Search results for "absorption spectroscopy"
showing 10 items of 828 documents
Rapid on-line sample dissolution assisted by focused microwave radiation for silicate analysis employing flame atomic absorption spectrometry: iron d…
2004
An on-line automated flow injection system with microwave-assisted sample digestion was used to perform silicate rock dissolution in acid medium for iron determination. For this purpose, a continuous flow system was built up by using an automatic flow injection analysis (FIA) system coupled to a flame atomic absorption spectrometer (FAAS), including a focused microwave oven unit. Inside the microwave cavity was inserted a polytetrafluoroethylene (PTFE) reactor coil (300cm length and 0.8mm i.d.) where the dissolution takes place. Chemical and flow variables as well as iron determination parameters were studied. In the flow system, a slurry of the rock sample (50mg in 200ml of acid mixture HF…
Direct determination of calcium, magnesium, sodium and potassium in water by flow injection flame atomic spectroscopy, using a dilution chamber
1989
A simple procedure to carry out the direct analysis of calcium, magnesium, sodium and potassium in water by flow injection analysis (FIA) using flame atomic absorption spectroscopy (AAS) or flame photometry (FP) has been developed, using a well stirred dilution chamber to extend the calibration range, and both a double injector and the merging zone technique to add a lanthanum solution to samples and standards. The results obtained in the analysis of real samples agree with those found by a batch flame atomic procedure. The use of the dilution chamber makes it possible to carry out the calibration using the dilution profile of a single concentrate standard for each element, and an empirical…
Slurries Introduction in Flow Injection Atomic Absorption Spectroscopic Analysis of Sewage Sludges
1990
Abstract The direct introduction of slurries in flow Injection-flame atomic absorption spectroscopy has been studied using a single-channel manifold. The influence of flow Injection parameters on the sensitivity and accuracy of this procedure has been established. A method has been developed for the determination of copper, manganese, and lead In sewage sludge where batch digestion of the samples In a microwave oven is carried out before dilution. Both sensitivity and limit of detection of the flow Injection analysis procedure are adequate for the analysis of actual samples (the limit of detection was 0.06, 0.05, and 0.3 ppm for copper, manganese, and lead, respectively). The accuracy of th…
Use of The Eggshells in Removing Heavy Metals from Waste Water - The Process Kinetics and Efficiency
2019
Abstract Studies of the efficiency of Ni, Cu and Cd cations removal from water solutions were carried out, with the use of clay limestone, hen eggshells from eggs for consumption and hen eggshells after hatching, which main element is calcium carbonate. Hen eggshells are a waste product, which can be used as a substitute of clay limestone in removing heavy metals from wet flue gas desulphurisation installation. Mixed solutions of Ni, Cu and Cd were used in the research, with the composition similar to the waste water from wet flue gas desulphurisation installation: Ni (0.009-0.053 mmol/dm3), Cu (0.008-0.057 mmol/dm3) and Cd (0.003-0.008 mmol/dm3). The metals were determined by flame atomic …
Flux growth at 1230 °C of cubic Tb2O3 single crystals and characterization of their optical and magnetic properties
2015
International audience; In this work, we present the first crystal growth of cubic Tb2O3 single crystals by a controlled atmosphere flux method which uses a heavy metal free solvent working at less than half the melting temperature of this sesquioxide. Cubic millimeter-sized crystals extracted from as-grown boules are phase (powder XRD) and chemically (GDMS) pure and exhibit a Verdet constant in the visible and near-infrared spectral ranges, which is at least three times higher than that of a commercial Tb3Ga5O12 (TGG) crystal. The 1.36 mm thick crystals display a transmission coefficient higher than 77% over the 525 nm–1.38 μm spectral range. The absorption spectrum, magnetic susceptibilit…
Lemon Juice, Sesame Paste, and Autoclaving Influence Iron Bioavailability of Hummus: Assessment by an In Vitro Digestion/Caco-2 Cell Model
2020
Hummus, an iron-containing plant-based dish mainly made from chickpea puré
Computer modelling of point defects in ABO3 perovskites and MgO
2004
We present results for basic intrinsic defects: F-type electron centers (O vacancy which trapped one or two electrons) and hole polarons bound to Mg or K vacancy in ionic MgO and partly covalent KNbO3 perovskite, respectively. We demonstrate that a considerable covalency of the perovskite chemical bonding makes the F-type centers therein much more similar to defects in partly-covalent quartz-type oxides rather than the conventional F centers in alkali halides and ionic MgO. Both one-site (atomic) and two-site (molecular) polarons are expected to coexist in KNbO3 characterized by close absorption energies. Our calculations confirm existence of the self-trapped electron polarons in KNbO3, KTa…
Defects in glasses
1995
Abstract The absence of long range order in the glass structure allows to define only point defects in these materials. They are: 1) intrinsic defects—atomic size local deviation from short range order; 2) impurity defects—isolated impurity atoms or ions in the glass network; 3) intrinsic impurity defects—complexes consisting of the impurity atoms chemically bonded to one of the intrinsic defect atoms. The latter defects are characteristic for the doped glasses. Presence of point defects in glasses introduces new spectroscopic properties of these solid materials. Defect generation, interaction and recombination reactions resulting from the external influence causes the glass spectroscopic p…
Atomic spectroscopy: a review
2010
Atomic Absorption Spectrometry 4653 Flame Atomic Absorption Spectrometry 4653 Electrothermal Atomic Absorption Spectrometry 4654 Volatile Species Generation Atomic Absorption Spectrometry 4654 Direct Solids Atomic Absorption Spectrometry 4655 Continuum Source Atomic Absorption Spectrometry 4655 Atomic Fluorescence Spectrometry 4655 Atomic Emission Spectrometry 4656 DC Arc and Low-Power RF Radiation Sources 4656 Inductively Coupled Plasmas 4656 Microwave Induced Plasmas 4658 Microplasmas 4658 Laser Induced Breakdown Spectroscopy 4658 Glow Discharge Optical Emission and Mass Spectrometry 4660 Fundamental Studies 4660 Methodological Studies and Applications of GD-OES and GDMS 4661 New GD Sourc…
Local dynamic properties of the heme pocket in native and solvent-induced molten-globule-like states of cytochrome c
2002
We report the Soret absorption band, down to cryogenic temperature, of native and molten-globule-like state of horse heart cytochrome c. The band profile is analyzed in terms of vibronic coupling of the heme normal modes to the electronic transition in the framework of the Franck-Condon approximation. From the temperature dependence of the Gaussian broadening and of the peak position, we obtain information on the 'bath' of low frequency harmonic motions of the heme group within the heme pocket. The reported data indicate that, compared to the native state, the less rigid tertiary structure of the molten globule is reflected in a higher flexibility of the heme pocket and in greater conformat…