrophotometric studies of charge transfer complexes of p-nitroaniline with benzoic acid in different polar solvents

    Singh, Neeti; Ahmad, Afaq

    2014-09-01

    The charge transfer complexes of the donor p-nitroaniline (PNA) with the π-acceptor benzoic acid (BEA) have been studied spectrophotometrically in various solvents such as acetone, ethanol, and methanol at room temperature using an absorption spectrophotometer. The outcome suggests that the formation of the CT-complex is comparatively high in less polar solvent. The stoichiometry of the CT-complex was found to be 1:1. The physical parameters of the CT-complex were evaluated by the Benesi-Hildebrand equation. The data are discussed in terms of the formation constant (KCT), molar extinction coefficient (ɛCT), Standard Gibbs free energy (ΔG0), oscillator strength (f), transition dipole moment (μEN), resonance energy (RN) and ionization potential (ID). The formation constant (KCT) of the complex was depends upon the nature of electron acceptor, donor, and polarity of solvents used. It is also observed that a charge transfer molecular complex is stabilized by hydrogen bonding. The formation of the complex has been confirmed by UV-visible, FT-IR, 1H NMR and TGA/DTA. The structure of the CT-complex is [(PNA)+ (BEA)-]. A general mechanism for its formation of the complex has also been proposed.

  20. Contributions te the study of methods and factors affecting the spectrophotometric determination of boron traces with carmin uranium compounds

    The study of some factors affecting the spectrophotometric determination of boron traces with carmin is made; the influence of carmin from different origin, the stability of complex carmin-boric acid in relation with the sulphuric acid concentration, the interference produced by ion nitrate, and the ion uraline and light influence are discussed. (Author) 36 refs

  1. Measurement of Capsaicinoids in Chiltepin Hot Pepper: A Comparison Study between Spectrophotometric Method and High Performance Liquid Chromatography Analysis

    Alberto González-Zamora

    2015-01-01

    Full Text Available Direct spectrophotometric determination of capsaicinoids content in Chiltepin pepper was investigated as a possible alternative to HPLC analysis. Capsaicinoids were extracted from Chiltepin in red ripe and green fruit with acetonitrile and evaluated quantitatively using the HPLC method with capsaicin and dihydrocapsaicin standards. Three samples of different treatment were analyzed for their capsaicinoids content successfully by these methods. HPLC-DAD revealed that capsaicin, dihydrocapsaicin, and nordihydrocapsaicin comprised up to 98% of total capsaicinoids detected. The absorbance of the diluted samples was read on a spectrophotometer at 215–300 nm and monitored at 280 nm. We report herein the comparison between traditional UV assays and HPLC-DAD methods for the determination of the molar absorptivity coefficient of capsaicin (ε280=3,410 and ε280=3,720 M−1 cm−1 and dihydrocapsaicin (ε280=4,175 and ε280=4,350 M−1 cm−1, respectively. Statistical comparisons were performed using the regression analyses (ordinary linear regression and Deming regression and Bland-Altman analysis. Comparative data for pungency was determined spectrophotometrically and by HPLC on samples ranging from 29.55 to 129 mg/g with a correlation of 0.91. These results indicate that the two methods significantly agree. The described spectrophotometric method can be routinely used for total capsaicinoids analysis and quality control in agricultural and pharmaceutical analysis.

  2. UV Spectrophotometric Method for Determination of Cinitapride in Pure and its Solid Dosage Form

    B. Thangabalan; A. Elphine Prabahar; R. Kalaichelvi; P. Vijayaraj Kumar

    2009-01-01

    A new, rapid, precise, accurate and sensitive analytical method was developed for the UV spectrophotometric assay of cinitapride (CTP). The drug obeyed the Beer's law and showed good correlation. It showed absorption maxima at 260 nm in methanol. The linearity was observed between 5-40 µg mL-1. The results of analysis were validated by recovery studies. The recovery was more than 99%. The proposed method is the only method available for spectrophotometric determination of the drug. It is simp...

  3. Spectrophotometric determination of association constant

    Spanget-Larsen, Jens

    2016-01-01

    Least-squares 'Systematic Trial-and-Error Procedure' (STEP) for spectrophotometric evaluation of association constant (equilibrium constant) K and molar absorption coefficient E for a 1:1 molecular complex, A + B = C, with error analysis according to Conrow et al. (1964). An analysis of the Charg...

  4. Spectrophotometric study of the samarium nitrate-water-dimethyl sulfoxide system

    Effect of water-dimethyl sulfoxide solvent composition (DMSO) on samarium (3) ion electron absorption spectrum is studies. It is shown, that the absorption maximum ware length λ and the molar absorption coefficient K of samarium (3) ion grow cymbately with the increase of DMSO molar shave (N) in water-DMSO solvent. It is ascertained that these dependences possess a bending point at N=0.5. A conclusion is made, that samarium ions with different solvate coating are present in the solution at the same time; on the average, the member of water and DMSO molecules in the ion solvate coating corresponds to their molar share in the solvent composition

  5. Determination of Cyproheptadine hydrochloride in Pure and Pharmaceutical forms : A Spectrophotometric study

    Sayanna

    2015-09-01

    Full Text Available Siimple and sensitive extractive spectrophotometric methods have been described for the determination of Cyproheptadine hydrochloride (CPH in pure form and in pharmaceutical formulations. The developed methods involved formation of coloured chloroform extractable ion-pair complexes of the CPH with triphenyl methane dyes viz., bromothymol blue (BTB, bromocresol green (BCG and bromocresol purple (BCP in acidic medium. The extracted complexes showed absorbance maxima at 419, 419 and 405nm with use of the above dyes, respectively. Beer’s law is obeyed in the concentration ranges 3.0-25, 2.5-22.5 and 1.5-25μg/ml with BTB, BCG and BCP respectively. The stoichiometry of the complex is found to be 1:1 in each case. The effect of concentration of dye, pH and interference of excipients have been studied and optimized. The limit of detection and limit of quantification have been determined for three methods. The methods are applied to the determination of CPH in commercial tablets and results of analysis are validated statistically through recovery studies also the methods are validated as per the guidelines of ICH.

  6. Studies on Tinospora cordifolia monosugars and correlation analysis of uronic acids by spectrophotometric methods and GLC.

    Kumar, Vineet; Nagar, Shipra

    2014-01-01

    Cold water-soluble (CWSP) and hot water soluble polysaccharides (HWSP) from Tinospora cordifolia stems were isolated and purified in 2.99% and 1.99% yield respectively. Complete hydrolysis followed by paper chromatography and GLC analysis indicated the presence of L-rhamnose, L-arabinose, D-xylose, D-mannose, D-galactose and D-glucose in molar ratio of 0.857, 1.106, 0.727, 0.526, 0.708 and 95.763 in CWSP and 0.697, 0.777, 2.048, 0.777, 0.292 and 95.408 in HWSP. The uronic acid content in the polysaccharide has been studied extensively using assorted approaches. It was quantitatively estimated by GLC analysis and spectrophotometric methods using carbazole, m-hydroxydiphenyl and 3,5-dimethylphenol as colorimetric reagents. GLC analyses indicated galacturonic acid content of 3.06% and 5.16% in CWSP and HWSP respectively. Estimation of uronic acid using 3,5-dimethylphenol corroborated the above analysis. The study resulted in composition of constituent monosugars of CWSP and HWSP and co-relation analysis of uronic acid content, leading to an unambiguous structural analysis. PMID:24274509

  7. Study on the Spectrophotometric Detection of Free Fatty Acids in Palm Oil Utilizing Enzymatic Reactions

    Nur Hidayah Azeman

    2015-07-01

    Full Text Available In this paper, a comprehensive study has been made on the detection of free fatty acids (FFAs in palm oil via an optical technique based on enzymatic aminolysis reactions. FFAs in crude palm oil (CPO were converted into fatty hydroxamic acids (FHAs in a biphasic lipid/aqueous medium in the presence of immobilized lipase. The colored compound formed after complexation between FHA and vanadium (V ion solution was proportional to the FFA content in the CPO samples and was analyzed using a spectrophotometric method. In order to develop a rapid detection system, the parameters involved in the aminolysis process were studied. The utilization of immobilized lipase as catalyst during the aminolysis process offers simplicity in the product isolation and the possibility of conducting the process under extreme reaction conditions. A good agreement was found between the developed method using immobilized Thermomyces lanuginose lipase as catalyst for the aminolysis process and the Malaysian Palm Oil Board (MPOB standard titration method (R2 = 0.9453.

  8. EXTRACTIVE SPECTROPHOTOMETRIC STUDIES OF ACETOPHENONE 2’, 4’-DIHYDROXY THIOSEMICARBAZONE WITH IRON

    P. K. Rana; R. S. Lokhande; S. M. Pitale; S.P. Janwadkar; P. S. Navarkar; D K Yadav

    2012-01-01

    Acetophenone 2’, 4’-Dihydroxy thiosemicarbazone (APDHTS) as a reagent for the extractive spectrophotometric determination of Iron. The reagent APDHTS gave instantaneous and stable violet colour with Iron at pH 5.0. A linear calibration graph over the concentration range 1 ppm to 10 ppm with a 3σ limit of detection of 0.66 ppm was obtained by applying the spectrophotometric method at wavelength 370 nm. The stoichiometry of the complex is established as 1:1 (M: L) by Job’s method of continuous ...

  9. Complexation of Iron by Dopamine Analogs; A Spectrophotometric and Potentiometric Study

    *T. Fiaz; N. Fatima; S. Z. A. Zaidi

    2013-01-01

    The chelation of Bio-essential metal, Iron, with dopamine analogs was studied at 30±2°C. Fe2+ formed intense color complex with these molecules with an absorbance maxima in visible region. A distinct peak of Fe-Carbidopa complex at 364nm with molar absorptivity of 1600 M-1 cm-1 was observed while that of Fe-Levodopa and Fe-Methyldopa were observed at 730nm with molar absorptivities of 306 M-1 cm-1 and 2300 M-1 cm-1, respectively. Potentiometric studies of the complex indicate that Fe(II) ...

  10. Extractive Spectrophotometric Determination of Ambrisentan

    Chandra Bala Sekaran; Telu Visalakshi; Avula Prameela Rani; Namasani Santhosh Kumar

    2013-01-01

    Purpose: Ambrisentan (ABS) is an antihypertensive drug used in the treatment of pulmonary atrial hypertension. The survey of literature for ABS revealed only two spectrophotometric methods for its quantification. The reported methods lack the sensitivity. This study is aimed at developing two sensitive extractive spectrophotometric methods for the determination of ABS in bulk and in tablets. Methods: The proposed methods are based on the formation of colored chloroform extractable io...

  11. A comparative study of novel spectrophotometric methods based on isosbestic points; application on a pharmaceutical ternary mixture.

    Lotfy, Hayam M; Saleh, Sarah S; Hassan, Nagiba Y; Salem, Hesham

    2014-05-21

    This work represents the application of the isosbestic points present in different absorption spectra. Three novel spectrophotometric methods were developed, the first method is the absorption subtraction method (AS) utilizing the isosbestic point in zero-order absorption spectra; the second method is the amplitude modulation method (AM) utilizing the isosbestic point in ratio spectra; and third method is the amplitude summation method (A-Sum) utilizing the isosbestic point in derivative spectra. The three methods were applied for the analysis of the ternary mixture of chloramphenicol (CHL), dexamethasone sodium phosphate (DXM) and tetryzoline hydrochloride (TZH) in eye drops in the presence of benzalkonium chloride as a preservative. The components at the isosbestic point were determined using the corresponding unified regression equation at this point with no need for a complementary method. The obtained results were statistically compared to each other and to that of the developed PLS model. The specificity of the developed methods was investigated by analyzing laboratory prepared mixtures and the combined dosage form. The methods were validated as per ICH guidelines where accuracy, repeatability, inter-day precision and robustness were found to be within the acceptable limits. The results obtained from the proposed methods were statistically compared with official ones where no significant difference was observed. PMID:24589996

  12. Spectrophotometric Study of the Effect of a Magnetic Field on Human Blood Components

    Kazin, V. N.; Makaryin, V. V.; Guzov, E. A.; Moshareva, V. A.; Kovchiy, K. A.

    2016-07-01

    We have used electronic spectroscopy and optical aggregometry to study the effect of a constant magnetic fi eld on blood components. Based on the absorption spectra, we observe a decrease in optical density for both plasma and whole blood samples. Based on the results of platelet aggregation studies, we identifi ed two groups of test subjects with opposite types of responses to exposure to a magnetic fi eld. The observed behavior is probably associated with changes in the spatial structure of the proteins.

  13. Determination of Cyproheptadine hydrochloride in Pure and Pharmaceutical forms : A Spectrophotometric study

    Sayanna; T. Veeraiah; Ch. Venkata Ramana Reddy

    2015-01-01

    Siimple and sensitive extractive spectrophotometric methods have been described for the determination of Cyproheptadine hydrochloride (CPH) in pure form and in pharmaceutical formulations. The developed methods involved formation of coloured chloroform extractable ion-pair complexes of the CPH with triphenyl methane dyes viz., bromothymol blue (BTB), bromocresol green (BCG) and bromocresol purple (BCP) in acidic medium. The extracted complexes showed absorbance maxima at 419, 419 and 405nm ...

  14. UO22+ - XO42 - H2O TRLFS and spectrophotometric speciation study (X=S, Se)

    Complex species [UO2(XO4)n(H2O)p]2-2n (X = S, Se) formation is of importance for geochemical studies (of, e.g., uranium mining and radioactive waste repositories - including safety studies). Speciation studies by Time-resolved Laser-induced Fluorescence Spectroscopy and UV-VIS absorption spectrophotometry led to deconvoluted individual species luminescence and absorption spectra (the former interpreted in terms of adiabatic excitation energy and uranyl group symmetric mode vibrational frequency), luminescence life-times and complex stability constants J3m (and corresponding enthalpy and entropy from Van't Hoff equation fit). Obtained zero ionic strength extrapolated values log J3m° for selenate complexes (2.7 + 0.3; 3.1 + 0.6) are smaller than for sulphate complexes, both absorption and luminescence spectra of selenates are similar to sulphate analogs. Preliminary study on temperature dependence of luminescence life-times has been started here for the [UO2(H2O)5]2+ species too. (author)

  15. Different spectrophotometric methods applied for the analysis of binary mixture of flucloxacillin and amoxicillin: A comparative study

    Attia, Khalid A. M.; Nassar, Mohammed W. I.; El-Zeiny, Mohamed B.; Serag, Ahmed

    2016-05-01

    Three different spectrophotometric methods were applied for the quantitative analysis of flucloxacillin and amoxicillin in their binary mixture, namely, ratio subtraction, absorbance subtraction and amplitude modulation. A comparative study was done listing the advantages and the disadvantages of each method. All the methods were validated according to the ICH guidelines and the obtained accuracy, precision and repeatability were found to be within the acceptable limits. The selectivity of the proposed methods was tested using laboratory prepared mixtures and assessed by applying the standard addition technique. So, they can be used for the routine analysis of flucloxacillin and amoxicillin in their binary mixtures.

  16. Spectrophotometric determination of volautile inorganic hydrides in binary gaseous mixtures

    A study was made on possibility of single and continuons analysis of binary mixtures (hydride-gas) for the content of volatile inorganic hydrides (VIH) from absorption spectra in the 185-280 nm band. Dependences of the percentage of VIH transmission on the wavelength are presented. It is shown that the maximum of their absorption depends on the element-hydrogen the bond length and binding energy. Detection limit for boron hydride was established to be n x 10-3% vol at 185-190 nm wavelength. Technique for spectrophotometric hydride determination in binary mixtures with hydrogen, argon, helium was developed. The technique provides the continuous control of gaseous mixture composition

  17. SPECTROPHOTOMETRIC ESTIMATION OF GEMFIBROZIL IN BULK AND PHARMACEUTICAL DOSAGE FORMS

    Parikh Vikas C.

    2011-06-01

    Full Text Available A simple, sensitive and accurate UV spectrophotometric method has been developed for the determination of Gemfibrozil in bulk and pharmaceutical tablet dosage formulation. This method obeys Beer’s law in the concentration range of 30-90 µg/ml. with correlation coefficient of 0.9993 and exhibiting maximum absorption at 276 nm with apparent molar absorptivity of 0.1703 × 104 L mole-1 cm-1. The method is accurate and precise and is extended to pharmaceutical tablet dosage forms and there was no interference from any common pharmaceutical additives and excipients. The results of analysis were validated statistically and by recovery studies.

  18. Spectrophotometric study of the charge transfer complexation of some porphyrin derivatives as electron donors with tetracyanoethylene

    El-Zaria, Mohamed E.

    2008-01-01

    Charge transfer complexes (CTC) of 5,10,15,20-tetraphenylporphyrin (TPP), 5,10,15,20-tetra(4-tolyl)porphyrin (TTP), 5,10,15,20-tetra(4-methoxyphenyl)porphyrin (TMP), Zn-5,10,15,20-tetraphenylporphyrin (Zn-TPP), and Zn-5,10,15,20-tetra(4-tolyl)porphyrin (Zn-TTP) with tetracyanoethylene (TCNE) have been studied at various temperatures in CH 2Cl 2 and CCl 4. The data are discussed in terms of equilibrium constant ( KCT), molar extinction coefficient ( ɛCT), thermodynamic standard reaction quantities (Δ G°, Δ H° and Δ S°), oscillator strength ( f), and transition dipole moment ( μ). The spectrum obtained for TPP/TCNE, TTP/TCNE, and TMP/TCNE systems shows two main absorption bands at 475 and 690 nm, which are not due to the absorption of any of the reactants. These bands are characteristic of an intermolecular charge transfer involving the overlap of the lowest unoccupied molecular orbital (LUMO) of the acceptor with the highest occupied molecular orbital (HOMO) of the donor. The results reveal that the interaction between the donors and acceptor is due to π-π * transitions by the formation of radical ion pairs. The stoichiometry of the complexes was found to be 1:1 ratio by the Job and straight line methods between donors and acceptor with the maximum absorption bands at wavelengths of 475 and 690 nm. The observed data show salvation effects on the spectral and thermodynamics properties of CTC. The ionization potential of the donors and the dissociation energy of the CTC were also determined and are found to be constant.

  19. Spectrophotometric studies on rhenium complexes of dio-o-hydroxy benzylidene and di-anisylidene thio-carbohydrazones and 3, 5-dimercapto-4 amino-4, 1, 2-triazole

    Spectrophotometric studies on the reactions of dio-o- hydroxybenzylidene and di-anisylidene thiocarbohydrazone and 3,5- dimercapto-4 amino 4,1,2 triazole have been made. The reagents can be utilised for the spectrophotometric determination of rhenium. The sensitivities of determination are comparable with the existing reagents including the other thiocarbohydrazide derivatives and the selectivity is higher 3,5 dimercapto-3 amino-4,1,2, triazole has been found to be more selective than other thiocarbohydrazide derivatives. The composition of the complexes in solution have been ascertained and overall and stepwise formation constants have been evaluated by standard methods. (author). 6 refs., 1 tab

  20. Validation of UV spectrophotometric methods for the determination of dothiepin hydrochloride in pharmaceutical dosage form and stress degradation studies

    Abdulrahman, Sameer A. M.; Basavaiah, K.; Cijo, M. X.; Vinay, K. B.

    2012-11-01

    Spectrophotometric methods have been developed for the determination of dothiepin hydrochloride (DOTH) in both pure and tablet dosage form and their limits of detection and quantification have been evaluated. The methods are based on the measurement of the absorbance of a DOTH solution either in 0.1 N HCl at 229 nm (method A) or in methanol at 231 nm (method B). Beer's law is obeyed over a concentration range of 1-16 μg/ml DOTH for both methods. Molar absorptivity values are calculated to be 2.48 × 104 and 2.42 × 104 l/(mol × cm) with Sandell sensitivity values of 0.0134 and 0.0137 μg/cm2 for methods A and B, respectively. The degradation behavior of DOTH was investigated under different stress conditions such as acid hydrolysis, alkaline hydrolysis, water hydrolysis, oxidation, dry heat treatment, and UV-degradation. The drug undergoes significant degradation under oxidative conditions only.

  1. Spectrophotometric and Voltammetric Studies on the Interaction of Heparin with Phenosafranine

    Wei SUN; Ya Qin DING; Kui JIAO

    2005-01-01

    The interaction of phenosafranine (PSF) with a glycosaminoglycans of heparin (Hep) in aqueous solution has been characterized by UV-Vis absorption spectrophotometry and cyclic voltammetry in pH 1.5 Britton-Robinson (B-R) buffer solution. The addition of Hep caused decrease of the absorbance of PSF at 532 nm and the redox peak current of PSF. The study showed that an supramolecular complex of PSF-Hep was formed because of the electrostatic attraction of negatively charged Hep with the positively charged PSF, which resulted in the decrease of the equilibrium concentration of PSF in solutions, and the decrease of the absorbance or the Peak current of PSF. The stoichiometry of the Hep/PSF complex was further calculated by voltammetric data with the result of 1:1 complex.

  2. An Introduction to Multivariate Curve Resolution-Alternating Least Squares: Spectrophotometric Study of the Acid-Base Equilibria of 8-Hydroxyquinoline-5-Sulfonic Acid

    Rodriguez-Rodriguez, Cristina; Amigo, Jose Manuel; Coello, Jordi; Maspoch, Santiago

    2007-01-01

    A spectrophotometric study of the acid-base equilibria of 8-hydroxyquinoline-5-sulfonic acid to describe the multivariate curve resolution-alternating least squares algorithm (MCR-ALS) is described. The algorithm provides a lot of information and hence is of great importance for the chemometrics research.

  3. Spectrophotometric and electrochemical study of neptunium ions in molten NaCl–CsCl eutectic

    The chemical oxidation states of NpO2+, Np4+ and Np3+ in NaCl–CsCl eutectic were controlled by using Cl2, O2, H2 and Ar gas mixtures, the redox behavior and electronic absorption properties of their Np ions were studied. The Np4+ was prepared from NpO2Cl by bubbling Cl2 gas into the melt in the presence of carbon rod. Np3+ was quantitatively prepared by bubbling H2–Ar gas mixture. The molar absorptivities of NpO2+, Np4+ and Np3+ were determined in molten NaCl–CsCl eutectic at 923 K and hypersensitive transitions of Np4+ and Np3+ ions were assigned. Since the polarizing ability of the cations in the NaCl–CsCl eutectic is lower than that in some other melts, it has been shown that the coordination symmetry of the Np–Cl complex is higher. In the electrochemical measurement of Np4+, the cathodic current for the reduction of Np4+ was found to be controlled by the diffusion of Np4+. The temperature dependence of the diffusion coefficient between 823 and 923 K was formulated to be lnDNp4+=-4304/T-6.172. The formal redox potential of the Np4+|Np3+ couple depended on the temperature, this dependence was formulated as ENp4+|Np3+∘′=-1.313+6.210×10-4TV (vs. Cl2|Cl−)

  4. One-electron oxidation of chlorophyll a and (tetraphenylporphyrinato)cobalt(II) by various metalloporphyrin cation radicals. Kinetic spectrophotometric studies

    One-electron oxidations of various metalloporphyrins in dichloroethane solutions were studied by kinetic spectrophotometric pulse radiolysis. Co/sup II/TPP (TPP = tetraphenylporphyrin) was found to produce Co/sup III/TPP while the Cd(II), Cu(II), Pb(II), and VO complexes, like the ZnTPP and MgTPP, yield the cation radicals. Ni/sup II/TPP is oxidized at the metal center in the presence of pyridine but at the ligand in its absence. The subsequent one-electron oxidation of chlorophyll a and Co/sup II/TPP by the above cation radicals was also followed. The rate constants for these reactions were found to be mostly in the range of 3 x 108-5 x 108 M-1 s-1, much lower than the expected diffusion-controlled rates

  5. Studies on the optimum flotation system for separation and spectrophotometric determination of ruthenium with Crystal Violet and Victoria Blue B

    The reaction of various chloride complexes of ruthenium with tin (II) chloride has been examined. Studies on the optimum conditions for separation of ruthenium from aqueous solutions after reaction with Crystal Violet (or Victoria Blue B) by flotation with weakly polar organic solvents have been carried out. A sensitive spectrophotometric method for determination of ruthenium based on the system: ruthenium-tin (II) chloride-Crystal Violet-toluene has been developed. Ruthenium is quantitatively floated in the form of a sparingly soluble precipitate. The separation of ruthenium is selective (simple salts of the dye are not floated). Acetone-aqueous solutions of the ion associate obey Beer's law in the 0.04 - 0.56 μg Ru/ml. The relative standard deviation is 1 - 4%. Osmium interfers with the determination of ruthenium

  6. Spectrophotometric determination of benazepril in tablets.

    Belal, F; Al-Zaagi, I A; Abounassif, M A

    2000-01-01

    A simple and sensitive spectrophotometric method has been developed for the determination of benazepril HCl in pharmaceutical formulations. The method is based on the reaction of the drug with potassium permanganate in the presence of sodium hydroxide to produce a bluish-green colored species measurable at 609.4 nm. The absorbance-concentration plot is linear over the range 1-8 microg ml(-1) with minimum detectability of 0.1 microg ml(-1) (2.17 x 10(-7) M). The molar absorptivity was 4.07 x 10(4) l mol(-1) cm(-1) with correlation coefficient (n = 6) of 0.9991. The different experimental parameters affecting the development and stability of the color were studied carefully and optimized. The proposed method was applied successfully to the determination of benazepril in its dosage forms, the percentage recoveries +/- SD (n = 9) were 99.79 +/- 1.40 and 100.50 +/- 1.48 for tablets containing 10 and 20 mg, respectively. The results obtained were in good agreement with those obtained using a reference spectrophotometric method. The proposed method could be applied to the determination of benazepril in presence of the co-formulated drug, hydrochlorothiazide. A proposal of the reaction pathway was presented. PMID:11204742

  7. Spectrophotometric method for ondansetron hydrochloride

    Patra Sradhanjali; Choudhury A.; Kar R; Barik B

    2007-01-01

    A new simple, sensitive spectrophotometric method in UV region has been developed for the estimation of ondansetron in bulk and solid dosage form. It shows maximum absorbance at 310 nm with water. Beer′s law obeys in the concentration range of 5-15 µg/ml. Results of the analysis were validated statistically and by recovery studies.

  8. Spectrophotometric method for ondansetron hydrochloride

    Patra Sradhanjali

    2007-01-01

    Full Text Available A new simple, sensitive spectrophotometric method in UV region has been developed for the estimation of ondansetron in bulk and solid dosage form. It shows maximum absorbance at 310 nm with water. Beer′s law obeys in the concentration range of 5-15 µg/ml. Results of the analysis were validated statistically and by recovery studies.

  9. Potentiometric and spectrophotometric studies of the complexation of Schiff-base hydrazones containing the pyrimidine moiety

    M. SHEBL

    2003-10-01

    Full Text Available Three Schiff-base hydrazones (ONN – donors were prepared by condensation of 2-amino-4-hydrazino-6-methylpyrimidine with 2-hydroxyacetophenone, 2-methoxybenzaldehyde and diacetyl to yield 2-OHAHP, 2-OMeBHP and DHP, respectively. The structures of these ligands were elucidated by elemental analysis, UV, IR, 1H-NMR and mass spectra. The metal–ligand stability constants of Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, UO22+ and Th4+ chelates were determined potentiometrically in two different media (75 % (v/v dioxane–water and ethanol–water at 283, 293, 303 and 313 K at an ionic strength of 0.05 M (KNO3. The thermodynamic parameters of the 1:1 and 1:2 complexes were evaluated and are discussed. The dissociation constants of 2-OHAHP, 2-OMeBHP and DHP ligands and the stability constants of Co2+, Ni2+ and Cu2+ with 2-OHAHP were determined spectrophotometrically in 75 % (v/v dioxane–water.

  10. EVALUATION OF HEAVY METALS IN ETHANOLIC LEAF EXTRACT OF ACACIA CATECHU AS INDICATOR OF POLLUTION BY ATOMIC ABSORPTION SPECTROPHOTOMETRIC (FAAS) ANALYSIS

    Lakshmi T; Rajendran R; Antony silvester

    2013-01-01

    Acacia catechu ethanolic leaf extract were selected to determine their heavy metals content and thereby to assure their safer therapeutic application. The trace and heavy metals were detected through atomic absorption spectrometry analysis. The selected medicinal plant material was procured from green chem herbal extracts, Bangalore, India and was digested with nitric acid and hydrochloric acid as specified. Absorbance was measured through atomic absorption spectrometer (AA 6030) and the conc...

  11. A spectrophotometric method for uranium determination

    A very sensitive extraction spectrophotometric method for the analysis of uranium based on the extraction of a uranium-benzoate-crystal violet complex by a mixture of xylene and benzene is described. The absorbance maximum is at 606 nm and molar absorptivity is 4.28x104 lxmol-1xcm-1. The interference due to a number of anions and cations studied without any pre-extraction was found to be within permissible limits. The method has been used for determining uranium in a synthetic solution, i.e., uranium in the presence of various other ions. The interference due to some cations was eliminated by the use of a masking agent (boric acid). (author)

  12. Sublimation of ice-tholins mixtures: A morphological and spectro-photometric study

    Poch, Olivier; Pommerol, Antoine; Jost, Bernhard; Carrasco, Nathalie; Szopa, Cyril; Thomas, Nicolas

    2016-03-01

    Sublimation, the direct transition from solid to gas phase, is a process responsible for shaping and changing the reflectance properties of many Solar System surfaces. In this study, we have characterized the evolution of the structure/texture and of the visible and near-infrared (VIS-NIR) spectral reflectance of surfaces made of water ice mixed with analogues of complex extraterrestrial organic matter, named tholins, under low temperature (water ice sublimated, we observed in situ the formation of a sublimation lag deposit made of a water-free porous (>90% porosity) network of organic filaments on top of the ice. The temporal evolution of the tholins and water ice spectral features (reflectance at the absorption bands wavelengths, red slope, from 0.40 to 1.90 μm) are analyzed throughout the sublimation of the samples. We studied how different mixtures of tholins with water (0.1 wt.% tholins as coating or inclusions within the water particles), and different ice particle sizes (4.5 ± 2.5 or 67 ± 31 μm) influence the morphological and spectral evolutions of the samples. The sublimation of the ice below the mantle produces a gas flow responsible for the ejection of mm to cm-sized fragments of the deposit in outbursts-like events. The results show remarkable differences between these samples in term of mantle structure, speed of mantle building, rates and surface area of mantle ejections. These data provide useful references for interpreting remote-sensing observations of icy Solar System surfaces, in particular the activity of comet nuclei where sublimation of organic-rich ices and deposition of organic-dust particles likely play a major role. Consequently, the data presented here could be of high interest for the interpretation of Rosetta, and also New Horizons, observations.

  13. The hydrolysis and precipitation of Pd(II) in 0.6 mol kg-1 NaCl: A potentiometric, spectrophotometric, and EXAFS study

    The hydrolysis of palladium was investigated in 0.6 mol kg-1 NaCl at 298.2 K. Potentiometric titrations of solutions at various total concentrations of palladium(II) revealed that dilute (millimolar) conditions can be used to monitor the proton release due to hydrolysis reactions up to 2 protons per palladium(II) as long as the equilibration time is kept small. Spectrophotometric titrations were used to corroborate the homogeneous changes in speciation for the PdCl3OH2- species and to extract its correlative molar absorption coefficients in the 210-320 nm range. The molar absorption coefficients are similar to those of PdCl42- but exhibit a broader distribution of excitation energies resulting from the blue shift of the dominant charge transfer bands due to the presence of OH-. The longer-term potentiometric titrations systematically yielded, on the other hand, precipitates which matured over a period of 6 weeks and resulted in a more extensive release of protons to the solution. Precipitation experiments at six different total palladium(II) concentrations in the 3-11 pH range showed the dominant precipitating phase as Pd(OH)1.72Cl0.28. The coordination environment of Pd in this solid was investigated by extended X-ray absorption fine structure spectroscopy (EXAFS) and yielded an average 1.75 O and 0.25 Cl per Pd atoms with a Pd-O distance of 2.0 (angstrom) and Pd-Cl of 2.1 (angstrom). Finally, the precipitation experiments showed the final products to be of larger solubility than a literature Pd(OH)2 solubility study in which the KCl media induced a solid phase transformation to Pd(OH)1.72Cl0.28. Polynuclear complexes Pdq(OH)r2q-r with q=r=[3,9] explain the combined precipitation and hydrolysis data and may represent subsets of [Pd(OH)2]n and/or [Pd(OH)1.72Cl0.28]n chains coiled into nanometer-sized spheroids previously described in the literature

  14. Study on Performance and Mechanism of Oil Absorption Materials

    韩梅; 吴兵; 李发生; 何绪文; 谷庆宝

    2001-01-01

    Both the commonly used and the PHBV based oil absorption materials were studied and the absorption mechanism was analyzed. The results show that the oil pick-up ratios and the absorption rates of molded PHBV are almost the same as that of oil absorption polypropylene felt. In addition, the oil-keeping ability of molded PHBV is superior to the latter. So the PHBV is a valuable and bio-degradable oil absorption material.

  15. Spectrophotometric determination of Ru(III) using rhodanine

    A simple and direct spectrophotometric method using 2-thion- thiazolid-4-one has been developed for determination of Ru(III). Molar absorptivity and Sandell's sensitivity are calculated to be 6.5555x103 L mol-1cm-1 and 0.0154 μg cm-2 respectively. The effect of various parameters including time, pH and volume of reagent has been studied. The Beer's law is obeyed over the range 0.202-6.873 μg of Ru(III). The method has been applied for the determination of Ru(III) in various synthetic and real samples. (author)

  16. A new, fast and accurate spectrophotometric method for the determination of the optical constants of arbitrary absorptance thin films from a single transmittance curve: application to dielectric materials

    Desforges, Jean; Deschamps, Clément; Gauvin, Serge

    2015-08-01

    The determination of the complex refractive index of thin films usually requires the highest accuracy. In this paper, we report on a new and accurate method based on a spectral rectifying process of a single transmittance curve. The agreements with simulated and real experimental data show the helpfulness of the method. The case of materials having arbitrary absorption bands at midpoint in spectral range, such as pigments in guest-host polymers, is also encompassed by this method.

  17. Multivariate curve resolution of incomplete fused multiset data from chromatographic and spectrophotometric analyses for drug photostability studies

    Highlights: • A new MCR-ALS algorithm is proposed for the analysis of incomplete fused multiset. • Resolution of the data allowed the description of amiloride kinetic photodegradation. • The new MCR-ALS algorithm can be easily applied to other drugs and chemicals. - Abstract: An advanced and powerful chemometric approach is proposed for the analysis of incomplete multiset data obtained by fusion of hyphenated liquid chromatographic DAD/MS data with UV spectrophotometric data from acid–base titration and kinetic degradation experiments. Column- and row-wise augmented data blocks were combined and simultaneously processed by means of a new version of the multivariate curve resolution-alternating least squares (MCR-ALS) technique, including the simultaneous analysis of incomplete multiset data from different instrumental techniques. The proposed procedure was applied to the detailed study of the kinetic photodegradation process of the amiloride (AML) drug. All chemical species involved in the degradation and equilibrium reactions were resolved and the pH dependent kinetic pathway described

  18. Multivariate curve resolution of incomplete fused multiset data from chromatographic and spectrophotometric analyses for drug photostability studies

    Luca, Michele De, E-mail: michele.deluca@unical.it [Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Via P. Bucci, Rende, CS 87036 (Italy); Ragno, Gaetano; Ioele, Giuseppina [Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Via P. Bucci, Rende, CS 87036 (Italy); Tauler, Romà [Department of Environmental Chemistry, IDAEA-CSIC, C/Jordi Girona, 18-26, Barcelona 08034 (Spain)

    2014-07-21

    Highlights: • A new MCR-ALS algorithm is proposed for the analysis of incomplete fused multiset. • Resolution of the data allowed the description of amiloride kinetic photodegradation. • The new MCR-ALS algorithm can be easily applied to other drugs and chemicals. - Abstract: An advanced and powerful chemometric approach is proposed for the analysis of incomplete multiset data obtained by fusion of hyphenated liquid chromatographic DAD/MS data with UV spectrophotometric data from acid–base titration and kinetic degradation experiments. Column- and row-wise augmented data blocks were combined and simultaneously processed by means of a new version of the multivariate curve resolution-alternating least squares (MCR-ALS) technique, including the simultaneous analysis of incomplete multiset data from different instrumental techniques. The proposed procedure was applied to the detailed study of the kinetic photodegradation process of the amiloride (AML) drug. All chemical species involved in the degradation and equilibrium reactions were resolved and the pH dependent kinetic pathway described.

  19. A comparative study of ICH validated novel spectrophotometric techniques for resolving completely overlapping spectra of quaternary mixtures

    Ali, Nouruddin W.; Abdelwahab, Nada S.; Abdelkawy, M.; Emam, Aml A.

    2016-02-01

    A pharmaceutically marketed mixture of Yohimbine, Alpha-tocopheryl acetate, Niacin, and Caffeine co-formulated as a promising therapy for erectile dysfunction. Simultaneous determination of the aforementioned pharmaceutical formulation without prior separation steps was applied using mean centering of ratio spectra and triple divisor spectrophotometric methods. Mean centering of ratio spectra method depended on using the mean centered ratio spectra in three successive steps which eliminated the derivative steps and so the signal to noise ratio was improved. The absorption spectra of the prepared solutions were measured in the wavelength range of 215-300 nm in the concentration ranges of 1-15, 3-15, 1-20, and 3-15 μg mL- 1 for Yohimbine, Alpha-tocopheryl acetate, Niacin, and Caffeine, respectively. The amplitudes of the mean centered third ratio spectra were measured at 250 nm and 268 nm for Yohimbine and Alpha-tocopheryl acetate, respectively and at peak to peak 272-273 and 262-263 nm for Niacin and Caffeine, respectively. In triple divisor method each drug in the quaternary mixture was determined by dividing the spectrum of the quaternary mixture by a standard spectrum of a mixture containing equal concentrations of the other three drugs. First derivative of these ratio spectra was obtained where determination could be achieved without any interference from the other three drugs. Amplitudes of 1-15, 3-15, 1-15, and 3-15 μg mL- 1 were used for selective determination of Yohimbine, Alpha-tocopheryl acetate, Niacin, and Caffeine, respectively. Laboratory prepared mixtures were analyzed by the developed novel methods to investigate their selectivity also, Super Act® capsules were successfully analyzed to ensure absence of interference from additives. The developed methods were validated according to the ICH guidelines. The proposed methods were statistically compared with each other and with the reported methods; using student t-test, F-test, and one way ANOVA

  20. EVALUATION OF HEAVY METALS IN ETHANOLIC LEAF EXTRACT OF ACACIA CATECHU AS INDICATOR OF POLLUTION BY ATOMIC ABSORPTION SPECTROPHOTOMETRIC (FAAS ANALYSIS

    Lakshmi.T

    2013-06-01

    Full Text Available Acacia catechu ethanolic leaf extract were selected to determine their heavy metals content and thereby to assure their safer therapeutic application. The trace and heavy metals were detected through atomic absorption spectrometry analysis. The selected medicinal plant material was procured from green chem herbal extracts, Bangalore, India and was digested with nitric acid and hydrochloric acid as specified. Absorbance was measured through atomic absorption spectrometer (AA 6030 and the concentration of different heavy metals in the plant sample was calculated. The quantitative determinations were carried out using standard calibration curve obtained by the standard solutions of different metals. The contents of heavy metals were found to be within the prescribed limit. Thus, on the basis of experimental outcome, it can be concluded that the plant material is safe and may not produce any harmful effect of metal toxicity during their therapeutic application. The investigated medicinal plants contains heavy metals such as arsenic (As, lead (Pb and mercury (Hg and cadmium (Cd, which were present within the permissible limit.

  1. DEVELOPMENT AND VALIDATION OF SPECTROPHOTOMETRIC METHOD FOR DETERMINATION OF TRIMETAZIDINE IN PHARMACEUTICAL DOSAGE FORMS

    Y. Naga Prasanna*, S. Archana, G.S. Sowjanya, S. Lalitha, M. Lalitha

    2013-01-01

    ABSTRACT: A simple and sensitive UV spectrophotometric method has been developed for the quantitative estimation of trimetazidine in bulk drug and pharmaceutical dosage forms (tablets). Trimetazidine exhibited absorption maximum at 269 nm in 0.1 N HCl and obeyed Beer’s law in concentration range 5-25 µg/ml. The result of analysis in this method has been validated statistically and by recovery studies. This method is extended for the analysis of drug in pharmaceutical formulations.

  2. DEVELOPMENT AND VALIDATION OF SPECTROPHOTOMETRIC METHOD FOR DETERMINATION OF TRIMETAZIDINE IN PHARMACEUTICAL DOSAGE FORMS

    Y. Naga Prasanna*, S. Archana, Y. Poornima, S. Lalitha and M. Lalitha

    2013-03-01

    Full Text Available ABSTRACT: A simple and sensitive UV spectrophotometric method has been developed for the quantitative estimation of trimetazidine in bulk drug and pharmaceutical dosage forms (tablets. Trimetazidine exhibited absorption maximum at 269 nm in 0.1 N HCl and obeyed Beer’s law in concentration range 5-25 µg/ml. The result of analysis in this method has been validated statistically and by recovery studies. This method is extended for the analysis of drug in pharmaceutical formulations.

  3. Existence and reactivity of three forms of orthophthalaldehyde in aqueous solutions. Polarographic, voltammetric, and spectrophotometric study.

    Salem, Nuha; Andreescu, Silvana; Kulla, Eliona; Zuman, Petr

    2007-05-31

    Orthophthalaldehyde (1,2-dicarboxaldehyde) (OPA) forms in the presence of a strong nucleophile with amino acids isoindole derivatives. The reaction is used in fluorometric determination of amino acids. The mechanism of these processes is not understood. OPA is present in aqueous solutions in three forms: unhydrated (I(a)), monohydrated acyclic (I(b)), and cyclic hemiacetal (I(c)). The absence of data for the molar absorptivities of these forms, together with overlap of their absorption bands, limits the application of spectrophotometry. Measurement of polarographic limiting currents of forms I(a) and I(b) enables determination of equilibrium constants K1 (formation of I(b)) and K2 (for the ring formation). The presence of these forms was supported by 1H NMR and 13C NMR. The rate of hydration of OPA is general-acid-base-catalyzed, but that of dehydration shows only specific-acid-base catalysis. The rate of hydration is controlled by general-acid-base-catalyzed addition of water to I(a). The rate of dehydration depends on the opening of the ring in I(c), which is specific-acid-base-catalyzed. At pH > 10 OPA undergoes a complex set of acid-base reactions (Scheme 3). The presence of polarographic anodic waves and oxidation on the gold electrode indicates the importance of the presence of a geminal diol form (II(a)). Establishment of equilibria among the three forms of OPA together with reactions at pH > 10 has to be considered in elucidating the reaction scheme of procedures using OPA as a reagent in the determination of amino acids. PMID:17488102

  4. Validated spectrophotometric methods for determination of some oral hypoglycemic drugs.

    Farouk, M; Abdel-Satar, O; Abdel-Aziz, O; Shaaban, M

    2011-02-01

    Four accurate, precise, rapid, reproducible, and simple spectrophotometric methods were validated for determination of repaglinide (RPG), pioglitazone hydrochloride (PGL) and rosiglitazone maleate (RGL). The first two methods were based on the formation of a charge-transfer purple-colored complex of chloranilic acid with RPG and RGL with a molar absorptivity 1.23 × 103 and 8.67 × 102 l•mol-1•cm-1 and a Sandell's sensitivity of 0.367 and 0.412 μg•cm-2, respectively, and an ion-pair yellow-colored complex of bromophenol blue with RPG, PGL and RGL with molar absorptivity 8.86 × 103, 6.95 × 103, and 7.06 × 103 l•mol-1•cm-1, respectively, and a Sandell's sensitivity of 0.051 μg•cm-2 for all ion-pair complexes. The influence of different parameters on color formation was studied to determine optimum conditions for the visible spectrophotometric methods. The other spectrophotometric methods were adopted for demtermination of the studied drugs in the presence of their acid-, alkaline- and oxidative-degradates by computing derivative and pH-induced difference spectrophotometry, as stability-indicating techniques. All the proposed methods were validated according to the International Conference on Harmonization guidelines and successfully applied for determination of the studied drugs in pure form and in pharmaceutical preparations with good extraction recovery ranges between 98.7-101.4%, 98.2-101.3%, and 99.9-101.4% for RPG, PGL, and RGL, respectively. Results of relative standard deviations did not exceed 1.6%, indicating that the proposed methods having good repeatability and reproducibility. All the obtained results were statistically compared to the official method used for RPG analysis and the manufacturers methods used for PGL and RGL analysis, respectively, where no significant differences were found. PMID:22466095

  5. A cylindrical furnace for absorption spectral studies

    R Venkatasubramanian

    2001-06-01

    A cylindrical furnace with three heating zones, capable of providing a temperature of 1100°C, has been fabricated to enable recording of absorption spectra of high temperature species. The temperature of the furnace can be controlled to ± 1°C of the set temperature. The salient feature of this furnace is that the material being heated can be prevented from depositing on the windows of the absorption cell by maintaining a higher temperature at both the ends of the absorption cell.

  6. Solvent extraction and spectrophotometric characteristics of mixed-ligand gadolinium, thulium and lutetium complexes with 4-(2-pyridylazo)resorcin and with acetic acid and its chloroderivatives

    Complexing and solvent extraction of gadolinium, thulium and lutetium with 4-(2-pyridylazo)resorcin and with acetic acid and its chloroderivatives are studied by radiochemical and spectrophotometric methods. Composition, stability constants and complex absorption molar coefficients are determined. The role and effect of additional ligands, organic solvents on basic physico-chemical characteristics of complexes produced are discussed

  7. A transient absorption study of allophycocyanin

    Y J Shiu; J M Zhang; M Hayashi; V Gulbinas; C M Yang; S H Lin

    2002-12-01

    Transient dynamics of allophycocyanin trimers and monomers are observed by using the pump-probe, transient absorption technique. The origin of spectral components of the transient absorption spectra is discussed in terms of both kinetics and spectroscopy. We find that the energy gap between the ground and excited states of the unexcited subunit of allophycocyanin monomer decreases via an interaction with another excited subunit. For allophycocyanin trimer, we find that the fast dynamics results from the fast internal conversion and the first excited state is the only one electronic state which can trap the final population.

  8. Spectrophotometric Analysis of Caffeine

    Showkat Ahmad Bhawani

    2015-01-01

    Full Text Available The nature of caffeine reveals that it is a bitter white crystalline alkaloid. It is a common ingredient in a variety of drinks (soft and energy drinks and is also used in combination with various medicines. In order to maintain the optimum level of caffeine, various spectrophotometric methods have been developed. The monitoring of caffeine is very important aspect because of its consumption in higher doses that can lead to various physiological disorders. This paper incorporates various spectrophotometric methods used in the analysis of caffeine in various environmental samples such as pharmaceuticals, soft and energy drinks, tea, and coffee. A range of spectrophotometric methodologies including chemometric techniques and derivatization of spectra have been used to analyse the caffeine.

  9. Spectrophotometric methods manipulating ratio spectra for simultaneous determination of binary mixtures with sever overlapping spectra: A comparative study

    Moustafa, H.; Fayez, Y.

    2014-12-01

    Three simple, specific and accurate spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of Rabeprazole sodium (RB) and Domperidone (DP) in their binary mixture without prior separation. Method A, is constant center spectrophotometric method (CC). Method B is a ratio difference spectrophotometric one (RD), while method C is a combined ratio isoabsorptive point-ratio difference method (RIRD). Linear correlations were obtained in range of 4-44 μg/mL for both Rabeprazole sodium and Domperidone. The mean percentage recoveries of RB were 99.69 ± 0.504 for method A, 99.83 ± 0.483 for (B) and 100.31 ± 0.499 for (C), respectively, and that of DP were 99.52 ± 0.474 for method A, 100.12 ± 0.505 for (B) and 100.16 ± 0.498 for (C), respectively. Specificity was investigated by analysis of laboratory prepared mixtures containing the cited drugs and their combined tablet dosage form. The obtained results were statistically compared with those obtained by the reported methods, showing no significant difference with respect to accuracy and precision. The three methods were validated as per ICH guidelines and can be applied for routine analysis in quality control laboratories.

  10. Spectrophotometric determination of uranium(VI) with 7-iodo-8-hydroxyquinoline-5-sulfonic acid (ferron)

    A new method is introduced to estimate uranium(VI) spectrophotometrically by extraction of its ferron (7-iodo-8-hydroxyquinoline-5-sulfonic acid) complex with 1% tridodecylamine in chloroform at pH 4.5. The optimum absorption wavelength is 380 mm. The stoichiometry of the uranium-ferron complex as indicated by a mole ratio plot is 1:2 and its dissociation constant is 3.24x10-9. The effects of various parameters on the absorption are studied. This method has a sensitivity of 0.028 ppm on Sandell's scale. Interferences are described. (author)

  11. The UV and IR Comparative Spectrophotometric Study of Some Saturated and Lacunary Polyoxometalates

    Grama Lavinia

    2014-06-01

    Full Text Available Objectives: The polyoxometalates are a class of inorganic compounds with controllable shapes and sizes, and with excellent properties that make them attractive for various applications. This study is aimed at the comparative UV and IR spectra of Keggin type polyoxometalates.

  12. The Nearby Field Galaxy Survey a spectrophotometric and photometric study of nearby galaxies

    Jansen, R A

    2001-01-01

    We report on our observing program to obtain integrated spectrophotometry, intermediate and high resolution major axis spectra, and U,B,R surface photo- metry of a representative sample of ~200 galaxies in the nearby field. The main goal of this program is to provide a comparison sample for high redshift studies and to study the variation in star formation rates (SFR), star forma- tion history (SFH), excitation, metallicity, and internal kinematics over a large range in galaxy luminosity and morphological type. In particular, we extend the work of Kennicutt (1992) to lower luminosity systems. We present the main results of our analysis sofar. In these proceedings, we condense the presented two atlases of (1) images and radial surface brightness profiles and color profiles, and (2) of images and integrated spectra into several example images, profiles and spectra, showing the general trends observed. For the original atlasses we refer to the electronic version, available at http://www.astro.rug.nl/~nfgs/ .

  13. Spectrophotometric study into complexing of vanadium(3) with salicylic acid derivatives

    Complexing of vanadium (3) with 5 amino-salicylic acid and amide of salicylhydroxamic acid has been studied. It has been shown that in acidic medium V3+ forms yellow complexes of the composition 1:1 with instability constants 2.2x10-19, 7.8x10-11, and 2.2x10-12, respectively. Complexes of V3+ with derivatives of salicylic acid can be used for determining V(3) content in the presence of V(4)

  14. Selectivity enhancement of Arsenazo(III) reagent towards heavier lanthanides using polyaminocarboxylic acids: A spectrophotometric study

    Matharu, Komal; Mittal, Susheel K.; Ashok Kumar, S. K.; Sahoo, Suban K.

    2015-06-01

    A new study has been conducted to quantify lanthanide(III) ions using Arsenazo III-polyaminocarboxylic acid (PACA) system. The study disclosed two different analytically important information: (i) λmax of lanthanide-Arsenazo III complexes for lighter lanthanides like Ce(III) and Nd(III) did not shift from its original position on addition of PACA and (ii) for heavier lanthanides like Dy(III), Tm(III) and Lu(III) a new λmax at 538 nm was observed, while wavelengths at 610 nm and 654 nm were disappeared in presence of ethylenediaminetertracetic acid (EDTA) and trans-1,2-Diaminocyclohexane-N,N,N‧,N‧-tetraacetic acid (DCTA), further the intensity of peak decreased with increase in lanthanide(III) ion concentration. Effect of ethylene glycol-bis(2-aminoethylether)-N,N,N‧,N‧-tetraacetic acid (EGTA) and N-(2-hydroxyethyl) ethylenediamine-N,N‧,N‧-triacetic acid (EDTA-OH) on Arsenzo(III)-Ln(III) complex is very weak and there is no analytically importance of such interaction. Moreover, this work confirms that Nd(III) and heavy lanthanides can be successfully determined with high accuracy in the working range of concentration of these metal ions.

  15. Interactions of major, minor and trace elements on the carbon rod atomic-absorption spectrophotometric determination of micro-amounts of ytterbium, holmium, dysprosium and thulium

    The electrothermal atomisation of trace amounts of some heavy rare earth elements has been investigated using a carbon rod atomiser. The interferences due to the components (major, minor and trace) of a common silicate matrix have been studied in order to obtain the best analytical conditions for future determinations. The detection limits (using uncoated graphite rods) are 5 pg of dysprosium, 3 pg of holmium and thulium and 0.4 pg of ytterbium. (author)

  16. Spectrophotometric intracutaneous analysis versus dermoscopy for the diagnosis of pigmented skin lesions: prospective, double-blind study in a secondary reference centre

    Glud, Martin; Gniadecki, Robert; Drzewiecki, Krzysztof T

    2009-01-01

    . Spectrophotometric intracutaneous analysis (SIAscopy) is a new, commercially available method of analyzing pigmented skin lesions noninvasively. The diagnosis is based on objective features such as the presence of dermal pigment, vascularity of the lesion, and the integrity of collagen. The objective of this study...... was to examine the usefulness of SIAscopy for the clinical diagnosis of malignant melanoma in a prospective, unbiased manner. We enrolled 65 patients with 83 lesions, where the diagnosis of melanoma could not be ruled out on the basis of the clinical evaluation by a nondermatologist. All lesions were...

  17. Determination of Modafinil in Tablet Formulation Using Three New Validated Spectrophotometric Methods

    In this study, three new UV spectrophotometric methods viz. linear regression equation (LRE), standard absorptivity (SA) and first order derivative (FOD) method were developed and validated for determination of modafinil in tablet form. The Beer-Lamberts law was obeyed as linear in the range of 10-50 μg/ mL and all the methods were validated for linearity, accuracy, precision and robustness. These methods were successfully applied for assay of modafinil drug content in tablets in the range of 100.20 - 100.42 %, 100.11 - 100.58 % and 100.25 - 100.34 %, respectively with acceptable standard deviation (less than two) for all the methods. The validated spectrophotometric methods may be successfully applied for assay, dissolution studies, bio-equivalence studies as well as routine analysis in pharmaceutical industries. (author)

  18. Kinetic Spectrophotometric Determination of Certain Cephalosporins in Pharmaceutical Formulations

    Omar, Mahmoud A.; Osama H. Abdelmageed; Tamer Z. Attia

    2009-01-01

    A simple, reliable, and sensitive kinetic spectrophotometric method was developed for determination of eight cephalosporin antibiotics, namely, Cefotaxime sodium, Cephapirin sodium, Cephradine dihydrate, Cephalexin monohydrate, Ceftazidime pentahydrate, Cefazoline sodium, Ceftriaxone sodium, and Cefuroxime sodium. The method depends on oxidation of each of studied drugs with alkaline potassium permanganate. The reaction is followed spectrophotometrically by measuring the rate of change of abs...

  19. Catalytic Spectrophotometric Determination of Chromium

    STOYANOVA, Angelina Miltcheva

    2005-01-01

    The catalytic effect of chromium(III) and chromium(VI) on the oxidation of sulfanilic acid by hydrogen peroxide was studied. The reaction was followed spectrophotometrically by measuring the absorbance of the reaction product at 360 nm. Under the optimum conditions 2 calibration graphs (for chromium(III) up to 100 ng mL-1, and for chromium(VI) up to 200 ng mL-1) were obtained, using the ``fixed time'' method with detection limits of 4.9 ng mL-1 and 3.8 ng mL-1, respectively...

  20. Determination of Tapentadol Hydrochloride in Tablets by Three New Validated Spectrophotometric Methods

    Deepti Jain

    2013-12-01

    Full Text Available Three UV spectrophotometric methods viz. linear regression equation (LRE, standard absorptivity (SA and first order derivative (FOD method were developed and validated according to ICH guideline. The methods were linear in the range of 10-50 μg/mL and validated methods were successfully applied for determination of tapentadol hydrochloride content in tablet dosage forms in the range of 100.42-100.64%, 100.31-100.54% and 100.10-100.59%, respectively. The standard deviation for all the methods was found to be less than one unit (0.45-0.83. The validated spectrophotometric methods may be successfully applied for assay, dissolution studies, bio-equivalence studies as well as routine analysis in pharmaceutical industries.

  1. Role of Ru(IlI) as an inhibitor in oxidation of lactose by (Cu(bipy)2)2+ in alkaline medium: spectrophotometric and kinetic studies

    Kinetics of oxidation of lactose by (Cu(bipy)2)2+ in alkaline medium using Ru(III) as an inhibitor has been studied spectrophotometrically at 40 °C. The studies show that the rate of the reaction is zero order with respect to (Cu(bipy)2)2+ and first order with respect to (lactose). The order of reaction is found to be two at low concentrations of OH- (from 1.48×105 to 3.47×105 M) and less than two at its high concentrations (from 4.27×105 to 6.31×105 M). There is a substantial decrease in the pseudo-zero order rate constant with increase in the concentration of Ru(III) chloride, indicating the role of Ru(III) chloride as an inhibitor. Decrease in the rate with increase in dielectric constant of the medium is observed, while ionic strength of the medium and bipyridyl concentration has no influence on the rate. Based on kinetic data and spectrophotometric evidences, a suitable mechanism is proposed for the studied reaction. (author)

  2. Derivative spectrophotometric determination of Ruthenium (III) using Diacetyl Monoxime Isonicotinoyl Hydrazone (DMIH)

    Ruthenium (III) forms a purple coloured water soluble complex with Diacetyl Monoxime Isonicotinoylhydrazone(DMIH) reagent in acidic buffer pH 4.5 with λmax at 346 nm. The molar absorptivity and Sandell's sensitivity are 1.4 X 104 L.mol-1.cm-1 and 0.0048 μg/cm2 respectively. The Beer's law validity range is 0.505 to 6.06 μg/ml. Ruthenium(III) forms (M:L) 1:1 complex with DMIH. Stability constant of the complex is 2.694X106. The derivative spectrophotometric determination of Ru(III) was carried out by measuring peak height method. The developed derivative spectrophotometric method was employed for the determination of Ruthenium (III) in synthetic samples of alloy and river water samples. The effect of various diverse ions is also studied. (author)

  3. Derivative spectrophotometric determination of uranium (VI using diacetyl monoxime isonicotinoyl hydrazone (DMIH

    ChandraSekhar Reddy Gadikota

    2011-08-01

    Full Text Available Uranium (VI forms a yellow coloured water soluble complex with diacetyl monoxime isonicotinoyl hydrazone (DMIH reagent in acidic buffer of pH 3.25 with ?max at 364 nm. The molar absorptivity and sandell’s sensitivity are 1.63 X 10 4 L.mol -1.cm-1 and 0.00307692 µg/cm 2, respectively. The Beer’s law validity range is 1.19–14.28 µg/mL. Uranium (VI forms (M:L 1:1 complex with DMIH and stability constant of the complex is 4.928 X 106 .The derivative spectrophotometric determination of U (VI was carried out by measuring peak height method. The developed derivative spectrophotometric method was employed for the determination of uranium (VI in rock and synthetic samples. The effect of various diverse ions was also studied.

  4. Method development, validation and stability study of ritonavir in bulk and pharmaceutical dosage form by spectrophotometric method

    Anindita Behera

    2011-01-01

    Full Text Available Background: Ritonavir is a protease inhibitor and mostly used as a booster for increasing the bioavailability of other protease inhibitors like Atazanavir Sulfate and Lopinavir. Aims: Quality assessment of the new dosage form of Ritonavir i.e. tablets is very essential, so two sensitive, simple and precise methods are developed for quantification of Ritonavir in bulk and tablet dosage forms. Materials and Methods: The first method is based on first order derivative method and the second is based on area under curve method. Both the methods are validated according to international conference of harmonization (ICH guidelines. A stability study of Ritonavir is done in UV - Visible Spectrophotometer under different stress conditions recommended by ICH guidelines. Results: The absorption maximum is found to be 239nm in methanol. The absorption maximum in first method is chosen at 253.2nm, and the linearity is found between 4 - 20 ΅g/ml with coefficient of correlation value 0.9981. In the second method, the range for area under curve selected is 237 - 242nm. The linearity is found between 4 -20 ΅g/ml with coefficient of correlation value 0.9992. Conclusion: The developed methods are validated and found to be simple, rapid, precise and cost-effective. The degradation study in tablet dosage form can be used as a stability indicating assay method.

  5. Accurate quantification of astaxanthin from Haematococcus crude extract spectrophotometrically

    Li, Yeguang; Miao, Fengping; Geng, Yahong; Lu, Dayan; Zhang, Chengwu; Zeng, Mingtao

    2012-07-01

    The influence of alkali on astaxanthin and the optimal working wave length for measurement of astaxanthin from Haematococcus crude extract were investigated, and a spectrophotometric method for precise quantification of the astaxanthin based on the method of Boussiba et al. was established. According to Boussiba's method, alkali treatment destroys chlorophyll. However, we found that: 1) carotenoid content declined for about 25% in Haematococcus fresh cysts and up to 30% in dry powder of Haematococcus broken cysts after alkali treatment; and 2) dimethyl sulfoxide (DMSO)-extracted chlorophyll of green Haematococcus bares little absorption at 520-550 nm. Interestingly, a good linear relationship existed between absorbance at 530 nm and astaxanthin content, while an unknown interference at 540-550 nm was detected in our study. Therefore, with 530 nm as working wavelength, the alkali treatment to destroy chlorophyll was not necessary and the influence of chlorophyll, other carotenoids, and the unknown interference could be avoided. The astaxanthin contents of two samples were measured at 492 nm and 530 nm; the measured values at 530 nm were 2.617 g/100 g and 1.811 g/100 g. When compared with the measured values at 492 nm, the measured values at 530 nm decreased by 6.93% and 11.96%, respectively. The measured values at 530 nm are closer to the true astaxanthin contents in the samples. The data show that 530 nm is the most suitable wave length for spectrophotometric determination to the astaxanthin in Haematococcus crude extract.

  6. Microwave absorption studies of MgB2 superconductor

    M K Bhide; R M Kadam; M D Sastry; Ajay Singh; Shashwati Sen; Manmeet Kaur; D K Aswal; S K Gupta; V C Sahni

    2002-05-01

    Microwave absorption studies have been carried out on MgB2 superconductor using a standard X-band EPR spectrometer. The modulated low-field microwave absorption signals recorded for polycrystalline (grain size ∼ 10m) samples suggested the absence of weak-link character. The field dependent direct microwave absorption has been found to obey a $\\sqrt{H}$ dependence with two different slopes, which indicated a transition from strongly pinned lattice to flux flow regime.

  7. Plutonium spectrophotometric analysis

    Plutonium ions in solution have absorption spectra so different that it is possible to use them for analytical purposes. Detailed studies have been performed in nitric solutions. Some very convenient methods for the determination of plutonium and its oxidation states, especially the ratios Pu(III):Pu(IV) and Pu(IV):Pu(VI) in a mixture of both, have been developed. These methods are described in this paper, including: a) Absorption spectra for plutonium (III), (IV), (VI) and mixtures. b) Relative extinction coefficients for the above mentioned species. c) Dependences of the relative extinction coefficients on the nitric acid concentration and the plutonium VI deviation from the Beer-Lambert law. The developed methods are simple and rapid and then, suitable in process control. Accuracy is improved when relative absorbance measurements are performed or controlled the variables which have effect on the spectra and extinction coefficients. (Author)

  8. A spectrophotometric study of the protonation processes of some N-[1-(benzimidazol-1-yl]methylbenzamide derivatives

    NADA U. PERISIC-JANJIC

    2000-01-01

    Full Text Available The protonation of N-[1-(benzimidazol-1-yl]methylbenzamide derivatives in aqueous acids (H2SO4 media was investigated, using a spectrophotometric method. The investigated compounds have two protonation processes. The first protonation process occurs in weakly acidic aqueous solutions (pH range and refers to the protonation of the benzimidazole part of the molecule. The second protonation process occurs in concentrated sulfuric acid solutions and refers to protonation of the amide group. The protonation constants of the second process were calculated by the Hammett and Cox-Yates method. The effect of chemical structure on the ionisation constants is discussed. A correlation between the protonation constants and antimicrobial activity was established.

  9. Mechanistic chemistry of oxidation of balsalazide with acidic chloramine-T and bromamine-T: A comparative spectrophotometric kinetic study

    Puttaswamy; S Dakshayani

    2014-11-01

    Balsalazide (BSZ) belongs to a class of non-steroidal anti-inflammatory drugs. Kinetics and mechanism of oxidation of BSZ with sodium N-halo-p-toluenesulfonamides viz., chloramine-T(CAT) and bromamine-T(BAT) in HClO4 medium have been spectrophotometrically investigated (max =357nm) at 303 K. Under comparable experimental conditions, reactions with both the oxidants follow a first-order dependence of rate on [BSZ] and fractional-order dependence on each [oxidant] and [HClO4]. Activation parameters and reaction constants have been computed. 2-hydroxy-5-nitroso-benzoic acid and 3-(4-nitroso-benzoylamino)-propionic acid are identified as the oxidation products of BSZ with both CAT and BAT. The rate of oxidation of BSZ is about five-fold faster with BAT than with CAT. Plausible mechanism and related rate law have been deduced for the observed kinetics.

  10. Radiant energy absorption studies for laser propulsion. [gas dynamics

    Caledonia, G. E.; Wu, P. K. S.; Pirri, A. N.

    1975-01-01

    A study of the energy absorption mechanisms and fluid dynamic considerations for efficient conversion of high power laser radiation into a high velocity flow is presented. The objectives of the study are: (1) to determine the most effective absorption mechanisms for converting laser radiation into translational energy, and (2) to examine the requirements for transfer of the absorbed energy into a steady flow which is stable to disturbances in the absorption zone. A review of inverse Bremsstrahlung, molecular and particulate absorption mechanisms is considered and the steady flow and stability considerations for conversion of the laser power to a high velocity flow in a nozzle configuration is calculated. A quasi-one-dimensional flow through a nozzle was formulated under the assumptions of perfect gas.

  11. Transient absorption microscopy studies of single metal and semiconductor nanostructures

    Johns, Paul; Sajini-Devadas, Mary; Hartland, Gregory V.

    2015-08-01

    Transient absorption microscopy is an experimental technique that allows nanomaterials to be studied with ultrafast time resolution and diffraction limited spatial resolution. This paper describes recent results from using transient absorption microscopy to investigate energy relaxation processes in single metal and semiconductor nanowires. The processes that have been examined include charge carrier trapping in semiconductor nanostructures, the motion of surface plasmon polaritons in metal nanowires, and the damping of the acoustic breathing modes of metal nanowires by high viscosity solvents.

  12. Absorptive capacity in European manufacturing: a Delphi study

    Jung Erceg, Petra; Pandža, Krsto; Armbruster, Heidi; Dreher, Carsten

    2012-01-01

    This paper sets out to discuss the results of a specific part of a Europe-wide Delphi study that considers issues of absorptive capacity in European manufacturing. Owing to the importance to competitiveness of increasing innovative capabilities in manufacturing it is highly relevant to explore how a wide community of manufacturing experts experience the phenomenon of absorptive capacity and sense future developments. A two round Delphi method was designed in which more than 3,000 experts from...

  13. Absorption heat cycles. An experimental and theoretical study

    A flow sheeting programme, SHPUMP, was developed for simulating different absorption heat cycles. The programme consists of ten different modules which allow the user to construct his own absorption cycle. The ten modules configurate evaporators, absorbers, generators, rectifiers, condensers, solution heat exchangers, pumps, valves, mixers and splitters. Seven basic and well established absorption cycles are available in the configuration data base of the programme. A new Carnot model is proposed heat cycles. Together with exergy analysis, general equations for the Carnot coefficient of performance and equations for thermodynamic efficiency, exergetic efficiency and exergy index, are derived, discussed and compared for both absorption heat pumps and absorption heat transformers. Utilizing SHPUMP, simulation results are presented for different configurations where absorption heat cycles are suggested to be incorporated in three different unit operations within both pulp and paper and oleochemical industries. One of the application studies reveled that an absorption heat transformer incorporated with an evaporation plant in a major pulp and paper industry, would save 18% of the total prime energy consumption in one of the evaporation plants. It was also concluded that installing an absorption heat pump in a paper drying plant would result in steam savings equivalent to 12 MW. An experimental absorption heat transformer unit operating with self-circulation has been modified and thoroughly tested. A reference heat transformer plant has been designed and installed in a major pulp and paper mill where it is directly incorporated with one of the evaporation plants. Preliminary plant operation data are presented. 72 refs, 63 figs, 33 tabs

  14. Spectrophotometric estimation of risperidone in tablets

    B. K. Jayanna; Devaraj, T. D.; Roopa, K. P.; G. Nagendrappa; H R Arun Kumar; Gowda, N.

    2014-01-01

    A simple, rapid and highly sensitive spectrophotometric method is developed for the determination of risperidone in tablet formulation. The method is based on the oxidation of drug using potassium permanganate in alkaline medium and excess potassium permanganate oxidizes 1,10-phenanthroline Fe(II). The measurement of decrease in absorbance of 1,10-phenanthroline Fe (II) was done at 415 nm. The beer′s law is obeyed in the concentration range of 5.0 to 40.0 μg/ml and molar absorptivity is found...

  15. Simultaneous spectrophotometric determination of drotaverine hydrochloride and paracetamol in tablet

    Mahaparale Sonali

    2010-01-01

    Full Text Available Two simple, accurate and reproducible spectrophotometric methods; Q analysis and first order derivative method have been described for the simultaneous estimation of drotaverine hydrochloride and paracetamol in combined tablet dosage form. Absorption maxima of drotaverine hydrochloride and paracetamol in distilled water were found to be 303.5 nm and 243.5 nm respectively. Beer′s law was obeyed in the concentration range 5-50 µg/ml for drotaverine and 5-60 µg/ml for paracetamol. In Q analysis method, two wavelengths were selected at isobestic point (277 nm and λmax of paracetamol (243.5 nm. In first order derivative method, zero crossing point for drotaverine hydrochloride and paracetamol were selected at 303.5 nm and 243.5 nm, respectively. The results of two methods were validated statistically and recovery studies were found to be satisfactory.

  16. Spectrophotometric Determination of Ezetimibe

    P. Baby Sudha Lakshmi; Ramchandran, D.; Rambabu, C.

    2010-01-01

    Two simple, sensitive, selective and accurate spectro-photometric methods (Method A and Method B) for the determination of eztimibe in bulk drug and pharmaceutical formulations (tablets) have been described. Method A and B are based on the redox/complex formation reaction of drug with 1,10-phenanthroline and hexacyano-ferrate(III) in presence of ferric chloride to form coloured chromogens exhibiting λmax at 510 and 740 nm respectively. The results of analysis for the two methods have been val...

  17. Spectrophotometric Procedure for Fast Reactor Advanced Coolant Manufacture Control

    Andrienko, O. S.; Egorov, N. B.; Zherin, I. I.; Indyk, D. V.

    2016-01-01

    The paper describes a spectrophotometric procedure for fast reactor advanced coolant manufacture control. The molar absorption coefficient of dimethyllead dibromide with dithizone was defined as equal to 68864 ± 795 l·mole-1·cm-1, limit of detection as equal to 0.583 · 10-6 g/ml. The spectrophotometric procedure application range was found to be equal to 37.88 - 196.3 g. of dimethyllead dibromide in the sample. The procedure was used within the framework of the development of the method of synthesis of the advanced coolant for fast reactors.

  18. Spectrophotometric and conductometric study of the complexation of N-salicylidene-2-aminophenol with Cu2+ in methanol + 1,4-dioxane binary solutions

    Biswas Rashmidipta

    2014-01-01

    Full Text Available The complexation reaction between N-salicylidene-2-aminophenol, abbreviated as SAP, with Cu2+ ion was studied in binary mixtures of methanol and 1,4-dioxane by using conductometric and spectrophotometric method at different temperatures. The stability constants (Kf for the 1:1 complex, Cu2+-SAP, were calculated from computer fitting of absorbance and molar conductance data against various mole ratios (cM:cL or cL:cM in different binary solvent mixtures. A non-linear behaviour was observed for the variation of logKf for the complex against the solvent compositions. Various thermodynamic parameters (ΔH, ΔS and ΔG for the formation of Cu2+-SAP complex were determined from the temperature dependence of stability constants (Kf. The overall results showed that the complexation reaction is entropy driven and is affected by the nature and composition of the mixed solvents.

  19. Chemical relevance of the copper(II)— L-carnosine system in aqueous solution: A thermodynamic and spectrophotometric study

    Daniele, Pier G.; Prenesti, Enrico; Zelano, Vincenzo; Ostacoli, Giorgio

    1993-08-01

    The copper(II)— L-carnosine (L -) system has been re-investigated in aqueous solution, at I = 0.1 mol dm -1, different temperatures (5⩽ t⩽45°C) and with metal to ligand ratios ranging from 3:1 to 1:3. Both potentiometry and visible spectrophotometry were employed. From an overall consideration of all experiments, [CuLH] 2+, [CuL] +, [CuLH -1]°, [Cu 2L 2H -2]° and [Cu 2LH -1] 2+ were recognized as the species which provide the best interpretation of experimental data. The complex formation constants, determined at different temperatures, allowed us to obtain reliable values of Δ H° and good estimates of Δ C° p. From visible spectrophotometric measurements, carried out at different pH and metal to ligand ratios, it was possible to calculate the electronic spectrum of each complex formed in solution. A structure is also proposed for each species, on the basis of thermodynamic and spectral results.

  20. Study on optical weak absorption of borate crystals

    Li, Xiaomao; Hu, Zhanggui; Yue, Yinchao; Yu, Xuesong; Lin, Zheshuai; Zhang, Guochun

    2013-10-01

    Borate crystal is an important type of nonlinear optical crystals used in frequency conversion in all-solid-state lasers. Especially, LiB3O5 (LBO), CsB3O5 (CBO) and CsLiB6O10 (CLBO) are the most advanced. Although these borate crystals are all constructed by the same anionic group-(B3O7)5-, they show different nonlinear optical properties. In this study, bulk weak absorption values of three borate crystals have been studied at 1064 nm by a photothermal common-path interferometer. The bulk weak absorption values of them along [1 0 0], [0 1 0] and [0 0 1] directions were obtained, respectively, to be approximately 17.5 ppm cm-1, 15 ppm cm-1 and 20 ppm cm-1 (LBO); 80 ppm cm-1, 100 ppm cm-1 and 40 ppm cm-1 (CBO); 600 ppm cm-1, 600 ppm cm-1 and 150 ppm cm-1 (CLBO) at 1064 nm. The results showed an obvious discrepancy of the values of these crystals along three axis directions. A correlation between the bulk weak absorption property and crystal intrinsic structure was then discussed. It is found that the bulk weak absorption values strongly depend on the interstitial area surrounded by the B-O frames. The interstitial area is larger, the bulk weak absorption value is higher.

  1. Comparative study of solvent properties for carbon dioxide absorption

    Aschenbrenner, O.; Styring, P. [University of Sheffield, Sheffield (United Kingdom)

    2010-07-01

    Several inexpensive and non-toxic solvents with low vapour pressures were investigated for their suitability as alternative solvents for the absorption of carbon dioxide from flue gas. The solvents include poly(ethylene glycol)s, poly(ethylene glycol) ethers, poly(ethylenimine) and glycerol-based substances. Solvent properties such as thermal stability, solubility of carbon dioxide and selectivity over nitrogen were investigated in a systematic study using a thermogravimetric analyser. Absorption results are reported for pure carbon dioxide and nitrogen as well as a mixture of both gases. Desorption and long-term sorption behaviour are also discussed. Glycerol and poly(ethylene glycol)s show a high solubility of carbon dioxide. Due to the high viscosity of the solvent, carbon dioxide absorption in poly(ethylenimine) is very slow in spite of the presence of favourable amine groups. PEG 300 was found to be the best solvent in this study and shows a high carbon dioxide solubility as well as good selectivity over nitrogen. The advantages of high stability, low solvent loss and low desorption energy of PEG 300 may outweigh its lower absorption capacity compared to the state-of-the-art solvent monoethanolamine, making it a potentially advantageous solvent for industrial carbon dioxide absorption processes.

  2. New spectrophotometric determination of Raloxifene hydrochloride in tablets

    Pavithra D

    2006-01-01

    Full Text Available Three new simple and sensitive spectrophotometric methods in UV/Vis region have been developed for the determination of raloxifene hydrochloride in bulk drug and in tablet formulations. Raloxifene hydrochloride exhibited maximum absorbance at 289 nm in methanol (method A with apparent molar absorptivity of 3.67x104 l/mol.cm and maximum absorbance at 303 nm in 0.1 M sodium hydroxide with apparent molar absorptivity of 3.60x104 l/mol.cm (method B. Third method is based on the formation of red coloured chromogen with ferric nitrate and 1,10-phenanthroline, which showed maximum absorbance at 511 nm with apparent molar absorptivity of 1.06x105 l/mol.cm. Beer′s law was obeyed in the concentration range of 5-25 g/ml for method A and B and in the range of 2-10 µg/ml for method C. Results of all methods were validated statistically and by recovery studies.

  3. Spectrophotometric investigations of the reaction between gold(III and potassium iodide

    GORDANA MILOVANOVIC

    2000-06-01

    Full Text Available The equilibria of the complex formation between AuCl4-n(OHn- and I- was studied spectrophotometrically in aqueous solutions containing KI:Au(III<2 in the acidity range from 1 M HCl to pH 7 at 25°C. From the hydrogen ion and Cl- ion dependence of the absorption spectra, it was found that AuCl2I2- and Au(OH2I2- complexes were formed. The equilibrium constants of complex formation were determined.

  4. Comparison of two methods for determining in vitro intestinal absorption of nutrients using rats fed different diets

    Absorption of sucrose, glucose, leucine and aspartate was studied using intestinal everted sac of rats fed on french bean diets namely PDR-14, HUR-137 and HUR-15 using casein as a control. Absorption of nutrients was monitored spectrophotometrically and by 14C radio assay of metabolites using scientillation counting. The absorption pattern of amino acids was found to be similar but of glucose and sucrose differed. Glucose was found to be more absorbed than sucrose in spectrophotometer assay and the pattern reversed in radio assay. Absorption of sucrose and leucine were higher by rats fed on HUR-137 diet and similarly, more aspartate was absorbed when fed on HUR-15 diet as demonstrated by both the methods. Rats fed on HUR-137 diet exhibited higher glucose absorption as shown by spectrophotometric assay, but rats on HUR-15 diet by radio assay. Absorption of nutrients differed significantly between casein and french beans

  5. Theoretical Study on Sulfur Dioxide Absorption with Citrate Solution

    薛娟琴; 洪涛; 王召启; 李林波

    2006-01-01

    The citrate absorption of SO2 is currently one of the most successful and economic methods to harness sulfur dioxide pollution.In order to theoretically elucidate the mechanism of SO2 absorption by citrate solution and provide theoretical instruction for experiments and industrial process, the theory of multi-buffer solution, combined with computer numerical calculation methods, was applied to study the distribution parameters of the components of the citrate solution in the process of SO2 absorption and the following results were obtained: (1) HCi2- and H2Ci- in the citrate solution played the dominant role in the absorption and desorption processes; (2) Through the calculation for the buffer capacity of citrate solution, it was found that the pH of the absorption and desorption solution should be in the range of 2~8, while at pH=4.5 the buffer capacity reached its maximum. Some valuable parameters were obtained, which are instructive to the ensuing experiments and industrial design.

  6. In vivo studies of biotin absorption in distal rat intestine

    The authors have extended their previous studies of biotin absorption in rat proximal jejunum (PJ) to examine biotin absorptive capacity of rat ileum (I) and proximal colon (PC) using in vivo intestinal loop technique. Intestinal loops (2.5 cm) were filled with 0.3 ml of solution containing (3H)-biotin and (14C)-inulin in phosphate buffer, pH 6.5. Biotin absorption was determined on the basis of luminal biotin disappearance after correction for inulin recovery and averaged (pmol/loop-10 min; X +/- SEM). In related experiments, 5-cm loops of PJ, distal I (DI), or PC were filled with 0.5 ml of solution of similar composition (1.0 μM biotin). The abdominal cavity was closed and the rats were allowed to recover from anesthesia, then sacrificed 3 hr after injection. Biotin absorption averaged 96.2% (PJ), 93.2% (DI), and 25.8% (PC) of the dose administered. These differences were reflected in the radioactive biotin content of plasma and intestinal loop, kidney, and liver. These data demonstrate significant biotin absorption in rat DI and PC, as required if the intestinal microflora are to be considered as a source of biotin for the host

  7. Artificial neural networks study of the catalytic reduction of resazurin: stopped-flow injection kinetic-spectrophotometric determination of Cu(II) and Ni(II)

    Magni, Diana M. [Departamento de Quimica, Facultad de Ingenieria Quimica, Universidad Nacional del Litoral, Santiago del Estero 2829, S3000AOM Santa Fe (Argentina); Olivieri, Alejandro C. [Departamento de Quimica Analitica, Facultad de Ciencias Bioquimicas y Farmaceuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario (Argentina); Bonivardi, Adrian L. [Departamento de Quimica, Facultad de Ingenieria Quimica, Universidad Nacional del Litoral, Santiago del Estero 2829, S3000AOM Santa Fe (Argentina) and Instituto de Desarrollo Tecnologico para la Industria Quimica, Gueemes 3450, S3000GLN Santa Fe (Argentina)]. E-mail: bonivar@fiqus.unl.edu.ar

    2005-01-10

    An artificial neural network (ANN) procedure was used in the development of a catalytic spectrophotometric method for the determination of Cu(II) and Ni(II) employing a stopped-flow injection system. The method is based on the catalytic action of these ions on the reduction of resazurin by sulfide. ANNs trained by back-propagation of errors allowed us to model the systems in a concentration range of 0.5-6 and 1-15 mg l{sup -1} for Cu(II) and Ni(II), respectively, with a low relative error of prediction (REP) for each cation: REP{sub Cu(II)} = 0.85% and REP{sub Ni(II)} = 0.79%. The standard deviations of the repeatability (s{sub r}) and of the within-laboratory reproducibility (s{sub w}) were measured using standard solutions of Cu(II) and Ni(II) equal to 2.75 and 3.5 mg l{sup -1}, respectively: s{sub r}[Cu(II)] = 0.039 mg l{sup -1}, s{sub r}[Ni(II)] = 0.044 mg l{sup -1}, s{sub w}[Ni(II)] = 0.045 mg l{sup -1} and s{sub w}[Ni(II)] = 0.050 mg l{sup -1}. The ANNs-kinetic method has been applied to the determination of Cu(II) and Ni(II) in electroplating solutions and provided satisfactory results as compared with flame atomic absorption spectrophotometry method. The effect of resazurin, NaOH and Na{sub 2}S concentrations and the reaction temperature on the analytical sensitivity is discussed.

  8. Effects of Omeprazole on Iron Absorption: Preliminary Study

    Mahmut Yaşar Çeliker

    2013-09-01

    Full Text Available Objective: Increasing numbers of pediatric and adult patients are being treated with proton pump inhibitors (PPIs. PPIs are known to inhibit gastric acid secretion. Nonheme iron requires gastric acid for conversion to the ferrous form for absorption. Ninety percent of dietary and 100% of oral iron therapy is in the nonheme form. To the best of our knowledge, the effect of PPIs on iron absorption has not been studied in humans. Our study assessed the relationship between omeprazole therapy and iron absorption in healthy subjects. Materials and Methods: We recruited 9 healthy volunteers between June 2010 and March 2011. Subjects with chronic illness, anemia, or use of PPI therapy were excluded. Serum iron concentrations were measured 1, 2, and 3 h after the ingestion of iron (control group. The measurements were repeated on a subsequent visit after 4 daily oral administrations of omeprazole at a dose of 40 mg (treatment group. Results: One female and 8 male volunteers were enrolled in the study with a mean age of 33 years. There was no statistical difference detected between baseline, 1-h, 2-h, and 3-h iron levels between control and treatment groups. Conclusion: Administration of omeprazole for a short duration does not affect absorption of orally administered iron in healthy individuals.

  9. Radioisotope studies for quantitative measurement of manganese absorption

    Purpose of the present study was to quantitatively determine the manganese absorption in growing rats by means of radioisotopes. First of all the following factors had to be investigated, which are significant for this determination: Measurability of stable and radioactive Mn in rat tissues; labelling of stable Mn and distribution of stable and radioactive Mn in the organism; verification of the isotope dilution method and of the comparative balance method with regard to its applicability for the determination of the true Mn absorption. We useed male and female Sprague-Dawley rats. The most important results are summarized in the following: in some separate tissues measurement of stable Mn was accompanied by difficulties. The measurement of radioactive Mn however, could be performed without any problems. 10 d after i.m. injection of 54Mn only 17% of the administered Mn was still detectable in the organism. However, there was no uniform tissue labelling found. Therefore it is possible to an only restricted extent to draw quantitative conclusions on the content of stable Mn. A high percentage of stable and radioactive Mn was found above all in the liver. The isotope dilution method permits by feces analysis to differentiate between unabsorbed Mn coming from the food and endogenic Mn coming from the organism itself. The effective Mn absorption was also determined by means of the comparative balance method. By means of the isotope dilution method we determined the quantitative Mn-absorption with staged Mn administration and the contribution of absorption and excretion to the homeostatic regulation mechanisms of Mn. We found that absorption and excretion help the organism to keep an almost constant Mn concentration even with a differing Mn supply. (orig./MG)

  10. Spectrophotometric analysis of Cabergoline in pharmaceutical preparations

    Salman, Demet; Dogan, Aysegul; Basci, Nursabah E.

    2011-01-01

    Cabergoline (CAB) is a synthetic ergoline dopamine agonist with high affinity to D2 receptors, thus used for the treatment of Parkinson's patients and hyperprolactinemia disorders. In this study, simple, fast, reliable and validated UV-VIS and 2nd order derivative spectrophotometric methods for determination of CAB in pharmaceutical preparations were developed without any previous sample preparation step. Determination of CAB was performed at 280 nm wavelength by UV-VIS spectrophotometry and ...

  11. A New Spectrophotometric Method for Measuring COD of Seawater

    LIU Ying; JI Hongwei; XIN Huizhen; LIU Li

    2006-01-01

    This research studied a new spectrophotometric method for measuring the chemical oxygen demand (COD) of seawater. In this method, the COD was measured using a spectrophotometer instead of titrating with sodium thiosulphate.The measuring wavelength was selected to be 470 nm, and the COD of three standard glucose solutions (COD = 0.5, 1.5 and2.5 mgL-1, respectively) and two seawater samples (from the South Yellow Sea and Jiaozhou Bay) were measured using the spectrophotometric method and titrimetric method respectively. The results showed that the spectrophotometric method was somewhat better than the titrimetric method. The relative standard deviation (RSD) of the spectrophotometric method was less than 2.7%, and the recovery of seawater samples ranged from 96.3% to 103.8%. In addition, the spectrophotometric method has other advantages such as expeditiousness, operation simplicity, analysis automatization, etc. Therefore the spectrophotometric method can be used to measure the COD of seawater with satisfactory results.

  12. Intestinal perfusion in the study of intestinal absorption

    Several techniques for studying absorption by means of intestinal perfusion have been developed. While the principle is simple, the practice is complicated by absorption of the solvent and by excretion of fluid into the lumen. To improve reliability a ''marker'' is incorporated into the system; it should behave as nearly as possible like the nutrient of interest, except that it should be unabsorbable. A great many markers, including several labelled with radionuclides, have been developed for use with numerous nutrients, and perfusion methods using double or triple tubes or occlusive balloons have been tested. The perfusion technique is too complicated for routine diagnostic use, but it offers at present the only possibility of studying the function of defined sections of the small intestine in the intact human. (author)

  13. Multi-wavelength spectrophotometric determination of the protolytic constants of tetracycline hydrochloride in some nonaqueous-water mixed solvents: A solvatochromism study

    Ghasemi, Jahan B.; Jalalvand, Ali R.

    2011-01-01

    Annihilation of the contribution of one chemical component from the original data matrix is a general method in rank annihilation factor analysis (RAFA). However, RAFA is not applicable for studying the protonation equilibria of multiprotic acids but in this study two-rank annihilation factor analysis (TRAFA) was used as an efficient chemometrics algorithm for determination of the protolytic constants (p Ka) of tetracycline hydrochloride (TCHC) in some nonaqueous-water mixed solvents such as acetonitrile (AN)-water and methanol (MeOH)-water from the spectral pH-absorbance data. The spectral data was obtained from spectrophotometric acid-base titrations of different solutions of TCHC at (25.0 ± 0.10) °C and an ionic strength of 0.10 M. In TRAFA algorithm the p Ka values were obtained with relationship between residual standard deviation (R.S.D.) and hypothetical p Ka values. In the case of TCHC, the spectra were divided in two consecutive subdivisions according to their pH range having two p Ka and TRAFA was run twice. The validity of the obtained p Ka values was checked with well-known chemometrics algorithms such as DATAN, EQUSPEC, SPECFIT/32 and SQUAD. The effects of changing solvent composition on the protolytic constants were explained by linear solvation energy relationships (LSER) utilizing solvatochromic parameters.

  14. How Much Cranberry Juice Is in Cranberry-Apple Juice? A General Chemistry Spectrophotometric Experiment

    Edionwe, Etinosa; Villarreal, John R.; Smith, K. Christopher

    2011-01-01

    A laboratory experiment that spectrophotometrically determines the percent of cranberry juice in cranberry-apple juice is described. The experiment involves recording an absorption spectrum of cranberry juice to determine the wavelength of maximum absorption, generating a calibration curve, and measuring the absorbance of cranberry-apple juice.…

  15. SHARDS: an optical spectro-photometric survey of distant galaxies

    Perez-Gonzalez, Pablo G; Barro, Guillermo; Villar, Victor; Cardiel, Nicolas; Ferreras, Ignacio; Rodriguez-Espinosa, Jose Miguel; Alonso-Herrero, Almudena; Balcells, Marc; Cenarro, Javier; Cepa, Jordi; Charlot, Stephane; Cimatti, Andrea; Conselice, Christopher J; Daddi, Emmanuele; Donley, Jennifer; Elbaz, David; Espino, Nestor; Gallego, Jesus; Gobat, R; Gonzalez-Martin, Omaira; Guzman, Rafael; Hernan-Caballero, Antonio; Muñoz-Tuñon, Casiana; Renzini, Alvio; Zaurin, Javier Rodriguez; Tresse, Laurence; Trujillo, Ignacio; Zamorano, Jaime

    2012-01-01

    (Abridged) We present the Survey for High-z Absorption Red and Dead Sources (SHARDS), an ESO/GTC Large Program carried out with GTC/OSIRIS. SHARDS is an ultra-deep optical spectro-photometric survey of the GOODS-N field (130 arcmin^2) at wavelengths 500 to 950 nm and using 24 contiguous medium-band filters (spectral resolution R 50). The data reach 26.5 mag (>3-sigma level) with sub-arcsec seeing in all bands. SHARDS main goal is obtaining accurate physical properties of interm- and high-z galaxies using well-sampled optical SEDs with sufficient spectral resolution to measure absorption and emission features. Among the different populations of high-z galaxies, SHARDS principal targets are massive quiescent galaxies at z>1. In this paper, we outline the observational strategy and include a detailed discussion of the special reduction and calibration procedures applied to the GTC/OSIRIS data. We present science demonstration results about the detection and study of emission-line galaxies (star-forming and AGN) ...

  16. Study of the behaviour of various phenolic compounds in the 4-aminoantipyrine and ultraviolet-ratio spectrophotometric methods without and with distillation.

    Farino, J; Norwitz, G; Boyko, W J; Keliher, P N

    1981-09-01

    It is customary in industrial analysis in the determination of phenols by the 4-aminoantipyrine (4-AAP) and ultraviolet-ratio spectrophotometric methods to report the total of phenolic compounds as phenol. A study was therefore made of the behaviour of 36 representative phenolic compounds in the 4-AAP and UV-ratio methods, with and without distillation, to ascertain the apparent recoveries relative to that for phenol. The Fisher phenol analyser was used for the UV-ratio method, which depends upon the bathochromic shift (from about 270 to about 290 nm) usually obtained when the solution of the phenol is made alkaline. The apparent recoveries by the 4-AAP method both with and without distillation varied from 0 to 100%. The apparent recoveries by the UV-ratio method without distillation varied from 0 to 148%, and those with distillation varied from 0 to 110%. Sixteen of the compounds tested without distillation gave less than 10% recovery by the 4-AAP method and eleven gave less than 10% recovery by the UV-ratio method. The results after distillation indicated that several of the compounds did not distil completely. PMID:18962987

  17. Spectrophotometric evaluation of surface morphology dependent catalytic activity of biosynthesized silver and gold nanoparticles using UV-vis spectra: A comparative kinetic study

    Ankamwar, Balaprasad; Kamble, Vaishali; Sur, Ujjal Kumar; Santra, Chittaranjan

    2016-03-01

    The development of eco-friendly and cost-effective synthetic protocol for the preparation of nanomaterials, especially metal nanoparticles is an emerging area of research in nanotechnology. These metal nanoparticles, especially silver can play a crucial role in various catalytic reactions. The biosynthesized silver nanoparticles described here was very stable up to 6 months and can be further exploited as an effective catalyst in the chemical reduction of 4-nitrophenol to 4-aminophenol. The silver nanoparticles were utilized as an efficient surface-enhanced Raman scattering (SERS) active substrate using Rhodamine 6G as Raman probe molecule. We have also carried out systematic comparative studies on the catalytic efficiency of both silver and gold nanoparticles using UV-vis spectra to monitor the above reaction spectrophotometrically. We find that the reaction follows pseudo-first order kinetics and the catalytic activity can be explained by a simple model based on Langmuir-Hinshelwood mechanism for heterogeneous catalysis. We also find that silver nanoparticles are more efficient as a catalyst compare to gold nanoparticles in the reduction of 4-nitrophenol to 4-aminophenol, which can be explained by the morphology of the nanoparticles as determined by transmission electron microscopy.

  18. Acid-base and Electrochemical Properties of Manganese meso(ortho- and meta-ethylpyridyl)porphyrins: Potentiometric, Spectrophotometric and Spectroelectrochemical Study of Protolytic and Redox Equilibria

    Weitner, Tin; Budimir, Ana; Batinić-Haberle, Ines

    2013-01-01

    The difference in electrostatics and reduction potentials between manganese ortho-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP) and manganese meta-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-3-PyP) is a challenging topic, particularly because of the high likelihood for their clinical development. Hence, a detailed study of the protolytic and electrochemical speciation of MnII–IVTE-2-PyP and MnII-IVTE-3-PyP in a broad pH range has been performed using the combined spectrophotometric and potentiometric methods. The results reveal that in aqueous solutions within the pH range ~2–13 the following species exist: (H2O)MnIITE-m-PyP4+, (HO)MnIITE-m-PyP3+, (H2O)2MnIIITE-m-PyP5+, (H2O)(HO)MnIIITE-m-PyP4+, (H2O)(O=)MnIIITE-m-PyP3+, (H2O)(O=)MnIVTE-m-PyP4+ and (HO)(O=)MnIVTE-m-PyP3+ (m = 2, 3). All the protolytic equilibrium constants that include the accessible species as well as the thermodynamic parameters for each particular protolytic equilibrium have been determined. The corresponding formal reduction potentials related to the reduction of the above species and the thermodynamic parameters describing the accessible reduction couples were calculated as well. PMID:21052598

  19. Spectrophotometric estimation of roxithromycin in tablet dosage forms

    Suhagia B; Shah S; Rathod I; Patel H; Doshi K; Parmar V

    2006-01-01

    A simple and sensitive spectrophotometric method has been developed for determination of roxithromycin in its pharmaceutical dosage forms. In the proposed method, roxithromycin is oxidized with potassium permanganate to liberate formaldehyde, which is determined in situ using acetyl acetone in the presence of ammonium acetate to give a yellow-coloured chromogen with absorption maxima at 412 nm. The method is found to be linear in the concentration range of 10-75 µg/ml with regression...

  20. Determination of Azithromycin in pharmaceutical dosage forms by Spectrophotometric method

    Suhagia B; Shah S; Rathod I; Patel H; Doshi K

    2006-01-01

    A simple and sensitive spectrophotometric method has been developed for determination of azithromycin in its pharmaceutical dosage forms. In the proposed method, azithromycin is oxidized with potassium permanganate to liberate formaldehyde, which is determined in situ using acetyl acetone, in the presence of ammonium acetate. A yellow coloured chromogen was obtained, having an absorption maxima at 412 nm. The method is found to be linear in the concentration range of 10-75 µg/ml, with ...

  1. Ellipsometric studies of the absorption of liquid by photo resist

    Jeong, Hee; Kyung, Jaesun; Park, Songyi; Lee, Kiyong; Lee, Hyungjoo; Cheon, Hyuknyeong; An, Ilsin; Lee, Sook

    2007-03-01

    In situ spectroscopic ellipsometry, deep UV ellipsometry, and imaging ellipsometry were employed to study the absorption of liquid by photoresist(PR) used for 193 nm immersion lithography. When 140 nm thick PR was soaked in water over a period of >70 minutes, ~7% increase in thickness was observed. From the analysis of ellipsometric spectra covering from near infrared to deep UV, we could estimates less than 2 vol. % uptake of water by PR after completion of soaking. This resulted in very small decrease in refractive index of PR (~0.4%). When imaging ellipsometry was used, the absorption of water by PR in much shorter periods could be detectible. In imaging ellipsometry, the microscopic images of (Δ,Ψ ) in small area are obtained thanks to two dimensional multi-channel detection systems such as CCD. Using imaging ellipsometry, we could observe the interaction of PR with water even upon 1 s of contact. Also, we found that the water absorption or interaction was not uniform over surface. More studies are required for the implication of this observation. Obviously, imaging ellipsometry is a good technique to inspect water mark in immersion lithography. We also repeated similar experiments for high reflective index liquid (JSR HIL-001) but to find negligible change by imaging ellipsometry.

  2. EXPERIMENTAL STUDY ON NATURAL FIBRES FOR GREEN ACOUSTIC ABSORPTION MATERIALS

    Lamyaa Abd ALRahman

    2013-01-01

    Full Text Available Natural fibre materials are one of the major ways to improve environmental pollution and new materials need to be considered to find the best solutions. This study presents an experimental investigation on pure micro porous materials from two types of fibres: Date Palm Fibre (DPF and Coconut Coir Fibre (CCF. This study was conducted to examine the potential for using these two types of fibres as sound absorbers. To account for the effects of the characteristics of these materials, such as thickness and density, on the acoustic absorption coefficient of a sound absorber, the measurements were conducted in an impedance tube on normal incidence acoustic absorption. The experimental data indicate that two peak values of Acoustic Absorption Coefficient (AAC are 0.98 at 1381.25 Hz-1506.25 Hz for the 40 mm thick sample and the AAC at high frequency for the same thickness is 0.99 at 4521.88-4906.25 Hz; for 20 mm thickness, the peak value is 0.84 at 2606.25-3025 Hz. The AAC of the CCF sample is 0.77 at 2434.38-2543.75 Hz for a 40 mm thickness, but for 20 mm thickness, the value is 0.71 at 4184.38-4575 Hz. The Acoustic Absorption Coefficients (AAC of the two types of materials were increased at all frequencies when the thickness of the sample was increased. The results show that date palm fibre and coconut coir fibre have good acoustic properties at low and high frequencies and can be used as an alternative replacement to conventional products. The comparisons between the two panels show a good potential because they are cheaper and lighter in comparison to asbestos and rock wool industrial materials.

  3. Use of Atomic Absorption Technique in Environmental Studies

    This chapter consists of some points including the process of atomic absorption, historical hint, key basics, the atom ionization and formation of plasma, applications in the device of atomic absorption, quantum analysis with atomic absorption, components of the device of atomic absorption, standardization of this device, atomic absorption in the the graphite furnace, supervising the analytical interventions, spectral interventions, non-spectral interventions, the utmost electric energy for atomization, preparation of standards and samples, the system of acidic digestion, similar analytical techniques.

  4. Spectrophotometric characteristics of 4-(2-pyridylazo)-resorcinol and its complex with cadmium in the presence of long-chain surfactants

    Tananajko, M.M.; Vysotskaya, T.I. (Kievskij Gosudarstvennyj Univ. (Ukrainian SSR))

    1982-06-01

    Spectrophotometric characteristics of 4-(2-pyridylazo)-resorcinol (PAR) are studied in a wide pH range depending on the concentration of long-chain surfactants: cetylpyridinium chloride (a cationic surfactant) and OP-10 (a nonionic surfactant). The bathochromic shift of reagent absorption bands is shown. Absorption spectra of the reagent and PAR chelate with cadmium are compared. It is shown that introduction of surfactants studied increases the sensibility of reactions for cadmium. The effect is clearly manifested with introduction of cetyl pyridinium chloride.

  5. Spectrophotometric studies of rhenium complexes with 4-amino 5-mercapto 3 phenyl 4:1:2 triazole

    The reagent 4-amino-5-mercapto 3 phenyl 4:1:2 triazole forms a stable reddish brown complex with rhenium on reducing it with stannous chloride in 1(M) to 5(M) hydrochloric acid medium and the metal can be estimated by extractive photometry in chloroform medium. The system obeys Beer's Law from 2-38 ppm at 380 nm. The molar absorptivity is 5.21 x 103 and the Sandell's sensitivity is 0.0351 μg cm-2. The metal forms a 1:1 complex (metal to ligand) with the ligand. Stability constant (log K) of the Re-complex has been evaluated by the Leden (4.25), Rossotti and Rossotti (4.34), and Harvey and Manning (4.53) methods. (author)

  6. Spectrophotometric determination of tranexamic acid using vanillin

    EM.A.Rind; M.G.H.Laghari; A.H.Memon; U.R.Mughal; F. Almani; N.Me-mon; M.Y.Khuhawar; M.L.Maheshwari

    2009-01-01

    A new spectrophotometric method has been examined for the determination of the tranexamic acid (TA)by derivatization with vanillin(VAN).The molar absorptivity of TA was calculated 25 160 L·mol-1·cm-1at λ max 354 nm and obeyed the Beer's law within 0.5-2.5 μg·mL-1.The color reaction was highly stable and didnot show any change in absorbance up to 24 h.The method was applied for the analysis of TA from capsules,injections and tooth pastes.The amounts of TA found in capsules,injections and tooth pastes of various pharmaceutical companies were observed with 249.0-250.9 mg/capsule,249.3-250.7 mg/injection and 0.048%-0.049%in tooth pastes with relative standard deviation(RSD)0.2%-5.0%(n=3).

  7. Spectrophotometric estimation of risperidone in tablets.

    Jayanna, B K; Devaraj, T D; Roopa, K P; Nagendrappa, G; Kumar, H R Arun; Gowda, N

    2014-09-01

    A simple, rapid and highly sensitive spectrophotometric method is developed for the determination of risperidone in tablet formulation. The method is based on the oxidation of drug using potassium permanganate in alkaline medium and excess potassium permanganate oxidizes 1,10-phenanthroline Fe(II). The measurement of decrease in absorbance of 1,10-phenanthroline Fe (II) was done at 415 nm. The beer's law is obeyed in the concentration range of 5.0 to 40.0 μg/ml and molar absorptivity is found to be 7.3932 × 10(4) l/mol/cm. The proposed method is well suited for the pharmaceutical formulations. PMID:25425761

  8. Spectrophotometric estimation of risperidone in tablets

    B K Jayanna

    2014-01-01

    Full Text Available A simple, rapid and highly sensitive spectrophotometric method is developed for the determination of risperidone in tablet formulation. The method is based on the oxidation of drug using potassium permanganate in alkaline medium and excess potassium permanganate oxidizes 1,10-phenanthroline Fe(II. The measurement of decrease in absorbance of 1,10-phenanthroline Fe (II was done at 415 nm. The beer′s law is obeyed in the concentration range of 5.0 to 40.0 μg/ml and molar absorptivity is found to be 7.3932 × 10 4 l/mol/cm. The proposed method is well suited for the pharmaceutical formulations.

  9. Spectrophotometric determination of ceftriaxone using 4-dimethylaminobenzaldehyde

    A new spectrophotometric method has been developed for the determination of the potent antibiotic (CF) by derivatization with 4-dimethylaminobenzaldehyde (DAB). The derivative indicated molar absorptivity of 5.3 * 10/sup 3/ L mol/sup -1/ at lemda max 397 nm and obeyed the Beers law within 20-100 micro gmL/sup -1/. The color reaction was highly stable and did not show any change in absorbance up to 24h. The mehtod was successfully applied for the determination of CF from various pharmaceutical preparations available in local market. The amounts of CF found in various pharmaceutical preparations were within 237.4-990 mg ampoule/sup -1/ with standard deviation(SD)+-0.0003-0.44 (N=3) respectively. (author)

  10. Extractive spectrophotometric determination of uranium with malachite green

    A sensitive spectrophotometric method based on the extraction of a uranium-benzoate-Malachite Green complex by chlorobenzene is described. The absorption maximum is at 635 nm and the molar absorptivity is 8.3 x 1041. mole -1 cm-1. A preliminary separation of uranium by extraction with methyl isobutyl ketone from acid-deficient aluminium nitrate solution is used to avoid interferences. An aliquot of the extract in then diluted with chlorobenzene and shaken with benzoate buffer containing Malachite Green (MG). The method has been applied for the determination of uranium in a synthetic leach solution. The complex extracted is probably [U02(C6H5C003-][MG+]. (author)

  11. SPECTROPHOTOMETRIC ESTIMATION OF GEMFIBROZIL IN BULK AND PHARMACEUTICAL DOSAGE FORMS

    Parikh Vikas C.; Karkhanis V.V

    2011-01-01

    A simple, sensitive and accurate UV spectrophotometric method has been developed for the determination of Gemfibrozil in bulk and pharmaceutical tablet dosage formulation. This method obeys Beer’s law in the concentration range of 30-90 µg/ml. with correlation coefficient of 0.9993 and exhibiting maximum absorption at 276 nm with apparent molar absorptivity of 0.1703 × 104 L mole-1 cm-1. The method is accurate and precise and is extended to pharmaceutical tablet dosage forms and there was no ...

  12. X-ray absorption studies of battery materials

    McBreen, J.

    1996-10-01

    X-ray absorption spectroscopy (XAS) is ideal for {ital in}{ital situ} studies of battery materials because both the probe and signal are penetrating x rays. The advantage of XAS being element specific permits investigation of the environment of a constituent element in a composite material. This makes it very powerful for studying electrode additives and corrosion of individual components of complex metal hydride alloys. The near edge part of the spectrum (XANES) provides information on oxidation state and site symmetry of the excited atom. This is particularly useful in study of corrosion and oxidation changes in cathode materials during charge/discharge cycle. Extended fine structure (EXAFS) gives structural information. Thus the technique provides both chemical and structural information. Since XAS probes only short range order, it can be applied to study of amorphous electrode materials and electrolytes. This paper discusses advantages and limitations of the method, as well as some experimental aspects.

  13. Total absorption study of beta decays relevant for nuclear applications

    In this contribution we will present an overview of recent studies of the beta decay of nuclei relevant for the calculation of the decay heat in nuclear reactors as a continuation of the work presented in (1). The measurements are performed using the best available technique to detect the beta feeding probability, the total absorption technique (TAS). In our studies we have combined the TAS technique with the use of a Penning Trap (JYFLTRAP, Univ. of Jyvaeskylae) as a high-resolution isobaric separator in order to guarantee high purity of the sources. A brief summary of the latest results of the measurements using a new segmented total absorption spectrometer, the faced challenges depending of the particular nuclei as well as new developments of the techniques of analysis will be discussed. The impact of the measurements on summation calculations of the decay heat in reactors, and in possible non-proliferation applications will be addressed. Future plans and the development of a new modular TAS detector (DTAS) for the DEcay SPECtroscopy (DESPCE) experiment at FAIR will also presented. (author)

  14. Studies on Steam Absorption Chillers Performance at a Cogeneration Plant

    Abd Majid Mohd Amin

    2014-07-01

    Full Text Available Absorption chillers at cogeneration plants generate chilled water using steam supplied by heat recovery steam generators. The chillers can be of either single-effect or double effect configuration and the coefficient of performance (COP depends on the selection made. The COP varies from 0.7 to 1.2 depending on the types of chillers. Single effect chillers normally have COP in the range of 0.68 to 0.79. Double effect chillers COP are higher and can reach 1.2. However due to factors such as inappropriate operations and maintenance practices, COP could drop over a period of time. In this work the performances of double effect steam absorption chillers at a cogeneration plant were studied. The study revealed that during the period of eleven years of operation the COP of the chillers deteriorated from 1.25 to 0.6. Regression models on the operation data indicated that the state of deterioration was projected to persist. Hence, it would be recommended that the chillers be considered for replacement since they had already undergone a series of costly repairs.

  15. Potentiometric and spectrophotometric study of the stability of magnesium carbonate and bicarbonate ion pairs to 150 °C and aqueous inorganic carbon speciation and magnesite solubility

    Stefánsson, Andri; Bénézeth, Pascale; Schott, Jacques

    2014-08-01

    The formation constants of magnesium bicarbonate and carbonate ion pairs have been experimentally determined in dilute hydrothermal solutions to 150 °C. Two experimental approaches were applied, potentiometric acid-base titrations at 10-60 °C and spectrophotometric pH measurements using two pH indicators, 2-naphthol and 4-nitrophenol, at 25 and 80-150 °C. At a given temperature, the first and second ionization constants of carbonic acid (K1, K2) and the ion pair formation constants for MgHCO3+(aq) (KMgHCO3+) and MgCO3(aq) (KMgCO3) were simultaneously fitted to the data. Results of this study compare well with previously determined values of K1 and K2. The formation constants of MgHCO3+(aq) and MgCO3(aq) ion pairs increased significantly with increasing temperature, with values of logKMgHCO3+ = 1.14 and 1.75 and of logKMgCO3 = 2.86 and 3.48 at 10 °C and 100 °C, respectively. These ion pairs are important aqueous species under neutral to alkaline conditions in moderately dilute to concentrated Mg-containing solutions, with MgCO3(aq) predominating over CO32-(aq) in solutions at pH >8. The predominance of magnesium carbonate over carbonate is dependent on the concentration of dissolved magnesium and the ratio of magnesium over carbonate. With increasing temperature and at alkaline pH, brucite solubility further reduced the magnesium concentration to levels below 1 mmol kg-1, thus limiting availability of Mg2+(aq) for magnesite precipitation.

  16. Acid-base and electrochemical properties of manganese meso(ortho- and meta-N-ethylpyridyl)porphyrins: potentiometric, spectrophotometric and spectroelectrochemical study of protolytic and redox equilibria.

    Weitner, Tin; Budimir, Ana; Kos, Ivan; Batinić-Haberle, Ines; Biruš, Mladen

    2010-12-28

    The difference in electrostatics and reduction potentials between manganese ortho-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP) and manganese meta-tetrakis(N-ethylpyridinium-3-yl)porphyrin (MnTE-3-PyP) is a challenging topic, particularly because of the high likelihood for their clinical development. Hence, a detailed study of the protolytic and electrochemical speciation of Mn(II-IV)TE-2-PyP and Mn(II-IV)TE-3-PyP in a broad pH range has been performed using the combined spectrophotometric and potentiometric methods. The results reveal that in aqueous solutions within the pH range ∼2-13 the following species exist: (H(2)O)Mn(II)TE-m-PyP(4+), (HO)Mn(II)TE-m-PyP(3+), (H(2)O)(2)Mn(III)TE-m-PyP(5+), (HO)(H(2)O)Mn(III)TE-m-PyP(4+), (O)(H(2)O)Mn(III)TE-m-PyP(3+), (O)(H(2)O)Mn(IV)TE-m-PyP(4+) and (O)(HO)Mn(IV)TE-m-PyP(3+) (m = 2, 3). All the protolytic equilibrium constants that include the accessible species as well as the thermodynamic parameters for each particular protolytic equilibrium have been determined. The corresponding formal reduction potentials related to the reduction of the above species and the thermodynamic parameters describing the accessible reduction couples were calculated as well. PMID:21052598

  17. Study on the elemental mercury absorption cross section based on differential optical absorption spectroscopy

    Zheng, Haiming; Yao, Penghui

    2015-08-01

    With the method of ultraviolet absorption spectrum, the exact absorption cross-section with the light source of the low-pressure mercury lamp was determined, during which the optimum wavelength for mercury concentrations inversion was 253.69 nm, the highest detection limit was 0.177 μg/cm3, and the lowest detection limit was 0.034 μg/cm3. Furthermore, based on the differential optical absorption spectroscopy(DOAS), the relationship between the integral parameters (IP) and the concentration as well as the signal-noise ration (SNR) under the conditions of gas flow was determined and the lowest detection limit was figured out to be 0.03524 μg/cm3, providing a method of DOAS to de-noise through the comparison between the mercury concentration values produced by DOAS and that produced by the wavelet de-noising method (db5). It turned out that the differential optical absorption spectroscopy had a strong anti-interference ability, while the wavelet de-noising method was not suitable for measuring the trace concentration change.

  18. Determination of 88Y in neutron activated rocks. Application of simplex optimization in spectrophotometric analysis

    A sensitive and selective spectrophotometric method for the determination of chemical recovery of 88Y in neutron activated rocks is developed with modified simplex optimization method. The spectrophotometric method is based on the reaction between rare earth elements and chlorophosphonazo III in aqueous solution containing Cu, Phen and ethanol. Under the experimental conditions, the maximum absorption wavelength is at 680 nm, the molar absorptivity is 1.06 x 104 m2/mol. The absorbance is linearly dependent on the concentration of yttrium when the concentration is below 0.6 mg/l. The variation coefficient is 0.87%

  19. Quasar Outflow Constraints using Broad Absorption Line Variability Studies

    McGraw, Sean; Shields, Joseph C.; Hamann, Fred; Capellupo, Daniel M.; Gallagher, Sarah; Brandt, W. Niel; Herbst, Hanna

    2016-01-01

    Quasar outflows are plausible candidates for AGN feedback processes influencing the host galaxy and may explain the established correlations between the supermassive black hole (SMBH) and the surrounding bulge. In order to better understand feedback and the physical conditions of the outflowing gas, observational constraints on absorber kinematics and energetics are needed. We are utilizing multiple epoch, rest frame UV quasar spectra to establish limits on outflow locations and total column densities for the purpose of estimating wind kinetic energies and momenta. We are also investigating the variability patterns of broad absorption lines (BALs) and mini-BALs across a range of ionization states to probe underlying connections between the various classes of absorbers. This work employs observations from the Sloan Digital Sky Survey, Hobby Eberly Telescope, and MDM observatory. We detect BAL variability in 3 out of 12 FeLoBAL quasars over multiple year timescales and conclude that the variable absorbers lie within tens of parsecs of the SMBH based on interpretations of the Fe II and Mg II BALS. We also measure significant BAL changes across daily to yearly timescales in a sample of 71 quasars with plausible detections of the P V 1117,1128 BAL. Detecting phosphorus in absorption is notable because it traces high column density outflows and is therefore relevant for studying AGN feedback. Constraints on outflow energetics and other selected results will be presented.

  20. Studies on the radiation absorption characteristics of various rocks

    Radiation absorption characteristics of nine different rocks, namely, ferrugenous quartz, metabasalt, larvikite, coarse grained diorite, coarse grained granite, coarse grained alkali granite, marble, quartz mica schist, and metamorphosed rock are studied. The rocks were collected from Jeddah, Makkah, Mina and Taif areas. Special attention was given on the availability, compactness, physical formation and uniform composition in selecting the rocks. The rocks were identified by optical method and their elemental composition determined by chemical analysis. The data were used to calculate the effective atomic numbers, half value layers mass and linear attenuation coefficients. The half value layers and the linear attenuation coefficientsof these rocks were determined experimentally using Am-241, Cs-137,and Co-60 sources. The results are compared with those obtained by theoretical calculations and agrre within 10%. Most of the rocks show much higher radiation attenuation characteristics than the standard concrete. Rocks containing higher percentage of Fe, Ca, Ti, and Mn show much higher radiation absorption characteristics than concrete. Only granites are found to be almost equivalent to concrete. 12 Ref

  1. Radioisotope techniques for the study of protein absorption

    The earliest attempt to use a labelled protein for the study of intestinal absorption was made in 1952. Researchers were able to show that an oral dose of I131-labelled casein was not absorbed as satisfactorily by patients with fibrocystic disease of the pancreas as by normal subjects. Their method basically consisted of feeding I131-labelled casein with a load of inactive protein and measuring the amount of unabsorbed radioactivity appearing in the faeces. This method was also used in patients with other pancreatic disorders in whom protein malabsorption was also demonstrated. However, this method did not show any malabsorption of protein in patients with coeliac disease, who are known to have a high faecal nitrogen similar to that found in pancreatic disease. One possible cause of this discrepancy could be deiodination of the labelled protein in the lumen of the bowel. To overcome this difficulty, H3-labelled albumin has recently been used to measure absorption in patients with intestinal disease. 2 figs, 1 tab

  2. Simpler spectrophotometric assay of paracetamol in tablets and urine samples

    Sirajuddin; Khaskheli, Abdul Rauf; Shah, Afzal; Bhanger, Muhammad Iqbal; Niaz, Abdul; Mahesar, Sarfaraz

    2007-11-01

    A very fast, economical and simpler direct spectrophotometric method was investigated for paracetamol (PC) determination in aqueous medium without using any chemical reagents. The method is based on the photo-absorption of the analyte at 243 nm after dissolution in water. The change in structure of PC after addition of water was studied by comparing the corresponding FTIR spectra. Optimization studies were conducted by using a 5 μg ml -1 standard solution of the analyte. Various parameters studied include, time for stability and measurement of spectra, effect of HCl, NaOH, CH 3COOH and NH 3 for change in absorbance and shift in spectra, interference by some analgesic drugs and some polar solvents and temperature effect. After optimization, Beer's law was obeyed in the range of 0.3-20 μg ml -1 PC solution with a correlation coefficient of 0.9999 and detection limit of 0.1 μg ml -1. The newly developed method was successfully applied for PC determination in some locally available tablets and urine samples. The proposed method is very useful for quick analysis of various types of solid and liquid samples containing PC.

  3. Spectrophotometric Determination of Certain Benzimidazole Proton Pump Inhibitors

    Syed, A. A.; Syeda, Ayesha

    2008-01-01

    Spectrophotometric method for the determination of certain proton pump inhibitors belonging to the benzimidazole class of compounds has been developed. The method is based on the reaction of omeprazole, lansoprazole, pantoprazole, rabeprazole and esomeprazole with iron (III) and subsequent reaction with ferricyanide under neutral condition which yields Prussian blue product with maximum absorption at 720–730 nm. The commonly encountered excipients and additives that often accompany pharmaceutical preparations did not interfere with the determination. The method was applied for the determination of omeprazole, lansoprazole, pantoprazole, rabeprazole and esomeprazole in pharmaceutical preparations and no difference was found statistically. Thus, the spectrophotometric method can be applied as inexpensive, rapid, easy, accurate and precise method for the routine analysis of the five proton pump inhibitors in pharmaceutical preparations. PMID:20046782

  4. Spectrophotometric determination of certain benzimidazole proton pump inhibitors

    Syed A

    2008-01-01

    Full Text Available Spectrophotometric method for the determination of certain proton pump inhibitors belonging to the benzimidazole class of compounds has been developed. The method is based on the reaction of omeprazole, lansoprazole, pantoprazole, rabeprazole and esomeprazole with iron (III and subsequent reaction with ferricyanide under neutral condition which yields Prussian blue product with maximum absorption at 720-730 nm. The commonly encountered excipients and additives that often accompany pharmaceutical preparations did not interfere with the determination. The method was applied for the determination of omeprazole, lansoprazole, pantoprazole, rabeprazole and esomeprazole in pharmaceutical preparations and no difference was found statistically. Thus, the spectrophotometric method can be applied as inexpensive, rapid, easy, accurate and precise method for the routine analysis of the five proton pump inhibitors in pharmaceutical preparations.

  5. Method development for arsenic analysis by modification in spectrophotometric technique

    M. A. Tahir

    2012-01-01

    Full Text Available Arsenic is a non-metallic constituent, present naturally in groundwater due to some minerals and rocks. Arsenic is not geologically uncommon and occurs in natural water as arsenate and arsenite. Additionally, arsenic may occur from industrial discharges or insecticide application. World Health Organization (WHO and Pakistan Standard Quality Control Authority have recommended a permissible limit of 10 ppb for arsenic in drinking water. Arsenic at lower concentrations can be determined in water by using high tech instruments like the Atomic Absorption Spectrometer (hydride generation. Because arsenic concentration at low limits of 1 ppb can not be determined easily with simple spectrophotometric technique, the spectrophotometric technique using silver diethyldithiocarbamate was modified to achieve better results, up to the extent of 1 ppb arsenic concentration.

  6. Continued studies of the gastrointestinal absorption of plutonium by rodents

    An investigation is being made of the absorption of plutonium from the gastrointestinal tract of rodents. In the mouse it has been found to be essentially independent of the oxidation state of plutonium and the administration medium. In the rat the absorption was higher than it was in the mouse, but not appreciably so. The values obtained for both mice and rats are about two orders of magnitude higher than the value adopted for the gastrointestinal absorption factor for plutonium in man

  7. Spectrophotometric determination of diloxanide furoate in its dosage forms.

    Al-Ghanam, S M; Belal, F

    2001-09-01

    A simple and sensitive spectrophotometric method has been developed for the determination of diloxanide furoate in its dosage forms. The method is based on the reaction of the drug with potassium permanganate in the presence of sodium hydroxide to produce a bluish green coloured species measurable at 610 nm. The absorbance-concentration plot is linear over the range 2.5-20 microg/ml with correlation coefficient (n = 8) of 0.9998 and minimum detectability of 0.2 microg/ml (6.1 x 10(-7) M). The molar absorptivity was 1.1 x 10(4) l/mol cm. The different experimental parameters affecting the development and stability of the colour were carefully studied and optimised. The proposed method was applied successfully for the determination of diloxanide furoate in its tablet form. The results obtained were in good agreement with those obtained using the official method. The proposed method could be applied to the determination of diloxanide furoate in presence of some co-formulated drugs. The effect of sensitisers and surfactants on the performance of the proposed method was also studied. A proposal of the reaction pathway was presented. PMID:11680811

  8. The influence of metal substrates and porcelains on the shade of metal-ceramic complex: A spectrophotometric study

    Kavitha Janardanan; Sreelal Thankappan Pillai; Harshakumar Karunakaran

    2012-01-01

    Background: The final esthetic outcome of a metal-ceramic restoration is influenced by several factors including the type of the underlying metal as well as the brand of the ceramic. Settings and Design: An in vitro study. Aims: The purpose of the in vitro study was to investigate the influence of four types of metal-ceramic alloys and two porcelain systems on the color co-ordinates of the metal-ceramic complex. It also aimed at establishing a color index which correlated the color of t...

  9. Spectrophotometric study of complexing between indium and chromazurol S in the presence of cetyl trimethyl-ammonium

    A study has been made into the interaction of indium with chromazurol S(XAS) in the presence of cetyltrimethylammonium (CTA) and an urotropin buffer solution with pH of 6. It is established that a complex compound with the following composition: In:XAS:CTA = 1:2:3 is formed. The number of protons detached when the complex is formed has been determined. The structure of the complex has been hypothesized. It is assumed that 3 protons are displaced during formation of [InR2x(CTA)3]sup(z-) or [In(OH)(HR)R(CTA)3]sup(z-) complex

  10. STOPPED-FLOW SPECTROPHOTOMETRIC STUDIES OF THE KINETICS OF INTERACTION OF DIHYDROXYFUMARIC ACID WITH THE DPPH FREE RADICAL

    N. Secara

    2010-01-01

    The reaction of dihydroxyfumaric acid with the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) was studied using the stopped-flow method, in order to describe the reaction kinetics. Dihydroxyfumaric acid reacts very rapidly with DPPH, the reaction being completed in several minutes. This 2-stoichiometric reaction proceeds in two stages, with reaction orders of 1 and 0.76 with respect to DPPH, and 0.5 and 0.3 with respect to DHF, respectively. The rate constant of the two stages of the react...

  11. Theoretical experimental study of the factors that govern the molybdenum absorption signal by means of electro thermic atomic absorption spectroscopy

    The formation of molybdenum carbides in the atomizer, used in the electro thermic atomic absorption spectroscopy, is responsible for incomplete analyte removal in its analysis. This generates the apparition of the memory effect and little precision in the results. In this work, different variables that could affect the molybdenum absorption sign were investigated, as well as the influence of hydrochloric acid on the memory effect, by means of studies in the different stages: drying, calcination and atomization, and the samples deposition order in molybdenum solutions, either acidified or not acidified

  12. Study of self-absorption in laser induced breakdown spectroscopy

    We present a simple analytical expression for self-absorption correction of a spectrum recorded in the image mode of a CCD camera. It is assumed that two spectra are available, F2 recorded with a back mirror and F1 recorded without. The corrected spectrum F0, free of self-absorption, is given by the following simple expression F0=(2F1)/(1+(F2−F1)/(GF1) ) . We discuss the influence of noise on subsequent inverse Abel transform. An example, illustrating proposed method for self-absorption correction and Abel inversion is given in details. - Highlights: • We present a simple expression for self-absorption correction in LIBS plasma. • Method needs two spectra recorded in the image mode of the CCD. • Abel transform is not necessary for self-absorption correction

  13. Spectrophotometric thermodynamic study of orientational isomers formed by inclusion of methyl orange into β-cyclodextrin nanocavity

    Kompany Zare, Mohsen; Mokhtari, Zeinab; Abdollahi, Hamid

    2012-01-01

    Spectrophotometry has been used to investigate the interaction of methyl orange (MO), an azo dye as a guest, with β-cyclodextrin (CD) as the host. Inclusion of methyl orange into β-cyclodextrin nanocavity leads to two orientational isomers, so-called inclumers, because of the asymmetric structure...... of methyl orange. This study was performed in basic and acidic media to yield the microconstants and thermodynamic parameters for inclusion complex formation equilibria in each media. The recorded data set at a constant temperature is rank deficient, because there is a linear dependency between...... concentration profiles of inclumers. This problem is overcome through the augmentation of multiwavelength data recorded at different temperatures. Titration of methyl orange solution with β-cyclodextrin solution was performed in five different temperatures, in order to calculate the formation microconstants for...

  14. Spectrophotometric retinal oximetry in pigs

    Traustason, Sindri; Kiilgaard, Jens Folke; Karlsson, Robert;

    2013-01-01

    PURPOSE: To assess the validity of spectrophotometric retinal oximetry, by comparison to blood gas analysis and intra-vitreal measurements of partial pressure of oxygen (pO2). METHODS: Female domestic pigs were used for all experiments (n=8). Oxygen fraction in inspired air was changed using a......, Reykjavik, Iceland). The device simultaneously acquires images at two wavelengths (570 nm and 600 nm) and specialized software automatically detects retinal blood vessels. In three pigs, invasive pO2-measurements were performed after the initial non-invasive measurements. RESULTS: Comparison of femoral......-measurements in three pigs. This relationship was approximately linear (R(2) = 0.45, p = 0.04). CONCLUSIONS: Non-invasive spectrophotometric oximetry is sensitive to changes in oxygen saturation in pigs and correlated with intravitreal pO2-measurements and with femoral artery pO2. Pigs present a higher intra...

  15. Spectrophotometric evaluation of optical performances of polarizing technologies for smart window applications

    In recent years, window-integrated solar protection systems are used and studied as a promising energy saving technology, both for cold and hot climates. In particular, smart windows, whose optical proprieties in the solar wavelength range can somehow be controlled, show interesting results, especially in reducing the air conditioning power consumption. With the improvement of nanolithography techniques as well as with the possibility of designing polarization intervals, coupled polarizing films show a good potential as a dynamic and wavelength-selective shading technology. In this paper, UV-Vis-NIR spectrophotometric measurements are carried out on two polarizing technologies, Polaroid crystalline polarizer and Wire Grid broadband polarizer, in single- and double- film layout, to evaluate their optical performances, i.e. spectral transmittance, reflectance and absorptivity. The solar radiation glazing factors, according to the standard UNI EN 410, are calculated. The measured data are also analyzed in detail to emphasize the optical peculiarities of the materials under study that do not stand out from the standard parameters, as well as the specific problems that arise in spectrophotometric evaluations of polarizing films

  16. Spectrophotometric determination of cyclizine hydrochloride in pure and pharmaceutical preparations

    A sensitive and simple spectrophotometric method for the estimation of cyclizine hydrochloride in both pure form and its pharmaceutical formulation is described. The method is based on the interaction of cyclizine hydrochloride with dichloronitrobenzene in alkaline media. Absorbance of the resulting yellowish orange complex is measured at 430 nm and is stable for more than 24 hours. The reaction obeys Beer's Law from 0.01 to 2.5 mg/10ml of cyclizine hydrochloride. Molar absorptivity is 0.2909 x 104 mol/sup -1/cm/sup -1/ and the relative standard deviation is 0.72%. Analytical data for determination of the pure compound is presented along with the application of the proposed method to the analysis of some pharmaceutical formulation. The method is reproducible and selective for cyclizine hydrochloride. The common excipients used as additives in pharmaceuticals do not interfere and the quantitative assessments of tolerable amount of other drugs not interfering are also studied. The results compare favourably with those of official procedures. (author)

  17. A Spectrophotometric Study of Plumage Color in the Eared Dove (Zenaida auriculata, the Most Abundant South American Columbiforme.

    Diego Javier Valdez

    Full Text Available For birds, plumage color perception is critical in social interactions such as courtship, in both monochromatic and dichromatic species. In the Eared Dove (Zenaida auriculata, perhaps the most abundant South American Columbiforme, the plumage of males and females looks alike and both sexes share the same melanistic coloration with gray and pink tones. The aim of this study was therefore to determine whether evident sexual dichromatism exists in the plumage of the Eared Dove using a spectrophotometry technique in the avian-visible range (300-700 nm. The results of the classic colorimetric variables analysis (hue, chroma and brightness show that males are in general brighter and have higher UV chroma values than females. The avian visual model points to differences in achromatic and chromatic levels between males and females in body regions possibly involved in sexual selection (e.g. the crown. The model also indicates chromatic or achromatic differences in body regions not subject to sexual selection such as the black spots on the wing coverts and white tail bands, both of which may be involved in intra- or inter-gender-specific communication.

  18. A Spectrophotometric Study of Plumage Color in the Eared Dove (Zenaida auriculata), the Most Abundant South American Columbiforme.

    Valdez, Diego Javier; Benitez-Vieyra, Santiago Miguel

    2016-01-01

    For birds, plumage color perception is critical in social interactions such as courtship, in both monochromatic and dichromatic species. In the Eared Dove (Zenaida auriculata), perhaps the most abundant South American Columbiforme, the plumage of males and females looks alike and both sexes share the same melanistic coloration with gray and pink tones. The aim of this study was therefore to determine whether evident sexual dichromatism exists in the plumage of the Eared Dove using a spectrophotometry technique in the avian-visible range (300-700 nm). The results of the classic colorimetric variables analysis (hue, chroma and brightness) show that males are in general brighter and have higher UV chroma values than females. The avian visual model points to differences in achromatic and chromatic levels between males and females in body regions possibly involved in sexual selection (e.g. the crown). The model also indicates chromatic or achromatic differences in body regions not subject to sexual selection such as the black spots on the wing coverts and white tail bands, both of which may be involved in intra- or inter-gender-specific communication. PMID:27213273

  19. Spectrophotometric evaluation of peroxide penetration into the pulp chamber from whitening strips and gel: An in vitro study

    Ramesh Bharti

    2013-01-01

    Full Text Available Aim: To investigate pulp chamber penetration of different concentration of hydrogen peroxide. Materials and Methods: Fifty extracted human maxillary central incisor teeth were taken and grouped into five ( n = 10. All teeth were cut approximately 3 mm apical to the cemento-enamel junction. Pulp was removed and the pulp chamber filled with acetate buffer. Buccal crown surfaces of teeth in the experimental groups were subjected to whitening strip and paint on whitener gel. Control group teeth were exposed to distilled water. The acetate buffer solution in each tooth was then transferred to a glass test tube after 30 min. Leuco-crystal violet dye and enzyme horse radish peroxidase were added. The optical density of resultant blue color in the tubes was measured by UV-visible spectrophotometer. The values were converted into microgram equivalents of hydrogen peroxide. Results: The results were evaluated statistically using nonparametric Mann-Whitney U test. Whitening strip showed the lowest pulpal peroxide penetration whereas paint on whitener gel showed highest pulpal peroxide penetration. Conclusion: This study demonstrate that peroxide is readily penetrate into the pulp chamber of teeth.

  20. Reduction and alkylation of cobalt(II) tetrakis(4-sulfonatophenyl)porphyrin in aqueous solutions. A kinetic spectrophotometric study

    The reactions of Co/sup II/TPPS (TPPS = tetrakis(4-sulfonatophenyl)prophyrin) with alkyl and hydroxyalkyl radicals have been studied by pulse radiolysis. The alkyl radicals undergo axial addition with rate constants of (1.2 to 1.9) x 109 M-1s-1 to form R-Co/sup III/TPPS complexes which either are stable (R = CH3) or undergo decomposition R = CH(CH3)2) to Co/sup I/TPPS and an olefin via a β-proton elimination mechanism (k1 = 0.3 s-1 at pH 8 and 3 s-1 at pH 13). The hydroxyalkyl radicals also form R-Co/sup III/TPPS with rate constants of (1.1 to 1.2) x 109 M-1 s-1. These adducts undergo heterolytic cleavage of the cobalt-carbon bond to form Co/sup I/TPPS and a carbonyl compound, with rate constants of 3.6 x 102s-1 (R = CH2OH) and 6.2 x 103 s-1 (R = C(OH)(CH3)2). The radicals (CH3)2CO- and CO2- reduce CO/sup II/TPPS to Co/sup I/TPPS by an outer-sphere mechanism with rate constants 7 x 108 and 2 x 108 M-1 s-1, respectively. Co/sup I/TPPS is oxidized to CH3Co/sup III/TPPS by CH3I (k2 = 3 x 105 M-1 s-1) and to Co/sup II/TPPS (probably through intermediate formation of Co/sup III/TPPS) by N2O (k2 less than or equal to 3 x 102 M-1 s-1). The reactivities of the present systems have been compared with those of other models suggested for vitamin B12 like cobaloximes, cobalamins, and other macrocyclic Co/sup II/ complexes. 36 references, 6 figures, 1 table

  1. Iron absorption and iron status related to diet : an experimental and epidemiological study

    Tidehag, Per

    1995-01-01

    The absorption of iron from the diet is a major determinant of the iron status of an individual. Accurate measures of iron absorption are thus essential in the determination of the effects of diet composition on iron absorption and status. The aim of these studies have firstly been to investigate different methods to measure iron absorption and effects of diet in both rats and humans. Secondly to describe variations in iron status in a general population and to relate the variations to diet. ...

  2. Povidone iodine skin absorption: an ex-vivo study.

    Nesvadbova, Martina; Crosera, Matteo; Maina, Giovanni; Larese Filon, Francesca

    2015-06-15

    Povidone iodine is a water-soluble complex used to disinfect the skin surface and it exerts prolonged germicidal action against a broad spectrum of germs. Indeed, it is often applied on burned skin, large wounds, deep tissues or mucosa. Notably some surgical hand-scrub solutions, which are considered safe antiseptics, contain large amounts of iodine that can be absorbed by skin. The aim of present study was to study the skin absorption of iodine after the application on the skin of povidone-iodine solution, used by health care workers during surgical procedure. We use Franz diffusion static cells with human skin. After 24h from the beginning of our measurement the iodine concentration in the receiving compartment was 11.59±6.3μg/cm(2). The medium flux calculated was 0.73±0.33μg/cm(2)/h with a lag time of 8.9±1.5h. These in vitro results confirmed that povidone iodine could pass through the skin in a relevant amount that can explain the clinical findings in burned or surgically treated patients. In professional use the repetitive contact with povidone iodine, also as soap, can cause iodine skin permeation that must be considered when the washing procedures are repeated more than 20 times a day. PMID:25858112

  3. [Study of retrieving formaldehyde with differential optical absorption spectroscopy].

    Li, Yu-Jin; Xie, Pin-Hua; Qin, Min; Qu, Xiao-Ying; Hu, Lin

    2009-01-01

    The present paper introduces the method of retrieving the concentration of HCHO with differential optical absorption spectroscopy (DOAS). The authors measured ambient HCHO in Beijing region with the help of differential optical absorption spectroscopy instrument made by ourself, and discussed numerous factors in retrieving the concentration of HCHO with differential optical absorption spectroscopy (DOAS), especially, the choice of HCHO wave band, how to avoid absorption of ambient SO2, NO2 and O3, and the influence of the Xenon lamp spectrum structure on the absorption of ambient HCHO. The authors achieved the HCHO concentration by simultaneously retrieving the concentrations of HCHO, SO2, NO2 and O3 with non-linear least square fitting method, avoiding the effect of choosing narrow wave of HCHO and the residual of SO2, NO2, O3 and the Xenon lamp spectrum structure in retrieving process to attain the concentration of HCHO, Finally the authors analyzed the origin of error in retrieving the concentration of HCHO with differential optical absorption spectroscopy (DOAS), and the total error is within 13.7% in this method. PMID:19385238

  4. Study on Kinetics of Hydrogen Absorption by Metal Hydride Slurries Ⅰ. Absorption of Hydrogen by Hydrogen Storage Alloy MlNi5 Suspended in Benzene

    安越; 陈长聘; 徐国华; 蔡官明; 王启东

    2002-01-01

    The absorption of hydrogen was studied in metal hydride slurry, which is formed by benzene and hydrogen storage alloy powder. The influence of temperature on the rate of absorption was discussed using three-phase mass transfer model. It is also concluded that the suitable absorption temperature is 313 K.

  5. Comparative study of five varieties of spodumene through optical absorption

    A comparative study of five varieties of spodumene crystals from Brazil through optical absorption spectroscopy, classified according to the colours lylac, colourless I, colourless II, yellow and green is reported. This series shows a consistent increase of the [Fe]/[Mn] ratio. The principal bands in the yellow sample are at 7,000 and 9,000 cm-1, and in the green sample besides these bands a band at 16,000 cm-1 is observed. In lylac, colourless I and colourless II samples, the principal bands are at 18,000 cm-1 and when irradiated two new bands appears at 15,700 cm-1 (E perpendicular to c) and 11,000 cm-1 (K perpendicular to c). It is suggested that in green and yellow samples the bands are due to Fe2+ (at 7,000 cm-1 and 9,000 cm-1) and due to Fe2+ - Fe3+ charge transfer (at 16,000 cm-1). In lylac and colourless I samples the model for Mn3+ at two different sites is applied. The colourless II corresponds to the case in which Mn3+ is at one site alone, being prohibited from occupying the second site due to higher Fe concentration. (Author)

  6. Determination of tacrolimus in pharmaceutical formulations by validated spectrophotometric methods

    T. M. BöER; Marques, M. R.; S. G. Cardoso

    2009-01-01

    Two simple, rapid and sensitive spectrophotometric methods were developed for the determination of tacrolimus in pharmaceutical dosage forms. The methods, based on the sulphuric acid reaction and on the iodine charge-transfer reaction, gave absorption peaks at 295 nm and 365 nm, respectively. The calibration curves were linear in the concentration range of 30-55 µg m...

  7. A spectrophotometric method for the determination Co-EDTA complexes

    Arunachalam Paraneeiswaran; Sudhir. K. Shukla; V.S. Sathyaseelan; Toleti Subba Rao

    2015-01-01

    A precise quantification of Co(II)EDTA complex is required to develop bioremediation approaches for Co(III)EDTA complex that is generated in various industrial processes. It is cumbersome to quantify Co(II)EDTA in a mixture of Co(II)EDTAand Co(III)EDTAby normal UV-visible spectrophotometric methods as both the complexes absorb significantly at 490 nm, which is the λ max of Co(II)EDTA. Whereas other sophisticated techniques such as gas chromatography, atomic absorption spectrophotometer, induc...

  8. Visible spectrophotometric determination of valdecoxib in tablet dosage forms

    Suganthi A

    2006-01-01

    Full Text Available A simple, accurate, rapid, and sensitive visible spectrophotometric method has been developed for the determination of valdecoxib in pure and pharmaceutical dosage forms. The method is based on the reaction of valdecoxib with potassium permanganate to form a bluish green coloured chromogen with an absorption maximum at 610 nm. Beer′s law was obeyed in the range of 5-25 mg/ml. The proposed method has been successfully applied to the analysis of the bulk drug and its dosage forms

  9. Shards: an optical spectro-photometric survey of distant galaxies

    Pérez-González, P. G.; Cava, A; Rodríguez-Espinosa, J. M.; Alonso-Herrero, A.; Cepa, Jordi; Donley, J. L.; Gallego, Jesús; González-Martín, Omaira; Hernán-Caballero, Antonio; Rodríguez Zaurín, Javier

    2013-01-01

    We present the Survey for High-z Absorption Red and Dead Sources (SHARDS), an ESO/GTC Large Program carried out using the OSIRIS instrument on the 10.4 m Gran Telescopio Canarias (GTC). SHARDS is an ultra-deep optical spectro-photometric survey of the GOODS-N field covering 130 arcmin2 at wavelengths between 500 and 950 nm with 24 contiguous medium-band filters (providing a spectral resolution R ∿ 50). The data reach an AB magnitude of 26.5 (at least at a 3σ level) with sub-arcsec seeing i...

  10. Direct spectrophotometric determination of vanadium with 3-hydroxy-3-phenyl-1-p-carboxyphenyltriazene

    3-hydroxy-3-phenyl-1-p-carboxyphenyltriazene was used for spectrophotometric determination of vanadium. The composition of the yellowish green complex is 1:1 (V:R) with maximum absorbance at 395 nm and working wavelength was chosen to be 420 nm using solvent as blank. Molar absorptivity and Sandell's sensitivity were found to be 9550 l/mole cm and 5.33 ng/cm2 respectively in the pH range 6.5 to 7.0. Beer's law was obeyed in the range 0.50 to 3.05 ppm of vanadium. Standard deviation 'σ' (10 determinations) using 2.54 ppm of vanadium was 0.002. Interference of 22 diverse ions was studied. (author). 9 refs., 1 tab

  11. Visible spectrophotometric estimation of diacerein in bulk and pharmaceutical dosage forms.

    Sivakumar, R; Nallasivan, Pk; Saranya, Kc; Sam, Solomon Wd; Akelesh, T; Venkatnarayanan, R

    2010-10-01

    Two simple, sensitive, accurate, rapid, and economical spectrophotometric methods have been developed for the estimation of diacerein in Pharmaceutical dosage forms. Method A is based on the reaction of diacerein with Folin-Ciocalteu reagent, in the presence of 0.5 N sodium hydroxide solution, giving a pink-colored chromogen, which shows maximum absorbance at 512 nm against reagent blank, while method B is based on the oxidation of diacerein with potassium permanganate in an alkaline medium giving a pink-colored chromogen, which shows maximum absorption at 497.5 nm. Beer's law was obeyed in the concentration range of 4 - 20 µg/ml for both methods A and B. Results of the analysis were validated statistically, and by recovery studies. PMID:21264105

  12. Theoretical Study of New Combined Absorption-Ejector Refrigeration System

    Abed, A. M.; Sopian, K.; Alghoul, M. A.; Al-Shamani, A. N.; Ruslan, M. H.; Mat, S.

    2015-09-01

    An improved system of the new combined single stage absorption cycle operated with NH3/H2O as working fluid was performed. In order to enhance performance the cycle a new configuration of absorption system was utilized. The performances of two configurations of the combined absorption cycle were compared; a) with common solution heat exchanger and b) divided the streamline of solution heat exchanger to recover the internal heat. Based on the analysis, it has been shown that the second configuration a significant reduction of the required generator and absorber loads by about 20% and 17% respectively, with increased coefficient of performance (COP) about 12% compared to the first configuration. This improvement in the overall COP is found due to improve energy utilization efficiency significantly.

  13. SOLID PHASE SPECTROPHOTOMETRIC DETERMINATION OF SELENIUM(IV) USING DITHISONE IMMOBILIZED IN A POLYMETHACRYLATE MATRIX

    Gavrilenko, N. A.; Saranchina, N. V.; Gavrilenko, M. A.

    2014-01-01

    This paper presents a solid-phase spectrophotometric method for the determination selenium(IV). The proposed method is based on the reaction between the selenium(IV) and dithizone immobilized into transparent polymethacrylate matrix in strongly acidic solution. It was shown that the interaction of selenium(IV) with dithizone in solid phase was accompanied by the formation of the complex with an absorption maximum 420 nm. The change of absorption at wavelength 610 nm corresponding to absorptio...

  14. 15N tracer methodology for absorption studies in nutrition research

    Proceeding from 15N analyses, 15N tracer methods, and a model of protein metabolism it is shown that the nitrogen balance is a useful concept for expressing the relationship between the overall nitrogen intake of the body and the nitrogen excretion. After admistering low doses of 15N-labelled substances like protein and amino acids, the kinetics of digestion and absorption can be followed by measuring the 15N abundance in serum and urine of patients. A significant delay in the nitrogen absorption indicates gastrointestinal disorders

  15. Zinc absorption study using an enriched stable isotope (70Zn)

    A weaning food from fermented soybean was prepared for increasing the bioavailability of zinc. The zinc absorption was compared with that of a weaning food from non-fermented soybean and normal staple food. A stable isotope tracer technique (70Zn) and neutron activation were used for determining the absorption of zinc. Nine children aged 7 to 18 months were tested. Zinc bioavailability of weaning food from fermented soybean is higher than that of normal weaning food. The weight increment and zinc nutrition of children having weaning food from fermented soybean are improved by this diet. 5 tabs

  16. Protonation effects on the UV/Vis absorption spectra of imatinib: A theoretical and experimental study

    Grante, Ilze; Actins, Andris; Orola, Liana

    2014-08-01

    An experimental and theoretical investigation of protonation effects on the UV/Vis absorption spectra of imatinib showed systematic changes of absorption depending on the pH, and a new absorption band appeared below pH 2. These changes in the UV/Vis absorption spectra were interpreted using quantum chemical calculations. The geometry of various imatinib cations in the gas phase and in ethanol solution was optimized with the DFT/B3LYP method. The resultant geometries were compared to the experimentally determined crystal structures of imatinib salts. The semi-empirical ZINDO-CI method was employed to calculate the absorption lines and electronic transitions. Our study suggests that the formation of the extra near-UV absorption band resulted from an increase of imatinib trication concentration in the solution, while the rapid increase of the first absorption maximum could be attributed to both the formation of imatinib trication and tetracation.

  17. Study of UCI4 structure and absorption spectra

    The two halides ThCl4 and ThBr4, which are isomorphic at room temperature, have a comparable behaviour when the temperature is lowered. The resonance line of the halogen isotope is split into two lines at a temperature of 96 K for ThBr4 and 70 K for ThCl4. These data confirm the observation of a phase transition first detected by Raman Spectroscopy. Though UCl4 is isomorphic with ThCl4 and ThBr4 at room temperature, it behaves differently versus temperature. The experiments performed from 4,2K to room temperature showed there is only one site for the halogen. UCl4 does not present a phase transition. Once some informations have been gathered on the matrices, optical absorption spectra on ThCl4:U4+ and UCl4 monocristals have been recorded in the visible and infrared ranges at 4,2 K and at room temperature. These spectra have many vibronic lines. To give a first interpretation of the pure electronic lines of U4+-ThCl4 and UCl4 studies on U4+-ThBr4 have been used, in particular the zero phonon lines which correspond to a Dsub(2d) symmetry, have been selected in comparison with the work done on ThBr4:U4+. The energy levels in ThCl4:U4+ and UCl4 have been fitted to the electrostatic parameters F0, F2,F4, F6, the spin orbit parameter, the configuration interaction parameters α, β, γ and crystal field parameters B02, B04, B44, B06, B46

  18. Spectrophotometric Determination of Zinc Using 7-(4-Nitrophenylazo)-8-Hydroxyquinoline-5-Sulfonic Acid

    Korn Maria das Graças Andrade; Ferreira Adriana Costa; Teixeira Leonardo Sena Gomes; Costa Antonio Celso Spínola

    1999-01-01

    A sensitive and selective spectrophotometric method is proposed for the rapid determination of zinc(II) using an 8-hydroxyquinoline derivative, 7-(4-nitrophenylazo)-8-hydroxyquinoline-5-sulfonic acid (p-NIAZOXS), as a new spectrophotometric reagent. The reaction between the p-NIAZOXS and zinc(II) is instantaneous at pH 9.2 (borax buffer) and the absorbance remains stable for over 24 h. The method allows the determination of zinc over the range of 0.05-1.0 mug mL-1 with a molar absorptivity of...

  19. Application of inorganic oxidants to the spectrophotometric determination of ribavirin in bulk and capsules.

    Darwish, Ibrahim A; Khedr, Alaa S; Askal, Hassan F; Mohamed, Ramadan M

    2006-01-01

    Eight spectrophotometric methods for determination of ribavirin have been developed and validated. These methods were based on the oxidation of the drug by different inorganic oxidants: ceric ammonium sulfate, potassium permanganate, ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate. The oxidation reactions were performed in perchloric acid medium for ceric ammonium sulfate and in sulfuric acid medium for the other reagents. With ceric ammonium sulfate and potassium permanganate, the concentration of ribavirin in its samples was determined by measuring the decrease in the absorption intensity of the colored reagents at 315 and 525 nm, respectively. With the other reagents, the concentration of ribavirin was determined by measuring the intensity of the developed colored reaction products at the wavelengths of maximum absorbance: 675, 780, 595, 595, 475, and 475 nm for reactions with ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate, respectively. Different variables affecting the reaction conditions were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9984-0.9998) were found between the absorbance readings and the concentrations of ribavirin in the range of 4-1400 microg/mL. The molar absorptivities were correlated with the oxidation potential of the oxidants used. The precision of the methods were satisfactory; the values of relative standard deviation did not exceed 1.64%. The proposed methods were successfully applied to the analysis of ribavirin in pure drug material and capsules with good accuracy and precision; the recovery values were 99.2-101.2 +/- 0.48-1.30%. The results obtained using the proposed spectrophotometric methods were comparable with those obtained with the official method stated in the United States Pharmacopeia. PMID

  20. Photo absorption studies of polyatomic molecules using Indus 1 synchrotron radiation source

    The Photophysics beamline is a medium resolution beamline designed for carrying out photo absorption and fluorescence experiments using the synchrotron radiation source Indus-l. This beamline has been commissioned recently and is in operation. An experimental setup for gas phase absorption studies has been developed and installed. Absorption spectra of a few polyatomicmolecules viz. benzene, ammonia, carbon disulphide and acetone were recorded in the wavelength region 1500 -3000 A. The results from this study indicated the satisfactory performance of the beam line as well as the experimental setup. Details of the first set of absorption experiments carried out are discussed in this report. (author)

  1. Spectrophotometric study of Co(II, Ni(II, Cu(II, Zn(II, Pd(II and Hg(II complexes with isatin- β-thiosemicarbazone

    SANDRA S. KONSTANTINOVIC

    2007-10-01

    Full Text Available The composition and stability of the complexes of isatin-b-thiosemicarba­zone with Co(II, Ni(II, Cu(II, Zn(II, Pd(II and Hg(II have been investigated us­ing spectrophotometric method at 30 °C and constant ionic strength of 0.1 mol dm-3 (KNO3 in 70 % ethanol. Experimental results indicate the formation of MeL and MeL2 complexes for Ni(II and Co(II, and MeL for Cu(II, Zn(II, Pd(II and Hg(II complexes, whose stability constants, bn, have been calculated using a com­puteri­zed iterative method of successive approximation.

  2. CdTe Nanowires studied by Transient Absorption Microscopy

    Kuno M.

    2013-03-01

    Full Text Available Transient absorption measurements were performed on single CdTe nanowires. The traces show fast decays that were assigned to charge carrier trapping at surface states. The observed power dependence suggests the existence of a trap-filling mechanism. Acoustic phonon modes were also observed, which were assigned to breathing modes of the nanowires. Both the fundamental breathing mode and the first overtone were observed, and the dephasing times provide information about how the nanowires interact with their environment.

  3. Study on hydrogen absorption/desorption properties of uranium alloys

    Ito, Hiroshi; Yamaguchi, Kenji; Yamawaki, Michio [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

    1996-10-01

    Hydrogen absorption/desorption properties of two U-Mn intermetallic compounds, U{sub 6}Mn and UMn{sub 2}, were investigated. U{sub 6}Mn absorbed hydrogen and the hydrogen desorption pressure of U{sub 6}Mn obtained from this experiment was higher than that of U, which was considered to be the effect of alloying, whereas UMn{sub 2} was not observed to absorb hydrogen up to 50 atm at room temperature. (author)

  4. In vitro absorption studies of acyclovir using natural permeation enhancers

    Dias, Remeth J.; Mali, Kailas K.; Ghorpade, Vishwajeet S.; Garje, Sandeep B.; Havaldar, Vijay D.

    2010-01-01

    Gastroretentive Delivery Systems are employed to improve the bioavailability of drugs which are absorbed through upper part of GIT, by increasing their retention time. Incorporation of permeability enhancers in the formulations of such drugs can further increase their bioavailability; however their use in the formulations is questionable due to the toxicity exhibited by them. Acyclovir is a class III drug having low oral bioavailability due to improper absorption. Mucoadhesive tab...

  5. Light Propagation and Gas Absorption Studies in Turbid Media Using Tunable Diode Llaser Techniques

    Mei, Liang

    2014-01-01

    Optical absorption spectroscopy is a widely used analytical tool for constituent analysis in many applications. According to the Beer-Lambert law, the transmitted light intensity through a homogeneous medium is an exponential function of the product of the concentration, the total pathlength, and the absorption cross-section of the absorbing substance. By studying the intensity loss at the unique absorption band of the absorbing substance, its concentration can be retrieved. However, this met...

  6. Optical absorption and fluorescence studies on imidazolium ionic liquids comprising the bis(trifluoromethanesulphonyl)imide anion

    Aniruddha Paul; Anunay Samanta

    2006-07-01

    Optical absorption and fluorescence behaviour of two rigorously purified imidazolium ionic liquids, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide are studied in the neat condition and in solution. Non-negligible absorption in the UV region with a long tail extending into the visible region is the main feature of the absorption. Excitation wavelength-dependent two-component fluorescence characterizes the emission behaviour of these liquids. That ion association gives rise to the long absorption tail and shifting fluorescence maximum, which appears to be common to most of the imidazolium ionic liquids, is evident from the effect of the conventional solvents.

  7. Study on the dynamics in absorption of 32P by hybrid wheat at elongate stage

    The dynamics of absorbing 32P of hybrid wheat at elongate stage is studied under pot culture conditions. The results show that the absorption capacity of hybrid wheat to 32P is in agreement with regression equation. The increased extent of absorption for them is greater than that for parent with time, and the reduction rate of absorption is lower than the parent significantly. Their root activity is much higher than that of the parent, too. The overall heterotic vigor of hybrid wheat on the absorption capacity to 32P is the sum of that of all organs

  8. Further evidence that in vitro percutaneous absorption studies can replace in vivo rat studies

    Current guidelines for the registration of agrochemicals in the USA often require the generation of dermal absorption data using the rat as a model for man. This is a time consuming study and requires the use of a large number of animals (at least 96 per formulation). Simpler in vitro alternatives have been suggested and shown to be acceptable. We have compared the data obtained from in vivo and in vitro dermal absorption studies conducted in parallel with four pesticides. Measurements of the radioactivity which could be washed from the skin, associated (on/in) skin and absorbed through the rat skin were made following application of radiolabeled pesticide in vivo and in vitro for 0.5, 1, 2, 4, 10 and 24 h. At 4, 10 and 24 h the in vitro experiments predicted the in vivo absorption within a factor of 2-3 or better. The amounts washed from and associated with skin were in even closer agreement. The in vivo data for the 0.5, 1 and 2 h time points were very variable making correlation with the in vitro data more difficult. The results show that the in vitro method predicts with sufficient accuracy in vivo absorption. The simpler more cost effective in vitro method should therefore be more fully utilized in risk assessment

  9. Contributions te the study of methods and factors affecting the spectrophotometric determination of boron traces with carmin uranium compounds; Contribucion al estudio del metodo y factores que afectan a la determinacion espectrofotometrica de trazas de boro con Carmin en compuestos de uranio

    Fernandez Cellini, R.; Gasco Sanchez, L.

    1956-07-01

    The study of some factors affecting the spectrophotometric determination of boron traces with carmin is made; the influence of carmin from different origin, the stability of complex carmin-boric acid in relation with the sulphuric acid concentration, the interference produced by ion nitrate, and the ion uraline and light influence are discussed. (Author) 36 refs.

  10. Study on Differential Optical Absorption Spectroscopy : Technique and its Applications

    Liu, Jianguo

    2002-01-01

    ln the first part of speech, with a description of the principle of DOAS (Differential Optical Absorption Spectroscopy), the design and realization of two different kinds of DOAS systems are nresented. 0ne is using a slotted disc raoid scanning device with a photomultiplier, which is suitable for ambient air quality measurement. It can measure total 16 kinds of pollutants such as SO_2, NO, N02, NH_3, O_3, C_6H_6, C_7H_8 and CH_2O etc., with detection limits of 1-2ppb. The other is using a UV ...

  11. Stratum corneum damage and ex vivo porcine skin water absorption - a pilot study

    Duch Lynggaard, C; Bang Knudsen, D; Jemec, G B E

    2009-01-01

    A simple ex vivo screening technique would be of interest for mass screening of substances for potential barrier disruptive qualities. Ex vivo water absorption as a marker of skin barrier integrity was studied on pig ear skin. Skin water absorption was quantified by weighing and weight changes were...

  12. Pilot Study on the Nano-Composites Coats of Radar Wave's Absorption

    HU Chuan-xin; ZhANG Lei; GAN Ai-feng; LI Wan-zhi; LIANG Wen-ting; ZHANG Chen-jia

    2004-01-01

    This thesis mainly introduced the guiding principle and physical model of the research on the nano-composites coats of radar wave's absorption, and then studied the qualitative analysis of the performance ameliorating of radar wave's absorption composite coats. And on the basis of the optimum design of multilayer wave's absorption materials, two new kinds of radar wave's absorption composite coats have been made, which are composed of nano-composites hydroxyl iron powder and hollow micro-sphere. The research indicated that the surface-density of these two new composite coats is less than 3.5 Kg/m2.The coats' thickness is about 1 mm. And the waves absorption capability is above the level of 5 db, in the range of 3 ~ 18GHz. Therefore the wave's absorption performance of these two new coats is better than nano-crystalloid in low frequency area. The pilot study has proved that the nano-composites coat's performance of radar wave's absorption excels the ordinary radar wave's absorption coats, so it needs to be further studied.

  13. Exposure study by determination of blood lead levels using electro-thermal atomic absorption in correlation with basophilic stippling

    Blood lead levels were determined in fifty traffic police personnel exposed to open traffic deputed at various crossings in Rawalpindi/Islamabad by electro-thermal atomic absorption spectrophotometric technique to monitor the levels. Blood comparison of lead concentration in the blood samples of policemen working at high density area versus those working at low density area was made. The range of the blood lead levels of subjects working in the high density traffic is 7.2 - 19.6 up/dl whereas the blood lead levels of subjects at lean traffic is 0.4 - 6.9 Mu g /dL. The accuracy of the method was checked by analyzing SRM wheat flour, rice flour and bovine liver. The results obtained were compared with reported values of other countries as well as with the exposure limits of WHO. (author)

  14. Study on tannin–metal interaction in aqueous solution using spectrophotometric titration and micelle-mediated separation/atomic absorption spectrometry

    Tannins, including hydrolysable and condensed tannins, are important secondary metabolites of vascular plants and are a major plant-derived carbon source in the environment. Due to the many phenolic hydroxyl groups characteristic of tannins, these compounds have been long been thought to play signi...

  15. STUDY ON EUROPEAN FUNDS ABSORPTION IN ROMANIA FOR MEASURE 313

    Florentina D. MATEI

    2014-06-01

    Full Text Available In this paper we wish to highlight the main causes of regional disparities in Romania in terms of absorption of European funds through Measure 313: Encouragement of tourism activities. The post-accession of Romania shows a major deficiency in attracting funds from the European Union, this situation is generated, in particular, by the lack of a coherent long-term vision of the authorities, insufficient resources for co-financing projects, low administrative capacity at central and local level, lack of inter-institutional coordination, public-private partnerships failures and insufficient skilled human resources . We will analyze the number of projects approved and implemented in each region of Romania (2007-2013 to establish the real possibilities of expansion of rural tourism.

  16. Raman and Infrared Absorption Study of Indigoid-based Pigments

    Manciu, Felicia; Durrer, William; Reza, Layra; Ramirez, Alejandra; Chianelli, Russell

    2009-04-01

    A fascinating aspect of Maya pigments is that despite the environmentally harsh humidity and high temperatures they resist fading and they have unprecedented stability. In this investigation, we address the question of how organic dye binds to inorganic palygorskite to form pigments. Our analysis by Raman and infrared absorption spectroscopies proves that different processes are taking place for the indigo-palygorskite system as compared with the thioindigo-palygorskite complex. While partial elimination of the selection rules for the centrosymmetric indigo and disappearance of the indigo N-H bonding, with conversion to dehydroindigo, is observed for the first compound, the latter shows no evident structure modification. The interaction between indigo and palygorskite is likely through oxygen and nitrogen. Only oxygen plays this role for the thioindigo-palygorskite complex.

  17. In situ x-ray-absorption spectroscopy study of hydrogen absorption by nickel-magnesium thin films

    Structural and electronic properties of co-sputtered Ni-Mg thin films with varying Ni to Mg ratio were studied by in situ x-ray absorption spectroscopy in the Ni L-edge and Mg K-edge regions. Codeposition of the metals led to increased disorder and decreased coordination around Ni and Mg compared to pure metal films. Exposure of the metallic films to hydrogen resulted in formation of hydrides and increased disorder. The presence of hydrogen as a near neighbor around Mg caused a drastic reduction in the intensities of multiple scattering resonances at higher energies. The optical switching behavior and changes in the x-ray spectra varied with Ni to Mg atomic ratio. Pure Mg films with Pd overlayers were converted to MgH2: The H atoms occupy regular sites as in bulk MgH2. Although optical switching was slow in the absence of Ni, the amount of H2 absorption was large. Incorporation of Ni in Mg films led to an increase in the speed of optical switching but decreased maximum transparency. Significant shifts in the Ni L3 and L2 peaks are consistent with strong interaction with hydrogen in the mixed films

  18. Roles of reactive oxygen species in UVA-induced oxidation of 5,6-dihydroxyindole-2-carboxylic acid-melanin as studied by differential spectrophotometric method.

    Ito, Shosuke; Kikuta, Marina; Koike, Shota; Szewczyk, Grzegorz; Sarna, Michal; Zadlo, Andrzej; Sarna, Tadeusz; Wakamatsu, Kazumasa

    2016-05-01

    Eumelanin photoprotects pigmented tissues from ultraviolet (UV) damage. However, UVA-induced tanning seems to result from the photooxidation of preexisting melanin and does not contribute to photoprotection. We investigated the mechanism of UVA-induced degradation of 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-melanin taking advantage of its solubility in a neutral buffer and using a differential spectrophotometric method to detect subtle changes in its structure. Our methodology is suitable for examining the effects of various agents that interact with reactive oxygen species (ROS) to determine how ROS is involved in the UVA-induced oxidative modifications. The results show that UVA radiation induces the oxidation of DHICA to indole-5,6-quinone-2-carboxylic acid in eumelanin, which is then cleaved to form a photodegraded, pyrrolic moiety and finally to form free pyrrole-2,3,5-tricarboxylic acid. The possible involvement of superoxide radical and singlet oxygen in the oxidation was suggested. The generation and quenching of singlet oxygen by DHICA-melanin was confirmed by direct measurements of singlet oxygen phosphorescence. PMID:26920809

  19. SHARDS: Survey for High-z Absorption Red & Dead Sources

    Pérez-González, P. G.; Cava, A; the SHARDS Team

    2012-01-01

    SHARDS, an ESO/GTC Large Program, is an ultra-deep (26.5 mag) spectro-photometric survey with GTC/OSIRIS designed to select and study massive passively evolving galaxies at z=1.0-2.3 in the GOODS-N field using a set of 24 medium-band filters (FWHM~17 nm) covering the 500-950 nm spectral range. Our observing strategy has been planned to detect, for z>1 sources, the prominent Mg absorption feature (at rest-frame ~280 nm), a distinctive, necessary, and sufficient feature of evolved stellar popul...

  20. SHARDS: AN OPTICAL SPECTRO-PHOTOMETRIC SURVEY OF DISTANT GALAXIES

    We present the Survey for High-z Absorption Red and Dead Sources (SHARDS), an ESO/GTC Large Program carried out using the OSIRIS instrument on the 10.4 m Gran Telescopio Canarias (GTC). SHARDS is an ultra-deep optical spectro-photometric survey of the GOODS-N field covering 130 arcmin2 at wavelengths between 500 and 950 nm with 24 contiguous medium-band filters (providing a spectral resolution R ∼ 50). The data reach an AB magnitude of 26.5 (at least at a 3σ level) with sub-arcsec seeing in all bands. SHARDS' main goal is to obtain accurate physical properties of intermediate- and high-z galaxies using well-sampled optical spectral energy distributions (SEDs) with sufficient spectral resolution to measure absorption and emission features, whose analysis will provide reliable stellar population and active galactic nucleus (AGN) parameters. Among the different populations of high-z galaxies, SHARDS' principal targets are massive quiescent galaxies at z > 1, whose existence is one of the major challenges facing current hierarchical models of galaxy formation. In this paper, we outline the observational strategy and include a detailed discussion of the special reduction and calibration procedures which should be applied to the GTC/OSIRIS data. An assessment of the SHARDS data quality is also performed. We present science demonstration results on the detection and study of emission-line galaxies (star-forming objects and AGNs) at z = 0-5. We also analyze the SEDs for a sample of 27 quiescent massive galaxies with spectroscopic redshifts in the range 1.0 < z ∼< 1.4. We discuss the improvements introduced by the SHARDS data set in the analysis of their star formation history and stellar properties. We discuss the systematics arising from the use of different stellar population libraries, typical in this kind of study. Averaging the results from the different libraries, we find that the UV-to-MIR SEDs of the massive quiescent galaxies at z = 1.0-1.4 are well described

  1. SHARDS: AN OPTICAL SPECTRO-PHOTOMETRIC SURVEY OF DISTANT GALAXIES

    Perez-Gonzalez, Pablo G.; Cava, Antonio; Barro, Guillermo; Villar, Victor; Cardiel, Nicolas; Espino, Nestor; Gallego, Jesus [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Ferreras, Ignacio [Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT (United Kingdom); Rodriguez-Espinosa, Jose Miguel; Balcells, Marc; Cepa, Jordi [Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife (Spain); Alonso-Herrero, Almudena [Instituto de Fisica de Cantabria, CSIC-Universidad de Cantabria, E-39005 Santander (Spain); Cenarro, Javier [Centro de Estudios de Fisica del Cosmos de Aragon, Plaza San Juan 1, Planta 2, E-44001 Teruel (Spain); Charlot, Stephane [Institut d' Astrophysique de Paris, CNRS, Universite Pierre and Marie Curie, UMR 7095, 98bis bd Arago, F-75014 Paris (France); Cimatti, Andrea [Dipartimento di Astronomia, Universita degli Studi di Bologna, I-40127 Bologna (Italy); Conselice, Christopher J. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Daddi, Emmanuele; Elbaz, David [CEA, Laboratoire AIM, Irfu/SAp, F-91191 Gif-sur-Yvette (France); Donley, Jennifer [Los Alamos National Laboratory, Los Alamos, NM (United States); Gobat, R. [Laboratoire AIM-Paris-Saclay, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d' Astrophysique, CEA Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); and others

    2013-01-01

    We present the Survey for High-z Absorption Red and Dead Sources (SHARDS), an ESO/GTC Large Program carried out using the OSIRIS instrument on the 10.4 m Gran Telescopio Canarias (GTC). SHARDS is an ultra-deep optical spectro-photometric survey of the GOODS-N field covering 130 arcmin{sup 2} at wavelengths between 500 and 950 nm with 24 contiguous medium-band filters (providing a spectral resolution R {approx} 50). The data reach an AB magnitude of 26.5 (at least at a 3{sigma} level) with sub-arcsec seeing in all bands. SHARDS' main goal is to obtain accurate physical properties of intermediate- and high-z galaxies using well-sampled optical spectral energy distributions (SEDs) with sufficient spectral resolution to measure absorption and emission features, whose analysis will provide reliable stellar population and active galactic nucleus (AGN) parameters. Among the different populations of high-z galaxies, SHARDS' principal targets are massive quiescent galaxies at z > 1, whose existence is one of the major challenges facing current hierarchical models of galaxy formation. In this paper, we outline the observational strategy and include a detailed discussion of the special reduction and calibration procedures which should be applied to the GTC/OSIRIS data. An assessment of the SHARDS data quality is also performed. We present science demonstration results on the detection and study of emission-line galaxies (star-forming objects and AGNs) at z = 0-5. We also analyze the SEDs for a sample of 27 quiescent massive galaxies with spectroscopic redshifts in the range 1.0 < z {approx}< 1.4. We discuss the improvements introduced by the SHARDS data set in the analysis of their star formation history and stellar properties. We discuss the systematics arising from the use of different stellar population libraries, typical in this kind of study. Averaging the results from the different libraries, we find that the UV-to-MIR SEDs of the massive quiescent galaxies at

  2. Experimental studies on the influence of porosity on membrane absorption process

    GAO Jian; REN Zhongqi; ZHANG Zeting; ZHANG Weidong

    2007-01-01

    Eight kinds of flat membranes with different micro-structures were chosen to carry out the membrane absorption experiments with CO2 and de-ionized water or According to experimental results,the membrane pores shape (stretched pore and cylinder pore) and membrane thickness do not affect the membrane absorption process,and the membrane porosity has only little influence on membrane absorption process for slow mass transfer system.However,the influence of porosity on the membrane absorption process became visible for fast mass transfer system.Moreover,the mass transfer behavior near the membrane surface on liquid side was studied.The results show that the influence of membrane porosity on mass transfer relates to flow condition,absorption system and distance between micro-pores,etc.

  3. Evaluation of the color durability of acrylic resin veneer materials after immersion in common beverages at different time intervals: A spectrophotometric study

    Shivani Kohli

    2015-06-01

    Full Text Available Background: Proper function, esthetics, and cost are the prime factors to be considered while selecting bridge veneering materials. The purpose of the study is to evaluate color durability of acrylic veneer materials after immersion in common beverages at different time intervals. Methods: Spectrophotometer was used for taking color measurements based on the transmission of light through the specimens made of the selected materials which were Tooth moulding powder (DPI and Acrylux (Ruthinium. Thirty specimens of standardized dimensions were prepared from each material. The specimens were divided into three groups of 10 each. One group of each material was immersed in tea (TajMahal and another group of each material in cola (Pepsi as the staining solutions. The remaining group of 10 from each material served as control and was stored in distilled water. Color measurements were obtained pre-immersion, and after 1, 15, and 30 days of immersion. Results: Tooth moulding powder displayed better color durability than Acrylux over the 1 month immersion period in both staining solutions. Tea resulted in more discoloration compared to cola (Pepsi. Conclusion: The difference in the color durability of Acrylux and Tooth moulding powder may be attributed to the differences in the composition of tested resin veneering materials, i.e. their polar properties, which contribute to the absorption of staining solution, and the different brands and the strengths of the solutions.

  4. Study on the interaction between fluoroquinolones and erythrosine by absorption, fluorescence and resonance Rayleigh scattering spectra and their application

    Wang, Jian; Liu, Zhongfang; Liu, Jiangtao; Liu, Shaopu; Shen, Wei

    2008-03-01

    In pH 4.4-4.5 Britton-Robinson (BR) buffer solution, fluoroquinolone antibiotics (FLQs) including ciprofloxacin (CIP), norfloxacin (NOR), levofloxacin (LEV) and lomefloxacin (LOM) could react with erythrosine (Ery) to form 1:1 ion-association complexes, which not only resulted in the changes of the absorption spectra and the quenching of fluorescence, but also resulted in the great enhancement of resonance Rayleigh scattering (RRS). These offered some indications of the determination of fluoroquinolone antibiotics by spectrophotometric, fluorescence and resonance Rayleigh scattering methods. The detection limits for fluoroquinolone antibiotics were in the range of 0.097-0.265 μg/mL for absorption methods, 0.022-0.100 μg/mL for fluorophotometry and 0.014-0.027 μg/mL for RRS method, respectively. Among them, the RRS method had the highest sensitivity. In this work, the spectral characteristics of the absorption, fluorescence and RRS, the optimum conditions of the reactions and the properties of the analytical chemistry were investigated. The methods have been successfully applied to determination of some fluoroquinolone antibiotics in human urine samples and tablets. Taking CIP-Ery system as an example, the charge distribution, the enthalpy of formation and the mean polarizability were calculated by density function theory (DFT) method. In addition, the reasons for the enhancement of scattering spectra were discussed.

  5. Spectrophotometric and Refractometric Determination of Total Protein in Avian Plasma

    Rodica Căpriță

    2013-10-01

    Full Text Available The aim of this study was to compare the total protein values obtained in heparin plasma of chickens by a spectrophotometric technique (biuret method, and the values obtained on the same day in the same samples by refractometry. The results obtained by refractometry (average value 2.638±0.153g% were higher than those obtained by the spectrophotometric method (average value 2.441±0.181g%. There was a low correlation (r = 0.6709 between the total protein values, determined with both methods. Protein is the major determinant of plasma refractive index, but glucose contributes too. The refractometric method is not recommended in chickens for the determination of total protein, because avian blood glucose concentration averages about twice than in mammalian blood.

  6. Stability Indicating UV Spectrophotometric Method for Determination of Dronedarone Hydrochloride

    Kshitija Kardile

    2015-01-01

    Full Text Available The objective of this study was to develop stability UV method for estimation of Dronedarone Hydrochloride in tablet to compare % degradation of this drug determined by this UV method to HPTLC method reported by us earlier. Analysis of bulk as well as marketed tablet formulation by exposure to same degradative conditions was done and % degradation obtained by spectroscopy was determined. Method development and validation was done as per ICH guidelines. % degradation observed by both methods was comparable. The variation in the results of this drug estimated by HPTLC and spectrophotometric method was statistically insignificant. This suggests that the spectrophotometric method is suitable to determine stability profile. Hence a simple UV spectrophotometry can be used to monitor stability of Dronedarone Hydrochloride.

  7. Gamma radiation absorption study on cryogenic multilayer insulation

    Full text: Photon radiation is a high energy flow, resulting from the radioactive decay of nuclei. At passing through a substance, the γ radiation interacts with atomic nuclei, with free electrons and bound electrons. Phenomena that can occur from these interactions are the photoelectric effect, the Compton effect and the generation of electron-positron pairs. They have the effect of attenuating the initial γ radiation. The degree of attenuation of radiation intensity depends on the energy of the γ radiation and the thick of crossed absorbing layer. The law of variation of γ radiation intensity in matter is: I=I0exp(-xμ), where: I0 is the initial intensity of radiation, I is the intensity of radiation that passed through the layer of matter, x is the thickness of the absorbing substance, μ is the radiation absorption coefficient of the substance. The paper aims at determining the half-value layer (HVL) of few materials that can be used in multilayer insulation as compared with other material properties for effective applications in different temperature conditions. (author)

  8. Cinchocaine hydrochloride determination by atomic absorption spectrometry and spectrophotometry.

    Abdel-Ghani, Nour T; Youssef, Ahmed F A; Awady, Mohamed A

    2005-05-01

    Two sensitive spectrophotometric and atomic absorption spectrometric procedures have been developed for determination of cinchocaine hydrochloride (Cin.Cl) in pure form and in pharmaceutical formulation. The spectrophotometric method was based on formation of an insoluble colored ion-associate between the cited drug and tetrathiocyanatocobaltate (CoTC) or hexathiocyanatochromate (CrTC) which dissolved and extracted in an organic solvent. The optimal experimental conditions for quantitative extraction such as pH, concentration of the reagents and solvent were studied. Toluene and iso-butyl alcohol proved to be the most suitable solvents for quantitative extraction of Cin-CoTC and Cin-CrTC ion-associates with maximum absorbance at 620 and 555 nm, respectively. The optimum concentration ranges, molar absorptivities, Ringbom ranges and Sandell sensitivities were also evaluated. The atomic absorption spectrometric method is based on measuring of the excess cobalt or chromium in the aqueous solution, after precipitation of the drug, at 240.7 and 357.9 nm, respectively. Linear application ranges, characteristic masses and detection limits were 57.99-361.9, 50.40 and 4.22 microg ml(-1) of Cin.Cl, in case of CoTC, while 37.99-379.9, 18.94 and 0.81 microg ml(-1) in case of CrTC. PMID:15910814

  9. Structural studies using X-ray absorption and scattering techniques

    The thesis presents extended X-ray absorption fine structure, EXAFS, and large angle X-ray scattering, LAXS, techniques; instrumentation, data collection and reduction, and applications. These techniques have been used to determine the structures of magnesium halides and organomagnesium halides in diethyl ether and tetrahydrofuran solution. The iodides were used for the LAXS measurements and Br K edge EXAFS data were collected for the corresponding bromides. Two different complexes are present in the diethyl ether solution of magnesium iodide; a polymeric chain-type structure where magnesium is tetrahedrally coordinated, as well as dimeric complex with octahedrally coordinated magnesium. Solvated MgI+ is the dominating species in tetrahydrofuran solution. The organomagnesium halides are present in diethyl ether solution as both solvated monomeric and dimeric complexes. Magnesium coordinates a halide ion, an alkyl or aryl group and four solvent molecules octahedrally in the monomeric complex. In the dimeric complex magnesium is octahedrally coordinated by two bridging halide ions, an alkyl or aryl group and three solvent molecules. The distribution of monomeric and dimeric complexes in various solutions are given by a dimerisation constant, Kdl. The results indicate that the Schlenk equilibrium is present in these solutions, however, in an extended form. In diethyl ether solution, where MgX2 does not dissociate, no MgX2 complex and thereby no Schlenk equilibrium has been observed. In tetrahydrofuran solution MgI2 has dissociated into mainly MgI+ and I-. This indicates that the concentration of MgI2 is low and that the Schlenk equilibrium should be expanded even further to include the dissociation equilibrium of the magnesium halide. In the thesis Fe K edge EXAFS data collected for the semireduced form of protein A of methane monooxygenase from Methylococcus capsulatus, are also presented. (139 refs.)

  10. Selective spectrophotometric determination of molybdenum(VI) and vanadium(V) with resacetophenone benzoic hydrazone in steels and alloys

    A spectrophotometric method for the determination of molybdenum(VI) and vanadium(V) using 2, 4-dihydroxyacetophenone benzoic hydrazone (RPBH) is reported. The reagent forms 1:1 yellow coloured complexes with Mo(VI) and V(V) at pH 3.5. The colour development of molybdenum complex is instantaneous and shows absorption maximum at 410nm. In the case of vanadium complex, maximum colour is developed after heating for 10 minutes on a water bath and show maximum absorption at 380nm. The molybdenum(VI) complex with a molar absorptivity of 3.6x103 l mol-1 cm-1 and Sandell's sensitivity of 0.02 μg/cm2, obeys Beer's law in the range 2.4 to 33.6 ppm. The vanadium(V) complex whose molar absorptivity and Sandell's sensitivity are 1.3x104 l mol-1 cm-1 and 0.004 μg/cm2 respectively, obeys Beer's law in the range 0.25 to 7.6 ppm. The effect of various diverse ions on the determination of the metal ions is studied. The method is applied for the determination of molybdenum and vanadium in steel and alloy samples. (author). 10 refs., 1 fig., 3 tabs

  11. Spectrophotometric determination of palladium (II) with rubeanic acid (RA) in presence of pyridine, piperidine and 3-picoline

    Unpretentious and exclusive methods for the spectrophotometric determination of trace amount of divalent palladium (II) have been developed with rubeanic acid (dithio-oxamide) in presence of secondary ligands like pyridine, piperidine and 3-picoline. Both direct and extraction spectrophotometry showed that coloured rubeanates are only stable in acidic medium. The violent yellow coloured products are formed below ph 5.0 with an absorption maxima at 416.0 and 422.0 (pyridine), 405.0 and 416.5 (piperidine) and 418.0 and 422.0 (3-picoline) both in direct and isoamyl alcohol (IAA) extracted system, respectively. Results indicate that the highest sensitivity and molar absorptivity of Pd-RA pyridine system in direct spectrophotometry were 0.01497 mu g Pd(II) cm/sup -2/ and 7107.89 L mol sup -1/ cm/sup -1/ respectively. IAA extracted Pd-RA-piperidine system was found to give a sensitivity of 0.01087 mu g(Pd(II) cm /sup -2/ and molar absorptivity of 9788.80 L mol /sup -1/ cm/sup -1/ which were the highest of all the system. The effects due to variation of pH, reagent concentrations, order of addition of reagents, time, temperature and solvent media on the absorption spectra have been investigated and the optimum conditions determined. The effects of diverse ions and their tolerance limit have also been studies. (author)

  12. Spectrophotometric determination of nitrite and nitrate using phosphomolybdenum blue complex.

    Zatar, N A; Abu-Eid, M A; Eid, A F

    1999-11-15

    A method for spectrophotometric determination of nitrite and nitrate is described. This method is based on the reduction of phosphomolybdic acid to phosphomolybdenum blue complex by sodium sulfide. The obtained phosphomolybdenum blue complex is oxidized by the addition of nitrite and this causes a reduction in intensity of the blue color. The absolute decrease in the absorbance of the blue color or the rate of its decrease is found to be directly proportional to the amount of nitrite added. The absorbance of the phosphomolybdenum blue complex is monitored spectrophotometrically at 814 nm and related to the concentration of nitrite present. The effect of different factors such as acidity, stability of the complex, time, temperature, phosphate concentration, molybdenum concentration, sodium sulfide concentration and the tolerance amount of other ions have been reported. Maximum absorbance is at 814 nm. The range of linearity using the conventional method is 0.5-2.0 ppm with molar absorptivity of 1.1 x 10(4) l mol(-1) cm(-1). and a relative standard deviation of 2.6% for five measurements. The range of linearity using the reaction rate method is 0.2-3.6 ppm with a relative standard deviation of 2.4% for five measurements. The method is applied for determination of nitrite and nitrate in water, meat products and vegetables. PMID:18967772

  13. Estimation of citicoline sodium in tablets by difference spectrophotometric method

    Sagar Suman Panda

    2013-01-01

    Full Text Available Aim: The present work deals with development and validation of a novel, precise, and accurate spectrophotometric method for the estimation of citicoline sodium (CTS in tablets. This spectrophotometric method is based on the principle that CTS shows two different forms that differs in the absorption spectra in basic and acidic medium. Materials and Methods: The present work was being carried out on Shimadzu 1800 Double Beam UV-visible spectrophotometer. Difference spectra were generated using 10 mm quartz cells over the range of 200-400 nm. Solvents used were 0.1 M NaOH and 0.1 M HCl. Results: The maxima and minima in the difference spectra of CTS were found to be 239 nm and 283 nm, respectively. Amplitude was calculated from the maxima and minima of spectrum. The drug follows linearity in the range of 1-50 μ/ml (R 2 = 0.999. The average % recovery from the tablet formulation was found to be 98.47%. The method was validated as per International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use: ICH Q2(R1 Validation of Analytical Procedures: Text and Methodology guidelines. Conclusion: This method is simple and inexpensive. Hence it can be applied for determination of the drug in pharmaceutical dosage forms.

  14. Estimation of very low concentrations of Ruthenium by spectrophotometric method using barbituric acid as complexing agent

    Spectrophotometric method employing numerous chromogenic reagents like thiourea, 1,10-phenanthroline, thiocyanate and tropolone is reported in the literature for the estimation of very low concentrations of Ru. A sensitive spectrophotometric method has been developed for the determination of ruthenium in the concentration range 1.5 to 6.5 ppm in the present work. This method is based on the reaction of ruthenium with barbituric acid to produce ruthenium(ll)tris-violurate, (Ru(H2Va)3)-1 complex which gives a stable deep-red coloured solution. The maximum absorption of the complex is at 491 nm due to the inverted t2g → Π(L-L ligand) electron - transfer transition. The molar absorptivity of the coloured species is 9,851 dm3 mol-1 cm-1

  15. Study on NO2 absorption by ascorbic acid and various chemicals

    LI Wei; WU Cheng-zhi; FANG He-liang; SHI Yao; LEI Le-cheng

    2006-01-01

    Study on NO2 absorption aimed at seeking a better NO2 absorption chemical at pH 4.5~7.0 for application to existing wet flue gas desulfurization (FGD). The results from the double-stirred reactor indicated thru ascorbic acid has very high absorption rate at this pH range. The rate constant of ascorbic acid reaction with NO2 (0~1000× 10-6 mol/mol) is about 3.54× 106 mol/(L.s)at pH 5.4~6.5 at 55 ℃.

  16. Two novel spectrophotometric methods for determinat ion of ternary mixture used as antihypertensive therapy in combined tablet dosage formulation

    Trupti Solanki; Jenee Christian; Kalpana Patel; Purvi Shah; Tejal Gandhi

    2015-01-01

    Aim: To develop and validate two novel spectrophotometric methods for the simultaneous determination of ternary mixture of Olmesartan medoxomil, Amlodipine besylate and Hydrochlorothiazide. Methods: The proposed methods, successive ratio derivative method and double divisor method involved treatment of normal absorption spectra of ternary mixture in UV probe software for the simultaneous determination of Olmesartan medoxomil, Amlodipine besylate and Hydrochlorothiazide in bulk and tablet ...

  17. Spectroscopy of α,ω-dithienyl polyenes: evidence for two-photon absorption states from fluorescence studies

    Natarajan, Lalgudi V.; Kirkpatrick, Sean M.; Sutherland, Richard L.; Sowards, Laura A.; Spangler, Charles W.; Fleitz, Paul A.; Cooper, Thomas M.

    1998-10-01

    The photophysics of a series (alpha) ,(omega) -dithienyl polyenes was studied. Both one photon excited fluorescence and fluorescence originating from two photon absorption states were investigated. There is strong evidence of two photon absorption from fluorescence studies in agreement with our earlier studies involving nonlinear absorption.

  18. Spectrophotometric Assay of Phenylephrine Hydrochloride Using 4-Aminoantipyrine and Copper (II

    Theia'a N. Al-Sabha

    2010-06-01

    Full Text Available A new spectrophotometric method is proposed for determination of phenylephrine hydrochloride. The method is based on the coupling of 4-aminoantipyrine (4-AAP with phenylephrine hydrochloride (PEH to give a new ligand that reacts with copper (II in the presence of sodium tetraborate buffer solution of pH 9.00 at 50 °C to give an intense red colored chelate having maximum absorption at 480 nm. The optimization of the experimental conditions is described. The method has been used for the determination of 2.0–50.0 μg/ml of PEH. The molar absorptivity is 5.34×103 L.mol.-1cm.-1 and the accuracy of the method is achieved by the value of average recovery (101.28 % and the precision is supported by relative standard deviation (RSD=1.25 % values. The results of the method was compared with those of the standard method. The interference of excipients was studied. The mechanism of the chemical reaction has been proposed. The proposed method was successfully applied for the determination of the PEH in pharmaceutical syrup formulations.

  19. Spectrophotometric assay of phenylephrine hydrochloride using 4-aminoantipyrine and copper (II)

    A new spectrophotometric method is proposed for determination of phenylephrine hydrochloride. The method is based on the coupling of 4-aminoantipyrine (4-AAP) with phenylephrine hydrochloride (PEH) to give a new ligand that reacts with copper (II) in the presence of sodium tetraborate buffer solution of pH 9.00 at 50 deg. C to give an intense red colored chelate having maximum absorption at 480 nm. The optimization of the experimental conditions is described. The method has been used for the determination of 2.0 - 50.0 mu g/ml of PEH. The molar absorptivity is 5.34 X 103 L. mol/sup -1/cm /sup- 1/ and the accuracy of the method is achieved by the value of average recovery (101.28 %) and the precision is supported by relative standard deviation (RSD=1.25 %) values. The results of the method was compared with those of the standard method. The interference of excipients was studied. The mechanism of the chemical reaction has been proposed. The proposed method was successfully applied for the determination of the PEH in pharmaceutical syrup formulations. (author)

  20. Absorption and spectroscopic ellipsometry study of electron irradiated magnesium aluminate spinel

    Magnesium aluminate spinels were irradiated by electron beams with energy of 1.7 MeV and fluence from 1013 to 1017 electrons cm-2. After irradiation, the samples were annealed at different temperatures from 100 to 500 C. Spectroscopic ellipsometry and absorption were used to study the effects of optical properties in the spinel produced by irradiation and subsequent annealing. The results obtained by absorption spectra showed that many F-type absorption centers were produced in the spinels. With increasing electron fluence, we observed an increase in optical absorption, especially in the vicinity of the absorption band at 5.3 eV. The concentration of F-type absorption centers increased as the electron fluence increased. The F-type absorption centers can be destroyed by isochronal annealing. The refractive index obtained by analyzing the ellipsometric spectra changed as the irradiation fluence and subsequent annealing temperature changed. Based on our findings, an attempt has been made to explain the above mentioned phenomena. (orig.)

  1. Absorption and spectroscopic ellipsometry study of electron irradiated magnesium aluminate spinel

    Yang Shenghong; Zhang Yueli; Mo Dang [State Key Lab. of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen Univ. Guangzhou (China)

    2010-08-15

    Magnesium aluminate spinels were irradiated by electron beams with energy of 1.7 MeV and fluence from 10{sup 13} to 10{sup 17} electrons cm{sup -2}. After irradiation, the samples were annealed at different temperatures from 100 to 500 C. Spectroscopic ellipsometry and absorption were used to study the effects of optical properties in the spinel produced by irradiation and subsequent annealing. The results obtained by absorption spectra showed that many F-type absorption centers were produced in the spinels. With increasing electron fluence, we observed an increase in optical absorption, especially in the vicinity of the absorption band at 5.3 eV. The concentration of F-type absorption centers increased as the electron fluence increased. The F-type absorption centers can be destroyed by isochronal annealing. The refractive index obtained by analyzing the ellipsometric spectra changed as the irradiation fluence and subsequent annealing temperature changed. Based on our findings, an attempt has been made to explain the above mentioned phenomena. (orig.)

  2. [Study on intestinal absorption features of oligosaccharides in Morinda officinalis How. with sigle-pass perfusion].

    Deng, Shao-Dong; Zhang, Peng; Lin, Li; Xiao, Feng-Xia; Lin, Jing-Ran

    2015-01-01

    To study the in situ intestinal absorption of five oligosaccharides contained in Morinda officinalis How. (sucrose, kestose, nystose, 1F-Fructofuranosyinystose and Bajijiasu). The absorption of the five oligosaccharides in small intestine (duodenum, jejunum and ileum) and colon of rats and their contents were investigated by using in situ single-pass perfusion model and HPLC-ELSD. The effects of drug concentration, pH in perfusate and P-glycoprotein inhibitor on the intestinal absorption were investigated to define the intestinal absorption mechanism of the five oligosaccharides in rats. According to the results, all of the five oligosaccharides were absorbed in the whole intestine, and their absorption rates were affected by the pH of the perfusion solution, drug concentration and intestinal segments. Verapamil Hydrochloride could significantly increase the absorptive amount of sucrose and Bajijiasu, suggesting sucrose and Bajijiasu are P-gp's substrate. The five oligosaccharides are absorbed mainly through passive diffusion in the intestinal segments, without saturated absorption. They are absorbed well in all intestines and mainly in duodenum and jejunum. PMID:25993803

  3. Studies on the optical absorption of copper-dopped myoglobin: conformational changes

    Optical absorption changes in the visible and near U.V. spectrum of myoglobin molecules are observed when copper ions are added to the macromolecule. The heme optical transitions are investigated through a theoretical simulation of the optical absorption spectrum. A study of the absorption band in the region of 700 nm associated with the copper - myoglobin complexes indicated the existence of two kinds of metal-protein complexes: one associated with the six or eitht first added copper ions and the other related with the higher concentrations. Conformational changes caused by thermal treatment are studied in myoglobin water solutions and solutions containing copper ions. The phenomenon named pre-denaturation is observed through the optical absorption at 245 nm. It is shown that interactions between myoglobin molecules occur in the pre-denaturation phenomenon. (Author)

  4. Studies concerning thermodynamics and kinetics of the absorption of halogenated hydrocarbons relevant to environment

    In the context of the research project the scrubbing of air contaminated by peculiar volatile organic compounds was investigated using the absorption technique by means of high boiling organics as washing liquids. Eight chlorinated hydrocarbons well known from technical processes were chosen to be representative for the volatile organic compounds. Eleven absorption media were selected on the basis of their physical properties. For the determination of the solubility data of the absorption media due to chlorinated hydrocarbons, nitrogen as well as a mixture of nitrogen and oxygen were used as carrier gas. The influence of the dipole moment of the absorption media on the amount of solubility - expressed as enrichment factor - was studied, too. Concerning the technical application, the thermostability and the stability against diluted inorganic acids were studied as well. (orig.). 56 figs., 8 tabs., 63 refs

  5. Simultaneous Spectrophotometric Determination of Four Components including Acetaminophen by Taget Factor Analysis

    2007-01-01

    UV Spectrophotometric Target Factor Analysis (TFA) was used for the simultaneous determination of four components (acetaminophen, guuaifenesin, caffeine, Chlorphenamine maleate) in cough syrup. The computer program of TFA is based on VC++ language. The difficulty of overlapping of absorption spectra of four compounds was overcome by this procedure. The experimental results show that the average recovery of each component is all in the range from 98.9% to 106.8% and each component obtains satisfactory results without any pre-separation.

  6. Evaluation of chromium concentration in cattle feces using different acid digestion and spectrophotometric quantification techniques

    N.K.P. Souza; E. Detmann; D. S. Pina; Valadares Filho, S. C.; C.B. Sampaio; A.C. Queiroz; C.M. Veloso

    2013-01-01

    The objective of this work was to evaluate combinations between acid digestion techniques and spectrophotometric quantification to measure chromium concentration in cattle feces. Digestion techniques were evaluated based on the use of nitric and perchloric acids, sulfuric and perchloric acids, and phosphoric acid. The chromium quantification in the solutions was performed by colorimetry and by atomic absorption spectrophotometry (AAS). When AAS was used, the addition of calcium chloride to th...

  7. Experimental Study on the Influence of Curing Conditions on Capillary Absorption of Concrete

    Li-cheng WANG; Bao, Jiu-Wen; Cheng, Bao-Juan

    2016-01-01

    Both the hardening process and formation of microstructure of concrete are significantly influenced by the curing condition. The capillary absorption of concrete is closely related to the structure and distribution of the pores within the material. This paper presents an experimental study on the influence of four curing conditions, i.e., standard curing, natural curing, water curing, and sealed curing, on the capillary absorption of normal concrete. Compressive strength tests on the cylinder...

  8. Polarization dependent interface properties of ferroelectric Schottky barriers studied by soft X-ray absorption spectroscopy

    Kohlstedt, H.; Petraru, A.; Denlinger, M. Meier J.; Guo, J.; Wanli, Y.; A. Scholl; Freelon, B.; Schneller, T.; Waser, R.; Yu, P; Ramesh, R.; Learmonth, T.; Glans, P.-A.; Smith, K. E.

    2008-01-01

    We applied soft X-ray absorption spectroscopy to study the Ti L-edge in ferroelectric capacitors using a modified total electron yield method. The inner photo currents and the X-ray absorption spectra were polarization state dependent. The results are explained on the basis of photo electric effects and the inner potential in the ferroelectric capacitors as a result of back-to-back Schottky barriers superimposed by the potential due to the depolarization field. In general, the presented metho...

  9. Analytical and Experimental Study of X-ray Absorption Coefficients of Material by Abel's Inversion

    S. J. Han

    2009-01-01

    The hard x-ray gamma-ray absorption by cylindrically symmetric U-238 test objects is studied by means of gamma-ray transmission measurements. To make a precise comparison between the theoretically modelled values and the absorption coefficients calculated from the experimental data, we have developed a highly accurate numerical code based on a new solution of Abel's integral equation. It is shown that progressive filtering, surface reflections by Compton scattering, and the enhanced backscatt...

  10. Influence of study design in assessing food effects on absorption of erythromycin base and erythromycin stearate.

    DiSanto, A R; Chodos, D J

    1981-01-01

    We performed a series of six single-dose and multiple-dose studies to evaluate the effect of food on the absorption of erythromycin base and erythromycin stearate. When we used a single-dose design, we found that an unprotected erythromycin base preparation was absorbed extensively if a prolonged fast preceded administration of the drug. A shorter faster period (as occurs in clinical settings) dramatically reduced the absorption of unprotected base; however, film-coated tablets seemed to be a...

  11. Calculation and study on model of crushing load of HTR absorption sphere

    The absorption sphere shutdown system is the second shutdown system of 10 MW HTR. The absorption sphere contains 25% B4C, dispersing in graphite matrix. The crushing load, which is an important performance parameter of the absorption sphere, closely relates to the diameter. The effect of graphite sphere diameter and density on the crushing load was studied using the graphite sphere to simulate HTR absorption spheres. Three kinds of graphites with different densities were chosen and processed into five types of spheres with different diameters, and then the crushing experiment was conducted. The results show that the crushing load of the sphere is proportional to the square of the diameter, and increases with the density. For a certain diameter of graphite sphere, increasing the density of the sphere is an effective way to enhance the crushing load. (authors)

  12. A study of energy absorption rate in a quantum dot and metallic nanosphere hybrid system

    We have studied energy absorption rate in a quantum dot-metallic nanosphere system embedded on a dielectric substrate. We applied a control field to induce dipole moments in the quantum dot and the metal nanosphere, and monitored the energy absorption using a probe field. These external fields induce dipole moments in the metal nanosphere and the quantum dot, and these two structures interact with one another via the dipole–dipole interaction. The density matrix method was used to evaluate the absorption, indicating that it can be shifted by moving the metal nanosphere close to the quantum dot. Also, absorption efficiency can either be quenched or enhanced by the addition of a metal nanosphere. This hybrid system can be used to create ultrafast switching and sensing nanodevices. (paper)

  13. The Ablation Properties of CO2 Laser Irradiating to Absorption Media: An In Vitro Study

    Sajee Sattayut

    2012-01-01

    Full Text Available This study aimed to compare histological affected zone of tissue samples irradiated by defocused CO2 laser at 1, 2, and 3W continuous wave with and without absorption media. The in vitro experiment was conducted in 70 tissue blocks. The samples were randomly allocated into 7 groups: 10 samples each group, namely, the groups irradiated with 1, 2, and 3W, defocused CO2 laser for 5 seconds, the groups irradiated with 1, 2, and 3W, defocused CO2 laser to the absorption media, and the media alone group as a control. Then the samples were stained with Masson’s trichrome and measured the affected borders under light microscope at 10 × 10 magnification. There was no histological alteration in the groups irradiated with the defocused CO2 laser to the absorption media while the groups without using the absorption media showed the tissue alteration by photoablation.

  14. Spectrophotometric determination of nitrite using salbutamol sulfate as a reagent

    Agrawal, Y.K.; Bhatt, P.N.

    1988-01-01

    A simple spectrophotometric method for the trace determination of nitrite (NO/sub 2//sup /minus//) is described. Nitrite is reacted with Salbutamol sulfate in acidic medium which gives a yellow color in alkaline medium (less than or equal to pH 7) and can be determined in the presence of several cations and anions. Beer's law is obeyed in the range of 1.8 to 27.6 ppm of nitrite with the molar absorptivity 1.8 /times/ 10/sup 3/ 1 /times/ mole /sup /minus/1/ /times/ cm/sup /minus/1/ at 410 nm. The proposed method can also be utilized for the determination of nitrate (NO/sub 3//sup /minus//) after its reduction to nitrite. The method has been applied for the determination of various samples containing traces of nitrite.

  15. Spectrophotometric determination of nitrite in simulated Purex Process solutions

    A spectrophotometric method for nitrite determination in simulated Purex Process solutions is presented, utilizing the Griess reagent for the formation of the coloured azocompound with an absorption maximum at 525 nm. Molar absortivity was 36,262 and the sensitivity of the method 10-6M for nitrite. The calibration curve is linear in the range of 2 to 30μg NO-2/25 ml in cells of 1 cm optical path. The method can be used in the presence of uranium up to limits of an U/NO-2 ratio of 150. Test solutions were prepared to simulate composition and concentrations as obtained by irradiating standard fuel with a neutro flux of 3.2 x 1013 n.s-1.cm-2, with a burn-up value of 33,000 Mwd/T and cooling time of two years. Nitrite determinations in these solutions were accurate within limits of 5%. (Author)

  16. Determination of Azithromycin in pharmaceutical dosage forms by Spectrophotometric method

    Suhagia B

    2006-01-01

    Full Text Available A simple and sensitive spectrophotometric method has been developed for determination of azithromycin in its pharmaceutical dosage forms. In the proposed method, azithromycin is oxidized with potassium permanganate to liberate formaldehyde, which is determined in situ using acetyl acetone, in the presence of ammonium acetate. A yellow coloured chromogen was obtained, having an absorption maxima at 412 nm. The method is found to be linear in the concentration range of 10-75 µg/ml, with regression coefficient of 0.9978. Various reaction parameters such as concentration of potassium permanganate and reagent, time required for oxidation, and maximum colour intensity were optimized. The method was validated, and can be used successfully to assay azithromycin in its pharmaceutical dosage forms viz. tablets, capsules, and injections.

  17. Spectrophotometric estimation of roxithromycin in tablet dosage forms

    Suhagia B

    2006-01-01

    Full Text Available A simple and sensitive spectrophotometric method has been developed for determination of roxithromycin in its pharmaceutical dosage forms. In the proposed method, roxithromycin is oxidized with potassium permanganate to liberate formaldehyde, which is determined in situ using acetyl acetone in the presence of ammonium acetate to give a yellow-coloured chromogen with absorption maxima at 412 nm. The method is found to be linear in the concentration range of 10-75 µg/ml with regression coefficient of 0.9987. No significant difference was found between the proposed method and the reported method when two-tailed t-tests are applied. Various reaction parameters, such as concentration of potassium permanganate and reagent, time required for oxidation and maximum colour intensity, were optimized. The method was validated and can be used successfully to assay roxithromycin in its pharmaceutical dosage form, viz, tablets.

  18. Spectrophotometric estimation of Lomefloxacin hydrochloride in pharmaceutical dosage form

    Suhagia B

    2006-01-01

    Full Text Available A simple and sensitive spectrophotometric method has been developed for the estimation of lomefloxacin hydrochloride in its marketed formulations. The method is based on the reaction between the drug and the dichlone, in the presence of crotonaldehyde in dimethylsulfoxide, which produces a blue chromogen with absorption maximum at 645 nm. The good agreement with Beer′s law was found in the concentration range of 5-100 µg/ml. The optimum reaction conditions and other analytical parameters are evaluated. Statistical comparison of the results with those of reported method shows good agreement, and indicated no significant difference in precision. The proposed method was found to be simple, accurate, and reproducible for the routine analysis of the drug in pharmaceutical dosage forms.

  19. Spectrophotometric determination of triclosan in personal care products

    Lu, Huihui; Ma, Hongbing; Tao, Guanhong

    2009-09-01

    A spectrophotometric method for the determination of triclosan in personal care products was proposed. It was based on the reaction of sodium nitrite with p-sulfanilic acid in an acidic medium to form diazonium ion, with which triclosan further formed an azo compound in an alkaline medium. The resulting yellow colored product has a maximum absorption at 452 nm. A good linear relationship ( r = 0.9999) was obtained in the range of 0-30 mg L -1 triclosan. A detection limit of 0.079 g L -1 was achieved and the relative standard deviation was 0.24% ( n = 11) at 14 mg L -1 triclosan. The proposed method has been applied to the analyses of triclosan in several personal care products and the results were in good agreement with those obtained by high-performance liquid chromatography.

  20. DECal: A Spectrophotometric Calibration System For DECam

    Marshall, J L; DePoy, D L; Prochaska, Travis; Allen, Richard; Behm, Tyler W; Martin, Emily C; Veal, Brannon; Villanueva,, Steven; Williams, Patrick; Wise, Jason

    2013-01-01

    DECal is a new calibration system for the CTIO 4 m Blanco telescope. It is currently being installed as part of the Dark Energy Survey and will provide both broadband flat fields and narrowband (about 1 nm bandwidth) spectrophotometric calibration for the new Dark Energy Camera (DECam). Both of these systems share a new Lambertian flat field screen. The broadband flat field system uses LEDs to illuminate each photometric filter. The spectrophotometric calibration system consists of a monochromator-based tunable light source that is projected onto the flat field screen using a custom line-to-spot fiber bundle and an engineered diffuser. Several calibrated photodiodes positioned along the beam monitor the telescope throughput as a function of wavelength. This system will measure the wavelength-dependent instrumental response function of the total telescope+instrument system in the range 300 < lambda < 1100nm. The spectrophotometric calibration will be performed regularly (roughly once per month) to determ...

  1. Spectrophotometric and high performance liquid chromatographic methods for sensitive determination of bisphenol A

    Zhuang, Yafeng; Zhou, Meng; Gu, Jia; Li, Xiangmei

    2014-03-01

    A new spectrophotometric method for the determination of trace amounts of bisphenol A based on a diazotization-coupling reaction was developed. In acidic solution, clenbuterol was first diazotized with sodium nitrite, then coupled with bisphenol A to from an azo-compound [I] in NH3-NH4Cl buffer, which shows a maximum absorption at 410 nm. The effects of the amount of sodium nitrite, diazo reaction time, the amount of clenbuterol, coupling reaction time and coupling reaction temperature have been examined. Under the optional conditions, the determination of the linear range of bisphenol A is 0.24-8.4 μg/mL, correlation coefficient is 0.9905 and detection limit of this method is 0.15 μg/mL. The spectrophotometric method is simple, rapid, high sensitivity with better accuracy. High performance liquid chromatography (HPLC) technique combined with this new spectrophotometric method has been also developed for the measurement of bisphenol A. The analysis was achieved on a C18 column using water and methanol as a mobile phase and the detection was done spectrophotometrically at 410 nm. These reported methods were applied to the determination of bisphenol A in hot water in contact with commercially available table-water bottle samples.

  2. Photochemical and thermal degradation of a naturally occurring dye used in artistic painting. A chromatographic, spectrophotometric and fluorimetric study on saffron

    Vida Vickackaite; Aldo Romani; Danilo Pannacci; Gianna Favaro

    2004-01-01

    Saffron is a yellow substance which is extracted from the stigmas of Crocus sativus L. and is used in painting, cooking and medicine. In this paper six components (trans and cis crocins) with carotenoid structures were separated from natural saffron by HPLC and were characterised by their absorption and emission spectra. Photochemical and thermal processes which degrade the dye were also investigated. The effect of light promoted the cis ⇄ trans isomerization, while the thermal ef...

  3. Spectrophotometric study of the reaction mechanism between DDQ as π-acceptor and potassium iodate and flucloxacillin and dicloxacillin drugs and their determination in pure and in dosage forms

    Mohamed, Gehad G.; Nour El-Dien, F. A.; Farag, Eman U.

    2006-09-01

    Two simple and accurate spectrophotometric methods are presented for the determination of β-lactam drugs, flucloxacillin (Fluclox) and dicloxacillin (Diclox), in pure and in different pharmaceutical preparations. The charge transfer (CT) reactions between Fluclox and Diclox as electron donors and 2,3-dichloro-5,6-dicyano- p-benzoquinone (DDQ) π-acceptor and potassium iodate via oxidation reduction reaction where the highly coloured complex species or the liberated iodine have been spectrophotometrically studied. The optimum experimental conditions have been studied carefully. Beer's law is obeyed over the concentration range of 2-450 μg ml -1 for Fluclox and 10-450 μg ml -1 for Diclox using DDQ reagent and at 50-550 μg ml -1 for Fluclox and 50-560 μg ml -1 for Diclox using iodate method, respectively. For more accurate results, Ringbom optimum concentration range is calculated and found to be 6-450 and 15-450 μg ml -1 for Fluclox and Diclox using DDQ, respectively, and 65-550 and 63-560 μg ml -1 for Fluclox and Diclox using iodine, respectively. The Sandell sensitivity is found to be 0.018 and 0.011 μg cm -2 for DDQ method and 0.013 and 0.011 μg cm -2 for iodate method for Fluclox and Diclox, respectively, which indicates the high sensitivity of both methods. Standard deviation (S.D. = 0.01-0.80 and 0.07-0.98) and relative standard deviation (R.S.D. = 0.13-0.44 and 0.11-0.82%) ( n = 5) for DDQ and iodate methods, respectively, refer to the high accuracy and precision of the proposed methods. These results are also confirmed by between-day precision of percent recovery of 99.87-100.2 and 99.90-100% for Fluclox and Diclox by DDQ method and 99.88-100.1 and 99.30-100.2% for Fluclox and Diclox by iodate method, respectively. These data are comparable to those obtained by British and American pharmacopoeias assay for the determination of Fluclox and Diclox in raw materials and in pharmaceutical preparations.

  4. Simple UV spectrophotometric assay of Mefenamic acid

    Dr. Safila Naveed

    2014-07-01

    Full Text Available Mefenamic acid belongs to non-steroidal antiinflammatory drugs (NSAID.. It is being used widely for the treatment of analgesia. It is also used as antirheumatic and antipyretic drug. Our aim of study is to develop a efficient least time consuming and simple spectrophotometric method for the assay of mefenamic acid. Comparision of assay of three different brands of mefenamic acid (mefnac,ponstan,dolar available in public medical store of Karachi, Pakistan has also been done. The assay is based on the ultraviolet UV absorbance maxima at about 288nm wavelength of mefenamic acid, water is used as solvent. A sample of drug was dissolved in water to produce a solution containing mefenamic acid. Similarly, a sample of ground tablets of different brand were dissolved in water and various dilutions were made. The absorbance of sample preparation was measured at 288nm against the solvent blank and the assay was determined by comparing with the absorbance of available brand. Our results reveals that among all the three brands of mefenamic acid (mefnac,ponstan,dolar rosulin and rovista shows highest percentage assay 107.5%. xplended and rosubar shows percent assay of 106.25% and 103.75% while rovactor shows lowest value for percentage assay 98.75%.

  5. Simple UV spectrophotometric assay of Clarithromycin

    Dr. Safila Naveed

    2014-09-01

    Full Text Available Clarithromycin belongs to semi-synthetic macrolide antibiotic class of drugs that inhibits bacterial protein synthesis.. Our aim of study is to develop a efficient least time consuming and simple spectrophotometric method for the assay of clarithromycin. Comparision of assay of five different brands of clarithromycin (klaricid,klaribact,rithmo,clariteck,E-clark available in public medical store of Karachi, Pakistan has also been done. The assay is based on the ultraviolet UV absorbance maxima at about 210nm wavelength of mefenamic acid, water is used as solvent. A sample of drug was dissolved in water to produce a solution containing mefenamic acid. Similarly, a sample of ground tablets of different brand were dissolved in water and various dilutions were made. The absorbance of sample preparation was measured at 210nm against the solvent blank and the assay was determined by comparing with the absorbance of available brand. Our results reveals that among all the five brands of clarithromycin (klaricid,klaribact,rithmo,clariteck,E-clark Klaribact shows highest percentage assay i.e 115.3846%. Klaricid and Claritecl shows percentage assay of 107.693%. Rithmo shows a percent assay of 92.307% while E-clark shows lowest value for percentage assay 84.6153%

  6. Autoradiographic studies on percutaneous absorption of flumethasone-pivalate

    The distribution of topically applied radioactive flumethasone-pivalate was studied by means of autoradiography (direct mounting method). This substance was deposited in horny and Malpighian layers of epidermis and skin appendages (hair follicle, sebaceous gland and apocrine gland) more densely than in epidermis. This distribution pattern was discussed in comparison with the distribution patterns of the previously studied topical corticosteroids, namely, hydrocortisone, hydrocortisone-17-butyrate, triamcinolone-acetonide, betamethasone-17-valerate, 17-α-desoxymethasone, fluocinolone-acetonide and beclomethasone-dipropionate. (auth.)

  7. A study of sound absorption by street canyon boundaries and asphalt rubber concrete pavement

    Drysdale, Graeme Robert

    A sound field model, based on a classical diffusion equation, is extended to account for sound absorption in a diffusion parameter used to model sound energy in a narrow street canyon. The model accounts for a single sound absorption coefficient, separate accommodation coefficients and a combination of separate absorption and accommodation coefficients from parallel canyon walls. The new expressions are compared to the original formula through numerical simulations to reveal the effect of absorption on sound diffusion. The newly established analytical formulae demonstrate satisfactory agreement with their predecessor under perfect reflection. As well, the influence of the extended diffusion parameter on normalized sound pressure levels in a narrow street canyon is in agreement with experimental data. The diffusion parameters are used to model sound energy density in a street canyon as a function of the sound absorption coefficient of the street canyon walls. The acoustic and material properties of conventional and asphalt rubber concrete (ARC) pavement are also studied to assess how the crumb rubber content influences sound absorption in street canyons. The porosity and absolute permeability of compacted specimens of asphalt rubber concrete are measured and compared to their normal and random incidence sound absorption coefficients as a function of crumb rubber content in the modified binder. Nonlinear trends are found between the sound absorption coefficients, porosity and absolute permeability of the compacted specimens and the percentage of crumb rubber in the modified binders. The cross-sectional areas of the air voids on the surfaces of the compacted specimens are measured using digital image processing techniques and a linear relationship is obtained between the average void area and crumb rubber content. The measured material properties are used to construct an empirical formula relating the average porosity, normal incidence noise reduction coefficients and

  8. QSAR Study and VolSurf Characterization of Human Intestinal Absorption of Druge

    胡桂香; 商志才; 等

    2003-01-01

    The prediction of human intestinal absorption is a major goal in the design,optimization,and selection of candidates for the develoment of oral drugs.In this study,a computerized method(VolSurf with GRID) was used as a novel tool for predicting human intestinal absorption of test compound,and for determining the critical molecular properties needed for human intestinal absorption.The tested molecules consisted of 20 diverse drug-like compounds.Partial least squares(PLS) discriminant analysis was used to correlate the experimental data with the theoretical molecular properties of human intestinal absorption.A good correlation(r2=0.95,q2=0.86) between the molecular modeling results and the experimental data demonstrated that human intestinal absorption could be predicted from the three-dimensional(3D) molecular structure of a compound .Favorable structureal properties identified for the potent intestinal absorption of drugs included strong imbalance between the center of mass of a molecule and the barycentre of its hydrophilic and hydrophobic regions and a definitive hydrophobic region as well as less hydrogen bonding donors and acceptors in the molecule.

  9. Autoradiographic studies on percutaneous absorption of clobetasol 17-propionate

    The distribution of topically applied radioactive clobetasol 17-propionate was studied by means of autoradiography (direct mounting method). In the time course study, the developed silver grain deposition on the epidermis and skin appendages appeared after 30 minutes of occlusive treatment, and then reached the maximum state after 5 hours. Reservoir phenomenon was noticed 24 hours after removal of the cream. The pattern of deposition on the epithelial component of the skin is similar to that of betamethasone 17-valerate. After 1 hour of simple application of the cream, the deposition was seen only on the horny layer in the in vitro experiment, whereas some deposition was noticed on the Malpighian layer of the epidermis and hair follicle in the in vivo experiment. (auth.)

  10. Spectrophotometric, voltammetric and cytotoxicity studies of 2-hydroxy-5-methoxyacetophenone thiosemicarbazone and its N(4)-substituted derivatives: A combined experimental-computational study

    Akgemci, Emine Guler; Saf, Ahmet Ozgur; Tasdemir, Halil Ugur; Türkkan, Ercan; Bingol, Haluk; Turan, Suna Ozbas; Akkiprik, Mustafa

    2015-02-01

    In this study, 2-hydroxy-5-methoxyacetophenone thiosemicarbazone (HMAT) and its novel N(4) substituted derivatives were synthesized and characterized by different techniques. The optical band gap of the compounds and the energy of HOMO were experimentally examined by UV-vis spectra and cyclic voltammetry measurements, respectively. Furthermore, the conformational spaces of the compounds were scanned with molecular mechanics method. The geometry optimization, HOMO and LUMO energies, the energy gap of the HOMO-LUMO, dipole moment of the compounds were theoretically calculated by the density functional theory B3LYP/6-311++G(d,p) level. The minimal electronic excitation energy and maximum wavelength calculations of the compounds were also performed by TD-DFT//B3LYP/6-311++G(d,p) level of theory. Theoretically calculated values were compared with the related experimental values. The combined results exhibit that all compounds have good electron-donor properties which affect anti-proliferative activity. The cytotoxic effects of the compounds were also evaluated against HeLa (cervical carcinoma), MCF-7 (breast carcinoma) and PC-3 (prostatic carcinoma) cell lines using the standard MTT assay. All tested compounds showed antiproliferative effect having IC50 values in different range. In comparison with that of HMAT, it was obtained that while ethyl group on 4(N)-substituted position decreased in potent anti-proliferative effect, the phenyl group on the position increased in anti-proliferative effect for the tested cancer cell line. Considering the molecular energy parameters, the cytotoxicity activities of the compounds were discussed.

  11. Novel spectrophotometric methods for simultaneous determination of Amlodipine, Valsartan and Hydrochlorothiazide in their ternary mixture

    Lotfy, Hayam M.; Hegazy, Maha A.; Mowaka, Shereen; Mohamed, Ekram Hany

    2015-04-01

    This work represents a comparative study of two smart spectrophotometric techniques namely; successive resolution and progressive resolution for the simultaneous determination of ternary mixtures of Amlodipine (AML), Hydrochlorothiazide (HCT) and Valsartan (VAL) without prior separation steps. These techniques consist of several consecutive steps utilizing zero and/or ratio and/or derivative spectra. By applying successive spectrum subtraction coupled with constant multiplication method, the proposed drugs were obtained in their zero order absorption spectra and determined at their maxima 237.6 nm, 270.5 nm and 250 nm for AML, HCT and VAL, respectively; while by applying successive derivative subtraction they were obtained in their first derivative spectra and determined at P230.8-246, P261.4-278.2, P233.7-246.8 for AML, HCT and VAL respectively. While in the progressive resolution, the concentrations of the components were determined progressively from the same zero order absorption spectrum using absorbance subtraction coupled with absorptivity factor methods or from the same ratio spectrum using only one divisor via amplitude modulation method can be used for the determination of ternary mixtures using only one divisor where the concentrations of the components are determined progressively. The proposed methods were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical formulation containing the cited drugs. Moreover comparative study between spectrum addition technique as a novel enrichment technique and a well established one namely spiking technique was adopted for the analysis of pharmaceutical formulations containing low concentration of AML. The methods were validated as per ICH guidelines where accuracy, precision and specificity were found to be within their acceptable limits. The results obtained from the proposed methods were statistically compared with the reported one where no significant

  12. 2-Hydroxy-4-n-butoxy-5-bromoacetophenone thiosemicarbazone as an extractive spectrophotometric reagent for nickel

    K N Patel; K. S. Parikh; Rashmin Manubhai Patel

    2011-01-01

    2-hydroxy-4-n-butoxy-5-bromoacetophenone thiosemicarbazone (HBBrAT) is spectrophotometric reagent for nickel (II) in chloroform. The metal ion reacts with 2-hydroxy-4-n-butoxy-5-bromoacetophenone thiosemicarbazone (HBBrAT) forming a dark brown coloured complex in the pH range 7.0-11.0. The complex shows maximum absorption at 440 nm. Beer’s law is obeyed in the range 2.74-6.86 µg/mL. The molar absorptivity and Sandell’s sensitivity are found to be 5229 Lmol-1cm-1 and 0.0105 &...

  13. The use of Fourier functions to eliminate interferences in spectrophotometric analysis (theory and application).

    Wahbi, A M; Abdine, H; Korany, M A

    1978-05-01

    The basic principle for the use of Fourier functions in spectrophotometric analysis is discussed. Fourier function coefficients are linearly related to concentration and are associated with relative standard deviations of less than 1%. The proper choice of function and range, number of points and the transformation of an absorption curve are discussed. New trigonometric functions are derived to correct for linear irrelevant absorption. The method is illustrated by the determination of progesterone and testosterone propionate in oily solutions without prior chromatography. The results obtained are compared with those obtained using orthogonal polynomials. PMID:674337

  14. Development of a dipodal Schiff base ligand with N-imine and O-naphtholate donors: A potential chelator towards Cu(II) metal ion established through potentiometric and spectrophotometric studies

    Baral, Minati, E-mail: minatib@gmail.com; Gupta, Amit [Department of Chemistry, National Institute of Technology, Kurukshetra, Haryana (India); Kanungo, B. K. [Department of Chemistry, Sant Longowal Institute of Engineering and Technology, Longowal, Punjab (India)

    2015-08-28

    A novel hydroxynaphthaldehyde derived Schiff base ligand N,N’-bis-[2-[(2-hydroxy-1-naphthyl)methyleneamino]ethyl]propanediamide (DOTA2HNAP) containing nitrogen and oxygen donor atoms has been developed. The lowest energy molecular structure of DOTA2HNAP and its complexes with Cu (II) metal ion were examined by molecular mechanics using MM+ force which later was re-optimized by semi-empirical method. The theoretical IR and UV spectra of the ligand were obtained using semi empirical/ZINDO/PM3 and were compared with the experimental ones. The coordinating ability of DOTA2HNAP with H{sup +} and Cu(II) ions was investigated in 1:99 (DMSO: water) binary solvent mixture at 25±1°C by potentiometric and spectrophotometric method. The electronic spectra of the ligand show three distinct peaks (253nm, 320nm and 360nm) implicating existence of the Schiff base in quinone form that was well supported by theoretical spectral studies. Out of various complex species forming in solution, all the metal ions show higher stability of complexes when in 1:1 metal-ligand stoichiometry, binding through two N-imine and two O-naphtholate groups.

  15. Development of a dipodal Schiff base ligand with N-imine and O-naphtholate donors: A potential chelator towards Cu(II) metal ion established through potentiometric and spectrophotometric studies

    A novel hydroxynaphthaldehyde derived Schiff base ligand N,N’-bis-[2-[(2-hydroxy-1-naphthyl)methyleneamino]ethyl]propanediamide (DOTA2HNAP) containing nitrogen and oxygen donor atoms has been developed. The lowest energy molecular structure of DOTA2HNAP and its complexes with Cu (II) metal ion were examined by molecular mechanics using MM+ force which later was re-optimized by semi-empirical method. The theoretical IR and UV spectra of the ligand were obtained using semi empirical/ZINDO/PM3 and were compared with the experimental ones. The coordinating ability of DOTA2HNAP with H+ and Cu(II) ions was investigated in 1:99 (DMSO: water) binary solvent mixture at 25±1°C by potentiometric and spectrophotometric method. The electronic spectra of the ligand show three distinct peaks (253nm, 320nm and 360nm) implicating existence of the Schiff base in quinone form that was well supported by theoretical spectral studies. Out of various complex species forming in solution, all the metal ions show higher stability of complexes when in 1:1 metal-ligand stoichiometry, binding through two N-imine and two O-naphtholate groups

  16. Absorption study of the Tc(IV) on rocks and minerals under simulated geological conditions

    The absorption of the technetium on rocks and minerals have been studied by using freshly quarried rocks to provide reducing conditions, without the addition of reductive reagents. The initial 99Tc concentration in this study was about 1 x 10-8 mol/l (0.62 Bq/ml). Technetium was not absorbed on tuff or granite under oxidizing conditions, but higher Kd values of Tc were obtained for granite under reducing conditions. The Tc absorbed on granite was not desorbed under reducing condition. This indicates the absorption reaction is irreversible

  17. Spectrophotometric determination of uranium using quercetin

    A spectrophotometric method for quantitative determination of uranium, using a flavone (quercetin) as complexing agent, is described. The method is based on the reaction between uranyl ion and alcoholic solution of quercetin with a complex formation of intense yellow color. (M.C.L.)

  18. Ultra-fast X-ray absorption spectroscopy for the study of matter in transient regime

    In this work, we study the physics of dense matter, plasmas or solids, using X-ray absorption spectroscopy. Through the use of sources produced by laser-matter interaction, we have measured the absorption spectra of aluminum and bromine plasmas, as well as those of vanadium dioxide (VO2). The measurement of absorption coefficients allows us to probe the dense matter and to study its properties. The experiments are carried out following the same principle: they use the same experimental set-up, called pump-probe. When the matter is dense, the absorption properties of an atom are modified by the surrounding environment. In a plasma, it is mainly the bound- bound transitions which are altered: the shapes of those spectral rays are modified. In a solid, the position of the neighbouring atoms in relation to the absorbing atom modify the structure of absorption levels (bound-free transition). The study of this structure allows us to measure the parameters of the material, and provides information such as the state of the electronic band or the interatomic gaps. The experiments carried out at the LULI have allowed us to probe plasmas in the relatively unknown regime of the Warm Dense Matter. One of the key parameters is that the plasma is characterised independently (FDI diagnostic). It allows for a better comparison of the measured absorption against a calculation made with the numerical model OPA-S. The experiments carried out at INRS have led to the realisation of an experimental system having the characteristics which allow the study of the dynamics of solids showing ultra-fast phase transition. For those experiments, we have used vanadium dioxide as a model system allowing us to test the feasibility of the method. (author)

  19. A laboratory experimental setup for photo-absorption studies using synchrotron radiation

    Shastri, A; Saraswati, P; Sunanda, K

    2002-01-01

    The photophysics beamline, which is being installed at the 450 MeV Synchrotron Radiation Source (SRS), Indus-l, is a medium resolution beamline useful for a variety of experiments in the VUV region viz. 500-2000 A. One of the major applications of this beamline is gas-phase photo-absorption studies. An experimental set up to be used for these experiments was designed, developed and tested in our laboratory. The setup consists of a high vacuum absorption cell, 1/4 m monochromator and detection system. For the purpose of testing, xenon and tungsten continuum sources were used and absorption spectra were recorded in the UV region. This setup was used to record the absorption spectrum of a few molecules like acetone, ammonia, benzene, formaldehyde and acetaldehyde in order to evaluate the performance of the experimental system which will subsequently be used with the photophysics beamline. Details of the design, fabrication and testing of the absorption cell and experimental procedures are presented in this repor...

  20. Study on Absorption and Regeneration Performance of Novel Hybrid Solutions for CO2 Capture

    Gao Jie; Yin Jun; Zhu Feifei; Chen Xin; Tong Ming; Kang Wanzhong; Zhou Yanbo; Lu Jun

    2016-01-01

    Recently, a kind of hybrid solution MEA-methanol shows a better CO2 capture performance over aqueous MEA solution. However, the vaporization of methanol is the biggest disadvantage that hinders its application, so it is necessary to minimize the vaporization of methanol during both the absorption and regeneration processes. In this work, two kinds of hybrid solutions were studied and compared with aqueous MEA solution and MEA-methanol solution, including MEA/TEA/methanol solution and MEA/glycerol/methanol solution. The absorption property of MEA/glycerol/methanol solution is better than aqueous MEA solution within a certain period of time and the absorption property of MEA/TEA/methanol solution is too poor to be used in CO2 capture. By increasing the concentration of TEA and decreasing the concentration of MEA, the absorption rate, CO2 capture efifciency and absorption capacity all decreased. Upon adding glycerol, the cyclic capacity decreased and the generation temperature increased, and moreover, the density and viscosity also increased considerably. So after adding TEA and glycerol, the CO2 capture performance of MEA-methanol solvent cannot be improved.

  1. On the Influence of the Sample Absorptivity when Studying the Thermal Degradation of Materials

    Pascal Boulet

    2015-08-01

    Full Text Available The change in absorptivity during the degradation process of materials is discussed, and its influence as one of the involved parameters in the degradation models is studied. Three materials with very different behaviors are used for the demonstration of its role: a carbon composite material, which is opaque, almost grey, a plywood slab, which is opaque and spectral-dependent and a clear PMMA slab, which is semitransparent. Data are analyzed for virgin and degraded materials at different steps of thermal degradation. It is seen that absorptivity and emissivity often reach high values in the range of 0.90–0.95 with a near-grey behavior after significant thermal aggression, but depending on the materials of interest, some significant evolution may be first observed, especially during the early stages of the degradation. Supplementary inaccuracy can come from the heterogeneity of the incident flux on the slab. As a whole, discrepancies up to 20% can be observed on the absorbed flux depending on the degradation time, mainly because of the spectral variations of the absorption and up to 10% more, depending on the position on the slab. Simple models with a constant and unique value of absorptivity may then lead to inaccuracies in the evaluation of the radiative flux absorption, with possible consequences on the pyrolysis analysis, especially for properties related to the early step of the degradation process, like the time to ignition, for example.

  2. HUBUNGAN ANTARA KNOWLEDGE SHARING CAPABILITY, ABSORPTIVE CAPACITY DAN MEKANISME FORMAL: STUDI KASUS INDUSTRI TEKNOLOGI INFORMASI DAN KOMUNIKASI DI INDONESIA

    Luciana Andrawina

    2008-01-01

    Full Text Available Knowledge is currently viewed as an important strategic resource in companies in order to gain competitive advantage. However, the success in generating competitive advantage will depend on the company’s ability to acquire and assimilate knowledge (potential absorptive capacity and to transform and exploit knowledge (realized absorptive capacity. This research proposed three hypotheses by processing the sampled data of 114 companies of information and communication technology industry in Indonesia. Based on the results, this study finds that knowledge sharing capability significantly influences potential absorptive capacity and the company’s ability to acquire and assimilate knowledge has a positive influence towards the company’s ability to transform and to exploit knowledge. The relationship between potential absorptive capacity and realized absorptive capacity is moderated by formal mechanism. Abstract in Bahasa Indonesia: Pengetahuan saat ini dipandang sebagai sumber daya strategis yang penting bagi perusahaan untuk dapat memiliki keunggulan bersaing. Kesuksesan perusahaan menghasilkan keunggulan bersaing tergantung pada kemampuan perusahaan mengakuisisi dan mengasimilasi pengetahuan (potential absorptive capacity dan mentransformasi dan mengeksploitasi pengetahuan (realized absorptive capacity. Penelitian ini mengajukan tiga hipotesis dengan mengolah data sampel dari 114 perusahaan pada industri teknologi informasi dan komunikasi di Indonesia. Hasil penelitian menemukan bahwa knowledge sharing capability berpengaruh signifikan terhadap potential absorptive capacity, kemampuan perusahaan mengakuisisi dan mengasimilasi berpengaruh signifikan terhadap kemampuan mentransformasi dan mengeksplotasi pengetahuan. Hubungan antara potential absorptive capacity dan realized absorptive capacity dimoderasi oleh mekanisme formal. Kata kunci: knowledge sharing capability, potential absorptive capacity, realized absorptive capacity, mekanisme formal

  3. Laser-induced absorption and fluorescence studies of photochromic Schiff bases

    Kownacki, K.; Mordzinski, A.; Wilbrandt, R.; Grabowska, A.

    1994-01-01

    Three photochromic Schiff bases: N-salicylideneaniline (SA), N-salicylidene-1-naphthylamine (SN), and N,N-bis-(salicylidene)-p-phenylenediamine (Bsp), were studied in acetonitrile by means of steady-state and time-resolved absorption and fluorescence spectroscopy, as well as semiempirical quantum...... chemical calculations. In all these molecules, the transient absorption and two-step laser-induced fluorescence spectra of long-lived transients are remarkably similar. The photochromic species is tentatively assigned to the non-hydrogen bonded form of the proton transfer reaction product with a...

  4. Optical absorption and luminescence study of cobalt-doped magnesium aluminosilicate glass ceramics

    Malyarevich, A. M.; Denisov, I. A.; Yumashev, K. V.; Dymshits, O. S.; Zhilin, A. A.

    2002-08-01

    Linear and nonlinear optical properties of cobalt-doped magnesium aluminosilicate transparent glass ceramics that were prepared under different conditions have been studied. It has been shown that absorption and luminescence spectra and absorption bleaching of these glass ceramics are defined mainly by tetrahedrally coordinated Co 2+ ions located in magnesium aluminum spinel nanocrystals. The lifetimes of the 4 T 1 ( 4 F) and 4 T 2 ( 4 F) excited states of the tetrahedral Co 2+ ions were found to be in the ranges 2540 and 120450 ns, respectively, depending on the Co concentration. 2002 Optical Society of America

  5. Thermoluminescence and optical absorption comparative studies with TLD-100 and pure LiF

    Optical absorption (OA) studies were carried out with LiF: Mg, Ti (TLD-100) and pure LiF exposed to X radiation, 77.4 C.kg-1 (3 x 105 R) with the aim of relating the thermoluminescent (TL) peaks presented by TLD-100 to its intrinsic and irradiation defects. After a 2800C thermal treatment for 15 minutes, an absorption band at 225 nm is observed in the TLD-100 OA spectrum. This band is not observed in the case of pure LiF. A correlation between TL peak 5 and the absorption band at 310 nm is established for TLD-100. These results agree with other publications and are explained. (author)

  6. Parameter Optimization on Experimental Study to Reduce Ammonia Escape in CO2 Absorption by Ammonia Scrubbing

    Hao Leng; Jianmin Gao; Mingyue He; Min Xie; Qian Du; Rui Sun; Shaohua Wu

    2016-01-01

    In order to research ammonia escape in CO2 absorption by ammonia scrubbing, ammonia escape was studied in CO2 absorption process using the bubbling reactor in different conditions as gas flow rate, CO2 ratio, absorbent temperature and ammonia concentration and quantity of escaped ammonia was measured by chemical titration. The results indicated that, the amount of ammonia escape can be around 20% of original amount in 90 min and the escaped amount will increase with the rise of gas flow rate, absorbent temperature, concentration of ammonia while decrease as CO2 ratio goes up. Through the analysis of the law of ammonia escape, at the same time, combined with ammonia escape and the influence of the relationship between the CO2 absorption efficiency, reducing ammonia escape working condition parameter optimization is given.

  7. Experimental studies of a zeeman-tuned xenon laser differential absorption apparatus.

    Linford, G J

    1973-06-01

    A Zeeman-tuned cw xenon laser differential absorption device is described. The xenon laser was tuned by axial magnetic fields up to 5500 G generated by an unusually large water-cooled dc solenoid. Xenon laser lines at 3.37 micro, 3.51 micro, and 3.99 micro were tuned over ranges of 6 A, 6 A, and 11 A, respectively. To date, this apparatus has been used principally to study the details of formaldehyde absorption lines lying near the 3 .508-micro xenon laser transition. These experiments revealed that the observed absorption spectrum of formaldehyde exhibits a sufficiently unique spectral structure that the present technique may readily be used to measure relative concentrations of formaldehyde in samples of polluted air. PMID:20125492

  8. Studies on mass energy-absorption coefficients and effective atomic energy-absorption cross sections for carbohydrates

    We measured here the mass attenuation coefficients (μ/ρ) of carbohydrates, Esculine (C15H16O9), Sucrose (C12H22O11), Sorbitol (C6H14O6), D-Galactose (C6H12O6), Inositol (C6H12O6), D-Xylose (C5H10O5) covering the energy range from 122 keV up to 1330 keV photon energies by using gamma ray transmission method in a narrow beam good geometry set-up. The gamma-rays were detected using NaI(Tl) scintillation detection system with a resolution of 8.2% at 662 keV. The attenuation coefficient data were then used to obtain the total attenuation cross-section (σtot), molar extinction coefficients (ε), mass-energy absorption coefficients (μen/ρ) and effective (average) atomic energy-absorption cross section (σa,en) of the compounds. These values are found to be in good agreement with the theoretical values calculated based on XCOM data. - Highlights: • Compute the values of mass attenuation coefficients (μ/ρ) of some carbohydrates. • The values of (μen/ρ) i.e. mass energy-absorption coefficient are calculated. • Effective atomic energy-absorption cross sections (σa,en). • Comparison of all (μ/ρ), (μen/ρ), (σa,en) values with XCOM program. • The measured data for carbohydrates are useful in radiation dosimetry and other fields

  9. Vibrational absorption spectra, DFT and SCC-DFTB conformational study and analysis of [Leu]enkephalin

    Abdali, Salim; Niehaus, T.A.; Jalkanen, Karl J.;

    2003-01-01

    The endogenous morphine-like pentapeptide, [Leu]enkephalin, which binds to the opiate receptor in the brain, spinal core and gut, is the subject of this study. Vibrational absorption (VA) measurements were carried out on [Leu] enkephalin in non-polar solvent, DMSO-D6 to stabilize the environment...

  10. Neuron Mid-Infrared Absorption Study for Direct Optical Excitation of Neurons

    Guo, Dingkai; Chen, Xing; Vadala, Shilpa; Leach, Jennie; Choa, Fow-Sen

    2011-01-01

    Neuron optical excitations are important for brain-circuitry explorations and sensory-neuron-stimulation applications. To optimize the stimulation, we identify neuron mid-IR absorption peaks in this study and discuss their meanings and delivery methods of mid-IR photons.

  11. An improved model for studies on transdermal drug absorption in-vivo in rats

    Vollmer, U.; Muller, B.W.; Wilffert, B.; Peters, Thies

    1993-01-01

    In rats, transdermal drug absorption can be studied under physiological conditions cannulating the peripheral skin vein, draining the area of the skin which is used for drug application, and collecting the blood. This method leads to decreased blood volume, which causes a reduction in skin blood flo

  12. An improved model for studies on transdermal drug absorption invivo in rats

    VOLLMER, U; MULLER, BW; WILFFERT, B; Peters, Thies

    1993-01-01

    In rats, transdermal drug absorption can be studied under physiological conditions by cannulating the peripheral skin vein, draining the area of the skin which is used for drug application, and collecting the blood. This method leads to decreased blood volume, which causes a reduction in skin blood

  13. Study of cancer cell lines with Fourier transform infrared (FTIR)/vibrational absorption (VA) spectroscopy

    Uceda Otero, E. P.; Eliel, G. S. N.; Fonseca, E. J. S.;

    2013-01-01

    In this work we have used Fourier transform infrared (FTIR) / vibrational absorption (VA) spectroscopy to study two cancer cell lines: the Henrietta Lacks (HeLa) human cervix carcinoma and 5637 human bladder carcinoma cell lines. Our goal is to experimentally investigate biochemical changes and d...

  14. Spectrophotometric determination of uranium using chromotrope 2R complexes

    A simple, fast and reliable spectrophotometric method for the determination and microextraction of trace amounts of uranium using chromotrope 2R as a chelating agent and 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid (IL) was used as an extractant solvent. Influence variables such as pH, volume of ligand and IL were inspected by full factorial design. In the view of Pareto chart a contour plot was studied to examine the significant variables and their interactions. The detection limit and the preconcentration factor were found to be 0.87 and 50 μg L-1, respectively. The developed method was successfully applied to ore samples. (author)

  15. Spectrophotometric determination of uranium(VI) in bacterial leach liquors using arsenazo-III

    A highly sensitive and precise spectrophotometric method for the direct determination of uranium(VI) in bacterial leach liquors, obtained by the action of Thiobacillus ferrooxidans and T. thiooxidans, from low-grade sandstone uranium ores, has been developed. Arsenazo-III formed an intense pink-violet complex at pH 2·0±0·1, which showed maximum absorption at 655 nm. Interference due to different metal ions, such as Al, Ca, Co, Cr, Fe, Mn, Mo, Zn and Zr, was successfully masked by diethylenetriaminepenta-acetic acid without inhibiting the formation of the uranium(VI)-arsenazo-III complex. This method was also found suitable for detecting low levels of uranium(VI) in mine waters, acid leach liquors and tailings liquids. The results obtained were found to be in close agreement with the values determined by fluorometric and indirect spectrophotometric methods. (author)

  16. Analysis of Protein by Spectrophotometric and Computer Colour Based Intensity Method from Stem of Pea (Pisum sativum at Different Stages

    Afsheen Mushtaque Shah

    2010-12-01

    Full Text Available In this study proteins were analyzed from pea plants at three different growth stages of stem by spectrophotometric i.e Lowry and Bradford quantitative methods and computer colour intensity based method. Though Spectrophotometric methods are regarded as classical methods, we report an alternate computer based method which gave comparable results. Computer software was developed the for protein analysis which is easier, time and money saving method as compared to the classical methods.

  17. Spectrophotometric Determination of Pipazethate HCl and Dextromethorphan HBr using Potassium Permanganate.

    Gouda, Ayman Abou El-Fetouh; El-Sheikh, Ragaa; El Shafey, Zeineb; Hossny, Nagda; El-Azzazy, Rham

    2008-12-01

    Rapid, simple and sensitive validated spectrophotometric methods have been described for the assay of pipazethate HCl (PiCl) and dextromethorphan HBr (DEX) either in pure form or in pharmaceutical formulations. The proposed methods were based on the oxidation of the studied drugs by a known excess of potassium permanganate in acidic medium and estimating the unreacted permanganate with amaranth dye (method A), acid orange II (method B), indigocarmine (method C) and methylene blue (method D), in the same acid medium at a suitable λmax=521, 485, 610 and 664 nm, respectively. Beer's law is obeyed in the concentration range of 2.0-16 and 2.0-15 μg mL(-1) for PiCl and DEX, respectively with correlation coefficient (n=6) ≥ 0.9993. The apparent molar absorptivity and sandell sensitivity values are in the range 1.062-1.484 × 10(4), 3.35-4.51 × 10(4) L mol(-1) cm(-1) and 29.36-41.03, 8.21-11.06 ng cm(-2) for PiCl and DEX, respectively. Different variables affecting the reaction were studied and optimized. The proposed methods were applied successfully to the determination of the examined drugs either in a pure or pharmaceutical dosage forms with good accuracy and precision. No interferences were observed from excipients and the results obtained were in good agreement with those obtained using the official methods. PMID:23675101

  18. Development and Validation of a UV - Spectrophotometric Method for Quantification of Atorvastatin in Tablets

    Mondal A

    2012-01-01

    Full Text Available A UV-spectrophotometric method has been developed for the quantitativeestimation of atorvastatin in tablet. The present study describes development and validation of UV-spectroscopic method for estimationof atorvastatin in tablet dosage form and validation of newlydeveloped method. During development of analytical method methanol:phosphate buffer (20:80,methanol:water(20:80,methanol:water (50:50,acetonitrile:water (10:90were tried but drug was found to be solublein methanol:water (50:50. Standard stock solution was prepared in methanol: water (50:50. The detection wave length (λmax was found tobe 248nm.Calibration curves were prepared.The proposed method obeysBeer's law in the range of 5-15μg/ml. Absorption maxima was determinedwith 10 μg/ml by scanning in the range of 200-400nm.Percent recoverystudies are in the range of 98.78%-100.36%. The method was validated in terms specificity,linearity,accuracy,range,precision,repeatability,robustness,system suitability,stability of analytical solution.Results of analysis were validated statistically and by specificity studies.From that it was observed that there is no interference of blank,excipients during the estimation of drug in formulation. This showsthe adaptability of the method for routine estimation of atorvastatinin tablet dosage form.

  19. Spectrophotometric Determination of Aminoglycoside Antibiotics Based on their Oxidation by Potassium Permanganate

    A rapid, simple and sensitive validated spectrophotometric methods have been described for the assay of neomycin and streptomycin either in pure form or in pharmaceutical formulations. The proposed methods were based on the oxidation of the studied drugs by a known excess of potassium permanganate in acidic medium and estimating the unreacted permanganate with amaranth dye (method A), acid orange II (method B), indigocarmine (method C), and methylene blue (method D), in the same acid medium at a suitable λmax=521, 485, 610 and 664 nm, respectively. Beer's law is obeyed in the concentration range of 5-10 and 2-7 mg mL-1 for neomycin and streptomycin, respectively. The apparent molar absorptivity and sandell sensitivity values are in the range 5.47-6.20x104, 2.35-2.91x105 L mol-1 cm-1 and 7.57-8.59, 5.01-6.2 ng cm-2 for neomycin and streptomycin, respectively. Different variables affecting the reaction were studied and optimized. The proposed methods were applied successfully to the determination of the examined drugs either in a pure or pharmaceutical dosage forms with good accuracy and precision. No interferences were observed from excipients and the results obtained were in good agreement with those obtained using the official methods

  20. Results of Self-Absorption Study on the Versapor 3000 Filters for Radioactive Particulate Air Sampling

    Since the mid-1980s the Pacific Northwest National Laboratory (PNNL) has used a value of 0.85 as a correction factor for the self absorption of activity of particulate radioactive air samples. More recently, an effort was made to evaluate the current particulate radioactive air sample filters (Versapor(regsign) 3000) used at PNNL for self absorption effects. There were two methods used in the study, (1) to compare the radioactivity concentration by direct gas-flow proportional counting of the filter to the results obtained after acid digestion of the filter and counting again by gas-flow proportional detection and (2) to evaluate sample filters by high resolution visual/infrared microscopy to determine the depth of material loading on or in the filter fiber material. Sixty samples were selected from the archive for acid digestion in the first method and about 30 samples were selected for high resolution visual/infrared microscopy. Mass loading effects were also considered. From the sample filter analysis, large error is associated with the average self absorption factor, however, when the data is compared directly one-to-one, statistically, there appears to be good correlation between the two analytical methods. The mass loading of filters evaluated was <0.2 mg cm-2 and was also compared against other published results. The microscopy analysis shows the sample material remains on the top of the filter paper and does not imbed into the filter media. Results of the microscopy evaluation lead to the conclusion that there is not a mechanism for significant self absorption. The overall conclusion is that self-absorption is not a significant factor in the analysis of filters used at PNNL for radioactive air stack sampling of radionuclide particulates and that an applied correction factor is conservative in determining overall sample activity. A new self absorption factor of 1.0 is recommended

  1. Molecular dynamics study of a CNT-buckyball-enabled energy absorption system.

    Chen, Heng; Zhang, Liuyang; Becton, Matthew; Nie, Hong; Chen, Jinbao; Wang, Xianqiao

    2015-07-14

    An energy absorption system (EAS) composed of a carbon nanotube (CNT) with nested buckyballs is put forward for energy dissipation during impact owing to the outstanding mechanical properties of both CNTs and buckyballs. Here we implement a series of molecular dynamics (MD) simulations to investigate the energy absorption capabilities of several different EASs based on a variety of design parameters. For example, the effects of impact energy, the number of nested buckyballs, and of the size of the buckyballs are analyzed to optimize the energy absorption capability of the EASs by tuning the relevant design parameters. Simulation results indicate that the energy absorption capability of the EAS is closely associated with the deformation characteristics of the confined buckyballs. A low impact energy leads to recoverable deformation of the buckyballs and the dissipated energy is mainly converted to thermal energy. However, a high impact energy yields non-recoverable deformation of buckyballs and thus the energy dissipation is dominated by the strain energy of the EAS. The simulation results also reveal that there exists an optimal value of the number of buckyballs for an EAS under a certain impact energy. Larger buckyballs are able to deform to a larger degree yet also need less impact energy to induce plastic deformation, therefore performing with a better overall energy absorption ability. Overall, the EAS in this study shows a remarkably high energy absorption density of 2 kJ g(-1), it is a promising candidate for mitigating impact energy and sheds light on the research of buckyball-filled CNTs for other applications. PMID:26074446

  2. A study to maximize the crash energy absorption efficiency within the limits of crash space

    The design of an engine room is important to protect the passenger from a crash impact by improving the absorption of the crash impact energy. The side member in the engine room absorbs most of the crash impact energy when the vehicle experiences a frontal crash. The side member is of two types: hat and 'U.' Analysis of the extent of energy absorption and the mechanism of the side member are necessary through a collapse mode in various load conditions. In this study, the design of experiments was used for evaluating the characteristics of the absorption of crash energy by side members through design variables. First, crash analysis was performed by experiment number extracted from the design of the experiment. Then, using the results of crash analysis, multiple regressions were conducted and sensitivity analysis performed for each design variable. Finally, the optimum design was developed for maximizing the absorption energy per unit weight considering various boundary conditions. In the present study, as a basic step for modeling the fatigue behavior of an extruded Al alloy cylinder, the fatigue crack growth data of the alloy was collected in two orientations. Microstructural analysis revealed that the material had recrystallized grains and clusters of constituent particles aligned in the direction of extrusion. Fatigue life of the samples revealed a shorter fatigue life representing a higher fatigue crack growth rate in the transverse direction

  3. Simulation of carbon dioxide absorption by sodium hydroxide solution in a packed bed and studying the effect of operating parameters on absorption

    Available in abstract form only. Full text of publication follows: In this study. simulation of carbon dioxide absorption by Sodium Hydroxide solution in a packed bed has been investigated. At first, mass and energy balances were applied around a differential height of the bed. So, the governing equations were obtained. Surface renewal theory by Danckwerts was used to represent the mass transfer operation Finally, by changing the operating parameters like solvent temperature, inlet gas composition pressure and height of the bed, the effect of these parameters on the absorption and the composition of carbon dioxide in exit stream have been investigated. (authors)

  4. Efficacy of casein phosphopeptide-amorphous calcium phosphate to prevent stain absorption on freshly bleached enamel: An in vitro study

    Raghuwar D Singh; Ram, Sabita M; Shetty, Omkar; Chand, Pooran; Yadav, Rakesh

    2010-01-01

    Background: Teeth when subjected to bleaching bring about the desiccation of the enamel, making it more susceptible to stain absorption. While subjecting the freshly bleached enamel surface to various surface treatments of Fluoride and Casein Phosphopeptide - Amorphous Calcium phosphate (CPP-ACP) brought about the reduction in stain absorption, which is assessed in this study. Aims: The study aims to evaluate the tea stain absorption on freshly bleached enamel surface of extracted human teeth...

  5. Kinetic Spectrophotometric Determination of Certain Cephalosporins in Pharmaceutical Formulations

    Mahmoud A. Omar

    2009-01-01

    Full Text Available A simple, reliable, and sensitive kinetic spectrophotometric method was developed for determination of eight cephalosporin antibiotics, namely, Cefotaxime sodium, Cephapirin sodium, Cephradine dihydrate, Cephalexin monohydrate, Ceftazidime pentahydrate, Cefazoline sodium, Ceftriaxone sodium, and Cefuroxime sodium. The method depends on oxidation of each of studied drugs with alkaline potassium permanganate. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 610 nm. The initial rate and fixed time (at 3 minutes methods are utilized for construction of calibration graphs to determine the concentration of the studied drugs. The calibration graphs are linear in the concentration ranges 5–15 g mL−1 and 5–25 g mL−1 using the initial rate and fixed time methods, respectively. The results are validated statistically and checked through recovery studies. The method has been successfully applied for the determination of the studied cephalosporins in commercial dosage forms. Statistical comparisons of the results with the reference methods show the excellent agreement and indicate no significant difference in accuracy and precision.

  6. Kinetic spectrophotometric determination of certain cephalosporins in pharmaceutical formulations.

    Omar, Mahmoud A; Abdelmageed, Osama H; Attia, Tamer Z

    2009-01-01

    A simple, reliable, and sensitive kinetic spectrophotometric method was developed for determination of eight cephalosporin antibiotics, namely, Cefotaxime sodium, Cephapirin sodium, Cephradine dihydrate, Cephalexin monohydrate, Ceftazidime pentahydrate, Cefazoline sodium, Ceftriaxone sodium, and Cefuroxime sodium. The method depends on oxidation of each of studied drugs with alkaline potassium permanganate. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 610 nm. The initial rate and fixed time (at 3 minutes) methods are utilized for construction of calibration graphs to determine the concentration of the studied drugs. The calibration graphs are linear in the concentration ranges 5-15 mug mL(-1) and 5-25 mug mL(-1) using the initial rate and fixed time methods, respectively. The results are validated statistically and checked through recovery studies. The method has been successfully applied for the determination of the studied cephalosporins in commercial dosage forms. Statistical comparisons of the results with the reference methods show the excellent agreement and indicate no significant difference in accuracy and precision. PMID:20140078

  7. Kinetic study of carbon dioxide absorption into glycine promoted diethanolamine (DEA)

    Pudjiastuti, Lily; Susianto, Altway, Ali; IC, Maria Hestia; Arsi, Kartika

    2015-12-01

    In industry, especially petrochemical, oil and natural gas industry, required separation process of CO2 gas which is a corrosive gas (acid gas). This characteristic can damage the plant utility and piping systems as well as reducing the caloric value of natural gas. Corrosive characteristic of CO2 will appear in areas where there is a decrease in temperature and pressure, such as at the elbow pipe, tubing, cooler and injector turbine. From disadvantages as described above, then it is important to do separation process in the CO2 gas stream, one of the method for remove CO2 from the gas stream is reactive absorption using alkanolamine based solution with promotor. Therefore, this study is done to determine the kinetics constant of CO2 absorption in diethanolamine (DEA) solution using a glycine promoter. Glycine is chosen as a promoter because glycine is a primary amine compound which is reactive, moreover, glycine has resistance to high temperatures so it will not easy to degradable and suitable for application in industry. The method used in this study is absorption using laboratory scale wetted wall column equipment at atmospheric of pressure. This study will to provide the reaction kinetics data information in order to optimize the separation process of CO2 in the industrialized world. The experimental results show that rising temperatures from 303,15 - 328,15 K and the increase of concentration of glycine from 1% - 3% weight will increase the absorption rate of carbon dioxide in DEA promoted with glycine by 24,2% and 59,764% respectively, also the reaction kinetic constant is 1.419 × 1012 exp (-3634/T) (m3/kmol.s). This result show that the addition of glycine as a promoter can increase absorption rate of carbon dioxide in diethanolamine solution and cover the weaknesses of diethanolamine solution.

  8. Separation and spectrophotometric determination of elements

    This book is a useful text intended as a reference for the laboratory that is either involved in spectrophotometric analysis or requires separations prior to analysis by any method. It attempts to cover a diverse series of topics in fewer than 700 pages. Part I of the book covers general topics such as separation schemes (solvent extraction, precipitation, volatility, ion exchange), principles and instrumentation used for spectrophotometry, and color reagents in only 119 pages. Entire books have been written on each of those subjects. The author must therefore resort to extensive referencing to cover each subject adequately. Part II, Methods for Separation and Determination of Individual Elements, discusses all elements - both nonmetals and metals and major procedures for the separation and spectrophotometric determination of each element are adequately covered

  9. A miniaturized stepwise injection spectrophotometric analyzer

    A novel micro-stepwise injection analyzer (μSWIA) has been developed for the automation and miniaturization of spectrophotometric analysis. The main unit of this device is a mixing chamber (MC) connected to the atmosphere. This part of the μSWIA provides rapid and effective homogenization of the reaction mixture components and completion of the reaction by means of gas bubbling. The μSWIA contained a rectangular labyrinth channel designed in way allowing one to eliminate bubbles by moving a solution from the MC to an optical channel. The light-emitting diode (LED) was used as a light emitter and the analytical signal was measured by a portable spectrophotometer. Fluid movement was attained via the use of a computer-controlled syringe pump. The μSWIA was successfully used for the spectrophotometric determination of cysteine in biologically active supplements and fodder by using 18-molybdo-2-phosphate heteropoly anion (18-MPA) as the reagent. (author)

  10. Application of potassium permanganate to spectrophotometric assay of metoclopramide hydrochloride in pharmaceuticals

    Devi, O. Zenita; Basavaiah, K.; Vinay, K. B.

    2012-01-01

    Two simple, sensitive, and cost-effective spectrophotometric methods are described for the determination of metoclopramide hydrochloride (MCP) in pharmaceutical dosage forms. The methods are based on a redox reaction between MCP and KMnO4 in alkaline and acid media. Direct spectrophotometry (method A) involves treating MCP with permanganate in an NaOH medium and measuring a bluish green product at 610 nm. In indirect spectrophotometry (method B), MCP is treated with a fixed concentration of KMnO4 in an H2SO4 medium, and after a specified time, the unreacted KMnO4 is measured at 545 nm. Under optimum assay conditions, Beer's law is obeyed over the ranges of 0.75-12.0 and 2.5-30.0 g/ml for methods A and B, respectively. Molar absorptivity values are calculated to be 2.33•104 and 2.66•104 l/mol cm for methods A and B, respectively, and corresponding Sandell's sensitivity values are 0.015 and 0.013 g/cm2. Limits of detection (LOD) and quantification (LOQ) are also reported. The applicability of the developed methods was demonstrated by the determination of MCP in tablet and injection forms. The accuracy and reliability of the proposed methods were further ascertained by recovery studies via standard addition technique.

  11. SPECTROPHOTOMETRIC METHODS FOR SIMULTANEOUS ESTIMATION OF CEFUROXIME SODIUM AND SULBACTAM SODIUM IN INJECTON

    F.M. Patel et al

    2012-09-01

    Full Text Available Cefuroxime is a 2nd-generation cephalosporin and Sulbactam is a β-Lactamase inhibitor. The combination formulation is used for the treatment of lower respiratory tract infection. Two new, simple, accurate and precise UV spectrophotometric methods have been developed and validated for the simultaneous determination of Cefuroxime Sodium (CEF and Sulbactam Sodium (SUL in their combined dosage forms. First method is based on simultaneous estimation of Cefuroxime at 279nm and Sulbactam at 259 nm, while other Q‐absorption Ratio method using two wavelengths, 259nm (λmax of SUL and 272nm (Isoabsorptive point. 0.01 N NaOH was the solvent used in all methods. Cefuroxime Sodium showed linearity in the range of 8-32μg/mL and Sulbactam sodium showed linearity in the range of 4-16μg/mL in all the methods. All methods were validated statistically and recovery studies were carried out. All methods were found to be accurate, precise and reproducible. These methods were applied to the assay of the drugs in marketed formulation, which were found in the range of 98.0% to 100.0% of the labelled value for both Cefuroxime and Sulbactam. Hence, the methods herein described can be successfully applied in quality control of combined pharmaceutical dosage forms.

  12. Kinetic spectrophotometric method for determination of amlodipine besylate in its pharmaceutical tablets

    Ashraf M. Mahmoud; Hanaa M. Abdel-Wadood; Niveen A. Mohamed

    2012-01-01

    A simple and sensitive kinetic spectrophotometric method has been developed and validated for determination of amlodipine besylate (AML). The method was based on the condensation reaction of AML with 7-chloro-4-nitro-2,1,3-benzoxadiazole in an alkaline buffer (pH 8.6) producing a highly colored product. The color development was monitored spectrophometrically at the maximum absorption λmax 470 nm. The factors affecting the reaction were studied and the conditions were optimized. The stoichiometry of the reaction was determined, and the reaction pathway was postulated. Moreover, both the activation energy and the specific rate constant (at 70 ℃) of the reaction were found to be 6.74 kcal mole-1 and 3.58 s -1, respectively. The initial rate and fixed time methods were utilized for constructing the calibration graphs lbr the determination of AML concentration. Under the optimum reaction conditions, the limits of detection and quantification were 0.35 and 1.05 ug/mL, respectively. The precision of the method was satisfactory; the relative standard deviations were 0.85-1.76%. The proposed method was successfully applied to the analysis of AML in its pure form and tablets with good accuracy; the recovery percentages ranged from 99.55 ± 1.69% to 100.65 ±1.48%. The results were compared with that of the reported method.

  13. Pregabalin and Tranexamic Acid Evaluation by Two Simple and Sensitive Spectrophotometric Methods

    Sher, Nawab; Fatima, Nasreen; Perveen, Shahnaz; Siddiqui, Farhan Ahmed; Wafa Sial, Alisha

    2015-01-01

    This paper demonstrates colorimetric visible spectrophotometric quantification methods for amino acid, namely, tranexamic acid and pregabalin. Both drugs contain the amino group, and when they are reacted with 2,4-dinitrophenol and 2,4,6-trinitrophenol, they give rise to yellow colored complexes showing absorption maximum at 418 nm and 425 nm, respectively, based on the Lewis acid base reaction. Detailed optimization process and stoichiometric studies were conducted along with investigation of thermodynamic features, that is, association constant and standard free energy changes. The method was linear over the concentration range of 0.02–200 µgmL−1 with correlation coefficient of more than 0.9990 in all of the cases. Limit of detection was in range from 0.0041 to 0.0094 µgmL−1 and limit of quantification was in the range from 0.0137 to 0.0302 µgmL−1. Excellent recovery in Placebo spiked samples indicated that there is no interference from common excipients. The analytical methods under proposal were successfully applied to determine tranexamic acid and pregabalin in commercial products. t-test and F ratio were evaluated without noticeable difference between the proposed and reference methods. PMID:25873964

  14. Development and Validation of Spectrophotometric Methods for Estimating Sulfamethoxazole in Pharmaceutical Preparations

    Sangita Sharma

    2010-07-01

    Full Text Available Four simple, sensitive, accurate, and rapid visible spectrophotometric methods (A, B, C and D have been developed for the estimation of sulfamethoxazole in pharmaceutical Preparation. They are based on the diazotization of sulfamethoxazole with sodium nitrite and hydrochloric acid followed by coupling with N-(1-naphthyl ethylenediamine dihydrochloride (Method A to form pink coloured chromogen, diphenylamine (Method B to form pink coloured chromogen, β-napthol (in alkaline medium (Method C to form a orange yellow coloured chromogen and Resorcinol (in alkaline medium (Method D to form orange red coloured chromogen and exhibiting absorption maxima λmax at 536 nm, 516 nm, 477 nm and 502 nm respectively. The coloured chromogens formed are stable for more than 2 h. Beer's law was obeyed in the concentration range of 4 -12 µg mL-1 in method A , 2 – 10 µg mL-1 in method B, 5 – 25 µg mL-1 in method C and 1 – 5 µg mL-1 in method D respectively. The Results of the four analysis have been validated statistically and by recovery studies. The results obtained in the proposed methods are in good agreements with labeled amounts, when marketed pharmaceutical preparations are analyzed.

  15. Spectrophotometric Method for Quantitative Determination of Cefixime in Bulk and Pharmaceutical Preparation Using Ferroin Complex

    Naeem Khan, M.; Qayum, A.; Ur Rehman, U.; Gulab, H.; Idrees, M.

    2015-09-01

    A method was developed for the quantitative determination of cefixime in bulk and pharmaceutical preparations using ferroin complex. The method is based on the oxidation of the cefixime with Fe(III) in acidic medium. The formed Fe(II) reacts with 1,10-phenanthroline, and the ferroin complex is measured spectrophotometrically at 510 nm against reagent blank. Beer's law was obeyed in the concentration range 0.2-10 μg/ml with a good correlation of 0.993. The molar absorptivity was calculated and was found to be 1.375×105 L/mol × cm. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.030 and 0.101 μg/ml respectively. The proposed method has reproducibility with a relative standard deviation of 5.28% (n = 6). The developed method was validated statistically by performing a recoveries study and successfully applied for the determination of cefixime in bulk powder and pharmaceutical formulations without interferences from common excipients. Percent recoveries were found to range from 98.00 to 102.05% for the pure form and 97.83 to 102.50% for pharmaceutical preparations.

  16. A spectrophotometric flow injection system for streptomycin determination in veterinary samples

    Frugeri, Pedro Marcos; Lago, Ayla Campos do; Wisniewski, Célio; Luccas, Pedro Orival

    2014-01-01

    In this work a spectrophotometric flow injection analysis system for streptomycin determination in veterinary samples, is being proposed. The method is based on streptomycin alkaline hydrolysis that forms guanidine, followed by the reaction with Fe(II). The colored product has absorption peak at 520 nm. To evaluate and optimize the system parameters, chemometrics tools, such as factorial design, Pareto chart and Doelhert design, were used. The veterinary samples are diluted in water and introduced in the FIA system, therefore no sample preparation is required. The optimized system presented: linear range of 60 up to 1000 mg L-1, limit of detection of 18 mg L-1 and sampling rate of 36 readings per hour. The precision was checked and the CV for veterinary sample readings were always less than 6.5%. The accuracy was studied by comparison with chromatographic method, thus, five samples of pharmaceutical veterinary were determined by HPLC and by the proposed method, and the results are in agreement (t-test, p = 0.05).

  17. Using the lymphatics to study nutrient absorption and the secretion of gastrointestinal hormones

    Kohan, Alison B.; Yoder, Stephanie M.; Tso, Patrick

    2011-01-01

    The lymph fistula rat model has traditionally been used to study the intestinal absorption of nutrients, especially lipids, but recently this model has also been used for studying the secretion of incretin hormones by the small intestine. The small intestine is not only responsible for the digestion and transport of dietary triacylglycerol, through the formation of chylomicrons, but it also secretes the incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like pep...

  18. Quantum cascade laser absorption spectroscopy - A new method to study molecular plasma components

    The recent development of quantum cascade lasers (QCLs) offers an attractive new option for the monitoring and control of industrial plasma processes and for trace-gas analysis as well as for highly time-resolved studies on the kinetics of plasma processes. The contribution reviews selected examples of the application of QCLs for infrared absorption studies in basic research and for plasma monitoring and control in industry.

  19. Quantum cascade laser absorption spectroscopy - A new method to study molecular plasma components

    Roepcke, J; Glitsch, S; Hempel, F; Lang, N; Welzel, S [INP Greifswald, F.-Hausdorff-Str. 2, 17489 Greifswald (Germany); Davies, P [University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom); Rousseau, A [LPP, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex (France); Wege, S, E-mail: roepcke@inp-greifswald.d [Plasway, Hauptstr. 7a, 01328 Dresden (Germany)

    2010-05-01

    The recent development of quantum cascade lasers (QCLs) offers an attractive new option for the monitoring and control of industrial plasma processes and for trace-gas analysis as well as for highly time-resolved studies on the kinetics of plasma processes. The contribution reviews selected examples of the application of QCLs for infrared absorption studies in basic research and for plasma monitoring and control in industry.

  20. Studies on mass energy-absorption coefficients and effective atomic energy-absorption cross sections for carbohydrates

    Ladhaf, Bibifatima M.; Pawar, Pravina P.

    2015-04-01

    We measured here the mass attenuation coefficients (μ/ρ) of carbohydrates, Esculine (C15H16O9), Sucrose (C12H22O11), Sorbitol (C6H14O6), D-Galactose (C6H12O6), Inositol (C6H12O6), D-Xylose (C5H10O5) covering the energy range from 122 keV up to 1330 keV photon energies by using gamma ray transmission method in a narrow beam good geometry set-up. The gamma-rays were detected using NaI(Tl) scintillation detection system with a resolution of 8.2% at 662 keV. The attenuation coefficient data were then used to obtain the total attenuation cross-section (σtot), molar extinction coefficients (ε), mass-energy absorption coefficients (μen/ρ) and effective (average) atomic energy-absorption cross section (σa,en) of the compounds. These values are found to be in good agreement with the theoretical values calculated based on XCOM data.

  1. Derivative Spectrophotometric Estimation of Ondansetron and Paracetamol

    Ravi Kumar, P.; M Murali Krishna; P. Bhanu Prakash; B. Anil Kumar; P. Madhusudhan

    2006-01-01

    A simple and reproducible spectrophotometric method, requiring no prior separation, has been developed for the estimation of ondansetron and paracetamol in combined dosage form. First order derivative spectroscopy method is adopted to eliminate spectral interference. The methods obey Beer’s Law in concentration ranges employed for evaluation. Ondansetron and paracetamol have λmax at 302 nm and 246 nm respectively in methanol. The results of analysis have been validated statistically and recov...

  2. An Atlas of Spectrophotometric Landolt Standard Stars

    Stritzinger, Maximilian; Suntzeff, Nicholas B.; Hamuy, Mario; Challis, Peter; Demarco, Ricardo; Germany, Lisa; Soderberg, A. M.

    2005-01-01

    We present CCD observations of 102 Landolt standard stars obtained with the R-C spectrograph on the CTIO 1.5 m telescope. Using stellar atmosphere models we have extended the flux points to our six spectrophotometric secondary standards, in both the blue and the red, allowing us to produce flux-calibrated spectra that span a wavelength range from 3050 \\AA to 1.1 \\micron. Mean differences between UBVRI spectrophotometry computed using Bessell's standard passbands and Landolt's published photom...

  3. Spectrophotometric Estimation of Azithromycin in Tablets

    B. K. Jayanna; G. Nagendrappa; Arunkumar,; Gowda, N.

    2012-01-01

    The present manuscript describes a simple, sensitive, accurate, precise and economical visible spectrophotometric method for the estimation of azithromycin from tablet formulation. The method is based on the reduction of potassium permanganate in alkaline medium with azithromycin. The measurement of decrease in absorbance of potassium permanganate at 547 nm was done, as it decolourises upon reduction by azithromycin. The method was used to determine between 2 and 20 μg/ml of azithromycin in t...

  4. Study on the prediction of visible absorption maxima of azobenzene compounds

    LIU Jun-na; CHEN Zhi-rong; YUAN Shen-feng

    2005-01-01

    The geometries of azobenzene compounds are optimized with B3LYP/6-311 G* method, and analyzed with nature bond orbital, then their visible absorption maxima are calculated with TD-DFT method and ZINDO/S method respectively. The results agree well with the observed values. It was found that for the calculation of visible absorption using ZINDO/S method could rapidly yield better results by adjusting OWFπ-π (the relationship between π-π overlap weighting factor) value than by the TD-DFT method. The method of regression showing the linear relationship between OWFπ-π and BLN-N (nitrogen-nitrogen bond lengths) as OWFπ-π=-8.1537+6.5638BLN-N, can be explained in terms of quantum theory, and also be used for prediction of visible absorption maxima of other azobenzne dyes in the same series. This study on molecules' orbital geometry indicates that their visible absorption maxima correspond to the electron transition from HOMO (the highest occupied molecular orbital) to LUMO (the lowest unoccupied molecular orbital).

  5. Study on Relative COP Changes with Increasing Heat Input Temperatures of Double Effect Steam Absorption Chillers

    Abd Majid Mohd Amin

    2016-01-01

    Full Text Available Absorption chillers at cogeneration plants generate chilled water using steam supplied by heat recovery steam generators. The chillers are mainly of double effect type. The COP of double effect varies from 0.7 to 1.2 depending on operation and maintenance practices of the chillers. Heat input to the chillers during operations could have impact on the COP of the chillers. This study is on relative COP changes with increasing the heat input temperatures for a steam absorption chiller at a gas fueled cogeneration plant. Reversible COP analysis and zero order model were used for evaluating COP of the chiller for 118 days operation period. Results indicate increasing COP trends for both the reversible COP and zero model COP. Although the zero model COP are within the range of double effect absorption chiller, it is not so for the actual COP. The actual COP is below the range of normal double effect COP. It is recommended that economic replacement analysis to be undertaken to assess the feasibility either to repair or replace the existing absorption chiller.

  6. Study and Development of near-Infrared Reflective and Absorptive Materials for Energy Saving Application

    Cui, Yu Xing

    Near-Infrared (NIR) materials find applications in the field of energy saving. Both NIR reflective and absorptive materials can be used as energy saving materials with different working principles. The reflective materials can reflect the NIR light preventing it from being transmitted. Silver thin films are the best option as reflective films based on its reflectivity and cost. On the other hand, NIR absorptive materials can effectively convert the absorbed NIR light from sunlight to heat or electric energy. The first part of this research explored methods of preparing silver thin films that could be processed at low cost. The second part involved the design, synthesis and characterization of nickel coordination polymers as NIR absorptive materials. In part 1, different solution based methods of preparing silver thin films were studied. A silver nanoparticles solution was used to make thin film by a spray-pyrolysis process. Another method involved the surface activation with a fluoro-compound or silver nanoparticles followed by electroless silver plating on different substrates. Both methods could be processed at low cost. The obtained silver films showed NIR reflection of 50˜90% with transmission of 15-28% in the visible region. In part 2, two Nickel coordination polymers were explored. Tetraamino compounds were used as bridging ligands to increase the scope of electronic delocalization and metal-ligand orbital overlap which would reduce the energy gap to the NIR region. As a result, both polymers showed broad NIR absorption with maximum of 835 and 880 nm, respectively. In addition, the polymer showed NIR halochromism. This ground study pointed out both Ni coordination polymers as NIR absorptive materials with NIR halochromism.

  7. Spectrophotometric validation of assay method for selected medicinal plant extracts

    Matthew Arhewoh

    2014-09-01

    Full Text Available Objective: To develop UV spectrophotometric assay validation methods for some selected medicinal plant extracts.Methods: Dried, powdered leaves of Annona muricata (AM and Andrographis paniculata (AP as well as seeds of Garcinia kola (GK and Hunteria umbellata (HU were separately subjected to maceration using distilled water. Different concentrations of the extracts were scanned spectrophotometrically to obtain wavelengths of maximum absorbance. The different extracts were then subjected to validation studies following international guidelines at the respective wavelengths obtained.Results: The results showed linearity at peak wavelengths of maximum absorbance of 292, 280, 274 and 230 nm for GK, HU, AM and AP, respectively. The calibration curves for the different concentrations of the extract gave R2 values ranging from 0.9831 for AM to 0.9996 for AP the inter-day and intra-day precision study showed that the relative standard deviation (% was ≤ 10% for all the extracts.Conclusion: The aqueous extracts and isolates of these plants can be assayed and monitored using these wavelengths.

  8. A new method of studying the relation between ionization rates and radio-wave absorption in polar-cap absorption events

    J. K. Hargreaves

    2005-02-01

    estimates based on the Gledhill profiles if extrapolated downward.

    Predictions based on the coefficients generated by the procedure are compared with the polar-cap absorption observed during some recent events. Typical electron-density values are derived, and the study provides an independent confirmation that the electron density and the production rate are related by a square-root law.

  9. Study on the interaction between diphenhydramine and erythrosin by absorption, fluorescence and resonance Rayleigh scattering spectra

    TANG XiaoLing; LIU ZhongFang; LIU ShaoPu; HU XiaoLi

    2007-01-01

    In pH 4.5 Britton-Robinson (BR) buffer solution, erythrosin (ET) can react with diphenhydramine (DP) to form a 1:1 ion-association complex, which not only results in the change of the absorption spectra, but also results in the great enhancement of resonance Rayleigh scattering (RRS) and the quenching of fluorescence. Furthermore, a new RRS spectrum will appear, and the maximum RRS wavelength was located at about 580 nm.In this work, the spectral characteristics of the absorption, fluorescence and RRS, the optimum conditions of the reaction and the properties of an analytical chemistry were investigated. A sensitive, simple and new method for the determination of DP by using erythrosin as a probe has been developed. The detection limits for DP were 0.0020 μg/mL for RRS method, 0.088 μg/mL for absorption method and 0.094 μg/mL for fluorophotometry. There was a linear relationship between the absorbance, RRS and fluorescence intensities and the drug concentration in the range of 0.0067-2.0, 0.29-6.4 and 0.31-3.2 μg/mL, respectively. The effects of the interaction of diphenhydramine and erythrosin on the absorption, fluorescence and resonance Rayleigh scattering spectra were discussed. In light polarization experiment, the polarization of RRS at maximum wavelength was measured to be P = 0.9779, and it revealed that the RRS spectrum of DP-ET complex consists mostly of resonance scattering and few resonance fluorescence. In this study, enthalpy of formation and mean polarizability were calculated by AM1 quantum chemistry method. In addition, the reaction mechanism and the reasons for the enhancement of scattering spectra and the energy transfer between absorption, fluorescence and RRS were discussed.

  10. A polarizable embedding DFT study of one-photon absorption in fluorescent proteins

    Beerepoot, Maarten; Steindal, Arnfinn H.; Kongsted, Jacob;

    2013-01-01

    A theoretical study of the one-photon absorption of five fluorescent proteins (FPs) is presented. The absorption properties are calculated using a polarizable embedding approach combined with density functional theory (PE-DFT) on the wild-type green fluorescent protein (wtGFP) and several of its...... shift from vacuum to protein. This is the first computational study of a range of fluorescent proteins using a polarizable embedding potential....... optimization of the chromophores within a frozen protein environment is needed in order to reproduce the experimental trends. Explicit account of polarization in the force field is not needed to yield the correct trend between the different FPs, but is necessary for reproducing the experimentally observed red...

  11. Intrinsic and extrinsic labeling for studies of manganese absorption in humans

    A dual-radioisotope method was used to simultaneously study whole-body manganese retention from a chicken liver based meal intrinsically labeled with 54Mn and extrinsically labeled with 52Mn. Manganese retention was monitored in a sensitive whole-body counter during approximately 30 d in six young adult women. Both radioisotopes were retained to a similar degree and excreted at identical rates. Retention at d 5 was 14.4 +/- 10.3 and 14.0 +/- 9.9% while retention at d 10 was 5.0 +/- 3.1 and 5.0 +/- 3.0% (X +/- SD) for 54Mn and 52Mn, respectively. From these results we conclude that the intrinsic and extrinsic Mn isotopes did form a common pool before absorption. The results can therefore be regarded as a direct validation of the use of extrinsic labeling for studies of Mn retention for estimating Mn absorption in man

  12. Autoradiographic study on percutaneous absorption of several oils useful for cosmetics

    Percutaneous absorption of five 14C-labelled oils, n-octadecane, decanoxy decane, 2-hexyldecanoxy octane, isopropyl myristate and glyceryl tri-(oleate), commonly used is cosmetics were studied from the point of view of their safety. In whole body autoradiography of hairless mice, there was no visible penetration into the skin and organs, whereas microautoradiography of guinea pigs showed local penetration. Isopropyl myristate penetrated to the greatest extent, whereas 2-hexyldecanoxy octane was hardly absorbed. Percutaneous absorption of these two oils, therefore, was examined in Angora rabbits by microautoradiography simultaneously with skin irritation potential by a histological method, from the following aspects, (1) patterns of penetration and irritation in relation to application time and (2) fate within the skin and pattern of irritation after application. In addition, intradermal metabolic fate was studied in vivo. (author)

  13. Extended-x-ray-absorption-fine-structure study of small Fe molecules isolated in solid neon

    We have used rare gas matrix isolation techniques in combination with extended x-ray absorption fine structure (EXAFS) to study the variation in interatomic distances for small Fe molecules in solid neon. A considerable contraction in the interatomic distances was observed for the metal molecules. An Fe-Fe distance of 2.03 +- l0.03 A for the lowest concentration of metal was observed. This is in good agreement with early EXAFS measurements in Fe2-Ar. We also carried out a careful study of the x-ray-absorption near-edge structure (XANES), and observed the appearance of considerable structure for a 1.5-at. % Fe sample. The XANES spectra were analyzed in terms of 1s-to-(3d,4s) and 1s-to-4p transitions

  14. STUDY OF AN ABSORPTION MACHINE FOR AN AMMONIA-WATER SYSTEM DECENTRALIZED TRIGENERATION

    M. M. Rashidi

    2016-05-01

    Full Text Available This paper deals with Study of an absorption machine for an ammonia-water system decentralized trigeneration. The effects of evaporator, absorber and boiler temperature on the coefficient of performance of this cycle investigate. Simulation results show that with increasing the evaporator and absorber temperature the coefficient of performance increased and decreased, respectively. By increasing boiler temperature the coefficient of performance is constant.

  15. Environmental Chamber Study of Atmospheric Chemistry and Secondary Organic Aerosol Formation Using Cavity Enhanced Absorption Spectroscopy

    Liu, Yingdi

    2011-01-01

    Air pollution and global climate change are important environmental issues that affect our society. Deeper understanding of atmospheric chemistry is required to understand these problems and to develop effective control strategies. Environmental chambers have been used for the past few decades to study atmospheric chemistry and investigate processes leading to secondary pollutant formation. This thesis work provides two different high sensitivity real time cavity enhance absorption spectrosco...

  16. A study on maximization of dynamic crushing energy absorption of square tubes with and without stiffener

    Han, Jing; Yamazaki, Koetsu

    2000-01-01

    The axial impact crushing behavior of square tubes with and without stiffeners are studied by Finite Element method, and comparisons of mean axial crushing force between numerical solutions and theoretical prediction as well as qualitative comparisons of folding patterns between numerical simulations and experimental observations are made and discussed. Based on the numerical analyses, maximization problems of dynamic crushing energy absorption of square tubes with and without stiffeners, res...

  17. An Empirical Study of the Relationship of IT Intensity and Organizational Absorptive Capacity on CRM Performance

    Ja-Shen Chen; Russell K.H. Ching

    2004-01-01

    In recent years, e-business has emerged as a mainstream business practice for engaging in global markets. To gain a competitive advantage in these highly competitive markets, many business organizations have turned to customer relationship management (CRM), an integrated system that draws upon the strengths of IT, to allow them to gain greater insights into their customers’ needs. This study examines the relationship of information technology (IT) intensity and organizational absorptive cap...

  18. Study on solar sources and polar cap absorption events recorded in Antarctica

    Perrone, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Parisi, M.; Dipartimento di Fisica, Universita` degli Studi di Roma, 00185 Rome, Italy; Meloni, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Damasso, M.; Dipartimento di Fisica, Università degli Studi di Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy; Galliani, M.; Dipartimento di Fisica, Università degli Studi di Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy

    2007-01-01

    Particularly intense events occurred on the Sun in a period around minimum of solar activity during cycle 23. We investigated the characteristics of September 2005 and December 2006 events and the properties of the correlated observations of ionospheric absorption, obtained by a 30 MHz riometer installed at Mario Zucchelli Station (MZS-Antarctica), and of geomagnetic activity recorded at Scott Base (Antarctica). Solar events are studied using the characteristics of CMEs measured with SoHO/LAS...

  19. Absorption and fluorescence studies of curcumin bound to liposomes and lymphocytes: effect of γ- irradiation

    Absorption and fluorescence spectral changes in curcumin were employed to follow its binding to liposomes and lymphocytes. The association constants indicated high affinity of curcumin to liposomes. Tumor lymphocytes show mere intense fluorescence of curcumin over the normal lymphocytes. The loss of curcumin in cells after γ-irradiation could be followed by reduction in curcumin fluorescence. The studies indicate that such fluorescence changes can be used as markers to understand the preferential loading of curcumin to cells. (author)

  20. Spectrophotometric determination of silicon and iron in magnesium metal

    Full text: A simple spectrophotometric method is described for the determination of trace quantities of silicon and iron in magnesium metal that is used in the Kroll's reduction process for the production of nuclear grade zirconium sponge. In Kroll's process, zirconium sponge is produced by the magnesio - thermic reduction of pure ZrCl4 by pyrovacuum treatment of the reduced mass to separate excess Mg and MgCl2 from Zirconium. The magnesio - thermic reduction involves the following reactions. ZrCl4 + 2 Mg → Zr + 2 MgCl2. The production of nuclear grade Zirconium sponge demands close control of quality of raw material and process parameters at various stages. Hence it is important to confirm the purity of Mg metal used for sponge production for it should not be a source for introducing any undesirable impurities. The method for determination of silicon is based on the principle that small quantities of dissolved silicic acid react with a solution of ammonium molybdate in an acid medium resulting in the formation of yellow complex H4 (SiMo12O40). Since the photometric measurement based on this yellow complex is insensitive, a selective reduction of this complex with reducing agents like hydrazine sulphate, stannous chloride, 1-amino-2-naphthal-4-sulphonic acid, etc. produces a blue colour due to formation of silicomolybdenum blue complex of uncertain composition. The intensity of blue colour is proportional to the amount of silicon. In the present case, ascorbic acid was used for the reduction to molybdenum blue that exhibits maximum absorption at 815 nm thereby permitting its quantification. The reaction conditions are adjusted so that only molybdosilicic acid and not the unreacted molybdic acid is reduced. Also the sensitive and popular method due to reaction of ferrous ions in aqueous solution with O-phenanthrolene with the formation of an orange red complex in the pH range of 2-9 that exhibits maximum absorption at 510 nm was applied for the determination of

  1. Titrimetric, spectrophotometric and kinetic methods for the assay of atenolol using bromate–bromide and methyl orange

    KANAKAPURA BASAVAIAH

    2006-05-01

    Full Text Available Three new methods have been developed for the determination of atenolol in bulk drug and in tablet formulation. The methods are based on the oxidation–bromination reaction of the drug by bromine, generated in situ by the action of acid on a bromate–bromide mixture. In the titrimetric method, the drug is treated with a known excess of bromate–bromide mixture in hydrochloric acid medium, followed by the determination of the unreacted bromine iodometrically. The spectrophotometric method involves the addition of a measured excess of bromate–bromide reagent in hydrochloric acid medium to atenolol, and after ensuring the reaction had gone to completion, the unreacted bromine is treated with a fixed amount of methyl orange, and absorbance measured at 520 nm. The absorbance was found to increase linearly with increasing concentration of atenolol. The kinetic method depends on the existence of a linear relationship between the concentration of the drug and the time of the oxidation–bromination reaction, as indicated by the bleaching of methyl orange acid colour. The working conditions were optimized. The titrimetric method is based on a 1:1 reaction stoichiometry (atenolol:bromate and is applicable over the 3–20 mg range. The spectrophotometric method permits micro determination of the drug (0.5–4.0 mg ml-1with an apparentmolar absorptivity of 4.13x104 lmol-1 cm-1 and detection limit of 0.07 mg ml-1. The kinetic method is applicable in the concentration range 5–25 mg ml-1 with a detection limit of 3.72 mg ml-1. The proposed methods were successfully applied to the determination of atenolol in tablet preparations with mean recoveries of 97.63 to 101.78 %. The reliability of the assay was established by parallel determination by the reference method and by recovery studies using the standard addition technique.

  2. Studies of K-absorption on light nuclei and the search for bound nuclear kaonic states

    The available experimental data on K-absorption on nuclei are rather old and scarce: they are not enough to understand the possible formation of aggregates of nucleons bound together by a kaon, known as 'Bound Kaonic Nuclear States'. The existence of such structures, suggested by a few theoretical models, has not been experimentally ascertained yet. To be observed, their width should be less than their binding energy. A possible decay channel for such states is the non mesonic one, leading to hyperon-nucleon (or light nuclei) final states. Therefore, experimental investigations of possible signatures are mainly based on the analysis of hyperon-nucleon(s) correlations (for instance, of Λp(d,t) pairs) and of invariant mass spectra. Complementary information may also be gathered from missing mass distributions. Recent experiments revived, with much larger statistics, the study of K-A absorption in light nuclei: namely, KEK-E549 studied the K-interactions on 4He, while FINUDA at DAΦNE collected a large statistics on K-6,7Li, K-9Be and K-12C. The experimental results obtained so far by the various experiments studying the K-absorption in nuclei are here summarized.

  3. Study on the application of cold vapor atomic absorption spectrometry and hydride generation atomic absorption spectrometry for the determination of Hg and As traces in sea water samples

    The trace amount of total mercury (Hg) and arsenic (As) in sea water samples were quantitatively determined by using the Atomic Absorption Spectrometry connected with the hydride generation technique (HG-AAS) for As, and with the cold vapour technique (CV-AAS) for Hg. The experiments were carried out at room temperature on a Hydride System Module (HS55) combined with an Atomic Absorption Spectrometer (VARIO 6, Analytik Jena AG). The effect of reductants concentration, and that of matrix on the absorption intensity of each analyzed element was studied in details. The sea water sample after fitrating through a membrane with 0.45(μm-hole size was pre-treated with an oxidant or an reductant to obtain the identical medium. The absorption intensity of each element was then measured on the VARIO-6 under the optimum parameters for spectrometer such as: maximum wavelength, current of hollow cathode lamp, and that for hydride system such as cell temperature, speed of peristaltic pump, pump time, reaction time and rewash time, ect. The analytical procedures were set-up and applied for the determination of these above mentioned elements in the synthesized sea water sample and in the real sea water samples with high precision and accuracy. (author)

  4. Polarographic and spectrophotometric determination of Nifuroxazide in pharmaceuticals. II. Determination of Nifuroxazide in suspensions.

    Szumińska, E; Cisak, A

    1990-01-01

    The properties of Ercefuryl suspensions which contain Nifuroxazide as active constituent were studied by spectrophotometry and polarography. On this basis two analytical methods for determination of Nifuroxazide content in suspensions were devised: one polarographic, based on the electrochemical reduction of the nitro-group, and a spectrophotometric, based on the absorbance measurements at 373 nm. PMID:12959248

  5. QUANTITATIVE ASSAY OF ALMOTRIPTAN MALATE IN PURE DRUG AND PHARMACEUTICAL PREPARATIONS USING SIMPLE AND CONVENIENT VISIBLE SPECTROPHOTOMETRIC METHODS

    U. VIPLOVA PRASAD

    2012-05-01

    Full Text Available Two direct, simple and sensitive visible spectrophotometric methods (M1&M2 are described for the assay of almotripan malate in pure and solid dosage forms. The method M1 involves oxidative coupling of drug with brucine in presence of sodium meta periodate and purple red colored species is formed and exhibits absorption maxima at 520nm. The method M2 is based on the formation of yellowish brown colored species by the drug with Folin reagent and exhibits absorption maxima at 450nm. Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges (8.0-24 μg/ml for method M1, (16-48 μg/ml for method M2 respectively. The proposed methods are applied to commercial available tablets and the results are statistically compared with those obtained by the reported UV reference method and validated by recovery studies. The results are found satisfactory and reproducible. These methods are applied successfully for the estimation of the almotriptan malate in the presence of other ingredients that are usually present in dosageforms. These methods offer the advantages of rapidity, simplicity and sensitivity and normal cost and can be easily applied to resource-poor settings without the need for expensive instrumentation and reagents.

  6. Spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from the OSIRIS instrument onboard the ROSETTA spacecraft

    Fornasier, S; Barucci, M A; Feller, C; Besse, S; Leyrat, C; Lara, L; Gutierrez, P J; Oklay, N; Tubiana, C; Scholten, F; Sierks, H; Barbieri, C; Lamy, P L; Rodrigo, R; Koschny, D; Rickman, H; Keller, H U; Agarwal, J; A'Hearn, M F; Bertaux, J -L; Bertini, I; Cremonese, G; Da Deppo, V; Davidsson, B; Debei, S; De Cecco, M; Fulle, M; Groussin, O; Güttler, C; Hviid, S F; Ip, W; Jorda, L; Knollenberg, J; Kovacs, G; Kramm, R; Kührt, E; Küppers, M; La Forgia, F; Lazzarin, M; Moreno, J J Lopez; Marzari, F; Matz, K -D; Michalik, H; Moreno, F; Mottola, S; Naletto, G; Pajola, M; Pommerol, A; Preusker, F; Shi, X; Snodgrass, C; Thomas, N; Vincent, J -B

    2015-01-01

    The Rosetta mission of the European Space Agency has been orbiting the comet 67P/Churyumov-Gerasimenko (67P) since August 2014 and is now in its escort phase. A large complement of scientific experiments designed to complete the most detailed study of a comet ever attempted are onboard Rosetta. We present results for the photometric and spectrophotometric properties of the nucleus of 67P derived from the OSIRIS imaging system, which consists of a Wide Angle Camera (WAC) and a Narrow Angle Camera (NAC). The disk-averaged phase function of the nucleus of 67P shows a strong opposition surge with a G parameter value of -0.13$\\pm$0.01 in the HG system formalism and an absolute magnitude $H_v(1,1,0)$ = 15.74$\\pm$0.02 mag. The integrated spectrophotometry in 20 filters covering the 250-1000 nm wavelength range shows a red spectral behavior, without clear absorption bands except for a potential absorption centered at $\\sim$ 290 nm that is possibly due to SO$_2$ ice. The nucleus shows strong phase reddening, with disk...

  7. Simple Spectrophotometric Method for Determination of Paroxetine in Tablets Using 1,2-Naphthoquinone-4-Sulphonate as a Chromogenic Reagent

    Ibrahim A. Darwish

    2009-01-01

    Full Text Available Simple and rapid spectrophotometric method has been developed and validated for the determination of paroxetine (PRX in tablets. The proposed method was based on nucleophilic substitution reaction of PRX with 1,2-naphthoquinone-4-sulphonate (NQS in an alkaline medium to form an orange-colored product of maximum absorption peak (λmax at 488 nm. The stoichiometry and kinetics of the reaction were studied, and the reaction mechanism was postulated. Under the optimized reaction conditions, Beer's law correlating the absorbance (A with PRX concentration (C was obeyed in the range of 1–8 μg mL−1. The regression equation for the calibration data was: A = 0.0031 + 0.1609 C, with good correlation coefficients (0.9992. The molar absorptivity (ε was 5.9×105 L mol−1 1 cm−1. The limits of detection and quantitation were 0.3 and 0.8 μg mL−1, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 2%. The proposed method was successfully applied to the determination of PRX in its pharmaceutical tablets with good accuracy and precisions; the label claim percentage was 97.17±1.06 %. The results obtained by the proposed method were comparable with those obtained by the official method.

  8. X-ray absorption spectroscopic studies of mononuclear non-heme iron enzymes

    Westre, T.E.

    1996-01-01

    Fe-K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the electronic and geometric structure of the iron active site in non-heme iron enzymes. A new theoretical extended X-ray absorption fine structure (EXAFS) analysis approach, called GNXAS, has been tested on data for iron model complexes to evaluate the utility and reliability of this new technique, especially with respect to the effects of multiple-scattering. In addition, a detailed analysis of the 1s{yields}3d pre-edge feature has been developed as a tool for investigating the oxidation state, spin state, and geometry of iron sites. Edge and EXAFS analyses have then been applied to the study of non-heme iron enzyme active sites.

  9. X-ray absorption study of intermediate valence in Sm1-xGdxS alloys

    X-ray absorption near edge structure (XANES) measurements above LH edge of Sm are employed to study the intermediate valence in Sm1-xGdxS(0.05 ≤ x ≤ 0.30) alloys. The split white lines at the LH edge of Sm are used to determine the average valence of SM in these alloys. The internal chemical pressure generated by substitution of smaller trivalent cation, Gd, for Sm drives the latter to a higher valence. Sm valence increases smoothly first and then undergoes an abrupt increment at a critical concentration of 16 at.% of Gd. At concentration of Gd higher than 16 at. % the increase in Sm valence is smooth and small. The data for Sm average valence for Sm1-xGdxS alloys obtained by LH absorption edges shows fair agreement with other techniques

  10. Review of Russian language studies on radionuclide behaviour in agricultural animals: part 1. Gut absorption

    An extensive programme of experiments was conducted in the former USSR on transfer of radionuclides to a wide range of different agricultural animals. Only a few of these studies were made available in the English language literature or taken into account in international reviews of gastrointestinal uptake. The paper gives extended information on Russian research on radionuclide absorption in the gut of farm animals performed in controlled field and laboratory experiments from the 1960s to the current time. The data presented in the paper, together with English language values, will be used to provide recommended values of absorption specifically for farm animals within the revision of the IAEA Handbook of Parameter Values IAEA [International Atomic Energy Agency, 1994. Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Temperate Environments, IAEA technical reports series No. 364. International Atomic Energy Agency, Vienna

  11. Hierarchical Decomposition Thermodynamic Approach for the Study of Solar Absorption Refrigerator Performance

    Emma Berrich Betouche

    2016-03-01

    Full Text Available A thermodynamic approach based on the hierarchical decomposition which is usually used in mechanical structure engineering is proposed. The methodology is applied to an absorption refrigeration cycle. Thus, a thermodynamic analysis of the performances on solar absorption refrigerators is presented. Under the hypothesis of an endoreversible model, the effects of the generator, the solar concentrator and the solar converter temperatures, on the coefficient of performance (COP, are presented and discussed. In fact, the coefficient of performance variations, according to the ratio of the heat transfer areas of the high temperature part (the thermal engine 2 Ah and the heat transfer areas of the low temperature part (the thermal receptor Ar variations, are studied in this paper. For low values of the heat-transfer areas of the high temperature part and relatively important values of heat-transfer areas of the low temperature part as for example Ah equal to 30% of Ar, the coefficient of performance is relatively important (approximately equal to 65%. For an equal-area distribution corresponding to an area ratio Ah/Ar of 50%, the COP is approximately equal to 35%. The originality of this deduction is that it allows a conceptual study of the solar absorption cycle.

  12. Comparison of Flurbiprofen Tablets Available In Pakistani Market and Their Absorption Studies

    Muhammad Hanif

    2015-06-01

    Full Text Available AbstractThe aim of this present work was to compare different parameters of various brands of flurbiprofen tablets collected from different retail pharmacies in the local market of Pakistan. Four brands A, B, C and D were tested for weight variation, hardness, friability, disintegration dissolution, HPLC assay and in vitro absorption studies in rabbit skin, stomach and intestine by using the prepacked Column RT 250-4.6 Purospher® STAR RP-18 end capped (5 µm and acetonitrile, phosphate buffer (pH 3.7 as mobile phase in the ratio of 1:1. Flurbiprofen was detected at 265 nm at the flow rate of 1 ml/min. Brand B was considered as reference. Similarity factor (f2 of brand B and C and brand B & D was found to be 61 and 51 and dissimilarity factors (f1 values were 5 and 9 respectively in same dissolution medium. Model dependent methods First order, Hixon crowell and Weibull model were used. The method was found to be sensitive and linear in the range of 10 to 700 ppm with 0.999 coefficient of correlation. Everted sac absorption studies of selected formulation showed 50% of drug absorption from stomach in first 3 hours, 21% through intestine and very negligible through skin.

  13. Numerical and experimental study of the effect of microslits on the normal absorption of structural metamaterials

    Ruiz, H.; Claeys, C. C.; Deckers, E.; Desmet, W.

    2016-03-01

    Resonant metamaterials are emerging as novel concepts to reduce noise levels in targeted frequency zones, so-called stop bands. The metamaterial concept improves acoustic behaviour through an increase of the insertion loss. This paper concerns a first investigation on the absorption capabilities of a resonant metamaterial when thermo-viscous effects are incorporated via the addition of microslits. In a previous work, a resonant metamaterial was obtained through the inclusion of resonating structures into cavities of an open honeycomb assembly. In this study, the air gap of the honeycomb structure is reduced so as to provide viscous losses for the travelling waves. Considering that the created resonant structures with open cavities are rigid, an equivalent fluid model is used to calculate the acoustical properties of a so called microslit metamaterial. It is demonstrated that the unit cell structure can be divided into parallel elements for which the acoustic impedance can be computed via the transfer matrix approach TMM in parallel and series. Likewise, it is shown that the structural response can be predicted by FEM models allowing studying the structural effects separately from the viscous-thermal effects predicted by the equivalent fluid model. Moreover, the combined effect of both approaches is shown experimentally where it is observed that: (i) The absorption of the resonant metamaterial is increased by the addition of microslits, (ii) the modes of the test sample appear as small peaks on the absorption curve of the microslit metamaterial, (iii) the structural modes are grouped below and above the stop band and, (iv) the resonant structures do not lead to additional absorption in the stop band region. Analytical models are compared to experimental measurements to validate the models and to show the potential of this material assembly.

  14. In vitro predictions of skin absorption of caffeine, testosterone, and benzoic acid: A multi-centre comparison study

    Sandt, J.J.M. van de; Burgsteden, J.A. van; Cage, S.; Carmichael, P.L.; Dick, I.; Kenyon, S.; Korinth, G.; Larese, F.; Limasset, J.C.; Maas, W.J.M.; Montomoli, L.; Nielsen, J.B.; Payan, J.-P.; Robinson, E.; Sartorelli, P.; Schaller, K.H.; Wilkinson, S.C.; Williams, F.M.

    2004-01-01

    To obtain better insight into the robustness of in vitro percutaneous absorption methodology, the intra- and inter-laboratory variation in this type of study was investigated in 10 European laboratories. To this purpose, the in vitro absorption of three compounds through human skin (9 laboratories)

  15. Spectrophotometric determination of ruthenium using 1-pentyl 4,6-dihydroxy-5-nitrosopyridine-3-carboxylate

    A method of spectrophotometric analysis for ruthenium, using the reagent 1-pentyl 4,6-dihydroxy-5-nitrosopyridine-3-carboxylate, has been developed. Several interferences are removed by extraction prior to the development of the purple color formed between PDNHPC and ruthenium. The molar absorptivity of the PDHNPC-ruthenium complex is 4.2 x 104 at 535 nm. The complex forms at a 3 : 1 ligand-metal ratio. This procedure provides the most sensitive colorimetric method for the determination of ruthenium. (author)

  16. Determination of Tapentadol Hydrochloride in Tablets by Three New Validated Spectrophotometric Methods

    Deepti Jain; Pawan Kumar Basniwal

    2013-01-01

    Three UV spectrophotometric methods viz. linear regression equation (LRE), standard absorptivity (SA) and first order derivative (FOD) method were developed and validated according to ICH guideline. The methods were linear in the range of 10-50 μg/mL and validated methods were successfully applied for determination of tapentadol hydrochloride content in tablet dosage forms in the range of 100.42-100.64%, 100.31-100.54% and 100.10-100.59%, respectively. The standard deviation for all the metho...

  17. A Simple Spectrophotometric Determination of Phosphate in Sugarcane Juices, Water and Detergent Samples

    Mahadevaiah; M. S. Yogendra Kumar; Mansour S. Abdul Galil; Suresha, M. S.; Sathish, M. A.; Nagendrappa, G.

    2007-01-01

    A simple spectrophotometric method is developed for the determination of phosphate in sugar cane juice, water and detergent samples. The method is based on the formation of phosphomolybdate with added molybdate followed by its reduction with sodium sulphide in aqueous sulfuric acid medium. The system obeys Lambert-Beer’s law at 715 nm in the concentration range 0.3-12.24 ppm. Molar absorptivity, correlation coefficient and Sandell’s sensitivity values were found to be 6.1x103 mol-1 cm-1, 0.99...

  18. Separate spectrophotometric determination of gadolinium and dysprosium in binary mixtures by phthalexones using nomogram

    The possibility has been shown of using different-ligand complexes of rare earths with phthalexones and cetylpyridinium for differential spectrophotometric determination of rare earths in mixtures. The molar absorptivities of individual components of a mixture are not constant values if the total mixture concentration changes. The application of an equation for calculation of mixture absorbances makes it possible to change concentration of the components in mixtures over a wide range (the limit Me1:Me2 ratio is 1:50). Simultaneous nomographic determinations of gadolinium and dysprosium in their mixtures were carried out

  19. Percutaneous absorption of selected hydrophilic compounds - an in vitro study on hairless mouse skin

    The objective of this study was to assess 1. the relationship between hydrophobicity and percutaneous absorption; and 2. the validity of the view that the skin can be diffusionally characterized as a simple lipoidal barrier. In the course of the permeability studies, a very slow but gradually accelerating permeation of the hydrophylic compounds was noted, a phenomenon that became very noticeable when the permeation profile was observed over longer periods e.g. 100 hours instead of the conventional 6-12 hours. The initial objective had to be expanded to search for the cause of the increasing permeability of these compounds. With urea reproduceable results were obtained in the preliminary study and therefore urea was chosen for this study. The percutaneous absorption studies of urea, thiourea, glycerol and glucose were executed by means of an in vitro method. The method included the use of a diffusion cell system where the skin was clamped between two diffusion cells. The ether-water partition coefficients of the hydrophylic compounds were determined by a simple radiotracer procedure. The radio-labelled compound was equilibrated between the ether and water phases and the sample taken from the phases were analysed by means of scintillation counting. The ether-water partition coefficients of hydrocortisone and its 21-n-alkyl esters were determined by means of a HPLC method. The significance of this study may be summarized as: 1. it showed errors of interpretation in previous work on the percutaneous absorption of hydrophilic compounds; 2. it confirmed the incompatibility of a simple lipid membrane mechanism with the behaviour of skin; and 3. it formed a basis for the systematic solution of the mechanism of increasing permeability as a function of time phenomenon, encountered with the studied hydrophilic compounds

  20. Quasar Absorption Lines in the Far Ultraviolet: An Untapped Gold Mine for Galaxy Evolution Studies

    Tripp, Todd

    2013-01-01

    This white paper emphasizes the potential of QSO absorption lines in the rest-frame far/extreme UV at rest-frame wavelengths from ~500 to 2000 A. In this wavelength range, species such as Ne VIII, Na IX, and Mg X can be detected, providing diagnostics of gas with temperatures >> 10^{6} K, as well as banks of adjacent ions such as O I, O II, O III, O IV, O V, and O VI (and similarly N I - N V; S II - S VI; Ne II - Ne VIII, etc.), which constrain physical conditions with unprecedented precision. A UV spectrograph with good sensitivity down to observed wavelengths of 1000 A can detect these new probes in absorption systems with redshift z(abs) > 0.3, and at these redshifts, the detailed relationships between the absorbers and nearby galaxies and large-scale environment can be studied from the ground. By observing QSOs at z = 1.0 - 1.5, HST has started to exploit extreme-UV QSO absorption lines, but HST can only reach a small number of these targets. A future, more sensitive UV spectrograph could open up this new...

  1. Studies on absorption of EC waves in assisted startup experiment on FTU

    Ramponi G.

    2012-09-01

    Full Text Available Assistance of EC wave for plasma breakdown and current ramp up is the proposed scenario for the ITER case, characterized by low toroidal electric field. The experimental results on many tokamaks clearly indicate the capabilities of the proposed scheme to have a robust breakdown in ITER. The key aspect of this technique is the EC power required, strongly related to the absorption of the wave in the initial stage of plasma formation. This aspect is generally neglected due to the diagnostics difficulties in the plasma formation phase. As a consequence a multi-pass absorption scheme is usually considered reasonable, leading to a strong absorption after many reflections on the walls. The present study exploits the high temporal and spatial resolution of the fast scanning interferometer of FTU together with the measure of residual power obtained by a sniffer probe. The absorbed EC power is calculated considering also the polarization rotation and the subsequent mode conversion after incidence on the internal wall and compared with that derived from experimental data. The resulting EC power distribution can explain differences observed between perpendicular and oblique injection results, indicating future investigations to define ITER power requirements.

  2. Optical absorption and fluorescence studies of praseodymium ion in chloroborophosphate glasses

    Full text: The interest in optical absorption and fluorescence studies of rare earth ions in glassy materials is increasing continuously in connection with laser research and related application. The absorption and fluorescence spectra of praseodymium ion in chloroborophosphate glasses have been recorded at room temperature. The chloroborophosphate glass specimens having composition in mob.% Na20 (26.08), B203 (14.57), P205(44.85), ZnCl2(14.50), Pr6011(R) [R= 0.0,0.1 and 0.2 moi.%] have been prepared by melt quenching technique. The spectra consists of seven absorption bands and three fluorescence bands. The observed optical spectra are discussed in terms of energy state and the intensity of the transitions. The various energy interaction parameters like Slater-Condon, Lande', Racah and bonding parameters have been computed. Judd-Ofeit intensity parameters and laser parameters have also been computed. These results shows that praseodymium doped chloroborophosphate glass specimen can be considered as good hosts for laser applications

  3. Ascorbic acid absorption in Crohn's disease. Studies using L-[carboxyl-14C]ascorbic acid

    Total body pool and intestinal absorption of ascorbic acid were studied in 12 patients undergoing operation for Crohn's disease (six with fistulae and six without) and in six control patients undergoing operation for reasons other than Crohn's disease. L-[carboxyl-14C]Ascorbic acid, 0.19-0.40 megabecquerels (MBq), was given orally. After a period of equilibration, the labeled ascorbic acid was flushed out of the patient's body tissues using large doses of unlabeled ascorbic acid. Intestinal absorption of ascorbic acid, assessed from the total cumulative urinary 14C recovery, was found to be similar in patients with fistulizing Crohn's disease (73.9 +/- 8.45%), those without fistulas (72.8 +/- 11.53%), and in controls (80.3 +/- 8.11%). Total body pools of ascorbic acid, calculated using the plasma 14C decay curves, were similar in patients with Crohn's disease with fistulas (17.1 +/- 5.91 mg/kg), patients without fistulas (9.6 +/- 3.58 mg/kg), and in controls (13.3 +/- 4.28 mg/kg). The results indicate that ascorbic acid absorption is normal in patients with both fistulizing and nonfistulizing Crohn's disease. The results suggest that routine supplements of vitamin C are not necessary unless oral ascorbic acid intake is low

  4. Study of the texture of porous solids using a technique of γ ray absorption

    A technique, which enables us to measure locally total porosity, open porosity and pore size distribution is developed. The total porosity is calculated from the bulk density. A gamma absorption gauge is set up fitted with a Cs137 source. This enables the determination of the density by layers of carbonaceous samples in a practically automatic way. By taking adequate precautions it is possible to obtain the density with a maximum error Δρ ≤ 0,005 g/cm3. The open porosity is evaluated by the absorption method after impregnation with bromoform. A new mercury porosimeter is developed using the absorption probe for the measurement of mercury infiltrated into the porous sample. Due to the localized character of exploration by this technique, the variations of porous texture in a heterogeneous sample can be studied. Used as a classical porosimeter, in the case of homogeneous samples, this apparatus is capable of exploring the equivalent diameters of pores between 500 μ and 0.14 μ with a maximum error ΔP ≤ 0.002. The possibility of exploration of heterogeneous samples, with the facility of determination of porosities due to macro-pores combined with the non-limiting character of the method in the field of high pressures differentiates this apparatus from all the porosimeters of former conception. Examples of utilization of this technique in the case of graphite-gas reactions are presented. (author)

  5. VO2+ ions in zinc lead borate glasses studied by EPR and optical absorption techniques.

    Prakash, P Giri; Rao, J Lakshmana

    2005-09-01

    Electron paramagnetic resonance (EPR) and optical absorption spectra of vanadyl ions in zinc lead borate (ZnO-PbO-B2O3) glass system have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of VO2+ ions. The values of spin-Hamiltonian parameters indicate that the VO2+ ions in zinc lead borate glasses were present in octahedral sites with tetragonal compression and belong to C4V symmetry. The spin-Hamiltonian parameters g and A are found to be independent of V2O5 content and temperature but changing with ZnO content. The decrease in Deltag( parallel)/Deltag( perpendicular) value with increase in ZnO content indicates that the symmetry around VO2+ ions is more octahedral. The decrease in intensity of EPR signal above 10 mol% of V2O5 is attributed to a fall in the ratio of the number of V4+ ions (N4) to the number of V5+ ions (N5). The number of spins (N) participating in resonance was calculated as a function of temperature for VO2+ doped zinc lead borate glass sample and the activation energy was calculated. From the EPR data, the paramagnetic susceptibility was calculated at various temperatures and the Curie constant was evaluated from the 1/chi-T graph. The optical absorption spectra show single absorption band due to VO2+ ions in tetragonally distorted octahedral sites. PMID:16043053

  6. EPR, optical absorption and luminescence studies of Cr3+-doped antimony phosphate glasses

    De Vicente, F. S.; Santos, F. A.; Simões, B. S.; Dias, S. T.; Siu Li, M.

    2014-12-01

    Antimony phosphate glasses (SbPO) doped with 3 and 6 mol% of Cr3+ were studied by Electron Paramagnetic Resonance (EPR), UV-VIS optical absorption and luminescence spectroscopy. The EPR spectra of Cr3+-doped glasses showed two principal resonance signals with effective g values at g = 5.11 and g = 1.97. UV-VIS optical absorption spectra of SbPO:Cr3+ presented four characteristics bands at 457, 641, 675, and 705 nm related to the transitions from 4A2(F) to 4T1(F), 4T2(F), 2T1(G), and 2E(G), respectively, of Cr3+ ions in octahedral symmetry. Optical absorption spectra of SbPO:Cr3+ allowed evaluating the crystalline field Dq, Racah parameters (B and C) and Dq/B. The calculated value of Dq/B = 2.48 indicates that Cr3+ ions in SbPO glasses are in strong ligand field sites. The optical band gap for SbPO and SbPO:Cr3+ were evaluated from the UV optical absorption edges. Luminescence measurements of pure and Cr3+-doped glasses excited with 350 nm revealed weak emission bands from 400 to 600 nm due to the 3P1 → 1S0 electronic transition from Sb3+ ions. Cr3+-doped glasses excited with 415 nm presented Cr3+ characteristic luminescence spectra composed by two broad bands, one band centered at 645 nm (2E → 4A2) and another intense band from 700 to 850 nm (4T2 → 4A2).

  7. X-ray absorption spectral studies of copper (II) mixed ligand complexes

    X-ray absorption spectra at the K-edge of copper have been studied in two copper mixed ligand complexes, one having tetramethyethylenediamine (tmen) and the other having tetraethyethylenediamine (teen) as one of the ligands. The spectra have been recorded at BL-8 dispersive extended X-ray absorption fine structure (EXAFS) beamline at the 2.5 GeV INDUS- 2 synchrotron, RRCAT, Indore, India. The data obtained has been processed using the data analysis program Athena. The energy of the K-absorption edge, chemical shift, edge-width and shift of the principal absorption maximum in the complexes have been determined and discussed. The values of these parameters have been found to be approximately the same in both the complexes indicating that the two complexes possess similar chemical environment around the copper metal atom. The chemical shift has been utilized to estimate effective nuclear charge on the absorbing atom. The normalized EXAFS spectra have been Fourier transformed. The position of the first peak in the Fourier transform gives the value of first shell bond length, which is shorter than the actual bond length because of energy dependence of the phase factors in the sine function of the EXAFS equation. This distance is thus the phase- uncorrected bond length. Bond length has also been determined by Levy's, Lytle's and Lytle, Sayers and Stern's (LSS) methods. The results obtained from LSS and the Fourier transformation methods are comparable with each other, since both are phase uncorrected bond lengths.

  8. Synthesis, electrochemical, spectrophotometric and potentiometric studies of two azo-compounds derived from 4-amino-2-methylquinoline in ethanolic-aqueous buffered solutions

    El-Attar, Mona A.; Ghoneim, Mohamed M. [Analytical Chemistry Research Unit, Chemistry Department, Tanta University (Egypt); Ismail, Iqbal M., E-mail: maema.2011@yahoo.com [Chemistry Department, Faculty of Science, King Abdul Aziz University, Jeddah (Saudi Arabia)

    2012-08-15

    Two azo-compounds, 2-methyl-4-(5-amino-2-hydroxy-phenylazo)-quinoline (2) and 2-methyl-4-(2-hydroxy-5-nitrophenylazo)-quinoline, derived from 4-amino-2-methylquinoline were synthesized. Their chemical structures were characterized and confirmed by means of elemental chemical analysis, infrared (IR) spectroscopy, {sup 1}H nuclear magnetic resonance (NMR) and mass spectrometry (MS). The electrochemical behavior of the starting compound (4-amino-2-methylquinoline) and of the two synthesized azo-derivatives was studied at the mercury electrode in the B-R universal buffer at various pH values (2-11.5) containing 40% (v/v) ethanol using dc-polarography, cyclic voltammetry and controlled-potential coulometry. Their electrode reaction pathways were elucidated and discussed. The dissociation constants (pKa) of the examined compounds, stability constants and stoichiometry of their complexes in solution with some transition metal ions (Co(II), Ni(II), Cu(II), La(III) and UO{sup 2+}{sub 2}) were determined. (author)

  9. Spectrophotometric study of neptunium (VI) complexation by nitrate ions; Etude par spectrophotometrie de la complexation du neptunium au degre d'oxydation (VI) par les ions nitrates

    Pochon, P. [CEA/VALRHO - site de Marcoule, Dept. de Recherche en Retraitement et en Vitrification (DRRV), 30 - Marcoule (France)]|[Conservatoire National des Arts et Metiers (CNAM), 75 - Paris (France)]|[Centre Regional Associe de Lyon, 69 (France)

    2000-07-01

    Neptunium(VI) complexation by nitrate ions was investigated by visible and near-infrared spectrophotometry, a technique suitable for observing the appearance and evolution of the species in solution. In the absence of reference spectra for Np(VI) nitrate- complexes, mathematical (factor analysis) tools were used to interpret the spectra. These chemo-metric techniques were first tested and validated on a simpler chemical system: Np(VI)complexation by the SiW{sub 11}O{sub 39}{sup 8-} anion. The test media used to investigate Np(VI) nitrate- complexes generally contain nitrate and perchlorate salts at high concentrations (high ionic strength). Media effects arising from the presence of cations, acidity or the perchlorate ion concentration are therefore significant, and no doubt account for the scattered values of the complexation constants published in the literature. The evolution of the neptunium spectra according to the parameters of the reaction medium illustrated these effects and allowed them to be quantified by a global 'perturbation constant'. In order to minimize the spectrum modifications due to media effects, the neptunium nitrate-complexes were studied at constant ionic strength in weak acidic media (2 mol.kg{sup -1}{sub H2O}) in the presence of sodium salts. The bulk formation constants and the spectrum of the NpO{sub 2}(NO{sub 3}){sup +} complex were determined for ionic strength values of 2.2, 4, 6 and 8 mol.kg{sup -1}{sub H2O}. The constants remained on the same order of magnitude regardless of the ionic strength; the thermodynamic constant {beta}{sub 1}{sup 0} determined from them according to specific interaction theory is thus probably of little significance. Conversely, the bulk constants can be corrected for the effects of the perchlorate ions by taking the global 'perturbation constant' into account. (author)

  10. A temperature dependent infrared absorption study of strong hydrogen bonds in bis(glycinium)oxalate

    Bhatt, Himal; Deo, M. N.; Murli, C.; Vishwakarma, S. R.; Chitra, R.; Sharma, Surinder M.

    2016-05-01

    We report infrared absorption studies on Bis(glycinium)oxalate, an organic complex of the simplest amino acid Glycine, under varying temperatures in the range 77 - 350 K. The measurements have been carried out in the spectral range 400 - 4000 cm-1 and the strongest O-H---O hydrogen bond, which plays a vital role in the structural stabilization, has been studied. Subtle changes in widths of modes and temperature dependent frequency variations have been observed near 250 K. The hydrogen bonding network remains stable in the entire temperature range. This is in contrast to its reported high pressure behavior.

  11. Mechanistic studies of ocular peptide absorption and its enhancement by various penetration enhancers

    Two major aspects of corneal peptide absorption, namely the transport mechanisms and the promoting effect of some penetration enhancers, were investigated. Studies on transport mechanisms involve (a) identification of transport pathways of peptides across the cornea, (b) determination of rate-limiting barrier(s) for peptide absorption, and (c) permselective properties of the cornea. To study the transport pathways of peptides, four model peptides differing in molecular size and charge were either fluorescently or radioactively labeled and their movement across the cornea was detected by laser scanning confocal microscopy and autoradiography. Results from these studies indicate that peptides can penetrate the cornea via different pathways, depending on the physicochemical properties and membrane specificity of the peptides. In all cases, the outermost layer of the corneal epithelium presents the rate-limiting barrier for peptide absorption. The results also indicate a charge discrimination effect to transport of negatively charged peptides. In permselectivity studies, it has been shown that the cornea, due to the presence of ionizable charged groups, is amphoteric and exhibits dual selective characteristics to transport of charged molecules. At pH's above the isoelectric point, 3.2, the cornea carries a net negative charge and is selective to positively-charged molecules. Below the isoelectric pH, the reverse is valid. The promoting mechanisms of penetration enhancers were studied microscopically using confocal fluorescence microscopy with the aid of a specific fluorescent membrane probe (3,3'-dioctadecyloxacarbocyanine) and a non-permeating polar tracer. All enhancers, including chelators, non-ionic surfactants, bile salts, and cytoskeleton-active agents, significantly increase membrane permeability depending on concentration and exposure time

  12. X-ray absorption spectroscopy and EPR studies of oriented spinach thylakoid preparations

    Andrews, J.C. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States). Structural Biology Div.

    1995-08-01

    In this study, oriented Photosystem II (PS II) particles from spinach chloroplasts are studied with electron paramagnetic resonance (EPR) and x-ray absorption spectroscopy (XAS) to determine more details of the structure of the oxygen evolving complex (OEC). The nature of halide binding to Mn is also studied with Cl K-edge and Mn EXAFS (extended x-ray absorption fine structure) of Mn-Cl model compounds, and with Mn EXAFS of oriented PS II in which Br has replaced Cl. Attention is focused on the following: photosynthesis and the oxygen evolving complex; determination of mosaic spread in oriented photosystem II particles from signal II EPR measurement; oriented EXAFS--studies of PS II in the S{sub 2} state; structural changes in PS II as a result of treatment with ammonia: EPR and XAS studies; studies of halide binding to Mn: Cl K-edge and Mn EXAFS of Mn-Cl model compounds and Mn EXAFS of oriented Br-treated photosystem II.

  13. Sonochemical assisted hydrothermal synthesis of ZnO: Cr nanoparticles loaded activated carbon for simultaneous ultrasound-assisted adsorption of ternary toxic organic dye: Derivative spectrophotometric, optimization, kinetic and isotherm study.

    Jamshidi, M; Ghaedi, M; Dashtian, K; Hajati, S; Bazrafshan, A A

    2016-09-01

    Chromium doped zinc oxide nanoparticles (ZnO: Cr-NPs) was synthesized by ultrasonically assisted hydrothermal method and characterized by FE-SEM, XRD and TEM analysis. Subsequently, this composite ultrasonically assisted was deposited on activated carbon (ZnO: Cr-NPs-AC) and used for simultaneous ultrasound-assisted removal of three toxic organic dye namely of malachite green (MG), eosin yellow (EY) and Auramine O (AO). Dyes spectra overlap in mixture (major problem for simultaneous investigation) of this systems was extensively resolved by derivative spectrophotometric method. The magnitude of variables like initial dyes concentration, adsorbent mass and sonication time influence on dyes removal was optimized using small central composite design (CCD) combined with desirability function (DF) approach, while pH was studied by one-a-time approach. The maximized removal percentages at desirability of 0.9740 was set as follow: pH 6.0, 0.019g ZnO: Cr-NPs-AC, 3.9min sonication at 4.5, 4.8 and 4.7mgL(-1) of MG, EY and AO, respectively. Above optimized points lead to achievement of removal percentage of 98.36%, 97.24%, and 99.26% correspond to MG, EY and AO, respectively. ANOVA for each dyes based p-value less than (removal of these dyes within 95% confidence interval, while their F-value for MG, EY and AO is 935, 800.2, and 551.3, respectively, that confirm low participation of this them in signal. The value of multiple correlation coefficient R(2), adjusted and predicted R(2) for simultaneous removal of MG is 0.9982, 0.9972 and 0.9940, EY is 0.9979, 0.9967 and 0.9930 and for AO is 0.9970, 0.9952 and 0.9939. The adsorption rate well fitted by pseudo second-order and Langmuir model via high, economic and profitable adsorption capacity of 214.0, 189.7 and 211.6mgg(-1) for MG, EY and AO, respectively. PMID:27150752

  14. Spectrophotometric determination of Cerium from Monazite Bangka using Tiron reagent

    To anticipate the analysis of individual rare earth element from monazite processing which have done at PTPBGN division and samples from other division of P2BGN, and to develop the Ce analysis method by spectrophotometric using tiron reagent. The purpose of the experiment is to find out the method and the condition of Ce analysis with high accuracy and applicable. The variable observation were cerium-tiron spectrum, pH, ligand concentration, buffer concentration, linearity, anion influence, limit detection, impurities of elements and complex stability. The complex of cerium-tiron produce the maximum absorption at 497.5 nm and stable until 8 hours. The optimum conditions of this method was : tiron concentration is 0.25 %, pH 8.5 with buffer solution sodium acetate is 0.3 M. Detection limit is 1.00 ppm and area of linearity between 1 - 100 ppm, and PO4, Fe, U and Ti was influence to this method. The content of Ce from 2 samples of monazite Bangka which determine by this method was 18%

  15. Catalytic spectrophotometric determination of iodine in coal by pyrohydrolysis decomposition

    Wu Daishe [School of Environmental Science and Engineering, Nanchang University, Nanchang 330031 (China); Institute of Geographic Sciences and Resources Research, CAS, Beijing 100101 (China)], E-mail: dswu@ncu.edu.cn; Deng Haiwen [School of Environmental Science and Engineering, Nanchang University, Nanchang 330031 (China); Wang Wuyi [Institute of Geographic Sciences and Resources Research, CAS, Beijing 100101 (China); Xiao Huayun [School of Environmental Science and Engineering, Nanchang University, Nanchang 330031 (China)

    2007-10-10

    A method for the determination of iodine in coal using pyrohydrolysis for sample decomposition was proposed. A pyrohydrolysis apparatus system was constructed, and the procedure was designed to burn and hydrolyse coal steadily and completely. The parameters of pyrohydrolysis were optimized through the orthogonal experimental design. Iodine in the absorption solution was evaluated by the catalytic spectrophotometric method, and the absorbance at 420 nm was measured by a double-beam UV-visible spectrophotometer. The limit of detection and quantification of the proposed method were 0.09 {mu}g g{sup -1} and 0.29 {mu}g g{sup -1}, respectively. After analysing some Chinese soil reference materials (SRMs), a reasonable agreement was found between the measured values and the certified values. The accuracy of this approach was confirmed by the analysis of eight coals spiked with SRMs with an indexed recovery from 94.97 to 109.56%, whose mean value was 102.58%. Six repeated tests were conducted for eight coal samples, including high sulfur coal and high fluorine coal. A good repeatability was obtained with a relative standard deviation value from 2.88 to 9.52%, averaging 5.87%. With such benefits as simplicity, precision, accuracy and economy, this approach can meet the requirements of the limits of detection and quantification for analysing iodine in coal, and hence it is highly suitable for routine analysis.

  16. Catalytic spectrophotometric determination of iodine in coal by pyrohydrolysis decomposition.

    Wu, Daishe; Deng, Haiwen; Wang, Wuyi; Xiao, Huayun

    2007-10-10

    A method for the determination of iodine in coal using pyrohydrolysis for sample decomposition was proposed. A pyrohydrolysis apparatus system was constructed, and the procedure was designed to burn and hydrolyse coal steadily and completely. The parameters of pyrohydrolysis were optimized through the orthogonal experimental design. Iodine in the absorption solution was evaluated by the catalytic spectrophotometric method, and the absorbance at 420 nm was measured by a double-beam UV-visible spectrophotometer. The limit of detection and quantification of the proposed method were 0.09 microg g(-1) and 0.29 microg g(-1), respectively. After analysing some Chinese soil reference materials (SRMs), a reasonable agreement was found between the measured values and the certified values. The accuracy of this approach was confirmed by the analysis of eight coals spiked with SRMs with an indexed recovery from 94.97 to 109.56%, whose mean value was 102.58%. Six repeated tests were conducted for eight coal samples, including high sulfur coal and high fluorine coal. A good repeatability was obtained with a relative standard deviation value from 2.88 to 9.52%, averaging 5.87%. With such benefits as simplicity, precision, accuracy and economy, this approach can meet the requirements of the limits of detection and quantification for analysing iodine in coal, and hence it is highly suitable for routine analysis. PMID:17920390

  17. Spectrophotometric determination of nicradipine and isradipine in pharmaceutical formulations

    S. M. Al-Ghannam

    2009-05-01

    Full Text Available A sensitive spectrophotometric method was developed for the determination of some 1,4-dihydropyridine compounds namely, nicardipine and isradipine either in pure form or in pharmaceutical preparations. The method is based on the reduction of nicardipine and isradipine with zinc powder and calcium chloride followed by further reduction with sodium pentacyanoaminoferrate (II to give violet and red products having the absorbance maximum at 546 and 539 nm with nicardipine and isradipine, respectively. Beer’s law was obeyed over the concentration range 8.0–180 μg/ml with the detection limit of 1.67 μg/ml for nicardipine and 8.0–110 μg/ml with the detection limit of 1.748 μg/ml for isradipine. The analytical parameters and their effects on the reported methods were investigated. The molar absorptivity, quantization limit, standard deviation of intercept (Sa, standard deviation of slope (Sb and standard deviation of the residuals (Sy/x were calculated. The composition of the result compounds were found 1:1 for nicardipine and 1:2 for isradipine by Job’s method and the conditional stability constant (Kf and the free energy changes (ΔG were calculated for compounds formed. The proposed method was applied successfully for the determination of nicardipine and isradipine in their dosage forms. The results obtained were in good agreement with those obtained using the reference or official methods. A proposal of the reaction pathway was presented.

  18. Ultrafast transient absorption studies of hematite nanoparticles: the effect of particle shape on exciton dynamics.

    Fitzmorris, Bob C; Patete, Jonathan M; Smith, Jacqueline; Mascorro, Xiomara; Adams, Staci; Wong, Stanislaus S; Zhang, Jin Z

    2013-10-01

    Much progress has been made in using hematite (α-Fe2 O3 ) as a potentially practical and sustainable material for applications such as solar-energy conversion and photoelectrochemical (PEC) water splitting; however, recent studies have shown that the performance can be limited by a very short charge-carrier diffusion length or exciton lifetime. In this study, we performed ultrafast studies on hematite nanoparticles of different shapes to determine the possible influence of particle shape on the exciton dynamics. Nanorice, multifaceted spheroidal nanoparticles, faceted nanocubes, and faceted nanorhombohedra were synthesized and characterized by using SEM and XRD techniques. Their exciton dynamics were investigated by using femtosecond transient absorption (TA) spectroscopy. Although the TA spectral features differ for the four samples studied, their decay profiles are similar, which can be fitted with time constants of 1-3 ps, approximately 25 ps, and a slow nanosecond component extending beyond the experimental time window that was measured (2 ns). The results indicate that the overall exciton lifetime is weakly dependent on the shape of the hematite nanoparticles, even though the overall optical absorption and scattering are influenced by the particle shape. This study suggests that other strategies need to be developed to increase the exciton lifetime or to lengthen the exciton diffusion length in hematite nanostructures. PMID:24058060

  19. Compositional dependence of absorption coefficient and band-gap for Nb2O5-SiO2 mixture thin films

    The absorption coefficient of composite films consisting of niobia (Nb2O5) and silica (SiO2) mixtures is studied for photon energies around the band gap. The films were deposited by co-evaporation and their composition was varied by changing the ratio of deposition rates of the two materials. Both, as-deposited and thermally annealed films were characterized by different techniques: the absorption coefficient was determined by spectrophotometric measurements and the structural properties were investigated using infrared spectroscopy, transmission electron microscopy and X-ray diffraction. The correlation between the variations of absorption properties and film composition and structure is established. The absorption coefficients determined experimentally are compared with the results derived from effective medium theories in order to evaluate the suitability of these theories for the studied composites

  20. Compositional dependence of absorption coefficient and band-gap for Nb{sub 2}O{sub 5}-SiO{sub 2} mixture thin films

    Sancho-Parramon, Jordi [Rudjer Boskovic Institute, Bijenicka c. 54, 10000 Zagreb (Croatia)], E-mail: j.sancho.parramon@gmail.com; Janicki, Vesna; Zorc, Hrvoje [Rudjer Boskovic Institute, Bijenicka c. 54, 10000 Zagreb (Croatia)

    2008-06-30

    The absorption coefficient of composite films consisting of niobia (Nb{sub 2}O{sub 5}) and silica (SiO{sub 2}) mixtures is studied for photon energies around the band gap. The films were deposited by co-evaporation and their composition was varied by changing the ratio of deposition rates of the two materials. Both, as-deposited and thermally annealed films were characterized by different techniques: the absorption coefficient was determined by spectrophotometric measurements and the structural properties were investigated using infrared spectroscopy, transmission electron microscopy and X-ray diffraction. The correlation between the variations of absorption properties and film composition and structure is established. The absorption coefficients determined experimentally are compared with the results derived from effective medium theories in order to evaluate the suitability of these theories for the studied composites.

  1. Spectrophotometric determination of nateglinide in bulk and tablet dosage forms

    Jain Suresh

    2009-01-01

    Full Text Available Nateglinide (NTG is available as tablet dosage form in 60 mg and 120 mg strength. In the present study, two simple, reproducible and efficient UV spectrophotometric methods for the estimation of this drug in bulk and pharmaceutical dosage forms have been developed. In method I, methanol-AR was used as solvent, while in method II, Methanol-AR + 10% V/V 3N NaOH was used as reference solvent. In method I, nateglinide shows λmax at 216 nm, which is then shifted to 225.4 nm on increasing the basicity of the reference solvent in method II. The linearity for nateglinide was observed to be statistically in the range of 10-100 μg/ml in method I and 100-1000 μg/ml in method II. Both the methods were validated using ANOVA. The recovery studies confirmed the accuracy of the proposed methods.

  2. First principle studies on the electronic structures and absorption spectra in KMgF{sub 3} crystal with fluorine vacancy

    Cheng Fang [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China); Liu Tingyu, E-mail: liutyyxj@163.co [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China); Zhang Qiren; Qiao Hailin; Zhou Xiuwen [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China)

    2010-08-01

    The experiments indicate that the perfect KMgF{sub 3} crystal has no absorption in the visible range, however the electron irradiation induces a complex absorption spectrum. The absorption spectra can be decomposed by five Gaussian bands peaking at 2.5 eV (488 nm), 3.4 eV (359 nm), 4.2 eV (295 nm), 4.6 eV (270 nm) and 5.2 eV (239 nm), respectively. The purpose of this paper is to seek the origins of the absorption bands. The electronic structures and absorption spectra either for the perfect KMgF{sub 3} or for KMgF{sub 3}: V{sub F}{sup +} with electrical neutrality have been studied by using density functional theory code CASTEP with the lattice structure optimized. The calculation results predicate that KMgF{sub 3}: V{sub F}{sup +} also exhibits five absorption bands caused by the existence of the fluorine ion vacancy V{sub F}{sup +} and the five absorption bands well coincide with the experimental results. It is believable that the five absorption bands are related to V{sub F}{sup +} in KMgF{sub 3} crystal produced by the electron irradiation.

  3. First principle studies on the electronic structures and absorption spectra in KMgF 3 crystal with fluorine vacancy

    Cheng, Fang; Liu, Tingyu; Zhang, Qiren; Qiao, Hailin; Zhou, Xiuwen

    2010-08-01

    The experiments indicate that the perfect KMgF 3 crystal has no absorption in the visible range, however the electron irradiation induces a complex absorption spectrum. The absorption spectra can be decomposed by five Gaussian bands peaking at 2.5 eV (488 nm), 3.4 eV (359 nm), 4.2 eV (295 nm), 4.6 eV (270 nm) and 5.2 eV (239 nm), respectively. The purpose of this paper is to seek the origins of the absorption bands. The electronic structures and absorption spectra either for the perfect KMgF 3 or for KMgF 3: VF+ with electrical neutrality have been studied by using density functional theory code CASTEP with the lattice structure optimized. The calculation results predicate that KMgF 3: VF+ also exhibits five absorption bands caused by the existence of the fluorine ion vacancy VF+ and the five absorption bands well coincide with the experimental results. It is believable that the five absorption bands are related to VF+ in KMgF 3 crystal produced by the electron irradiation.

  4. A study on Fresnel absorption and reflections in the keyhole in deep penetration laser welding

    On the basis of a keyhole photograph obtained experimentally, the keyhole profiles are determined by the method of polynomial fitting. Then the behaviour of the laser beam in the keyhole is analysed by tracing a ray of light using geometrical optics theory; the Fresnel absorption and reflections in the keyhole are systematically studied, and the laser intensities absorbed on the keyhole walls are calculated. By comparing the laser intensity absorbed on the keyhole walls with the heat flux lost there, the mechanism of energy balance on the keyhole walls is discussed. (author)

  5. Nonequilibrium Superconductivity and Quasiparticle Dynamics Studied by Photoinduced Activation of mm-Wave Absorption

    We present a study of nonequilibrium superconductivity in DyBa2Cu 3O7-δ using photoinduced activation of mm-wave absorption. We monitor the time evolution of the thin film transmissivity at 5 cm-1 subject to pulsed infrared radiation. In addition to a positive bolometric signal we observe a second, faster, decay with a sign opposite to the bolometric signal for T>40 K . We attribute this to the unusual properties of quasiparticles residing near the nodes of an unconventional superconductor, resulting in a strong enhancement of the recombination time. copyright 1997 The American Physical Society

  6. A large acceptance detector system (LADS) for studies of pion absorption

    Alteholz, T.; Androi`c, D.; Backenstoss, G. [Basel Univ. (Switzerland)]|[Carnegie-Mellon Univ., Pittsburg, PA (United States)]|[Karlsruhe Univ. (Germany)] [and others; LADS Collaboration

    1996-05-01

    A large acceptance detector system (LADS) has been designed and built at the Paul Scherrer Institute to study multi-particle final states following pion-nucleus absorption. It consists of a 28-sector cylinder of plastic scintillators of 1.6 m active length and 1.4 m diameter, two cylindrical wire chambers, and two 14-sector plastic scintillator end-caps which close each end. The nearly 4{pi} solid angle coverage of this detector minimizes uncertainties associated with extrapolations over unmeasured regions of phase space. The design and the performance of the LADS detector are presented. (orig.).

  7. Study of the dispersion phenomena connected with the absorption by recoilless nuclear resonance fluorescence

    In nuclear resonance fluorescence as in the optical field abnormal dispersion curves are related to the absorption lines. It is possible, by using quadrupolar or magnetic splitting of the line in the case of recoilless resonance fluorescence (Moessbauer effect) to obtain differential dispersion effects between the two orthogonal linear or the two inverse circular components of the incident gamma radiation. These effects induce bi-refraction phenomena or Faraday rotation on the gamma beam, which have been studied on Fe-57 enriched absorbers. (author)

  8. X-ray scattering and absorption studies of MnAs/GaAs heterostructures

    Huang, S.; Ming, Z. H.; Soo, Y. L.; Kao, Y. H.; Tanaka, M.; Munekata, H.

    1996-02-01

    Ferromagnetic MnAs thin films grown on GaAs (001) substrates by molecular-beam epitaxy have been studied by the methods of grazing incidence x-ray scattering, x-ray diffraction, and extended x-ray-absorption fine structure. Microstructures in two films prepared with different first-layer growth conditions (template effects) are compared in terms of the interfacial roughness in the layer structure, lattice constants, epilayer thickness, local environment surrounding the Mn atoms, coordination number, and local disorder. Our results indicate that the template effects can cause significant differences in the local structures and crystallinity of the MnAs epitaxial layers.

  9. X-ray absorption study of tribofilms from ZDDP and overbased salicylate detergents

    Yong Wan; M. Kasrai; G.M. Bancroft

    2009-01-01

    The interaction of overbased salicylate detergents with zinc dialkyldithiophosphates (ZDDP) and its effect on the formation of tribofilms under boundary lubrication have been studied by means of X-ray absorption near-edge structure spectroscopy. The results show that addition of metallic detergents to neat ZDDP results in the change of surface chemistry of the tribofilm formed from neat ZDDP. Calcium from detergents is digested in the tribofilm. For the high overbased detergents, the deposit of overbasing agent CaCO3 in the tribofilm is also observed along with the formation of calcium phosphate in tribofilms.

  10. A rapid spectrophotometric method for the determination of mercury in environmental, biological, soil and plant samples using diphenylthiocarbazone

    AHMED, M. Jamaluddin; Alam, Md Shah

    2003-01-01

    A simple, sensitive and highly selective direct spectrophotometric method for the determination of trace levels of mercury(II) in various samples is described. Diphenylthiocarbazone (dithizone) reacts in slightly acidic 50% aqueous 1,4-dioxane media (0.18–1.80 M sulphuric acid) with mercury(II) to give an orange chelate which has an absorption maximum at 488 nm. The average molar absorption co-efficient and Sandell's sensitivity were found to be 2.5×104l mol−1 cm−1 and 0.015 μg of Hg(II) cm−2...

  11. Application of quantum cascade laser absorption spectroscopy to studies of fluorocarbon molecules

    Welzel, S; Roepcke, J [Leibniz Institute for Plasma Science and Technology, Felix-Hausdorff-Str. 2, D-17489 Greifswald (Germany); Stepanov, S; Meichsner, J, E-mail: welzel@inp-greifswald.d [Institute of Physics, Ernst-Moritz-Arndt University, Felix-Hausdorff-Str. 6, D-17489 Greifswald (Germany)

    2009-03-01

    The recent advent of quantum cascade lasers (QCLs) enables room-temperature mid-infrared spectrometer operation which is particularly favourable for industrial process monitoring and control, i.e. the detection of transient and stable molecular species. Conversely, fluorocarbon containing radio-frequency discharges are of special interest for plasma etching and deposition as well as for fundamental studies on gas phase and plasma surface reactions. The application of QCL absorption spectroscopy to such low pressure plasmas is typically hampered by non-linear effects connected with the pulsed mode of the lasers. Nevertheless, adequate calibration can eliminate such effects, especially in the case of complex spectra where single line parameters are not available. In order to facilitate measurements in fluorocarbon plasmas, studies on complex spectra of CF{sub 4} and C{sub 3}F{sub 8} at 7.86{mu}m (1269 - 1275 cm{sup -1}) under low pressure conditions have been performed. The intra-pulse mode, i.e. pulses of up to 300 ns, was applied yielding highly resolved spectral scans of {approx}1 cm{sup -1} coverage. Effective absorption cross sections were determined and their temperature dependence was studied in the relevant range up to 400 K and found to be non-negligible.

  12. Resolution of overlapped spectra for the determination of ternary mixture using different and modified spectrophotometric methods

    Moussa, Bahia Abbas; El-Zaher, Asmaa Ahmed; Mahrouse, Marianne Alphonse; Ahmed, Maha Said

    2016-08-01

    Four new spectrophotometric methods were developed, applied to resolve the overlapped spectra of a ternary mixture of [aliskiren hemifumarate (ALS)-amlodipine besylate (AM)-hydrochlorothiazide (HCT)] and to determine the three drugs in pure form and in combined dosage form. Method A depends on simultaneous determination of ALS, AM and HCT using principal component regression and partial least squares chemometric methods. In Method B, a modified isosbestic spectrophotometric method was applied for the determination of the total concentration of ALS and HCT by measuring the absorbance at 274.5 nm (isosbestic point, Aiso). On the other hand, the concentration of HCT in ternary mixture with ALS and AM could be calculated without interference using first derivative spectrophotometric method by measuring the amplitude at 279 nm (zero crossing of ALS and zero value of AM). Thus, the content of ALS was calculated by subtraction. Method C, double divisor first derivative ratio spectrophotometry (double divisor 1DD method), was based on that for the determination of one drug, the ratio spectra were obtained by dividing the absorption spectra of its different concentrations by the sum of the absorption spectra of the other two drugs as a double divisor. The first derivative of the obtained ratio spectra were then recorded using the appropriate smoothing factor. The amplitudes at 291 nm, 380 nm and 274.5 nm were selected for the determination of ALS, AM and HCT in their ternary mixture, respectively. Method D was based on mean centering of ratio spectra. The mean centered values at 287, 295.5 and 269 nm were recorded and used for the determination of ALS, AM and HCT, respectively. The developed methods were validated according to ICH guidelines and proved to be accurate, precise and selective. Satisfactory results were obtained by applying the proposed methods to the analysis of pharmaceutical dosage form.

  13. Resolution of overlapped spectra for the determination of ternary mixture using different and modified spectrophotometric methods.

    Moussa, Bahia Abbas; El-Zaher, Asmaa Ahmed; Mahrouse, Marianne Alphonse; Ahmed, Maha Said

    2016-08-01

    Four new spectrophotometric methods were developed, applied to resolve the overlapped spectra of a ternary mixture of [aliskiren hemifumarate (ALS)-amlodipine besylate (AM)-hydrochlorothiazide (HCT)] and to determine the three drugs in pure form and in combined dosage form. Method A depends on simultaneous determination of ALS, AM and HCT using principal component regression and partial least squares chemometric methods. In Method B, a modified isosbestic spectrophotometric method was applied for the determination of the total concentration of ALS and HCT by measuring the absorbance at 274.5nm (isosbestic point, Aiso). On the other hand, the concentration of HCT in ternary mixture with ALS and AM could be calculated without interference using first derivative spectrophotometric method by measuring the amplitude at 279nm (zero crossing of ALS and zero value of AM). Thus, the content of ALS was calculated by subtraction. Method C, double divisor first derivative ratio spectrophotometry (double divisor (1)DD method), was based on that for the determination of one drug, the ratio spectra were obtained by dividing the absorption spectra of its different concentrations by the sum of the absorption spectra of the other two drugs as a double divisor. The first derivative of the obtained ratio spectra were then recorded using the appropriate smoothing factor. The amplitudes at 291nm, 380nm and 274.5nm were selected for the determination of ALS, AM and HCT in their ternary mixture, respectively. Method D was based on mean centering of ratio spectra. The mean centered values at 287, 295.5 and 269nm were recorded and used for the determination of ALS, AM and HCT, respectively. The developed methods were validated according to ICH guidelines and proved to be accurate, precise and selective. Satisfactory results were obtained by applying the proposed methods to the analysis of pharmaceutical dosage form. PMID:27128521

  14. Characterization on the Mean Molar Absorptivity of Amino Acids in Microbial Lipopeptides

    2006-01-01

    The molar absorption coefficients of each of 14 kinds of amino acids were determined by the spectrophotometric method, and the mean molar absorption coefficients of 37 different mixtures of each with amino acid composition exactly equivalent to that of the peptide chain of the corresponding lipopeptide were determined based on calculation or experimental. The significance of the results is that the mean molar absorption coefficients strongly demonstrate the regular patterns, though different amino acids bear quite different molar absorption coefficients.

  15. Spectrophotometric variability of the magnetic CP star alpha2 CVn

    Sokolov, N A

    2011-01-01

    The spectrophotometric variability of the classical magnetic CP star alpha2 CVn in the ultraviolet spectral region from 1150 to 3200 A is investigated. This study is based on the archival International Ultraviolet Explorer data obtained at different phases of the rotational cycle. The brightness of the star at spectral region from 3015 to 3138 A is constant over the period of rotation which means that the so called 'null wavelength region' exist on these wavelengths. Moreover, the minima values of the amplitude of light curves are reached in the spectral region at \\lambda \\lambda 1660 and 1900 A. The monochromatic light curves in the 'pseudo-continuum' of this star change their shape with wavelength. All light curves with \\lambda 2505 A shows the phase displacement of the minimum from 0.0 at \\lambda 2505 A to 0.3 at \\lambda 2993 A.

  16. Spectrophotometric intracutaneous analysis for differential diagnosis of pigmented skin lesions

    Е. V. Filonenko

    2013-01-01

    Full Text Available The non-invasive diagnosis of pigmented skin lesions by spectrophotometric intracutaneous analysis (SIA-scopy using device for dermatoscopy (SIAscope V by Astron Clinica, Ltd was approved in P.A.Herzen Moscow Cancer Research Institute. The method is based on analysis of light interaction with wavelength of 440–960 nm anf human skin, which is recorded by change of image on scan. The comparative analysis of SIA-scopy and histological data in 327 pigmented skin lesions in 147 patients showed, that SIA had high diagnostic efficiency for cutaneous melanoma: the sensitivity was 96%, specifity – 94%, diagnostic accuracy – 94%. For study of malignant potential of pigmented lesions by SIA-scopy the most informative capacity was obtained for assessment of melanin in papillary dermis, status of blood vessels and collagen fibres (SIA-scans 3, 4, 5.

  17. Kinetic spectrophotometric determination of bromide in clidinium-c drug

    Ali Sheibani; M. Reza Shishehbore; Zahra Tavakolian Ardakani

    2011-01-01

    A simple, rapid and sensitive method has been described for the determination of the trace amounts of bromide. The method is based on the catalytic effect of bromide ion on the oxidation of methylene blue by bromate in sulfuric acid media. The reaction is monitored spectrophotometrically by measuring the decrease in the absorbance of methylene blue at 665 nm. Bromide was determined in the range of 0.05-1.90 μg/mL with the detection limit of 0.03 μg/mL. The relative standard deviations of five replicate determinations of 0.20 and 10.0 μg/mL of bromide were 2.4% and 1.8%, respectively. The influence of potential interfering ions and substances was studied. The method is applied to the analysis of bromide in clidinium-c tablet as a real sample.

  18. Non-destructive studies of fuel pellets by neutron resonance absorption radiography and thermal neutron radiography

    Many isotopes in nuclear materials exhibit strong peaks in neutron absorption cross sections in the epithermal energy range (1–1000 eV). These peaks (often referred to as resonances) occur at energies specific to particular isotopes, providing a means of isotope identification and concentration measurements. The high penetration of epithermal neutrons through most materials is very useful for studies where samples consist of heavy-Z elements opaque to X-rays and sometimes to thermal neutrons as well. The characterization of nuclear fuel elements in their cladding can benefit from the development of high resolution neutron resonance absorption imaging (NRAI), enabled by recently developed spatially-resolved neutron time-of-flight detectors. In this technique the neutron transmission of the sample is measured as a function of spatial location and of neutron energy. In the region of the spectra that borders the resonance energy for a particular isotope, the reduction in transmission can be used to acquire an image revealing the 2-dimensional distribution of that isotope within the sample. Provided that the energy of each transmitted neutron is measured by the neutron detector used and the irradiated sample possesses neutron absorption resonances, then isotope-specific location maps can be acquired simultaneously for several isotopes. This can be done even in the case where samples are opaque or have very similar transmission for thermal neutrons and X-rays or where only low concentrations of particular isotopes are present (<0.1 atom% in some cases). Ultimately, such radiographs of isotope location can be utilized to measure isotope concentration, and can even be combined to produce three-dimensional distributions using tomographic methods. In this paper we present the proof-of-principle of NRAI and transmission Bragg edge imaging performed at Flight Path 5 (FP5) at the LANSCE pulsed, moderated neutron source of Los Alamos National Laboratory. A set of urania mockup

  19. Study of the effect of Chinese medicine on calcium absorption with isotopic tracer technique

    The present work was undertaken to study the effect of Chinese medicine on calcium absorption. Female Wistar rats, 3 months old, weighing 250-275 g, were randomly divided into ten groups of 5 rats each. The rats were individually housed in stainless steel metabolic cages in an environmentally controlled room (temperature, 20 degree C; relative humidity, 30%-60%; reversed light : dark cycle, 12:12 hr). Isotopic tracer technique was conducted to study the absorption of calcium acetate and calcium acetate + Chinese medicine in rats. The two calcium supplements were irradiated in a nuclear reactor for 4.95 d at neutron flux of φ=6.1 x 1013 n/cm2·s. Then they were prepared from concentrated 47Ca solution (10 mg/ml) with cyclodextrin. The animals received oral doses of 25 mg calcium as calcium acetate or calcium acetate + Chinese medicine via an intragastric gavage. The animals were fasted overnight preceding and food was resumed 3 hrs after the gavage. Blood, heart, lung, liver, spleen, stomach, kidney, small intestine, large intestine and femur samples of the rats were taken upon sacrifice at 0.5, 1, 2, 4, 12, 24, 48, 72, 120, 168 hrs after dosing and assayed for 47Ca. Urine and feces samples were collected separately after dosing and assayed for 47Ca. The radioactivity of the samples was counted with a high pure Ge detector and a PC-based Ortec MCA. Its energy resolution was l.85 keV at 1332.5 keV and the relative detection efficiency was 30 %. The dead time was controlled within 10 % to reduce the count loss. Weighed 47CaCO3 was used as reference materials. A big distance between the samples and detector was kept to overcome the geometric effect caused by different shape and size of the samples. The gamma energy spectra were analyzed with a multipurpose gamma ray spectrum analysis software package. The parameters were evaluated by means of general linear model, using analysis of covariance with SAS 6.12 for Windows. The results showed that peroral 47Ca was mainly

  20. Symmetry Breaking in Platinum Acetylide Chromophores Studied by Femtosecond Two-Photon Absorption Spectroscopy.

    Rebane, Aleksander; Drobizhev, Mikhail; Makarov, Nikolay S; Wicks, Geoffrey; Wnuk, Pawel; Stepanenko, Yuriy; Haley, Joy E; Krein, Douglas M; Fore, Jennifer L; Burke, Aaron R; Slagle, Jonathan E; McLean, Daniel G; Cooper, Thomas M

    2014-05-15

    We study instantaneous two-photon absorption (2PA) in a series of nominally quasi-centrosymmetric trans-bis(tributylphosphine)-bis-(4-((9,9-diethyl-7-ethynyl-9H-fluoren-2-yl) ethynyl)-R)-platinum complexes, where 11 different substituents, R = N(phenyl)2(NPh2), NH2, OCH3, t-butyl, CH3, H, F, CF3, CN, benzothiazole, and NO2, represent a range of electron-donating (ED) and electron-withdrawing (EW) strengths, while the Pt core acts as a weak ED group. We measure the 2PA cross section in the 540-810 nm excitation wavelength range by complementary femtosecond two-photon excited fluorescence (2PEF) and nonlinear transmission (NLT) methods and compare the obtained values to those of the Pt-core chromophore and the corresponding noncentrosymmetric side group (ligand) chromophores. Peak 2PA cross sections of neutral and ED-substituted Pt complexes occur at S0 → Sn transitions to higher energy states, above the lowest-energy S0 → S1 transition, and the corresponding values increase systematically with increasing ED strength, reaching maximum value, σ2 ∼ 300 GM (1 GM = 10(-50) cm(4) s), for R = NPh2. At transition energies overlapping with the lowest-energy S0 → S1 transition in the one-photon absorption (1PA) spectrum, the same neutral and ED-substituted Pt complexes show weak 2PA, σ2 NO2, while in the S0 → Sn transition region the peak 2PEF cross section decreases. We explained this effect by breaking of inversion symmetry due to conformational distortions associated with low energy barrier for ground-state rotation of the ligands. Our findings are corroborated by theoretical calculations that show large increase of the permanent electric dipole moment change in the S0 → S1 transition when ligands with strong EW substituents are twisted by 90° relative to the planar chromophore. Our NLT results in the S0 → S1 transition region are quantitatively similar to those obtained from the 2PEF measurement. However, at higher transition energy corresponding to S0

  1. Proposing a Caco-2/HepG2 cell model for in vitro iron absorption studies.

    Scheers, Nathalie M; Almgren, Annette B; Sandberg, Ann-Sofie

    2014-07-01

    The Caco-2 cell line is well established as an in vitro model for iron absorption. However, the model does not reflect the regulation of iron absorption by hepcidin produced in the liver. We aimed to develop the Caco-2 model by introducing human liver cells (HepG2) to Caco-2 cells. The Caco-2 and HepG2 epithelia were separated by a liquid compartment, which allowed for epithelial interaction. Ferritin levels in cocultured Caco-2 controls were 21.7±10.3 ng/mg protein compared to 7.7±5.8 ng/mg protein in monocultured Caco-2 cells. The iron transport across Caco-2 layers was increased when liver cells were present (8.1%±1.5% compared to 3.5%±2.5% at 120 μM Fe). Caco-2 cells were exposed to 0, 80 and 120 μM Fe and responded with increased hepcidin production at 120 μM Fe (3.6±0.3 ng/ml compared to 2.7±0.3 ng/ml). The expression of iron exporter ferroportin in Caco-2 cells was decreased at the hepcidin concentration of 3.6 ng/ml and undetectable at external addition of hepcidin (10 ng/ml). The apical transporter DMT1 was also undetectable at 10 ng/ml but was unchanged at the lower concentrations. In addition, we observed that sourdough bread, in comparison to heat-treated bread, increased the bioavailability of iron despite similar iron content (53% increase in ferritin formation, 97% increase in hepcidin release). This effect was not observed in monocultured Caco-2 cells. The Caco-2/HepG2 model provides an alternative approach to in vitro iron absorption studies in which the hepatic regulation of iron transport must be considered. PMID:24746839

  2. X-ray absorption Studies of Zinc species in Centella asiatica

    Dehipawala, Sunil; Cheung, Tak; Hogan, Clayton; Agoudavi, Yao; Dehipawala, Sumudu

    2013-03-01

    Zinc is a very important mineral present in a variety of vegetables. It is an essential element in cellular metabolism and several bodily functions. We used X-ray fluorescence, and X-ray Absorption near Edge structure(XANES) to study the amount of zinc present in several leafy vegetables as well as its chemical environment within the plant. Main absorption edge position of XANES is sensitive to the oxidation state of zinc and is useful when comparing the type of zinc present in different vegetables to the standard zinc present in supplements. Normalized main edge height is proportional to the amount of zinc present in the sample. Several leafy greens were used in this study, such as Spinacia oleracea, Basella alba, Brassica oleracea, Cardiospermum halicacabumand Centella asiatica. All of these plant leaves contained approximately the same amount of zinc in the leaf portion of the plant and a slightly lower amount in the stems, except Centella asiatica. Both leaves and stems of the plant Centella asiatica contained nearly two times the zinc compared to other plants. Further investigation of zinc's chemical environment within Centella asiatica could lead to a much more efficient dietary consumption of zinc. Use of the National Synchrotron Light Source, Brookhaven National Laboratory, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886

  3. In Situ X-Ray Absorption Spectroscopy Study of the LiNiO2 Electrode

    Mansour, A. N.; McBreen, J.; Melendres, C. A.

    1997-03-01

    LiNiO2 is one of the most promising active material for the development of novel 4V rechargeable lithium batteries. Recent x-ray diffraction studies showed that the electrochemical reactivity of this electrode is sensitive to the structure of the starting material as well as the charged products. To further examine this material, we have conducted an x-ray absorption spectroscopy (XAS) study to determine the structure of this electrode as a function of its charge state. Specifically, the x-ray absorption Ni K-edge energy, the pre-edge structure, and local structure parameters such as bond lengths, coordination numbers and disorders were investigated at various states of charge corresponding to Li_(1-x)NiO2 for x values of 0.0, 0.11, 0.23, 0.34, 0.45, 0.82, and 0.99. The charging which proceeds via lithium de-intercalation was conducted using constant current anodization at 0.5 mA in a non aqueous electrolyte consisting of 1M LiPF6 in 1:1:3 propylene ! carbonate, ethylene carbonate and dimethyl carbonate. The XAS results for this electrode will be compared with those of γ-NiOOH and KNiIO_6, the latter being used as a reference for quadrivalent nickel.

  4. Absorption studies after eleal J-pouch anastomosis for ulcerative colitis

    Absorption studies were performed in 17 patients with ulcerative colities operated on with colectomy and an ileal two-limbed J-pouch anastomosis. The patients were studied 3 and ≥ 18 months after closure of the temporary ileostomy. Increased stool mass was found in all patients and was unchanged with time. Moderate steatorrhoea was present in 29% of the patients 3 months postoperatively, but faecal fat excretion normalized with time. Calcium absoption was normal in all but one patient regardless of time after operation. An abnormal bacterial deconjugatio, evaluated by a 14C-glycocholic acid breath test was present in 27% of the patients and increased significantly with time. 40% of the patients had increased faecal bile acid excretion. B12 malabsorption was present in 29-35% of the patients. In conclusion, ileal J-pouch anastomosis for ulcerative colitis causes increased stool mass in all patients and produces moderate bile acid deconjugation and malabsoption in about one-third to half. Substitution therapy with vitamin B12 is necessary in about one-third of the patients. Intestinal adaptation as far as absorption is concerned is minimal after the first 3 postoperative months. 29 refs., 8 figs

  5. Ultraviolet transient absorption, transient grating and photon echo studies of aqueous tryptophan

    Ajdarzadeh, Ahmad; Consani, Cristina; Bräm, Olivier; Tortschanoff, Andreas; Cannizzo, Andrea [Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire de Spectroscopie Ultrarapide, ISIC, Station 6, FSB, CH-1015 Lausanne (Switzerland); Chergui, Majed, E-mail: Majed.chergui@epfl.ch [Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire de Spectroscopie Ultrarapide, ISIC, Station 6, FSB, CH-1015 Lausanne (Switzerland)

    2013-08-30

    Highlights: ► We report ultrafast UV studies of tryptophan in water. ► We compared UV transient absorption, photon echo, transient grating and ultrafast fluorescence. ► The results are consistent between these techniques, suggesting avenues for 2D coherent UV spectroscopies. - Abstract: We compare UV transient grating (TG) experiments of aqueous tryptophan with transient absorption (TA) and fluorescence up-conversion measurements. The TG and TA signals show a bi-exponential rise with sub-ps and ps time constants, which are consistent with the fluorescence studies. Using experimental data, we provide an equation for the homodyne-detected TG signal, taking into account the sub-100 fs internal conversion of tryptophan after excitation. In addition, we measure a sub-100 fs homogeneous electronic dephasing time for tryptophan in water by the photon echo (PE) technique. These measurements provide a consistent picture of excited state dynamics of aqueous tryptophan that may serve as a basis for coherent 2D-UV spectroscopy of biosystems.

  6. Ultraviolet transient absorption, transient grating and photon echo studies of aqueous tryptophan

    Highlights: ► We report ultrafast UV studies of tryptophan in water. ► We compared UV transient absorption, photon echo, transient grating and ultrafast fluorescence. ► The results are consistent between these techniques, suggesting avenues for 2D coherent UV spectroscopies. - Abstract: We compare UV transient grating (TG) experiments of aqueous tryptophan with transient absorption (TA) and fluorescence up-conversion measurements. The TG and TA signals show a bi-exponential rise with sub-ps and ps time constants, which are consistent with the fluorescence studies. Using experimental data, we provide an equation for the homodyne-detected TG signal, taking into account the sub-100 fs internal conversion of tryptophan after excitation. In addition, we measure a sub-100 fs homogeneous electronic dephasing time for tryptophan in water by the photon echo (PE) technique. These measurements provide a consistent picture of excited state dynamics of aqueous tryptophan that may serve as a basis for coherent 2D-UV spectroscopy of biosystems

  7. Experimental study of absorption of iron in foods using whole-body counter

    Male rats of Wistar strain which showed normal hematological picture were given 59Fe-labeled foods orally, and the iron absorption rate was determined by an animal whole body counter. When 59Fe was given in a mixture with each of gruel, spinach, cow's milk, the yolk, and the yolk with orange juice, the iron absorption rates in each food were 9.4%, 8.9%, 6.6%, 10.8% and 7.2% respectively. None of these foods seemed to inhibit the 59Fe absorption. When 59Fe was given in a mixture with chicken, the iron absorption rate was 35.8%. This result suggested that the chicken promoted the 59Fe absorption. When the yolk labeled in vivo with 59Fe was given, the iron absorption rate was 4.9%. If the yolk labeled in vitro was used, the absorption rate was 10.8%. When the yolk labeled in vivo with 59Fe was given with orange juice, the iron absorption rate was 13.3%. If the yolk labeled in vivo with 59Fe was given, the absorption rate was 7.2%. Orange juice had no effect on the iron absorption when the yolk labeled in vitro was used. After chicken eggs labeled in vivo with 59Fe was given to children, the iron absorption was determined by a whole body counter; the rate averaged 5.4 in the children without anemia and 24.7 in those with anemia. (Ueda, J.)

  8. Simple spectrophotometric methods for quantification of modafinil us-ing 1,2-naphthoquinone-4-sulphonate and 2,4-dinitrophenol as analyti-cal reagents

    Burla Sunitha Venkata Seshamamba

    2014-10-01

    Full Text Available Two simple visible spectrophotometric methods are developed and validated for the quantifica-tion of modafinil using 1,2-naphthoquinone-4-sulphonic acid (NQS method and 2,4-dinitrophenol (DNP method as analytical reagents. The NQS method involves the reaction of modafinil with 1,2-naphthoquinone-4-sulphonate in alkaline medium at room conditions to form a yellow colored product exhibiting maximum absorption at 430 nm. DNP method is based on the proton transfer from 2,4-dinitrophenol to modafinil at room conditions and then we have the formation of yellow colored ion-pair complex exhibiting maximum absorption at 475 nm. Dif-ferent variables affecting the reaction were studied and optimized. Under the optimized experi-mental conditions, Beer's law is obeyed in the concentration ranges of 10-100 and 8-60 μg/mL with the detection of limit values of 0.486 and 0.258 μg/mL for NQS method and DNP method, respectively The molar absorptivity and Sandell's sensitivity for both of the methods are report-ed. The methods were validated in terms of accuracy, precision and robustness. The results were satisfactory. The proposed methods were effectively applied to the analysis of the modafinil in their tablet formulations. The recoveries were 99.92% and 99.96% with RSD and 0.863% and 0.722% for NQS and DNS methods, respectively. The assay was not interfered by common ex-cipients.

  9. Theoretical studies on the one- and two-photon absorption properties of azulenylporphyrins and azulene-fused porphyrins

    Li Wen-Chao; Feng Ji-Kang; Ren Ai-Min; Zhang Xiang-Biao; Sun Jia-Zhong

    2009-01-01

    The electronic structures, one-photon absorption (OPA) and two-photon absorption (TPA) properties of the azulenylporphyrins and azulene-fused porphyrins have been comparatively studied by using DFT/B3LYP/6-31G(d)and the ZINDO/SDCI method. With the number of azulenyl groups increasing, the OPA wavelengths of all molecules are red-shifted in 400-600 nm and the two-photon absorption cross section is gradually enlarged. The azulene-fused structures facilitate an expanding conjugated area and increasing TPA cross section. The origin of TPA properties of studied compounds is studied with a two-level model. In summary, the azulene-fused porphyrins exhibit strong two-photon absorption.

  10. Simulation study on the performance of solar/natural gas absorption cooling chillers

    Highlights: ► The overall performance of the solar/natural gas chillers is analysed and discussed. ► The system operates in regions with abundant solar energy and cheap natural gas. ► The maximum daily cover of solar energy (between time of day 8 and 17) is about 58%. ► An optimum generator temperature gives a minimum number of flat plate collectors. ► This system compensates the peak-valley load difference and reduces CO2 gas emissions. - Abstract: Solar radiation is a clean form of energy and solar cooling systems is one of the technologies which allow obtaining an important energy saving. Natural gas is a cheaper fuel than oil. It also burns cleaner than oil. Natural gas and renewable energy are complementary and in the future, the alignment of natural gas and renewable energy may be the most effective way to service the demand for clean energy. This paper presents a numerical study of solar/natural gas single effect lithium bromide absorption chillers. The development of this system is based on hot water chiller. As auxiliary power, fire from the natural gas burners is used to heat the hot water on its way to the generator. The overall performance of the absorption chiller system is analysed and discussed. For an evaporator temperature of 5 °C and when the condenser temperature is varied from 28 °C to 36 °C and generator temperatures is varied from 54 to 83 °C the maximum COP is 0.82 and the maximum exergetic efficiency is about 30%. For a given condenser temperature there is an optimum generator temperature for which the number of flat plate collectors is minimum. This optimum generator temperature corresponds to the generator temperature giving the maximum COP and exergy efficiency of the absorption cooling system. The solar/natural gas single effect lithium bromide absorption chillers, using solar energy as the energy source with only limited amount of gas as auxiliary power, not only reduces greatly the cost for electricity and operates in

  11. Atomic Transition Frequencies, Isotope Shifts, and Sensitivity to Variation of the Fine Structure Constant for Studies of Quasar Absorption Spectra

    Berengut, J. C.; Dzuba, V. A.; Flambaum, V. V.; King, J. A.; Kozlov, M. G.; Murphy, M. T.; Webb, J. K.

    Theories unifying gravity with other interactions suggest spatial and temporal variation of fundamental "constants" in the Universe. A change in the fine structure constant, α = {e}2/hslash c , could be detected via shifts in the frequencies of atomic transitions in quasar absorption systems. Recent studies using 140 absorption systems from the Keck telescope and 153 from the Very Large Telescope, suggest that α varies spatially (61). That is, in one direction on the sky α seems to have been smaller at the time of absorption, while in the opposite direction it seems to have been larger.

  12. Study of the influence on radiation, chemical and thermic treatment in Cesium and Cobalt absorption in natural zeolites

    The influence of radiation and thermic treatment of zeolites from El Piojillo (Villa Clara), Orozco (Pinar del Rio) and Palmarito (Santiago de Cuba) deposits in the absorption of cesium-137 is studied. It was verified that as it generally occurs in zeolites, the thermic treatment influences negatively the absorption and the radiation treatment with dose up to 105 Gy does not affect it. Alternatives to chemical and chemical-thermic treatment for zeolite from El Piojillo are also applied. It was noted that previous treatment with NH4OH at 2000C in the vacuum stove and its contact in dynamic regime with NaNO3 improves its capacity of cobalt absorption

  13. An experimental study on relationship between hammett substituent constant and electronic absorption wavelength of some azo dyes

    SIDIR, Yadigar GÜLSEVEN; Sidir, Isa; BERBER, Halil; Tasal, Erol

    2011-01-01

    In this study, absorption spectra of sixteen azo dyes have been recorded in various solvents. These azo dyes have substituents such as OH, SO3H, Cl, I, NO2, C2H5 and OCH3 in different positions of phenyl ring. There is a shift in ?max whose amount is dependent upon the type and position of substituent on the ring. The effects of substituent on the absorption spectra of azo dyes are interpreted by correlation of absorption maximum wavelengths (nm) with the hammett substituent parameters. Charg...

  14. Spectrophotometric study on the proton transfer reaction between 2-amino-4-methylpyridine with 2,6-dichloro-4-nitrophenol in methanol, acetonitrile and the binary mixture 50% methanol + 50% acetonitrile

    Al-Ahmary, Khairia M.; Habeeb, Moustafa M.; Al-Obidan, Areej H.

    2016-02-01

    Proton transfer reaction between 2-amino-4-methylpyridine (2AMP) as the proton acceptor with 2,6-dichloro-4-nitrophenol (DCNP) as the proton donor has been investigated spectrophotometrically in methanol (MeOH), acetonitrile (AN) and a binary mixture composed of 50% MeOH and 50% AN (AN-Me). The composition of the complex has been investigated utilizing Job's and photometric titration methods to be 1:1. Minimum-maximum absorbance equation has been applied to estimate the formation constant of the proton transfer reaction (KPT) where it reached high values in the investigated solvent confirming its high stability. The formation constant recorded higher value in AN compared with MeOH and mixture of AN-Me. Based on the formation of stable proton transfer complex, a sensitive spectrophotometric method was suggested for quantitative determination of 2AMP. The Lambert-Beer's law was obeyed in the concentration range 0.5-8 μg mL- 1 with small values of limits of detection and quantification. The solid complex between 2AMP with DCNP has been synthesized and characterized by elemental analysis to be 1:1 in concordant with the molecular stoichiometry in solution. Further analysis of the solid complex was carried out using infrared and 1H NMR spectroscopy.

  15. Development Of New Visible Spectrophotometric Methods For Quantitative Determination Of Almotriptan Malate As An Active Pharmaceutical Ingredient In Formulations

    U. Viplava Prasad

    2012-06-01

    Full Text Available Purpose: The aim of the investigation was to see the simple and sensitive visible spectrophotometric methods for the determination of the almotriptan malate in bulk and tablet dosage forms. Methods: Two simple, sensitive and cost effective visible spectrophotometric methods (M1-M2 were developed for the estimation of almotriptan malate in bulk and dosage forms. The first method (M1 is based on the formation of blue reduced product by treating drug with Folin Ciocalteu (FC reagent in the presence of sodium carbonate solution with an absorption maximum of 770nm. The second method (M2 is based on the complex formation product by drug with 1, 10-phenanthroline in the presence of Fe (III as an oxidant in phosphoric acid medium with an absorption maximum of 510nm. Results: Beer’s law obeyed in the concentration range of 4-12μg/ml and 1-5 μg/ml for methodM1 and M2 respectively. No interference was observed from the usually existing additives in pharmaceutical formulations and the applicability of the methods was examined by analyzing AXERT tablets containing AM. Conclusion: The reported methods for its assay involve sophisticated equipment, which are very costly and pose problems of maintenance. To overcome these problems, the use of visible spectrophotometric technique is justifiable. The statistical data proved the accuracy, reproducibility and the precision of the proposed methods.

  16. EPR and optical absorption studies of VO2+ ions in alkaline earth aluminoborate glasses

    Electron paramagnetic resonance (EPR) and optical absorption studies have been carried out for VO2+ ions in calcium aluminoborate glasses. The EPR spectra of all the glass samples exhibit resonance signals, characteristic of VO2+ ions. The values of spin-Hamiltonian parameters indicate that the VO2+ ions in calcium aluminoborate glasses were present in octahedral co-ordination with a tetragonal compression and belong to C4v symmetry. The number of spins (N) participating in resonance was calculated as a function of concentration as well as temperature. It is observed that variation of N with temperature obeys the Boltzmann law. From the EPR data, the paramagnetic susceptibility (χ) is calculated at various temperatures and the Curie constant (C) was evaluated from the 1/χ-T graph. The Fermi contact interaction parameter (k), dipolar hyperfine coupling parameter (P) have been calculated and these values are found to be independent of V2O5 content and temperature. The optical absorption spectrum exhibits two bands corresponding to the d-d transition 2B2g → 2Eg and 2B2g → 2A1g in the order of increasing energy. The theoretical values of optical basicity (Λth) of the glasses have also been evaluated

  17. Chiral photochromic compounds as optical molecular sensors. An absorption, fluorescence and CD-spectroscopic study

    Complete text of publication follows. Spiropyrans are photochromic compounds investigated widely for their potential applications in molecular sensors, switches and 3D-memories. Their photochromism is essentially an equilibrium between a colored and a colorless isomer, which can be shifted by irradiation with UV or visible light. The crowned chiral conjugates CSP1, CSP2 and CSP3 were synthesized in our laboratory. In order to characterize these hosts as potential molecular optical sensors, their photochromism and complex formation with metal ions and chiral amino guests were studied by absorption, fluorescence and CD-spectroscopy. Irradiation by UV light induces a ring-opening reaction in the spiropyrane moieties of CSP1-3. The addition of metal ions and chiral amino guests shifts the equilibrium towards the open-ring form under dark conditions. The analysis of the absorption, fluorescence and CD spectra shows large equilibrium constants for complexations of Li+, Ca2+, Ba2+ and Mg2+ ions. In the reactions with chiral guests moderate enantioselectivities were observed.

  18. Resonant inverse photoemission study of late transition metals at 3p absorption edge

    Full text: Resonant inverse photoemission spectra (RIPES) of late transition metals (TM) were observed near TM 3p absorption edge. The RIPES spectra of polycrystalline Co, Ni and Cu, as well as single crystal Ni, were observed. Figure 1 shows resonant IPES spectra of polycrystalline Co, Ni and Cu, which were prepared by evaporation. These spectra ware excited by energy above 3p absorption edge (off-resonance). Since a core hole is created by these energies, TM 3d → 3p fluorescence peak is observed in each spectrum at high energy, which is indicated by vertical bars. The main peak just above EF is TM 3d structure, while TM 4sp is observed at 10 ∼ 15 eV. In resonant spectra, the 3d structure changes its intensity, while the 4sp structure does not. In case of Ni metal, satellite structures are also observed at about 2 and 4 eV. From a calculation by Tanaka and Jo, which is based on the Anderson impurity model, the observation of satellite structures suggests the 10 ∼ 20 % 3d8 in ground state The RIPES spectra in this study give us a direct evidence of 3d8 component in Ni metal

  19. Study of the influence of chemical binding on resonant absorption and scattering of neutrons

    At present time the problem of taking into account of the crystalline binding in the heavy nuclei resonance range is not correctly treated in nuclear data processing codes. The present work deals separately with resonant absorption and scattering of neutrons. The influence of crystalline binding is considered for both types of reactions in the harmonic crystal frame work. The harmonic crystal model is applied to the study of resonant absorption cross sections to show the inconsistency of the free gas model widely in use in reactor neutronics. The errors due to the use of the latter were found to be non negligible. These errors should be corrected by introducing a more elaborated harmonic crystal model in codes for resonances analysis and on the nuclear data processing stage. Currently the influence of crystalline binding on transfer cross section in the resonance domain is taken into account in a naive manner using the model of the free nucleus at rest in the laboratory system. In this work I present a formalism (Uncoupled Phonon Approximation) which permits to consider in more detail the crystalline structure of the nuclear fuel. This formalism shows new features in comparison with the static model. (author)

  20. X-ray absorption studies of graphite intercalates and metal-ammonia solutions

    X-ray absorption spectroscopy (XAS) was used to study the arsenic fluorocomplexes, including the AsF5 and AsF6- intercalates of graphite, and rubidium metal-ammonia solutions. The As-F distances obtained for AsF3 and AsF5 gas are both in excellent agreement with electron diffraction data (within 0.004 A). A superior measurement which is significantly shorter than the accepted value of the bond distance in an undistorted AsF6- octahedra is reported. Both the XAES and EXAFS data presented support the hypothesis that the AsF5 oxidizes graphite upon intercalation to produce AsF6- and AsF3 intercalant species. Changes in the Rb K-edge features which are consistent with the known properties of Rb-NH3 are correlated with conductivity and delocalization of the solvated electrons. In the XAES region, intensity and position changes of absorption transitions are explained. In the EXAFS region, the Rb-N bond distance and the relative number of nitrogen atoms in the first shell are measured. XAS has been shown to provide unique information about the nature of the metal-ammonia phase separation, phase transition, and density fluctuations

  1. Theoretical studies of electron absorption by ion cyclotron RF fast waves

    A leading alternate method for central current drive in reactor grade plasmas involves the use of low frequency ion cyclotron RF (ICRF) fast waves at f0 CT, where fCT is the tritium ion cyclotron frequency. The absorption mechanisms in this case are a combination of electron transit time magnetic pumping (TTMP) and electron Landau damping (ELD). A toroidal full-wave ICRF code was recently implemented at MIT which should provide an ideal tool for studying such ICRF current drive scenarios. This code is a finite element calculation which employs a spectral expansion of the electric field in poloidal Fourier modes. The code takes into account non-circular geometry of flux surfaces and includes the effect of the poloidal magnetic field. Variation in the parallel refractive index (nparallel) of the injected ICRF waves can be properly treated with this model, thus providing accurate estimates of the parameter ω/kparallelvte. Presently, the calculation of electron absorption in this code is being modified to properly account for the combined effects of electron TTMP and ELD. Results are presented for proposed fast wave current drive experiments on DIII-D. 2 refs

  2. [Study on Differential Optical Absorption Spectroscopy Data Processing Based on Chirp-Z Transformation].

    Zheng, Hai-ming; Li, Guang-jie; Wu, Hao

    2015-06-01

    Differential optical absorption spectroscopy (DOAS) is a commonly used atmospheric pollution monitoring method. Denoising of monitoring spectral data will improve the inversion accuracy. Fourier transform filtering method is effectively capable of filtering out the noise in the spectral data. But the algorithm itself can introduce errors. In this paper, a chirp-z transform method is put forward. By means of the local thinning of Fourier transform spectrum, it can retain the denoising effect of Fourier transform and compensate the error of the algorithm, which will further improve the inversion accuracy. The paper study on the concentration retrieving of SO2 and NO2. The results show that simple division causes bigger error and is not very stable. Chirp-z transform is proved to be more accurate than Fourier transform. Results of the frequency spectrum analysis show that Fourier transform cannot solve the distortion and weakening problems of characteristic absorption spectrum. Chirp-z transform shows ability in fine refactoring of specific frequency spectrum. PMID:26601381

  3. Femtosecond Transient Absorption Studies in Cadmium Selenide Nanocrystal Thin Films Prepared by Chemical Bath Deposition Method

    M. C. Rath

    2007-01-01

    Full Text Available Dynamics of photo-excited carrier relaxation processes in cadmium selenide nanocrystal thin films prepared by chemical bath deposition method have been studied by nondegenerate femtosecond transient pump-probe spectroscopy. The carriers were generated by exciting at 400 nm laser light and monitored by several other wavelengths. The induced absorption followed by a fast bleach recovery observed near and above the bandgap indicates that the photo-excited carriers (electrons are first trapped by the available traps and then the trapped electrons absorb the probe light to show a delayed absorption process. The transient decay kinetics was found to be multiexponential in nature. The short time constant, <1 picosecond, was attributed to the trapping of electrons by the surface and/or deep traps and the long time constant, ≥20 picoseconds, was due to the recombination of the trapped carriers. A very little difference in the relaxation processes was observed in the samples prepared at bath temperatures from 25∘C to 60∘C.

  4. Spectrophotometric determination of zirconium with Chrome Azurol s in aqueous streams of nuclear fuel reprocessing

    A sensitive and reproducible spectrophotometric method for the determination of zirconium is developed. The method is based on the formation of stable bluish violet colour complex with Chrome Azurol S (CAS) with maximum absorption at 598 nm. The complex formed obeys Beer's law in the range of 1-7 μg/mL. Under optimum conditions, the sensitivity of the proposed method, (i.e. the detection limit), molar absorptivity and Sandell's sensitivity values are 2.42 μg/mL, 3.93 x103 L.Mol-1.cm-1 and 2.54 x 10-4 μg/cm2 respectively. Relative standard deviation is less than 2% and correlation coefficient is 0.997. The present method is highly sensitive, selective, rapid and simple. It can be applied for the direct determination of zirconium in environmental, industrial, water and nuclear reprocessing samples. (author)

  5. Study of interplanetary hydrogen from Lyman alpha emission and absorption determination

    The purpose of the work submitted in this paper is to contribute to the study of interplanetary hydrogen from Lyman alpha emission and absorption measurements, carried out on board the D2A, OSO-8 and Copernicus satellites. This study, which was undertaken from the D2A satellite, moved us to study the interplanetary environment as from observations made from the following experiments placed on board the OSO-8 and Copernicus satellites. The experiment set up on board the OSO-8 satellite made it possible to obtain the profile of the solar alpha Lyman emission. An absorption profile was observed for the first time on these profiles and this made it possible to attribute them to interplanetary hydrogen and enabled us to make a direct and local determination of the solar ionization rate. - The spectrometer set up on board Copernicus made it possible to obtain the emission spectrum of the interplanetary environment at the same time as the geocorona. The overall velocity of the interplanetary environment was deduced from the Doppler shift between the two spectra. In the first part, the principle of the REA and POLAR experiments is recalled but only the REA experiment is described in detail, particularly the problems arising from the construction and calibration of the cell. In the second part, a study of the interplanetary environment made from the D2A determinations is presented in synthesized form. On the other hand, the study to which theses initial results led us is presented in detail. Finally, in the third part, the results obtained by means of the OSO-8 and Copernicus satellites are given

  6. An Atlas of Spectrophotometric Landolt Standard Stars

    Stritzinger, M; Hamuy, M; Challis, P M; Demarco, R; Germany, L; Soderberg, A M; Stritzinger, Maximilian; Suntzeff, Nicholas B.; Hamuy, Mario; Challis, Peter; Demarco, Ricardo; Germany, Lisa

    2005-01-01

    We present CCD observations of 102 Landolt standard stars obtained with the R-C spectrograph on the CTIO 1.5 m telescope. Using stellar atmosphere models we have extended the flux points to our six spectrophotometric secondary standards, in both the blue and the red, allowing us to produce flux-calibrated spectra that span a wavelength range from 3050 \\AA to 1.1 \\micron. We find mean differences between $UBVRI$ spectrophotometry computed using Bessell's standard passbands and Landolt's published photometry to be 1% or less. Observers in both hemispheres will find these spectra useful for flux-calibrating spectra and through the use of accurately constructed instrumental passbands be able to compute accurate corrections to bring instrumental magnitudes to any desired standard photometric system (S-corrections). In addition, by combining empirical and modeled spectra of the Sun, Sirius and Vega, we calculate and compare synthetic photometry to observed photometry taken from the literature for these three stars.

  7. The spectrophotometric determination of boron in tourmalines

    LJILJANA JAKSIC

    2005-02-01

    Full Text Available A procedure for the spectrophotometric determination of macro amounts of boron in tourmaline with azomethine H is described. The used tourmaline concentrate was obtained by magnetic separation and heavy-liquids purification of the schorl zone of pegmatite or granite aplite. The samples of tourmaline were decomposed by fusion with anhydrous sodium carbonate and taken up in dilute hydrochloric acid. The interfering effects of iron and aluminium were eliminated by masking with an EDTA – NTA solution. After pH adjustment, the boron was reacted with azomethine H and the absorbance of the obtained coloured complex was measured at 415 nm. The results are compared with those obtained by other procedures. The relative error of the determination was less than 3 %.

  8. Spectrophotometric investigation of hydrolysis of orthovanadate ion

    Equilibrium constants determined by the spectrophotometric method at 25 deg C and ion forces 0.5, 1.0, 2.0, 3.0 for the reactions VO43-+H+=HVO42- (1); HVO42-+OH-=VO43-+H2O (2), in which lgK are respectively equal to 13.34+-0.01; 13.28+-0.02; 13.15+-0.02; 13.10+-0.03 for reaction (1) and 0.37+-0.01; 0.45+-0.02; 0.75+-0.01; 0.90+-0.03 for reaction (2) in NaCl medium as well as 13.40+-0.02; 13.37+-0.03; 13.35+-O.02; 13.33+-0.03 for reaction (1) and 0.34+-0.01; 0.38+-0.03; 0.54+-0.02; 0.69+-0.02 for reaction (2) in KCl medium

  9. Spectrophotometric determination of azathioprine in pharmaceutical formulations.

    Lakshmi, C S; Reddy, M N

    1998-12-01

    Four simple and sensitive visible spectrophotometric methods (A-D) have been described for the assay of azathioprine (ATP) either in pure form or in pharmaceutical formulations. Methods A and B are based on the oxidation of ATP with excess N-bromosuccinimide (NBS) or chloramine-T (CAT) and determining the consumed NBS or CAT with a decrease in colour intensity of celestine blue (CB) (method A) or gallocyanine (GC) (method B), respectively. Methods C and D are based on the diazotisation of reduced azathioprine (RATP) with excess nitrous acid and estimating either the consumed nitrous acid (HNO(2)) with cresyl fast violet acetate (CFVA) (method C) or by coupling reaction of the diazonium salt formed with N-1-naphthyl ethylene diamine dihydrochloride (NED) (method D). All of the variables have been optimized and the reactions presented. The concentration measurements are reproducible within a relative standard deviation of 1.0%. Recoveries are 99.2-100.3%. PMID:18967434

  10. Spectrophotometric estimation of azithromycin in tablets

    B K Jayanna

    2012-01-01

    Full Text Available The present manuscript describes a simple, sensitive, accurate, precise and economical visible spectrophotometric method for the estimation of azithromycin from tablet formulation. The method is based on the reduction of potassium permanganate in alkaline medium with azithromycin. The measurement of decrease in absorbance of potassium permanganate at 547 nm was done, as it decolourises upon reduction by azithromycin. The method was used to determine between 2 and 20 μg/ml of azithromycin in the final measured solution. There is no interference from the ingredients commonly found in azithromycin tablets with this method. The results for the determination of azithromycin in tablets were in good agreement with the labelled quantities and related analytical parameters are calculated.

  11. Spectrophotometric estimation of azithromycin in tablets.

    Jayanna, B K; Nagendrappa, G; Arunkumar; Gowda, N

    2012-07-01

    The present manuscript describes a simple, sensitive, accurate, precise and economical visible spectrophotometric method for the estimation of azithromycin from tablet formulation. The method is based on the reduction of potassium permanganate in alkaline medium with azithromycin. The measurement of decrease in absorbance of potassium permanganate at 547 nm was done, as it decolourises upon reduction by azithromycin. The method was used to determine between 2 and 20 μg/ml of azithromycin in the final measured solution. There is no interference from the ingredients commonly found in azithromycin tablets with this method. The results for the determination of azithromycin in tablets were in good agreement with the labelled quantities and related analytical parameters are calculated. PMID:23626394

  12. Monte Carlo study of characteristics of uranium L-edge from X-ray absorption spectrometry

    Park, Seunghoon; Kwak, Sung-Woo; Shin, Jung-Ki; Kang, Han-Byeol; Chung, Heejun [Korea Institute of Nuclear Nonproliferation and Control, Daejeon (Korea, Republic of)

    2015-05-15

    L-edge densitometry (LED) which is specially called X-ray Absorption Spectrometry (XAS) for uranium xray analysis is a technique of determination of uranium concentration as a continuous x-ray energy beams transmit a uranium liquid sample for safeguard. Compared to K-edge densitometer, since relatively lower energy of uranium L series energy than K series energy, L-edge densitometer does not require a liquid nitride cooling system. In this study, the simulation of uranium L-edge densitometer is performed using Monte Carlo method. Ledge spectrum, such as spectrum jumps, can be confirmed by the simulation. In further study, improvement of counting efficiency through collimation of x-ray, and shielding will be considered for detailed design of L-edge densitometer.

  13. Experimental study of impact energy absorption in aluminium square tubes with thermal triggers

    Nuno Peixinho

    2012-04-01

    Full Text Available This study presents an approach for the improvement of crashworthiness properties of aluminium tubular structures using initiators introduced through localized heating. The main objective of this approach is to improve the ability to absorb impact energy in a progressive and controlled manner by a local modification of material properties. Through a localized heating in areas previously chosen for initiation, associated with the softening of the aluminium alloy the deformation can be introduced precisely, forcing the tubular structure to deform in a mode of high energy absorption and reducing the maximum load in a controlled manner. This study presents the properties for an aluminium alloy 6061-T5 modified by thermal treatment by the use of a laser beam. Experimental results are presented of quasi-static and impact tests of tubular structures using the proposed approach. This concept appears as possible and effective in the experimental work presented.

  14. USING FLY ASH TO STUDY ON THE MECHANISM OF THE ABSORPTION OF HEAVY METAL IONS IN WASTEWATER

    程建光

    2000-01-01

    Using the method of sedentary thermal experiment, the use of fly ash to remove Zn2+,Cu2+ and Pb2+ in waste water was studied. Special attention was paid to the effects of pH and time degree of activity on absorbing ability. The freundlich model applicable to the absorption data was set. Also the mechanism of absorption and ultra-micro structure of fly ash with the help of TEM was put forward.

  15. Synthesis and Study of Two-photon Absorption Behavior of 3- (3-Arylacryloyl) -chromen-2-one Derivatives

    SONG Hua-Can; LIANG Hui-Fen; SUN Yi-Feng; YAO Jun-Hua

    2003-01-01

    @@ The study on two-photon absorption materials has attracted a lot of attention in recent years, many good re search results have been obtained in the field of two-photon fluorescent microscopy and imaging. [ 1 ~ 4] It was found in our laboratory that some 3-(3-arylacryloyl)-chromen-2-one derivatives possess good two-photon absorption behav-ior, [5] therefore, a series of this family of compounds was synthesized.

  16. Studies of solvent effects on reaction dynamics using ultrafast transient absorption spectroscopy

    Harris, Don Ahmasi

    Ultrafast transient absorption spectroscopy was used to investigate the solvent dependent reaction dynamics of two prototypical chemical systems: (1) The ring-opening reaction of 1,3-cyclohexadiene, the isolated chromophore in Provitamin D, and (2) The photolysis of various Vitamin B12 cofactors. We investigated the influence of solvent polarity on the ground state conformational relaxation of 1,3,5-cis hexatriene subsequent to the ring opening of 1,3-cyclohexadiene in methanol and 1-propanol solvents. Comparisons to the conformational relaxation in alkane solvents studied earlier demonstrated a surprising influence of solvent polarity on single bond isomerization. Temperature dependent transient absorption measurements were performed on 1,3,5-cis hexatriene in cyclohexane and 1-propanol to determine the effect of solvent polarity on the activation energy barrier for ground state single bond isomerization. These measurements conclude that the polar solvent lowers the energy barrier for single bond isomerization allowing conformational relaxation to proceed faster in alcohol solvents compared to alkane solvents. With no perceived polar transition state for single bond isomerization, this result disagrees with the conventional view of solvation and differentiates the single bond isomerization dynamics of polyenes from alkanes. Transient absorption spectroscopy was also utilized to study the solvent effects in the photolysis of various B12 cofactors in different environments. We investigated the solvent dependent photolysis of adenosylcobalamin, methylcobalamin, and cyanocobalamin in water and ethylene glycol as a function of solvent temperature. In comparing the radical cage escape of adenosylcobalamin and cyanocobalamin, we determined a larger than expected hydrodynamic radii for the diffusing radicals in water compared to ethylene glycol, thus making necessary a revised perspective of solvent interaction with the diffusing radical. In addition, we investigated the

  17. Application of UV-Vis spectrophotometric and chemiluminescent methods for evaluation of the antioxidant action of curcumin

    Stanchev Stancho

    2012-01-01

    Full Text Available Curcumin (1,7-bis(4-hydroxy-3-methoxyphenyl-1,6-heptadiene-3,5- dione is a natural biological active substance with an antioxidant activity. The ability of curcumin to inhibit the free radical mechanisms can be used in a prevention of diseases such as cancer and coronary heart disease. The UV-VIS spectrophotometric and chemiluminescent dynamic methods for determination of antioxidant activity of curcumin were developed. The spectrophotometric method includes investigation of the interaction between DNA, isolated from HL-60 cells, and curcumin. The decreasing of the absorption of curcumin in the presence of HL-60 DNA against the blank sample can be a measurement for some complex formation between curcumin and DNA. The chemiluminescent method involves three tests for detection of luminol - depending chemiluminescence on the base of model systems which generate superoxide, hydroxide and hypochlorite radicals. The strongest decay of chemilunimescence was registered at the highest concentration of curcumin (100 μmol/L.

  18. Validated spectrophotometric methods for the estimation of moxifloxacin in bulk and pharmaceutical formulations

    Motwani, Sanjay K.; Chopra, Shruti; Ahmad, Farhan J.; Khar, Roop K.

    2007-10-01

    New, simple, cost effective, accurate and reproducible UV-spectrophotometric methods were developed and validated for the estimation of moxifloxacin in bulk and pharmaceutical formulations. Moxifloxacin was estimated at 296 nm in 0.1N hydrochloric acid (pH 1.2) and at 289 nm in phosphate buffer (pH 7.4). Beer's law was obeyed in the concentration range of 1-12 μg ml -1 ( r2 = 0.9999) in hydrochloric acid and 1-14 μg ml -1 ( r2 = 0.9998) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.63 × 10 4 l mol -1 cm -1 and 9.5 ng cm -2/0.001 A in hydrochloric acid; and 4.08 × 10 4 l mol -1 cm -1 and 10.8 ng cm -2/0.001 A in phosphate buffer media, respectively indicating the high sensitivity of the proposed methods. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.0402, 0.1217 μg ml -1 in hydrochloric acid and 0.0384, 0.1163 μg ml -1 in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of moxifloxacin in pharmaceutical formulations (tablets, i.v. infusions, eye drops and polymeric nanoparticles). The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation moxifloxacin in different dosage forms and dissolution studies.

  19. Study on the absorption site of divalent cations in the intestinal loop, using the multitracer technique

    The duodenum is thought to be the principal site for Ca absorption, which showed a significant increase in Ca absorption during pregnancy. The active transport of Mg in the colon may occur in a nonpregnant state, while no such evidence was observed during gestation. The present data suggest that each part of the intestinal loop is responsible for the absorption of a particular cation. (author)

  20. Experimental study of a thermochemical compressor for an absorption/compression hybrid cycle

    Highlights: ► Experimental study of a thermochemical compressor for absorption/compression cycle. ► Spray adiabatic absorber using NH3–LiNO3 solution working fluid. ► It is able to operate between 57 and 110 °C varying concentration between 0.46 and 0.59. ► The increase of absorber pressure decreases the circulation ratio. ► The numerical model performed agrees with the experimental results. -- Abstract: An experimental study of a thermochemical compressor with ammonia–lithium nitrate solution as working fluid has been carried out. This compressor incorporates a single-pass adiabatic absorber and all the heat exchangers are of the plate type: absorber subcooler, generator and solution heat exchanger. The thermochemical compressor has been studied as part of a single-effect absorption chiller hybridized with an in-series low-pressure compression booster. The adiabatic absorber uses fog jet injectors. The generator hot water temperatures for the external driving flow are in the range of 57–110 °C and the absorber pressures range between 429 and 945 kPa. Experimental results are compared with a numerical model showing a high agreement. The performance of the thermochemical compressor, evaluated through the circulation ratio, improves for higher absorber pressures, indicating the potential of pressure boosting. For the same circulation ratio, the driving hot water inlet temperature decreases with the rise of the absorber pressure. The thermochemical compressor, based on an adiabatic absorber, can produce refrigerant with very low driving temperatures, between 57 and 70 °C, what is interesting for solar cooling applications and very low temperature residual heat recovery. Efficiencies and cooling power are offered when this hybrid thermochemical compressor is implemented in a chiller, showing the effect of different operating parameters.

  1. Rotational molecular dynamics of laser-manipulated bromotrifluoromethane studied by x-ray absorption

    We present a computational study of the rotational molecular dynamics of bromotrifluoromethane (CF3Br) molecules in gas phase. The rotation is manipulated with an off-resonant 800 nm laser. The molecules are treated as rigid rotors. Frequently, we use a computationally efficient linear rotor model for CF3Br, which we compare with selected results for full symmetric-rotor computations. The expectation value 2 θ>(t) is discussed. Especially, the transition from impulsive to adiabatic alignment, the temperature dependence of the maximally achievable alignment, and its intensity dependence are investigated. In a next step, we examine resonant x-ray absorption as an accurate tool to study laser manipulation of molecular rotation. Specifically, we investigate the impact of the x-ray pulse duration on the signal (particularly its temporal resolution) and study the temperature dependence of the achievable absorption. Most importantly, we demonstrated that using picosecond x-ray pulses, one can accurately measure the expectation value 2 θ>(t) for impulsively aligned CF3Br molecules. We point out that a control of the rotational dynamics opens up a novel way to imprint shapes onto long x-ray pulses on a picosecond time scale. For our computations, we determine the dynamic polarizability tensor of CF3Br using ab initio molecular linear-response theory in conjunction with wave function models of increasing sophistication: Coupled-cluster singles (CCS), second-order approximate coupled-cluster singles and doubles (CC2), and coupled-cluster singles and doubles (CCSD).

  2. Kinetic and Diagnostic Studies of Molecular Plasmas Using Laser Absorption Techniques

    Within the last decade mid infrared absorption spectroscopy between 3 and 20 μm, known as Infrared Laser Absorption Spectroscopy (IRLAS) and based on tuneable semiconductor lasers, namely lead salt diode lasers, often called tuneable diode lasers (TDL), and quantum cascade lasers (QCL) has progressed considerably as a powerful diagnostic technique for in situ studies of the fundamental physics and chemistry of molecular plasmas. The increasing interest in processing plasmas containing hydrocarbons, fluorocarbons, organo-silicon and boron compounds has lead to further applications of IRLAS because most of these compounds and their decomposition products are infrared active. IRLAS provides a means of determining the absolute concentrations of the ground states of stable and transient molecular species, which is of particular importance for the investigation of reaction kinetics. Information about gas temperature and population densities can also be derived from IRLAS measurements. A variety of free radicals and molecular ions have been detected, especially using TDLs. Since plasmas with molecular feed gases are used in many applications such as thin film deposition, semiconductor processing, surface activation and cleaning, and materials and waste treatment, this has stimulated the adaptation of infrared spectroscopic techniques to industrial requirements. The recent development of QCLs offers an attractive new option for the monitoring and control of industrial plasma processes as well as for highly time-resolved studies on the kinetics of plasma processes. The aim of the present article is threefold: (i) to review recent achievements in our understanding of molecular phenomena in plasmas (ii) to report on selected studies of the spectroscopic properties and kinetic behaviour of radicals, and (iii) to describe the current status of advanced instrumentation for TDLAS in the mid infrared

  3. X-ray absorption studies of gamma irradiated Nd doped phosphate glass

    This paper presents the X-ray absorption near edge structure (XANES) studies of Nd doped phosphate glasses before and after gamma irradiation. The intensity and location of LIII edge white line peak of Nd changes depending on its concentration as well as on the ratio of O/Nd in the glass matrix. The decrease in the peak intensity of white line after gamma irradiation indicates towards reduction of Nd3+ to Nd2+ in the glass matrix, which increases with an increase in the doses of gamma irradiation. Similarity in the XANES spectra of Nd doped phosphate glasses and Nd2O3 suggests that coordination geometry around Nd3+ in glass samples may be identical to that of Nd2O3

  4. X-ray absorption studies of gamma irradiated Nd doped phosphate glass

    Rai, V. N., E-mail: vnrai@rrcat.gov.in [Indus Synchrotron Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India); Rajput, Parasmani; Jha, S. N.; Bhattacharyya, D. [Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India)

    2015-06-24

    This paper presents the X-ray absorption near edge structure (XANES) studies of Nd doped phosphate glasses before and after gamma irradiation. The intensity and location of L{sub III} edge white line peak of Nd changes depending on its concentration as well as on the ratio of O/Nd in the glass matrix. The decrease in the peak intensity of white line after gamma irradiation indicates towards reduction of Nd{sup 3+} to Nd{sup 2+} in the glass matrix, which increases with an increase in the doses of gamma irradiation. Similarity in the XANES spectra of Nd doped phosphate glasses and Nd{sub 2}O{sub 3} suggests that coordination geometry around Nd{sup 3+} in glass samples may be identical to that of Nd{sub 2}O{sub 3}.

  5. Optical absorption and photoluminescence studies of gold nanoparticles deposited on porous silicon

    Amran, Tengku Sarah Tengku; Hashim, Md Roslan; Al-Obaidi, Nihad K. Ali; Yazid, Hanani; Adnan, Rohana

    2013-01-01

    We present an investigation on a coupled system consists of gold nanoparticles and silicon nanocrystals. Gold nanoparticles (AuNPs) embedded into porous silicon (PSi) were prepared using the electrochemical deposition method. Scanning electron microscope images and energy-dispersive X-ray results indicated that the growth of AuNPs on PSi varies with current density. X-ray diffraction analysis showed the presence of cubic gold phases with crystallite sizes around 40 to 58 nm. Size dependence on the plasmon absorption was studied from nanoparticles with various sizes. Comparison with the reference sample, PSi without AuNP deposition, showed a significant blueshift with decreasing AuNP size which was explained in terms of optical coupling between PSi and AuNPs within the pores featuring localized plasmon resonances.

  6. Magnetization and Specific Absorption Rate Studies of Ball-Milled Iron Oxide Nanoparticles for Biomedicine

    P. Burnham

    2013-01-01

    Full Text Available Comparative studies are presented of iron oxide nanoparticles in the 7–15 nm average diameter range ball milled in hexane in the presence of oleic acid. Transmission electron microscopy identified spherical particles of decreasing size as milling time and/or surfactant concentration increased. Micromagnetic characterization via Mössbauer spectroscopy at room temperature yielded broadened magnetic spectroscopic signatures, while macromagnetic characterization via vibrating sample magnetometry of 7-8 nm diameter particles showed largely superparamagnetic behavior at room temperature and hysteretic at 2 K. Zero-field and field-cooled magnetization curves exhibited a broad maximum at ~215 K indicating the presence of strong interparticle magnetic interactions. The specific absorption rates of ferrofluids based on these nanoparticle preparations were measured in order to test their efficacies as hyperthermia agents.

  7. Study on the surface hydroxyl group on solid breeding materials by infrared absorption spectroscopy

    Tanaka, Satoru; Taniguchi, Masaki [Tokyo Univ. (Japan). Faculty of Engineering

    1996-10-01

    Hydroxyl groups on the surface of Li{sub 2}O were studied by using a diffuse reflectance method with Fourier transform infrared absorption spectroscopy at high temperature up to 973K under controlled D{sub 2}O or D{sub 2} partial pressure. It was found that hydroxyl groups could exist on Li{sub 2}O surface up to 973K under Ar atmosphere. Under D{sub 2}O containing atmosphere, only the sharp peak at 2520cm{sup -1} was observed at 973K in the O-D stretching vibration region. Below 973K, multiple peaks due to the surface -OD were observed and they showed different behavior with temperature or atmosphere. Multiple peaks mean that surface is not homogeneous for D{sub 2}O adsorption. Assignment of the observed peaks to the surface bonding structure was also discussed. (author)

  8. A microwave absorption study in the thermochromic SrMnO{sub 3}

    Alvarez, G. [Departamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, 04510 Coyoacan, DF (Mexico)], E-mail: memodin@yahoo.com; Heiras, J. [Centro de Ciencias de la Materia Condensada, Universidad Nacional Autonoma de Mexico, Apartado Postal 356, 22800 Ensenada, BC (Mexico); Castellanos, M. [Facultad de Quimica, Universidad Nacional Autonoma de Mexico, Cd. Universitaria, 04510 Mexico DF (Mexico); Valenzuela, R. [Departamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, 04510 Coyoacan, DF (Mexico)

    2008-07-15

    We report electron paramagnetic resonance (EPR) and magnetically modulated microwave absorption spectroscopy (MAMMAS) studies at X-band (8.8-9.6 GHz) on powdered SrMnO{sub 3} in the 90-400 K temperature range. EPR spectrum shows one broad single-line at room temperature, which is observed only above 280.5 K, being compatible with an antiferromagnetic order. The onset of the para-antiferromagnetic transition has been determined from the temperature dependence of three main parameters extracted from the EPR spectra: resonant field (H{sub res}), peak-to-peak linewidth ({delta}H{sub pp}) and integrated intensity (I{sub EPR}). The MAMMAS response shows a change in the region 276-283 K, compatible with the para-antiferromagnetic transition, without presenting any significant change in the region of thermochromism.

  9. Studies on mass attenuation coefficient, mass energy absorption coefficient and kerma of some vitamins

    Highlights: ► Kerma is essential for nuclear medicine, diagnostics and radiation dosimeter. ► The values of μm and μe/ρ depends on the photon energy and chemical content of vitamins. ► New experiments should be performed to study physical parameters of biomolecules. -- Abstract: The mass attenuation coefficients for some vitamins (retinol, beta-carotene, thiamine, riboflavin, niacinamide, pantothenic acid, pyridoxine, biotin, folic acid, cyanocobalamin, ascorbic acid, cholecalciferol, alpha-tocopherol, ketamine, hesperidin) were determined experimentally and theoretically at 356.61, 661.66, 1250 and 1408.01 keV photon energies by using a NaI(Tl) scintillation detector. Also, the mass energy absorption coefficients and kerma have been calculated. The calculated values were compared with the semi-empirical values for vitamins.

  10. Electronic topological transition in zinc under pressure: An x-ray absorption spectroscopy study

    Zinc metal has been studied at high pressure using x-ray absorption spectroscopy. In order to investigate the role of the different degrees of hydrostaticity on the occurrence of structural anomalies following the electronic topological transition, two pressure transmitting media have been used. Results show that the electronic topological transition, if it exists, does not induce an anomaly in the local environment of compressed Zn as a function of hydrostatic pressure and any anomaly must be related to a loss of hydrostaticity of the pressure transmitting medium. The near-edge structures of the spectra, sensitive to variations in the electronic density of states above the Fermi level, do not show any evidence of electronic transition whatever pressure transmitting medium is used

  11. Hydrogen absorption study of Ti-based alloys performed by melt-spinning

    Ribeiro, R.M.; Lemus, L.F.; Santos, D.S. dos, E-mail: rafaella@metalmat.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (PEMM/COPPEP/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Metalurgica e de Materiais

    2013-11-01

    The hydrogen absorption and desorption of Ti{sub 53}Zr{sub 27}Ni{sub 20} icosahedral quasicrystal (ICQ) and Ti{sub 50}Ni{sub 50} shape memory alloy (SMA) melt-spun ribbons was studied. Samples were exposed to hydrogen gas at 623 K and 4 MPa for 1000 minutes. The total capacity of hydrogen obtained for Ti{sub 53}Zr{sub 27}Ni{sub 20} and Ti{sub 50}Ni{sub 50} was 3.2 and 2.4 wt. % respectively. The Thermal Desorption Spectrometry (TDS) of the hydrogenated alloys shows that both alloys start to desorb hydrogen around 750 K. X-ray diffraction (XRD) patterns, performed after hydrogenation, indicate a complete amorphization of the Ti{sub 53}Zr{sub 27}Ni{sub 20} i-phase alloy, while the Ti{sub 50}Ni{sub 50} alloy remained crystalline after hydride formation. (author)

  12. Study of near infrared absorption spectroscopy of selected pairs of organic solvents for quality control applications

    Organic solvents of various combinations and ratios, such as ethanol/commercial petrol; benzene/ethanol; toluene/commercial petrol and toluene/benzene were studied by near infrared (NIR) absorption spectroscopy. NIR spectrometer of 850-1700 nm produced distinctly separable spectral ranges for all the combinations; 1400 to 1650 nm for ethanol/commercial petrol; 1125 to 1150 nm for benzene/ethanol; 1130 to 1150 nm for toluene/commercial petrol and 1175 to 1210 nm for toluene/benzene. The calibration curves were drawn for the given pair concentrations. From the linear fitting parameters it is evident that each pair has different slope, which establishes reliability of the technique. The results revealed that each solvent in the mixture gives a clear trend of spectral region. This may be used for the analysis of mixtures of organic solvents. The technique may be utilized for the quality assurance. (author)

  13. Efficacy of casein phosphopeptide-amorphous calcium phosphate to prevent stain absorption on freshly bleached enamel: An in vitro study

    Singh Raghuwar

    2010-01-01

    Full Text Available Background: Teeth when subjected to bleaching bring about the desiccation of the enamel, making it more susceptible to stain absorption. While subjecting the freshly bleached enamel surface to various surface treatments of Fluoride and Casein Phosphopeptide - Amorphous Calcium phosphate (CPP-ACP brought about the reduction in stain absorption, which is assessed in this study. Aims: The study aims to evaluate the tea stain absorption on freshly bleached enamel surface of extracted human teeth with varied surface treatment. The stain absorption was evaluated at the end of one hour and 24 hours post bleaching. Materials and Methods: Forty extracted human permanent maxillary central incisors were subjected to bleaching with 10% carbamide peroxide for eight days. They were divided into four groups of 10 each. Group I was control group. Group II was immersed in tea solution without surface treatment, while Group III and IV were immersed in tea solution with surface treatment of topical Fluoride and CPP-ACP respectively. Spectrophotometer was used for color analysis. Results: Surface treatment with CPP-ACP and topical fluoride on freshly beached enamel surface, significantly reduced the stain absorption. Conclusion: Remineralizing agents reduce stain absorption after tooth bleaching.

  14. Nutrition and magnesium absorption.

    Brink, E.J.

    1992-01-01

    The influence of various nutrients present in dairy products and soybean-based products on absorption of magnesium has been investigated. The studies demonstrate that soybean protein versus casein lowers apparent magnesium absorption in rats through its phytate component. However, true magnesium absorption was neither affected by soybean protein in the diet nor by supplemental phytate. The inhibitory influence of soybean protein and phytate on apparent magnesium absorption was found to be cau...

  15. A study of luminescence and absorption spectra of GaP

    Experimental luminescence and absorption spectra of GaP at room temperature are presented. A theoretical analysis has been performed on the luminescence and absorption spectra in GaP. The experimental data are in good agreement with the theoretical results. (author). 18 refs, 8 figs

  16. Vitamin D-mediated calcium absorption in patients with clinically stable Crohn's disease: a pilot study

    Vitamin D is the critical hormone for intestinal absorption of calcium. Optimal calcium absorption is important for proper mineralization of bone in the prevention of osteoporosis and osteoporotic fractures, among other important functions. Diseases associated with gut inflammation, such as Crohn's ...

  17. Validation of spectrophotometric method for lactulose assay in syrup preparation

    Mahardhika, Andhika Bintang; Novelynda, Yoshella; Damayanti, Sophi

    2015-09-01

    Lactulose is a synthetic disaccharide widely used in food and pharmaceutical fields. In the pharmaceutical field, lactulose is used as osmotic laxative in a syrup dosage form. This research was aimed to validate the spectrophotometric method to determine the levels of lactulose in syrup preparation and the commercial sample. Lactulose is hydrolyzed by hydrochloric acid to form fructose and galactose. The fructose was reacted with resorcinol reagent, forming compounds that give absorption peak at 485 nm. Analytical methods was validated, hereafter lactulose content in syrup preparation were determined. The calibration curve was linear in the range of 30-100 μg/mL with a correlation coefficient (r) of 0.9996, coefficient of variance (Vxo) of 1.1 %, limit of detection of 2.32 μg/mL, and limit of quantitation of 7.04 μg/mL. The result of accuracy test for the lactulose assay in the syrup preparation showed recoveries of 96.6 to 100.8 %. Repeatability test of lactulose assay in standard solution of lactulose and sample preparation syrup showed the coefficient of variation (CV) of 0.75 % and 0.7 %. Intermediate precision (interday) test resulted in coefficient of variation 1.06 % on the first day, the second day by 0.99 %, and 0.95 % for the third day. This research gave a valid analysis method and levels of lactulose in syrup preparations of samples A, B, C were 101.6, 100.5, and 100.6 %, respectively.

  18. Study on the improved structure of dye-sensitized solar cells for enhancing light absorption

    LIU Yong; SHEN Hui; DENG Youjun

    2007-01-01

    The absorption coefncients of N719 or N3 dyes at the longer wavelength region (>600 nm)are not enough to catch photons efficiently,but the solar spectrum has a large photon flux in the wavelength region between 500 and 1,000 nm,so it is desirable to enhance the absorption of light by the dye-sensitized solar cells(DSSC)to achieve higher efficiencies.To solve this problem,an improved structure Of DSSC for enhancing light absorption is introduced in this paper, and I-V characteristics of DSSC are measured to illustrate the enhancement of the light absorption and efficiency.As a result,the improved DSSC exhibits higher light absorption and solar-to-electric conversion efficiency than traditional DSSC.

  19. X-ray diffraction and absorption spectroscopic studies on plastic sheets used in green houses

    A study of the morphology and light-transmissivity in nine commercial samples of low-density polyethylene sheets (LDPE) was carried out. The sheets were of the qualities prepared for use in agricultural green houses and tunnels. The sheets were produced by the plastic-film extrusion process in five Jordanian plastic factories. The variations in the samples were determined in terms of crystallinity, crystallite size, crystallite orientation, heat of fusion, and melting point. X-ray diffraction, UV/visible absorption spectroscopy, and differential scanning calorimetry (DSC) techniques were used. The nine samples had relatively small x-ray crystallinity (20-41%) and low DSC crystallinity (21-29%); the crystallite size were relatively large (8.4-13.4 nm), but the crystallites were not well-oriented relative to the extrusion direction. The melting point was in the temperature range 112.7-118.9 degrees celsius, and the heat of fusion was in the range 60.3 - 83.7 J/g. There was no relation between the crystallinity, which was relatively low in all the samples, and the transmissivity of visible light. Annealing of LDPE sheets in vacuum improved the crystallinity especially at temperatures below the melting point. Free annealing resulted in better crystallization than annealing at constant length. Drawing of LDPE sheets improved the crystallinity and crystallite orientation, and samples with higher crystallinity and crystallite orientation showed better transmissivity of visible light. The UV absorption difference among the samples was not remarkable, and x-ray diffraction crystallinity revealed the variations in the morphology more sensitively than the DSC method. 56 refs., 17 figs., 12 tabs. (A.M.H.)

  20. Adsorption of mercury on lignin: Combined surface complexation modeling and X-ray absorption spectroscopy studies

    Adsorption of mercury (Hg) on lignin was studied at a range of pH values using a combination of batch adsorption experiments, a surface complexation model (SCM) and synchrotron X-ray absorption spectroscopy (XAS). Surface complexation modeling indicates that three types of acid sites on lignin surfaces, namely aliphatic carboxylic-, aromatic carboxylic- and phenolic-type surface groups, contributed to Hg(II) adsorption. The bond distance and coordination number of Hg(II) adsorption samples at pH 3.0, 4.0 and 5.5 were obtained from extended X-ray absorption fine structure (EXAFS) spectroscopy analysis. The results of SCM and XAS combined reveal that the predominant adsorption species of Hg(II) on lignin changes from HgCl20 to monodentate complex –C–O–HgCl and then bidentate complex –C–O–Hg–O–C– with increasing pH value from 2.0 to 6.0. The good agreement between SCM and XAS results provides new insight into understanding the mechanisms of Hg(II) adsorption on lignin. - Highlights: ► Lignin exhibits a high Hg(II) adsorption capability. ► Adsorption of Hg(II) on lignin is strongly pH-dependent. ► HgCl20, –C–O–HgCl and –C–O–Hg–O–C– are the main adsorption species of Hg(II). - Adsorption of Hg(II) on lignin is strongly pH-dependent, and the main adsorption Hg(II) species change from HgCl20 to –C–O–HgCl and –C–O–Hg–O–C– as pH increases from 2.0 to 6.0.

  1. [Study on determination of plume velocity by passive differential optical absorption spectroscopy].

    Li, Ang; Xie, Pin-hua; Liu, Wen-qing; Liu, Jian-guo; Dou, Ke; Lin, Yi-hui

    2008-10-01

    Differential optical absorption spectroscopy (DOAS) technique has been used to measure various trace gases in the atmosphere by their strongly structured absorption of radiation in the UV and visible spectral range. Passive DOAS using the zenith scattered sunlight as the light source can obtain the continuous column density distribution of air pollutants (such as SO2 and NO2) by scanning the plume emitted from sources on a mobile platform, then with the plume velocity information the total emission value can be ultimately estimated. In practice it is hard to calculate the total emission because there is no efficient way to accurately get the plume velocity which is the most important parameter. Usually the wind speed near ground is used as the actual plume speed, which constitutes the greatest source of uncertainty in the passive DOAS measurements for the total emission calculation. A passive DOAS method for the determination of plume velocity of pollution source was studied in the present paper. Two passive DOAS systems were placed under the plume along the plume transmission direction to observed the scattered sunlight at one fixed sepasation angle, and then the plume velocity was derived from the time delay resulting from the plume moving a certain distance, and also the plume height needed in the plume velocity calculation was measured by the same two passive DOAS systems. Measurement of the plume emitted from a certain power plant was carried out by the two passive DOAS systems and the plume velocities of 3.6 and 5.4 m x s(-1) at two separate moments were derived. The comparison with the wind speed measured at the same time by the single theodolite wind observation method indicates that this optical remote sensing method based on passive DOAS can be used to determine the plume velocity by monitoring the total emission from sources. PMID:19123375

  2. Study of an intense proton beam profiler based on laser absorption

    Among the challenges of high current proton accelerators, the development of new beam diagnostics is of major importance. The main difficulty for these instruments, is the beam power which deteriorates any instruments used to catch it. The chosen detectors are therefore 'non-interceptive systems. After an introduction concerning characteristics of the used accelerator (chapter I), parameters defining a beam of particles are presented (chapter II). Among these ones, the profile is an important beam characteristic for its transport. After the description of the different types of beam profilers, their problematic application to intense beams is discussed. New physical phenomena have to be used for profilers. Thus, we have prospected optical luminescence phenomena. The light produced during the interaction of protons with the residual gas and/or locally injected is a source of informations on beam characteristics. In chapters III and IV, there is an experimental and theoretical analysis of the luminescence. Chapter V is a direct application of spectroscopic measurements to estimate the output of protons with a non-interceptive technique. With the spectral analysis, the idea of a profiler based on laser absorption is developed. This presentation is both theoretical and experimental (chapters 6 and 7). The laser absorption needs the use of metastable states we define in the chapter 6. The evolution of the metastable states, with time and space, has been rigorously studied to discuss the concept of an optical profiler. Chapter VII presents all the necessary instrumentation for the use of a laser and the first measurements with the beam. At the thesis end, the first recorded profile is presented. An experimental critic is presented with a description of the different sources of errors and the proposed cures. (author)

  3. Theoretical modeling of the spectroscopic absorption properties of luciferin and oxyluciferin: A critical comparison with recent experimental studies

    Highlights: ► The calculated absorption spectra were compared with experimental data. ► Shapes and absorption maxima were reproduced for luciferin and oxyluciferin spectra. ► The effect of the solvent largely changes the electronic transition probabilities. ► Higher excitations provide an important contribution to the main absorption peak. - Abstract: Firefly luciferin and its oxidated form, oxyluciferin, are two heterocyclic compounds involved in the enzymatic reaction, catalyzed by redox proteins called luciferases, which provides the bioluminescence in a wide group of arthropods. Whereas the electronic absorption spectra of D-luciferin in water at different pHs are known since 1960s, only recently reliable experimental electronic spectra of oxyluciferin have become available. In addition oxyluciferin is involved in a triple chemical equilibria (deprotonation of the two hydroxyl groups and keto-enol tautomerism of the 4-hydroxythiazole ring), that obligates to select during an experiment a predominant species, tuning pH or solvent polarity besides introducing chemical modifications. In this study we report the absorption spectra of luciferin and oxyluciferin in each principal chemical form, calculated by means of perturbed matrix method (PMM), which allowed us to successfully introduce the effect of the solvent on the spectroscopic absorption properties, and compare the result with available experimental data.

  4. Tunable Microwave Absorption Frequency by Aspect Ratio of Hollow Polydopamine@α-MnO2 Microspindles Studied by Electron Holography.

    She, Wen; Bi, Han; Wen, Zhiwei; Liu, Qinghe; Zhao, Xuebing; Zhang, Jie; Che, Renchao

    2016-04-20

    A tunable response frequency is highly desirable for practical applications of microwave absorption materials but remains a great challenge. Here, hollow lightweight polydopamine@α-MnO2 microspindles were facilely synthesized with the tunable absorption frequency governed by the aspect ratio. The size of the hard template is a key factor to achieve the unique shape; the polymer layer with uniform thickness plays an important role in obtaining spindles with homogeneous size. With the aspect ratio increasing, the maximum reflection loss, as well as the absorption bandwidth (<-10 dB), increases and then decreases; meanwhile, the microwave absorption band shifts to the low frequency. The optimized aspect ratio of the cavity about the hollow polydopamine@α-MnO2 microspindles is ∼2.8. With 3 mm thickness at 9.7 GHz, the strongest reflection reaches -21.8 dB, and the width of the absorbing band (<-10 dB) is as wide as 3.3 GHz. Via electron holography, it is confirmed that strong charge accumulates around the interface between the polydopamine and α-MnO2 layers, which mainly contributes to the dielectric polarization absorption. This study proposes a reliable strategy to tune the absorption frequency via different aspect ratio polymer@α-MnO2 microspindles. PMID:27027922

  5. Theoretical modeling of the spectroscopic absorption properties of luciferin and oxyluciferin: A critical comparison with recent experimental studies

    Anselmi, Massimiliano, E-mail: m.anselmi@caspur.it [Department of Chemistry, University of Rome ' La Sapienza' , P.le Aldo Moro 5, 00185 Rome (Italy); Marocchi, Simone [Department of Chemistry, University of Rome ' La Sapienza' , P.le Aldo Moro 5, 00185 Rome (Italy); Aschi, Massimiliano [Department of Chemistry, Chemical Engineering and Materials, University of L' Aquila, Via Vetoio (Coppito 1), 67100 Coppito, L' Aquila (Italy); Amadei, Andrea [Department of Chemistry, University of Rome ' Tor Vergata' , Via della Ricerca Scientifica 1, 00133 Rome (Italy)

    2012-01-02

    Highlights: Black-Right-Pointing-Pointer The calculated absorption spectra were compared with experimental data. Black-Right-Pointing-Pointer Shapes and absorption maxima were reproduced for luciferin and oxyluciferin spectra. Black-Right-Pointing-Pointer The effect of the solvent largely changes the electronic transition probabilities. Black-Right-Pointing-Pointer Higher excitations provide an important contribution to the main absorption peak. - Abstract: Firefly luciferin and its oxidated form, oxyluciferin, are two heterocyclic compounds involved in the enzymatic reaction, catalyzed by redox proteins called luciferases, which provides the bioluminescence in a wide group of arthropods. Whereas the electronic absorption spectra of D-luciferin in water at different pHs are known since 1960s, only recently reliable experimental electronic spectra of oxyluciferin have become available. In addition oxyluciferin is involved in a triple chemical equilibria (deprotonation of the two hydroxyl groups and keto-enol tautomerism of the 4-hydroxythiazole ring), that obligates to select during an experiment a predominant species, tuning pH or solvent polarity besides introducing chemical modifications. In this study we report the absorption spectra of luciferin and oxyluciferin in each principal chemical form, calculated by means of perturbed matrix method (PMM), which allowed us to successfully introduce the effect of the solvent on the spectroscopic absorption properties, and compare the result with available experimental data.

  6. DEVELOPMENT AND VALIDATION OF DUAL WAVELENGTH SPECTROPHOTOMETRIC METHOD FOR SIMULTANEOUS ESTIMATION OF CEFIXIME TRIHYDRATE AND OFLOXACIN IN TABLET DOSAGE FORM

    Patel Satish A

    2011-07-01

    Full Text Available The present manuscript describe simple, sensitive, rapid, accurate, precise and economic dual wavelength spectrophotometric method was developed for the simultaneous determination of cefixime trihydrate (CEFI and ofloxacin (OFLO in combined tablet dosage form. The utility of dual wavelength data processing program is its ability to calculate unknown concentration of components of interest in a mixture containing an interfering component. The principle for dual wavelength method is “the absorbance difference between two points on the mixture spectra is directly proportional to the concentration of the component of interest”. The method was based on determination of ofloxacin at 350 nm using its absorptivity value and cefixime at 264 nm after deduction of absorbance due to ofloxacin. The two drugs follow Beer-Lanbert’s law over the concentration range of 2-14 µg/ml. The method was successfully applied to pharmaceutical dosage form because no interference from the tablet excipients was found. The results of analysis have been validated statistically and by recovery studies.

  7. Utility of Redox Reactions for the Spectrophotometric Determination of Tinidazole in pure form and in dosage form

    Two simple and sensitive spectrophotometric methods for the determination of tinidazole in pure form and in dosage forms are described. Both methods are based on redox reactions and use Folin-Ciocalteu (Method A) and ferric ferricyanide (Method B) as chromogenic agents. Method A is based on the measurement of blue coloured species (max: 700nm) produced when the drug is reacted with Foin-Ciocalteu reagent in alkaline medium, whereas the method B involves treating the drug with Iron (III) in acid medium and subsequent interaction of iron (II) with ferricyanide to form Prussian blue measurable at 760nm. The working conditions of both methods have been optimized. Regression analysis of Beer's Law plots showed good correlation in the concentration ranges 5-50 and 5-40 ug ml for methods A and B, respectively. The apparent molar absorptivity and Sandell sensitivity values are calculated to be 5.02 x 1000 and 3.36 x 1000l mol cm, and 69.15 and 103.45 ng cm, respectively, for methods A and B. Detection and qualification limits for both methods are calculated. The methods were successfully applied to the determination of tinidazole in bulk drug and its formulations. Excipients used as additives in formulations did not interfere. Statistical treatment of experimental result indicates that the accuracy and precision of the methods are analytically acceptable. The validity of methods was evaluated by parallel determination by an established procedure, and by recovery studies. (author)

  8. Development and Validation of Spectrophotometric Methods for Determination of Thiamphenicol in Capsule Forms

    Golcu, Aysegul; Tarinc, Derya

    2011-01-01

    A simple and direct spectrophotometric method is developed for the determination of Thiamphenicol (THIA) in pharmaceutical formulations. The optimum conditions for the analysis of phosphate buffer at pH 2.0 of drug is studied. Under the optimum conditions, the  drug could be assayed in the concentration range 1.10-5-6.10-5 M. Detection and quantification limits are calculated.

  9. Spectrophotometric Determination of Pipazethate HCl and Dextromethorphan HBr using Potassium Permanganate

    Gouda, Ayman Abou El-Fetouh; El-Sheikh, Ragaa; El Shafey, Zeineb.; Hossny, Nagda.; El-Azzazy, Rham

    2008-01-01

    Rapid, simple and sensitive validated spectrophotometric methods have been described for the assay of pipazethate HCl (PiCl) and dextromethorphan HBr (DEX) either in pure form or in pharmaceutical formulations. The proposed methods were based on the oxidation of the studied drugs by a known excess of potassium permanganate in acidic medium and estimating the unreacted permanganate with amaranth dye (method A), acid orange II (method B), indigocarmine (method C) and methylene blue (method D), ...

  10. SIMULTANEOUS ESTIMATION OF ABACAVIR, LAMIVUDINE AND ZIDOVUDINE IN COMBINED TABLET DOSAGE FORM BY UV SPECTROPHOTOMETRIC METHOD

    Nagulwar Vaishali P; Bhusari Kishor P

    2011-01-01

    The present study deals with the development of an accurate, economical and reproducible UV spectrophotometric method for the simultaneous estimation of abacavir, lamivudine and zidovudine in pure bulk drug and in combined tablet dosage form. The stock solutions were prepared in acetonitrile followed by the further required dilutions with distilled water. The λ max for abacavir, lamivudine, and zidovudine were observed at 295.6, 279.8 and 266.2 nm respectively and linearity was also shown at ...

  11. Gemifloxacin mesylate: UV spectrophotometric method for quantitative determination using experimental design for robustness

    Clésio Soldateli Paim; Fernanda Führ; Martin Steppe; Elfrides Eva Scherman Schapoval

    2012-01-01

    This study describes the validation of UV spectrophotometric method for quantitative determination of gemifloxacin mesylate (GFM) in tablets using methanol as solvent. The method was specific, linear, precise, exact and robust at 272 and 343 nm. The results confirmed that the method in both wavelengths is valid and useful to the routine quality control of GFM in coated tablets. The validate method was compared to liquid chromatography (HPLC), microbiological assay and visible (VIS) spectropho...

  12. Improved Spectrophotometric Calibration of the SDSS-III BOSS Quasar Sample

    Margala, Daniel; Kirkby, David; Dawson, Kyle; Bailey, Stephen; Blanton, Michael; Schneider, Donald P.

    2015-01-01

    We present a model for spectrophotometric calibration errors in observations of quasars from the third generation of the Sloan Digital Sky Survey (SDSS-III) Baryon Oscillation Spectroscopic Survey (BOSS) and describe the correction procedure we have developed and applied to this sample. Calibration errors are primarily due to atmospheric differential refraction and guiding offsets during each exposure. The corrections potentially reduce the systematics for any studies of BOSS quasars, includi...

  13. Successive spectrophotometric resolution as a novel technique for the analysis of ternary mixtures of pharmaceuticals

    Lotfy, Hayam M.; Tawakkol, Shereen M.; Fahmy, Nesma M.; Shehata, Mostafa A.

    2014-03-01

    A novel spectrophotometric technique was developed for the simultaneous determination of ternary mixtures, without prior separation steps. This technique was called successive spectrophotometric resolution technique. The technique was based on either the successive ratio subtraction or successive derivative subtraction. The mathematical explanation of the procedure was illustrated. In order to evaluate the applicability of the methods a model data as well as an experimental data were tested. The results from experimental data related to the simultaneous spectrophotometric determination of lidocaine hydrochloride (LH), calcium dobesilate (CD) and dexamethasone acetate (DA); in the presence of hydroquinone (HQ), the degradation product of calcium dobesilate were discussed. The proposed drugs were determined at their maxima 202 nm, 305 nm, 239 nm and 225 nm for LH, CD, DA and HQ respectively; by successive ratio subtraction coupled with constant multiplication method to obtain the zero order absorption spectra, while by applying successive derivative subtraction they were determined at their first derivative spectra at 210 nm for LH, 320 nm or P292-320 for CD, 256 nm or P225-252 for DA and P220-233 for HQ respectively. The calibration curves were linear over the concentration range of 2-20 μg/mL for both LH and DA, 6-50 μg/mL for CD, and 3-40 μg/mL for HQ. The proposed methods were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical formulation containing the cited drugs with no interference from other dosage form additives. The proposed methods were validated according to the ICH guidelines. The obtained results were statistically compared with those of the official BP methods for LH, DA, and CD, and with the official USP method for HQ; using student t-test, F-test, and one way ANOVA, showing no significant difference with respect to accuracy and precision.

  14. Catalytic and kinetic spectrophotometric method for determination of vanadium(V by 2,3,4-trihydroxyacetophenonephenylhydrazone

    P.V. Chalapathi

    2014-12-01

    Full Text Available A new catalytic and kinetic spectrophotometric method for the determination of vanadium(V was studied using 2,3,4-trihydroxyacetophenonephenylhydrazone (THAPPH as an analytical reagent. The present method was developed on the catalytic effect of vanadium on oxidation of THAPPH by hydrogen peroxide in hydrochloric acid–potassium chloride buffer (pH = 2.8 at the 20th minute. The metal ion has formed 1:2 (M:L complex with THAPPH. Beer’s law was obeyed in the range 20–120 ng/mL of V(V at λmax 390 nm. The sensitivity of the method was calculated in terms of molar absorptivity (1.999 × 105 L mol−1cm−1 and Sandell’s sensitivity (0.000254 μg cm−2, shows that this method is more sensitive. The standard deviation (0.0022, relative standard deviation (0.56%, confidence limit (±0.0015 and standard error (0.0007 revealed that the developed method has more precision and accuracy. The stability constant was calculated with the help of Asmu’s (9.411 × 10−11 and Edmond’s & Birnbaum’s (9.504 × 10−11 methods at room temperature. The interfering effect of various cations and anions was also studied. The present method was successfully applied for the determination of vanadium(V in environmental and alloy samples. The method’s validity was checked by comparing the results obtained with atomic-absorption spectrophotometry and also by evaluation of results using F-test.

  15. SPECTROPHOTOMETRIC ESTIMATION OF MONTELUKAST FROM BULK DRUG AND TABLET DOSAGE FORM

    S.R. Bhagade

    2013-11-01

    Full Text Available Two Simple, accurate, precise and sensitive spectrophotometric methods for estimation of Montelukast sodium (MON have been developed and validated. The zero order spectroscopic method (Method I and area under curve method (Method II have developed. The proposed methods are validated according to ICH Q2B guidelines. The Montelukast sodium gives maximum absorbance at 241nm in chloroform and observed linearity 2-20 μg/ml for zero order method and 4-20 μg/ml for area under curve method. The stability of drug in chloroform has been studied and drug shows good stability in Chloroform. The recovery by method I and method II are 99.52 ± 0.069, 101.93± 0.11 respectively. The both spectrophotometric methods can be applied for routine analysis of Montelukast sodium in tablet formulation and in bulk drug.

  16. Spectrophotometric determination of metals in Pakistani and foreign brand cigarette tobacco

    Tobacco smoking and related uses are major cause of various diseases in human beings. In the present study forty one various brands of cigarettes from Pakistan, United States, United Kingdom and Japan have been selected for determination of iron, nickel and copper spectrophotometrically. The concentration of Fe, Ni and Cu in tobacco of each forty-one brands of national and foreign brands cigarette is given in this article. The spectrophotometric determination of Fe, Ni and Cu in forty one brands of national and foreign cigarettes reveals that the concentrations of these metals depends on different conditions, such as soil condition, fertilizer and sprays during the tobacco growth. However, Cigarette manufacturing companies could have a significant role in their concentration levels. The results obtained by this technique are in good agreement with the reported literature values. (A.B.)

  17. Kinetic spectrophotometric method for the determination of norfloxacin in pharmaceutical formulations.

    Rahman, Nafisur; Ahmad, Yasmin; Hejaz Azmi, Syed Najmul

    2004-03-01

    A simple and sensitive kinetic spectrophotometric method is described, based on the oxidation of norfloxacin with alkaline potassium permanganate. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 603 nm. The initial rate and fixed time (at 3 min) methods are utilized for constructing the calibration graphs to determine the concentration of the drug. The calibration graphs are linear in the concentration ranges 2.0-20 microg ml(-1) and 1.0-20 microg ml(-1) using the initial rate and fixed time methods, respectively. The results are validated statistically and through recovery studies. The method has been successfully applied to the determination of norfloxacin in commercial dosage forms. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision. PMID:15018997

  18. Large-solid-angle study of pion absorption on 3He

    Measurements have been made of π+ absorption on 3He at Tπ+=118, 162, and 239 MeV using the Large Acceptance Detector System. The nearly 4π solid angle coverage of this detector minimizes uncertainties associated with extrapolations over unmeasured regions of phase space. The total absorption cross section is reported. In addition, the total cross section is divided into components in which only two or all three nucleons play a significant role in the process. These are the first direct measurements of the total and three nucleon absorption cross sections

  19. OPTIMIZING CONDITIONS FOR SPECTROPHOTOMETRIC DETERMINATION OF TOTAL POLYPHENOLS IN WINES USING FOLIN-CIOCALTEU REAGENT

    Daniel Bajčan

    2013-02-01

    Full Text Available Wine is a complex beverage that obtains its properties mainly due to synergistic effect of alcohol, organic acids, arbohydrates, as well as the phenolic and aromatic substances. At present days, we can observe an increased interest in the study of polyphenols in wines that have antioxidant, antimicrobial, anti-inflammatory, anti-cancer and many other beneficial effects. Moderate and regular consumption of the red wine especially, with a high content of phenolic compounds, has a beneficial effect on human health. The aim of this work was to optimize conditions for spectrophotometric determination of total polyphenols in winwas to optimize conditions for spectrophotometric determination of total polyphenols in winwas to optimize conditions for spectrophotometric determination of total polyphenols in winwas to optimize conditions for pectrophotometric determination of total polyphenols in wine using Folin-Ciocaulteu reagent. Based on several studies, in order to minimize chemical use and optimize analysis time, we have proposed a method for the determination of total polyphenols using 0.25 ml Folin-Ciocaulteu reagent, 3 ml of 20% Na2CO3 solution and time of coloring complex 1.5 hour. We f

  20. Spectrophotometric Examination of Rough Print Surfaces

    Erzsébet Novotny

    2011-05-01

    Full Text Available The objective was to assess the impact of the surface texture of individual creative paper types (coated or patternedon the quality of printing and to identify to what extent the various creative paper types require specific types ofspectrophotometers. We used stereomicroscopic images to illustrate unprinted and printed surfaces of creative papertypes. Surface roughness was measured to obtain data on the unevenness of surfaces. Spectrophotometric tests wereused to select the most suitable spectrophotometer from meters with different illumination setup for testing anygiven print. For the purpose of testing, we used spectrophotometers which are commonly available generally used totest print products for colour accuracy. With the improvement of measuring geometries, illumination setup, colourmeasurement becomes more and more capable of producing reliable results unaffected by surface textures. Our testshave proved this fact by showing that the GretagMacbeth Spectrolino with annular illumination is less sensitive tosurface texture than the X-Rite Spetrodensitometer and the Techkon SpetroDens with directional illumination. Furthertests have brought us to the conclusion that there is a difference even between the two devices with directionalillumination. While the X-Rite 530 Spectrodensitometer is more suitable for testing coated surfaces, the TechkonSpectroDens can come close to ΔE*ab values produced by the annular illuminated device for textured surfaces.

  1. An Atlas of Spectrophotometric Landolt Standard Stars

    Stritzinger, Maximilian; Suntzeff, Nicholas B.; Hamuy, Mario; Challis, Peter; Demarco, Ricardo; Germany, Lisa; Soderberg, A. M.

    2005-08-01

    We present CCD observations of 102 Landolt standard stars obtained with the Ritchey-Chrétien spectrograph on the Cerro Tololo Inter-American Observatory 1.5 m telescope. Using stellar atmosphere models, we have extended the flux points to our six spectrophotometric secondary standards, in both the blue and the red, allowing us to produce flux-calibrated spectra that span a wavelength range from 3050 Å to 1.1 μm. Mean differences between UBVRI spectrophotometry computed using Bessell's standard passbands and Landolt's published photometry were determined to be 1% or less. Observers in both hemispheres will find these spectra useful for flux-calibrating spectra, and through the use of accurately constructed instrumental passbands, will be able to compute accurate corrections to bring instrumental magnitudes to any desired standard photometric system (S-corrections). In addition, by combining empirical and modeled spectra of the Sun, Sirius, and Vega, we calculate and compare synthetic photometry to observed photometry taken from the literature for these three stars.

  2. Scintillation response of Xe gas studied by gamma-ray absorption and Compton electrons

    Swiderski, L.; Chandra, R.; Curioni, A.; Davatz, G.; Friederich, H.; Gendotti, A.; Gendotti, U.; Goeltl, L.; Iwanowska-Hanke, J.; Moszyński, M.; Murer, D.; Resnati, F.; Rubbia, A.; Szawlowski, M.

    2015-07-01

    In this study we report on the scintillation response of Xe gas under irradiation of gamma-rays in the energy range between 50 keV and 1.5 MeV. Xe gas was pressurized to 50 bar and tested as a detector for gamma spectroscopy. The gas was confined in a titanium vessel of 200 mm length and 101 mm diameter with 2.5 mm thick walls. The vessel was sealed with two 3 inch diameter UV transparent windows. The inner surface of the vessel was covered with a reflecting wavelength shifter. Two photomultipliers coupled to both windows at the end of the vessel allowed for registration of 3700 photoelectrons/MeV, which resulted in 7.0% energy resolution registered for 662 keV γ-rays from a 137Cs source. The non-proportionality of the photoelectron yield and intrinsic resolution was studied with gamma photoabsorption peaks. Due to the thickness of the detector vessel, the response of the Xe gas as a scintillator in the low energy range was performed by means of a Compton Coincidence Technique and compared with the gamma absorption results. The shape of the non-proportionality characteristics of Xe gaseous scintillator was compared to the results obtained for NaI:Tl, LaBr3:Ce and LYSO:Ce. A correlation between non-proportionality and intrinsic resolution of Xe gaseous scintillator was pointed out.

  3. Shock tube/laser absorption studies of the decomposition of methyl formate

    Ren, Wei

    2013-01-01

    Reaction rate coefficients for the major high-temperature methyl formate (MF, CH3OCHO) decomposition pathways, MF → CH3OH + CO (1), MF →CH2O+CH2O (2), and MF→ CH4 + CO2 (3), were directly measured in a shock tube using laser absorption of CO (4.6 μm), CH2O (306 nm) and CH4 (3.4 μm). Experimental conditions ranged from 1202 to 1607 K and 1.36 to 1.72 atm, with mixtures varying in initial fuel concentration from 0.1% to 3% MF diluted in argon. The decomposition rate coefficients were determined by monitoring the formation rate of each target species immediately behind the reflected shock waves and modeling the species time-histories with a detailed kinetic mechanism [12]. The three measured rate coefficients can be well-described using two-parameter Arrhenius expressions over the temperature range in the present study: k1 = 1.1 × 1013 exp(-29556/T, K) s -1, k2 = 2.6 × 1012 exp(-32052/T, K) s-1, and k3 = 4.4 × 1011 exp(-29 078/T, K) s-1, all thought to be near their high-pressure limits. Uncertainties in the k1, k2 and k3 measurements were estimated to be ±25%, ±35%, and ±40%, respectively. We believe that these are the first direct high-temperature rate measurements for MF decomposition and all are in excellent agreement with the Dooley et al. [12] mechanism. In addition, by also monitoring methanol (CH3OH) and MF concentration histories using a tunable CO2 gas laser operating at 9.67 and 9.23 μm, respectively, all the major oxygen-carrying molecules were quantitatively detected in the reaction system. An oxygen balance analysis during MF decomposition shows that the multi-wavelength laser absorption strategy used in this study was able to track more than 97% of the initial oxygen atoms in the fuel. © 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

  4. X-ray absorption studies of bismuth valence and local environments in borosilicate waste glasses

    Highlights: ► Bi in high level nuclear waste glasses was of interest due to melt foaming issues. ► Bi was also found associated with phosphate in some samples. ► X-ray absorption spectroscopy found similar Bi bonding within all glasses studied. ► The glasses contain Bi3+O3 environments with average Bi–O distances near 2.13 Å. ► No Bi-phosphate glass domains nor any link between Bi and melt foaming were observed. - Abstract: X-ray absorption spectra (XAS) were collected and analyzed to characterize bismuth (Bi) environments in borosilicate glass formulations developed for the immobilization of high level nuclear wastes (HLW), from the bismuth phosphate process. Therefore, the structural role of Bi in these glasses is of interest; in addition in the present study, more particular interest in Bi originated from unusual foaming that was observed during melt cooling, where it was initially suspected that Bi3+ reduction to Bi0 may generate oxygen that caused the foaming. Observations from scanning electron microscopy of some HLW glass samples indicated a Bi-phosphate association. Bi LIII XAS of 13 Bi-containing waste glass formulations of various compositions were measured that exhibited varying degrees of melt foaming. The Bi XAS are similar for all glasses investigated, and indicate Bi3+O3 nearest-neighbor environments with Bi–O distances near 2.13 Å. This environment is similar to the most localized Bi coordination characteristics in the crystalline Bi-silicates, eulytite (Bi4Si3O12) and bismutoferrite (BiFe2Si2O8OH). However, the Bi-environments in the glasses are distinctly different from the Bi-site in crystalline BiPO4; therefore, XAS indicates no evidence of Bi-phosphate domains in the glasses measured. No XAS evidence was observed in any of the glasses investigated for Bi clustering, such as metallic Bi, or Bi–O–Bi bonding. Since the local Bi environments look similar for all glasses investigated, Bi XAS data and analyses show no association

  5. Quantum theory and experimental studies of absorption spectra and photoisomerization of azobenzene polymers

    Pedersen, Thomas Garm; Ramanujam, P.S.; Johansen, P.M.;

    1998-01-01

    The microscopic properties of azobenzene chromophores are important for a correct description of optical storage systems based on photoinduced anisotropy in azobenzene polymers. A quantum model of these properties is presented and verified by comparison to experimental absorption spectra for trans...... and cis isomers of cyano methoxy azobenzene. In addition, the trans --> cis quantum efficiency is measured, and hence the combined experimental and theoretical work allows one to determine the essential molecular properties, including magnitude and anisotropy of the absorption cross section and...

  6. Hierarchical Decomposition Thermodynamic Approach for the Study of Solar Absorption Refrigerator Performance

    Emma Berrich Betouche; Ali Fellah; Ammar Ben Brahim; Fethi Aloui; Michel Feidt

    2016-01-01

    A thermodynamic approach based on the hierarchical decomposition which is usually used in mechanical structure engineering is proposed. The methodology is applied to an absorption refrigeration cycle. Thus, a thermodynamic analysis of the performances on solar absorption refrigerators is presented. Under the hypothesis of an endoreversible model, the effects of the generator, the solar concentrator and the solar converter temperatures, on the coefficient of performance (COP), are presented an...

  7. Nasal Drug Delivery : In Vitro Studies on Factors Influencing Permeability and Implications on Absorption

    Wadell, Cecilia

    2002-01-01

    Nasal delivery is a feasible alternative to oral or parenteral administration for some drugs because of the high permeability of the nasal epithelium, rapid drug absorption across this membrane and avoidance of hepatic first-pass metabolism. The main objective of this thesis was to investigate factors influencing the permeability of the nasal mucosa to various compounds and to evaluate implications for drug absorption via the nasal route. Porcine nasal mucosa mounted in an Ussing chamber sys...

  8. Spectrophotometric determination of trace amounts of cadmium and lead with iodide and rhodamine B

    Highly sensitive spectrophotometric methods have been developed for determination of cadmium and lead, based on the CdI42- or PbI42- anionic complexes with Rhodamine B in the presence of polyvinyl alcohol to form ion-association complexes. The molar absorptivity is 4.2x105 l x mole-1 x cm-1 at 600 nm for cadmium and 5.7x105 l x mole-1 x cm-1 at 610 nm for lead. The complexes have the composition [CdI 42-] x [RhB+]2 and [PbI42-] x [RhB+]2 as established by Job's method of continuous variations and the molar-ratio method. The colour reaction selectivity is fairly good and the method can be applied for direct spectrophotometric determination of cadmium or lead in some pure metals. A species [PbI3-] x [RhB+] can also be formed, and extracted into toluene or a toluene/diethyl ether micture. (Authors)

  9. Extraction-spectrophotometric determination of niobium with 1,2,4,6-tetraphenylpyridinium perchlorate and thiocyanate

    1,2,4,6-Tetraphenylpyridinium (TPP+) as the acetate or perchlorate was used as a counter ion in the spectrophotometric determination of Nb(V) by extraction into toluene of the anionic Nb(V) -thiocyanate complex from 4 to 6 M hydrochloric acid. The molar absorptivity of the ion-association complex, whose composition was shown to be NbOCl(SCN)3-.TPP+, was 2.82 x 104 l mol-1cm-1 at 395 nm. Beer's law was obeyed over the range 0.1 to 2.5 μg ml-1 of Nb(V). The method was applied to the determination of niobium in standard steels and ores with good precision and accuracy. 1-(4'-Nitrophenyl)-2,4,6-triphenylpyridinium (nitro-TPP+) perchlorate was also synthesised and used in the spectrophotometric determination of Nb(V), but did not show advantages over TPP+. The fluorescence of TPP+ and Nb(V)-SCN--TPP+ solutions in toluene also disappeared when nitro-TPP+ was used, owing to the paramagnetic effect of the NO2 group. (author)

  10. Titrimetric and spectrophotometric determination of doxycycline hyclate using bromate-bromide, methyl orange and indigo carmine

    Pavagada Jagannathamurthy Ramesh

    2010-07-01

    Full Text Available One titrimetric and two indirect spectrophotometric methods are described for the determination of doxycycline hyclate (DCH in bulk drug and in its formulations. The methods use bromate-bromide, methyl orange and indigo carmine as reagents. In titrimetry (method A, DCH is treated with a known excess of bromate- -bromide mixture in acid medium and the residual bromine is back titrated iodometrically after the reaction between DCH and in situ bromine is ensured to be complete. In spectrophotometric methods, the excess of bromine is estimated by treating with a fixed amount of either methyl orange (method B or indigo carmine (method C and measuring the change in absorbance either at 520 or 610 nm. Titrimetric method is applicable over 1-8 mg range and the calculations are based on a 1:2 (DCH:bromate stoichiometric ratio. In spectrophotometry, the calibration graphs were found to be linear over 0.25-1.25 and 1.0-5.0 μg mL-1 for method B and C, respectively, with corresponding molar absorptivity values of 2.62×105 and 6.97×104 L mol-1 cm-1. The accuracy and precision of the assays were determined by computing the intra-day and inter-day variations at three different levels of DCH.

  11. Alanine dosimetry using a spectrophotometric ferric-xylenol orange complex readout

    Laere, K. van; Buysse, J.; Berkvens, P. (Ghent Rijksuniversiteit (Belgium). Lab. voor Kernfysica)

    1989-01-01

    The spectrophotometric dosimetric method using the indirect oxidation of ferrous ions after dissolution of irradiated DL-and L-alanine has been thoroughly investigated with respect to its composition, read-out procedure and dose-response. Optimal concentration of 0.10 N H{sub 2}SO{sub 4}, 0.2 mM xylenol orange and 0.2 mM Fe{sup 2+} were found, giving an absorption maximum at 547 nm. Standardization of chemical processing procedures allows a reproducibility better than 0.5%. The useful dose range has been extended to 0.03-12 kGy by means of slightly different read-out procedure. The quantitative concept of ''indirect yield'', G{sub id}, was introduced for this procedure as a measure of the indirect oxidation capacity of the radicals. It was found to be G{sub id,0}(Fe{sup 3+}) 7.1 ions/100 eV transferred into the alanine. The spectrophotometric readout combines the highly advantageous use of alanine as a dosemeter with the straightforwardness, accuracy and low costs of the chemical procedure. (author).

  12. Alanine dosimetry using a spectrophotometric ferric-xylenol orange complex readout

    The spectrophotometric dosimetric method using the indirect oxidation of ferrous ions after dissolution of irradiated DL-and L-alanine has been thoroughly investigated with respect to its composition, read-out procedure and dose-response. Optimal concentration of 0.10 N H2SO4, 0.2 mM xylenol orange and 0.2 mM Fe2+ were found, giving an absorption maximum at 547 nm. Standardization of chemical processing procedures allows a reproducibility better than 0.5%. The useful dose range has been extended to 0.03-12 kGy by means of slightly different read-out procedure. The quantitative concept of ''indirect yield'', Gid, was introduced for this procedure as a measure of the indirect oxidation capacity of the radicals. It was found to be Gid,0(Fe3+) 7.1 ions/100 eV transferred into the alanine. The spectrophotometric readout combines the highly advantageous use of alanine as a dosemeter with the straightforwardness, accuracy and low costs of the chemical procedure. (author)

  13. Unimolecular decomposition of formic and acetic acids: A shock tube/laser absorption study

    Elwardany, A.

    2014-07-16

    The thermal decomposition of formic acid (HCOOH) and acetic acid (CH3COOH), two carboxylic acids which play an important role in oxygenate combustion chemistry, were investigated behind reflected shock waves using laser absorption. The rate constants of the primary decomposition pathways of these acids:(HCOOH → CO + H2 O (R 1); HCOOH → CO2 + H2 (R 2); CH3 COOH → CH4 + CO2 (R 3); CH3 COOH → CH2 CO + H2 O (R 4)) were measured using simultaneous infrared laser absorption of CO, CO2 and H2O at wavelengths of 4.56, 4.18 and 2.93 microns, respectively. Reaction test conditions covered temperatures from 1230 to 1821 K and pressures from 1.0 to 6.5 atm for dilute mixtures of acids (0.25-0.6%) in argon. The rate constants of dehydration (R1) and decarboxylation (R2) reactions of formic acid were calculated by fitting exponential functions to the measured CO, CO2 and H2O time-history profiles. These two decomposition channels were found to be in the fall-off region and have a branching ratio, k1/k2, of approximately 20 over the range of pressures studied here. The best-fit Arrhenius expressions of the first-order rates of R1 and R2 were found to be:(k1 (1 atm) = 1.03 × 1011 exp (- 25651 / T) s- 1 (± 37 %); k1 (6.5 atm) = 9.12 × 1012 exp (- 30275 / T) s- 1 (± 32 %); k2 (1 atm) = 1.79 × 108 exp (- 21133 / T) s- 1 (± 41 %); k2 (6.5 atm) = 2.73 × 108 exp (- 20074 / T) s- 1 (± 37 %)). The rate constants for acetic acid decomposition were obtained by fitting simulated profiles, using an acetic acid pyrolysis mechanism, to the measured species time-histories. The branching ratio, k4/k3, was found to be approximately 2. The decarboxylation and dehydration reactions of acetic acid appear to be in the falloff region over the tested pressure range:(k3 (1 atm) = 3.18 × 1011 exp (- 28679 / T) s- 1 (± 30 %); k3 (6 atm) = 3.51 × 1012 exp (- 31330 / T) s- 1 (± 26 %); k4 (1 atm) = 7.9 × 1011 exp (- 29056 / T) s- 1 (± 34 %); k4 (6 atm) = 6.34 × 1012 exp (- 31330 / T) s

  14. A study on the inhibitory mechanism for cholesterol absorption by α-cyclodextrin administration

    Takahiro Furune

    2014-12-01

    Full Text Available Background: Micelle formation of cholesterol with lecithin and bile salts is a key process for intestinal absorption of lipids. Some dietary fibers commonly used to reduce the lipid content in the body are thought to inhibit lipid absorption by binding to bile salts and decreasing the lipid solubility. Amongst these, α-cyclodextrin (α-CD is reportedly one of the most powerful dietary fibers for decreasing blood cholesterol. However, it is difficult to believe that α-CD directly removes cholesterol because it has a very low affinity for cholesterol and its mechanism of action is less well understood than those of other dietary fibers. To identify this mechanism, we investigated the interaction of α-CD with lecithin and bile salts, which are essential components for the dissolution of cholesterol in the small intestine, and the effect of α-CD on micellar solubility of cholesterol.Results: α-CD was added to Fed-State Simulated Intestinal Fluid (FeSSIF, and precipitation of a white solid was observed. Analytical data showed that the precipitate was a lecithin and α-CD complex with a molar ratio of 1:4 or 1:5. The micellar solubility of cholesterol in the mixture of FeSSIF and α-CD was investigated, and found to decrease through lecithin precipitation caused by the addition of α-CD, in a dose-dependent manner. Furthermore, each of several other water-soluble dietary fibers was added to the FeSSIF, and no precipitate was generated.Conclusion: This study suggests that α-CD decreases the micellar solubility of cholesterol in the lumen of the small intestine via the precipitation of lecithin from bile salt micelles by complex formation with α-CD. It further indicates that the lecithin precipitation effect on the bile salt micelles by α-CD addition clearly differs from addition of other water-soluble dietary fibers. The decrease in micellar cholesterol solubility in the FeSSIF was the strongest with α-CD addition.

  15. Study about the capillary absorption and the sorptivity of concretes with Cuban limestone aggregates

    Howland, J. J.

    2013-12-01

    Full Text Available The objective of this study was to demonstrate the possibility to obtain concretes in Cuba with values of effective porosity below of 10%, using limestone aggregates with high levels of absorption (higher than 1% in many cases, and values of Sorptivity below of 5 x 10-5 m/s1/2 as is established in the document prepared by the DURAR Latin Working Group, for structures exposed to very aggressive environments. The experimental results showed that the use of the trial method of capillary absorption of Göran Fagerlund, were obtained concretes with effective porosity below of the 10%, for water/cement ratios of 0.4 and 0.45, but the values of sorptivities were very high. Nevertheless the subsequent use of the trial method of the ASTM C1585, that use cylinders probes with bigger depth and different processing, permits to obtain the desired sorptivity values for water/cement ratios of 0.4 and 0.45 whenever would be fulfilled the Good Practices of the Construction.El objetivo del estudio fue demostrar la posibilidad de lograr en Cuba, con el empleo de áridos calizos de elevada absorción (mayores del 1% en muchos casos, hormigones con valores de porosidad efectiva inferiores al 10% y de velocidad de absorción capilar (Sorptividad inferiores a 5 x 10-5 m/s1/2, tal como establece el documento elaborado por la RED DURAR del CYTED para estructuras expuestas a ambientes muy agresivos. Los resultados experimentales mostraron que con la aplicación del método de ensayo de absorción capilar de Göran Fagerlund se obtuvieron porosidades efectivas inferiores al 10% para relaciones agua/cemento de 0,4 y 0,45, pero los valores de sorptividad fueron muy elevados. No obstante la aplicación posterior del método de ensayo de la ASTM C1585 que utiliza probetas de mayor espesor y diferente tratamiento, permitió obtener los valores indicados de sorptividad para relaciones agua/cemento de 0,4; 0,45 siempre que se cumplan las Buenas Prácticas constructivas.

  16. Trace determination and separation of tin (II by floatation-spectrophotometric using kalmagyte and CTAB

    Sabah Shiri

    2013-12-01

    Full Text Available A novel floatation-spectrophotometric extraction method was developed for the recovery of tin (II from aqueous samples prior to determination by UV spectrophotometric detection. The method is based on the formation of a complex between tin (II and kalmagyte in pH=8. The complex is floated in the interface of n-hexane and aqueous phases. After removing the aqueous phase, the floated particles are dissolved in methanol and the absorbance is measured at 637 nm. Different parameters of the floatation-spectrophotometric technique such as reagent concentration, pH, surfactant, standing time and interfering ions were studied and optimized to obtain the best extraction results with the minimum interference from other compounds. Under these conditions, the extraction of the target compound was almost complete (mean values of recovery was more than 92.6% in a short time (6 min. The optimized method demonstrated good linearity (r2 > 0.9991 in the range of 4-350 ng/mL, sensitivity (limit of detection for tin (II, 1.7 ng/mL, accuracy (0.19–7.35% and precision (3.66%, 4.21%. The applicability of the proposed method was demonstrated by extraction of tin(II from different water samples.

  17. Determination of boron in niobium-zirconium alloys by distillation separation-curcumin spectrophotometric method

    Study was made on the distillation spearation-curcumin spectrophotometric method, which is used for the analysis of steel. In this method, a sample is dissolved in sulfuric acid and ammonium sulfate, and the solution is distilled by adding methanol to separate boron, and boron is colorized by curcumin for spectrophotometric determination. In the direct spectrophotometric determination of boron in Nb-Zr alloys by the methylene blue or curcumin method, the effect of coexistent elements such as Nb and Ta must be eliminated by means of dilution or separation with phytin. However, this method enables of determine boron in the distilled and separated solution with curcumin by stipulating a fixed amount of sulfuric acid and ammonium sulfate to be used for dissolving the sample, regardless of Nb and Ta contents, without any precipitation being formed. The recovery experiment using 2.5% Nb-Zr alloy and the analysis of in-house standard samples and JAERI-Z3 showed that this is a satisfactory analysis method. This procedure did not require any complex and skillful separating operation, and could shorten the analysis time in comparison with the phytin separation-methylene blue procedure. In addition, it can determine boron not less than 0.05 ppm, and is adequately applicable to the analysis with the specified value not more than 0.5 ppm for the advanced thermal reactor FUGEN. (Kobatake, H.)

  18. Protolytic equilibria in homogeneous and heterogeneous systems of ketoconazole and its direct spectrophotometric determination in tablets

    MIRJANA P. VOJIC

    2005-02-01

    Full Text Available The acid-base equilibria of a diprotic, slightly hydrosoluble base ketoconazole were studied in homogeneous and heterogeneous water systems. The determinations were performed at 25 ºC at a constant ionic strength of 0.1M(NaCl. The acidity constant Ka1 was determined by potentiometric (pKa1 3.20 and spectrophotometric (pKa1 3.26 methods. A pKa2 constant of 6.10 was obtained based on the equilibrium constants pKs0 4.84 and pKs1 –1.26, determined in a heterogeneous ketoconazole system. The obtained values of the constants served to calculate the solubility and the distribution of the equilibrium forms of ketoconazole as a function of pH. On the basis of the distribution of the equilibrium forms of ketoconazole, a spectrophotometric method for the determination of its content in commercial tablets was developed. The determinations were performed at 225 nm in 0.1 M HCl. The method is simple and rapid and enables the direct spectrophotometric determination of the content of ketoconazole without previous isolation.

  19. X-ray diffraction and absorption spectroscopic studies of copper mixed ligand complexes with aminophenol as one of the ligands

    X-ray diffraction (XRD) and X-ray absorption spectroscopic (XAS) studies have been conducted on two copper complexes, i.e., copper macrocyclic complex of succinic acid and ortho aminophenol (complex-1) and copper macrocyclic complex of pthalic acid and ortho aminophenol (complex-2). The diffraction pattern of the complexes have been recorded using Rigaku RINT-2000 X-ray diffractometer equipped with rotating anode X-ray tube operated at 40 kV and 100 mA. The X-ray absorption spectra of the complexes have been recorded at the K-edge of copper on Cauchois type bent crystal spectrograph having radius 0.4 m employing a mica crystal, oriented to reflect from (100) planes, for dispersion. The X-ray absorption near edge structure (XANES) parameters, viz., chemical shift, energy position of the principal absorption maximum and edge-width have been determined and discussed. From the extended X-ray absorption fine structure (EXAFS) data, the bond lengths have been calculated using three methods, namely, Levy's method, Lytle, Sayers and Stern's (LSS) method and Fourier transformation method. The results obtained have been compared with each other and discussed.

  20. A Groundbased Imaging Study of Galaxies Causing DLA, subDLA, and LLS Absorption in Quasar Spectra

    Rao, Sandhya M; Turnshek, David A; Monier, Eric M; Nestor, Daniel B; Quider, Anna M

    2011-01-01

    We present results from a search for galaxies that give rise to damped Lyman alpha (DLA), subDLA, and Lyman limit system (LLS) absorption at redshifts 0.1 ~= 0.3 A) whose HI column densities were determined by measuring the Ly-alpha line in HST UV spectra. Photometric redshifts, galaxy colors, and proximity to the quasar sightline, in decreasing order of importance, were used to identify galaxies responsible for the absorption. Our sample includes 80 absorption systems for which the absorbing galaxies have been identified, of which 54 are presented here for the first time. The main results of this study are: (i) the surface density of galaxies falls off exponentially with increasing impact parameter, b, from the quasar sightline relative to a constant background of galaxies, with an e-folding length of ~46 kpc. Galaxies with b >~ 100 kpc calculated at the absorption redshift are statistically consistent with being unrelated to the absorption system. (ii) log N(HI) is inversely correlated with b at the 3.0 sig...