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81.
Zuloaga O Etxebarria N Fernández LA Madariaga JM 《Fresenius' Journal of Analytical Chemistry》2000,367(8):733-737
The microwave-assisted extraction (MAE), accelerated solvent extraction (ASE) and Soxhlet extraction of two isomers of hexachlorocyclohexane, alpha-HCH and gamma-HCH, from a polluted landfill soil have been optimized following different experimental designs. In the case of microwave-assisted extraction, the following variables were considered: pressure, extraction time, microwave power, percentage of acetone in n-hexane mixture and solvent volume. When ASE extraction was studied the variables were pressure, temperature and extraction time. Finally, the percentage of acetone in n-hexane mixture and the extraction time were the only variables studied for Soxhlet extraction. The concentrations obtained by the three extraction techniques were, within their experimental uncertainties, in good agreement. This fact assures the possibility of using both ASE and MAE techniques in the routine determination of lindane in polluted soils and sediments. 相似文献
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Castro K Pessanha S Proietti N Princi E Capitani D Carvalho ML Madariaga JM 《Analytical and bioanalytical chemistry》2008,391(1):433-441
A complete multianalytical study of a hand-coloured map from the seventeenth century is presented. The pigments atacamite,
massicot, minium, gypsum, carbon black and vermilion were determined by means of XRF and Raman spectroscopy. The state of
conservation of the cellulosic support was monitored by means of unilateral NMR. The analysis was nondestructive and noninvasive,
and thus several spectra were collected from the same areas, yielding more reliable results without damaging the artwork.
The role of copper pigments in the oxidation processes observed in the cellulosic support is discussed, as well as the possible
provenance of atacamite as a raw material instead of as a degradation product of malachite. 相似文献
84.
Castro K Sarmiento A Maguregui M Martínez-Arkarazo I Etxebarria N Angulo M Barrutia MU González-Cembellín JM Madariaga JM 《Analytical and bioanalytical chemistry》2008,392(4):755-763
A complete study of several English polychromed alabaster sculptures is presented. The support, pigment, and binders were
characterised by combining μEDXRF, μRaman, and FTIR spectroscopies. Among the pigments, minium, vermilion, lead white, carbon
black, red iron oxide, and a degraded green copper pigment were determined, together with gold leaf. The presence of the rare
mineral moolooite (copper oxalate) was also found as a degradation product in the green areas, where weddellite (calcium oxalate
dihydrate) was also determined. These facts, together with degradation of the green copper pigment, suggest microbiological
degradation of the original materials. Remains of glue and a varnish were also determined by FTIR spectroscopy and principal-components
analysis (PCA) of the spectra. Finally, PCA analysis was carried out to confirm whether the pieces came from the same quarry. 相似文献
85.
Martínez-Arkarazo I Sarmiento A Usobiaga A Angulo M Etxebarria N Madariaga JM 《Talanta》2008,75(2):511-516
Thermodynamic and Raman spectroscopic speciation was used to define the operating conditions for an innovative cleaning treatment of the decayed carbonate-based stones using ion exchange technology. The conditioning process of the Lewatit OC1071 anion exchanger with EDTA (Y) was monitored by ionic chromatography. Characterisation of the initial (R-Cl) and the final (R2-H2Y) forms of the ion exchanger was carried out by dispersive Raman microprobe spectroscopy. The subtraction spectrum obtained between the chloride and the EDTA forms of the ion exchanger shows Raman bands at 1403, 1324, 1223, 1122, 932, 908, 591, 431 and 350 cm(-1), which agree with bands showed in the spectrum of the standard solution of the H2Y(2-) species. Therefore, this seems to be the EDTA species which takes part in the cleaning treatment performed by using resin poultices on black crusted limestone samples from an historical building. 相似文献
86.
We analyse different error propagation mechanisms for conservativeand nonconservative time-integrators of nonlinear Schrödingerequations. We use a geometric approach based on interpretingwaves as relative equilibria. 相似文献
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