Search results for "Spectroscopy"
showing 10 items of 10293 documents
An on-line system for preconcentration and determination of lead in wine samples by FAAS
2002
A flow injection method has been developed for the direct determination of free available Pb(II) and total Pb content in wine samples. The method is based on the chemical sorption of Pb(II), from pH 7 buffered solutions, on a packed polyurethane foam column, modified by addition of 2-(2-benzothiazolylazo)-p-cresol (BTAC). After this step, lead was directly eluted with a stream of 0.1 mol l(-1) HCl into an air C(2)H(2) flame in which lead was determined by atomic absorption spectrometry. Total lead was analyzed after sample digestion with nitric acid and hydrogen peroxide, being free available lead determined by direct sample on-line preconcentration and elution. The method provides a limit …
Expressing forest origins in the chemical composition of cooperage oak woods and corresponding wines by using FTICR-MS.
2008
A non-targeted, ultra-high-resolution mass spectrometric, direct analysis of oak-wood extracts from two species (Quercus robur L. and Quercus petraea Liebl.) from three French forests, and of a wine aged in barrels derived therefrom has been performed to identify families of metabolites that could discriminate both the species and the geographical origin of woods. From 12 T ultra-high-resolution Fourier transform ion cyclotron resonance mass spectra of wood extracts, hundreds of mass signals were identified as possible significant biomarkers of the two species, with phenolic and carbohydrate moieties leading the differentiation between Q. robur and Q. petraea, respectively, as corroborated …
Detection of bias errors in ETAASDetermination of copper in beer and wine samples
2005
A method that evidences changes in the shape of the absorbance profiles obtained by graphite furnace atomic absorption spectrometry (ETAAS) is proposed. The method is based upon the apparent content curves model previously described for molecular spectroscopy and it permits the detection of possible sources of bias errors. Moreover, a procedure that allows to detect the existence of constant and/or proportional errors is also described. Both models has been applied to the determination of copper in wine and beer samples with and without pre-treatment of the samples. Results obtained evidence the usefulness of the proposed models.
Exposure assessment to ochratoxin A from the consumption of Italian and Hungarian wines
2005
Abstract A total of 267 wine samples including 19 dessert, 186 red, 11 rose and 51 white produced mostly in the years 1997–2002 in Italian and Hungarian regions were analyzed for ochratoxin A (OTA) using inmunoaffinity column (IAC) clean-up and HPLC with fluorimetric detection. None of Hungarian wine samples were contaminated with this mycotoxin. For Italian red wines, 84% of the samples were positive for OTA ranged from 0.01 to 4.00 ng/mL. Furthermore, OTA was detected in 63% of dessert, in 56% of rose and in 19% of white wine samples ranged from 0.01 to 1.64, from 0.01 to 1.04 and from 0.01 to 0.21 ng/mL, respectively. A study of OTA daily exposure assessment in Italian wines was also car…
Searching the most appropriate sample pretreatment for the elemental analysis of wines by inductively coupled plasma-based techniques.
2008
Different sample preparation methods were evaluated for the simultaneous multielement analysis of wine samples by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Microwave-assisted digestion in closed vessel, thermal digestion in open reactor, and direct sample dilution were considered for the determination of Li, Be, Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Y, Mo, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Tl, Pb, and Bi in 12 samples of red wine from Valencia and Utiel-Requena protected designation of origin. ICP-MS allows the determination of 17 elements in most…
Elemental fingerprint of wines from the protected designation of origin Valencia
2009
Abstract Inductively coupled plasma optical emission (ICP-OES), in combination with different chemometric approaches, has been used to verify the origin of different red wine samples from Utiel-Requena, Jumilla, Yecla and Valencia protected designation of origin (PDO). The ability of multivariate analysis methods, such as hierarchical cluster analysis (HCA), principal component analysis (PCA), classification and regression trees (CARTs) and discriminant analysis (DA), to achieve wine classification from their elemental contents has been investigated. The calculations were performed using 38 variables (contents of Al, Ba, Be, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Gd, Ho, K, La, Li, Lu, Mg,…
A Brief Review of the Effects of Pressure on Wolframite-Type Oxides
2018
In this article, we review the advances that have been made on the understanding of the high-pressure (HP) structural, vibrational, and electronic properties of wolframite-type oxides since the first works in the early 1990s. Mainly tungstates, which are the best known wolframites, but also tantalates and niobates, with an isomorphic ambient-pressure wolframite structure, have been included in this review. Apart from estimating the bulk moduli of all known wolframites, the cation–oxygen bond distances and their change with pressure have been correlated with their compressibility. The composition variations of all wolframites have been employed to understand their different structural phase …
Local atomic and electronic structure of tungsten ions in AWO4 crystals of scheelite and wolframite types
2001
Abstract X-ray absorption spectroscopy was used to study the local atomic and electronic structure of tungsten ions in polycrystalline scheelite CaWO4 and wolframite-type ZnWO4 and NiWO4. The W L1- and L3-edges X-ray absorption near edge structure (XANES) signals suggest tetrahedral coordination of tungsten ions in CaWO4 and strongly distorted octahedral coordination in ZnWO4 and NiWO4. Accurate analysis of the W L3-edge extended X-ray absorption fine structure (EXAFS) signals by the regularization procedure was performed to reconstruct the radial distribution functions within the first coordination shell around tungsten atoms in AWO4 crystals and polycrystalline WO3, which was utilized for…
Bio-inspired consolidants derived from crystalline nanocellulose for decayed wood
2018
Abstract Novel bio-inspired materials derived from crystalline nanocellulose (CNC) have been tested as wood consolidants. A suspension of CNC, produced by acid hydrolysis of cellulose and used as such or mixed with lignin and/or siloxane derivatives (PDMS), was applied on rotted wood samples of Norway spruce. X-Ray diffraction analysis on CNC powder showed high crystallinity index. Dynamic light scattering (DLS) measurement indicated a nearly uniform particle size distribution with an average hydrodynamic diameter for pure CNC smaller than that in the mixtures. Raman and FTIR spectroscopies suggested interactions between lignin, PDMS and CNC components. The storage modulus of wood samples, …
MULTIDISCIPLINARY STUDY FOR THE DATING AND THE RESTORATION OF THE SAN VITO WOODEN PULPIT OF MUSEO DIOCESANO OF PALERMO
2017
The aim of the present research is to investigate the execution techniques of San Vito wooden pulpit in the Museo Diocesano of Palermo and to provide helpful information to dating it in addition to technical, historical and artistic evaluations. In particular, this paper describes the application of analytical techniques (imaging diagnostics techniques, Scanning Electron Microscopy coupled with X-ray Energy Dispersive spectroscopy Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy and Fourier Transform Infrared Spectroscopy) to better understand the pulpit characteristics, both support and decoration, useful to plan and perform the correct restoration.