Search results for " Spectroscopy"
showing 10 items of 6851 documents
Fabrication and characterization of vacuum deposited fluorescein thin films
2011
Simple vacuum evaporation technique for deposition of dyes on various solid surfaces has been developed. The method is compatible with conventional solvent-free nanofabrication processing enabling fabrication of nanoscale optoelectronic devices. Thin films of fluorescein were deposited on glass, fluorine-tin-oxide (FTO) coated glass with and without atomically layer deposited (ALD) nanocrystalline 20 nm thick anatase TiO2 coating. Surface topology, absorption and emission spectra of the films depends on their thickness and the material of supporting substrate. On a smooth glass surface the dye initially formes islands before merging into a uniform layer after 5 to 10 monolayers. On FTO cove…
Determination of one compound in the presence of a single interference. Linear absorbances method
1992
The paper exposes the theoretical and experimental principles of an analytical procedure for the determination of one compound in the presence of another with an overlapping absorption spectrum, without the need to use any standard solutions of the latter. The proposed method was applied to the determination of binary mixtures of known composition in order to assess its accuracy and precision.
A comparative study on sample preparation procedures for supplementary foods by ICP-OES: Green chemistry considerations
2015
An inductively coupled plasma optical emission (ICP-OES) method was developed for the simultaneous determination of major, minor and trace elements in food. Preliminary studies focused on selecting suitable operational conditions in order to provide the highest sensitivity and to maximize the number of analytes to be determined without spectral or matrix interference. Ruthenium and rhenium were evaluated as internal standards and samples were analyzed at different dilution levels. Furthermore, a comparative study was carried out by using three sample digestion methods, microwave-assisted digestion with HNO3/H2O2, dry ashing and dry ashing with Mg(NO3)2/MgO as an ashing aid. Adequate precisi…
Determination of Cd, Cu, Pb and Zn content of infant formulas by differential pulse anodic stripping voltammetry (DPASV).
1994
The differential pulse anodic stripping voltammetry (DPASV) method described is based on the one reported by Hasse et al., but adapted to normal laboratory conditions. The values obtained in the estimation of the analytical parameters (linearity, detection and quantification limits, precision and accuracy) show that in the conditions described the method is sensitive enough, reliable and useful for determining these elements in infant formulas. A comparison between DPASV and atomic absorption spectroscopy (AAS) methods in the conditions described here shows that the former is less sensitive but that they are similar in precision. The cadmium, copper, lead and zinc contents of different type…
Gaia -ESO Survey: Analysis of pre-main sequence stellar spectra
2015
This paper describes the analysis of UVES and GIRAFFE spectra acquired by the Gaia-ESO Public Spectroscopic Survey in the fields of young clusters whose population includes pre-main sequence (PMS) stars. Both methods that have been extensively used in the past and new ones developed in the contest of the Gaia-ESO survey enterprise are available and used. The internal precision of these quantities is estimated by inter-comparing the results obtained by such different methods, while the accuracy is estimated by comparison with independent external data, like effective temperature and surface gravity derived from angular diameter measurements, on a sample of benchmarks stars. Specific strategi…
Characterization of particle morphology of biochanin A molecularly imprinted polymers and their properties as a potential sorbent for solid-phase ext…
2014
Abstract Molecularly imprinted polymers (MIPs) with biochanin A as a template were obtained using a bulk polymerization with non-covalent imprinting approach. The polymers were prepared in acetonitrile as porogen, using ethylene glycol dimethacrylate (EDMA) as cross-linking agent. The synthesis, with an application of 1′,1′-azobis(cyclohexanecarbonitrile) (ACHN) as an initiator, has been performed thermally. During the synthesis process the effect of different functional monomers such as methacrylic acid (MAA), acrylamide (AA) and 4-vinylpyridine (4-VP) was investigated. The application of nitrogen sorption porosimetry, scanning electron microscopy (SEM), and Fourier transform infrared spec…
Zur protonenkatalysierten Aralkylierung von 1,2,3-Trimethylindol und 1,2,3,4-Tetrahydrocarbazol mit Arylaldehyden
1987
1,2,3-Trimethylindol (2) liefert mit Benzaldehyden die Kondensationsprodukte 5 und 6, wahrend aus den NH-Indolen 1 und 3 die Verbindungen 7 und 8 entstehen. Proton-catalyzed Aralkylation of 1,2,3-Trimethylindole and 1,2,3,4-Tetrahydrocarbazole with Arylaldehydes Reaction of 1,2,3-trimethylindole (2) with benzaldehydes leads to the condensation compounds 5 and 6, the NH-indoles 1 and 3, however, give 7 and 8.
Some observations on the determination of total heavy metals in sewage sludge by atomic absorption spectrophotometry after a pressurized acid digesti…
1990
Abstract An economical and simple method for the flame atomic absorption spectrometric determination of Cd, Pb, Ni, Cu, Fe, and Zn in sewage sludges is described. Samples are treated with concentrated HNO 3 in a thermal oven using Pyrex glass tubes hermetically sealed with Bakelite screw caps. The effect of the digestion parameters, such as digestion time, acid volume, sample mass, and temperature, were studied. The precision and accuracy of this procedure were evaluated by the analysis of two BCR (Community Bureau of Reference, European Communities) certified sewage sludge samples (CRM 146 and 144).
Flame atomic absorption analysis of gold in jewelry samples
1990
A new procedure is proposed for the determination of gold by flame atomic absorption in jewelry samples. The method is based on the acid digestion of 10 mg of sample in a microwave oven and on the on-line dilution, using a three-way valve. The dynamic range of the technique is extended to 100 mg/l gold solutions and using a weighted bracketing method for the treatment of the results, accuracy errors lower than 2% can be found in the analysis of real samples as compared with those obtained by fire assay. The method is very fast and implies only little damage to the jewelry samples.
Estimation of Arsenic Bioaccessibility in Edible Seaweed by an in Vitro Digestion Method
2003
The aim of this study was to examine the bioaccessibility (maximum soluble concentration in gastrointestinal medium) of total (AsT) and inorganic (AsI) arsenic contents and the effect on them of cooking edible seaweed, a food of great interest because of its high As content. An in vitro gastrointestinal digestion (pepsin, pH 2, and pancreatin−bile extract, pH 7) was applied to obtain the mineral soluble fraction of three seaweeds (Hizikia fusiforme, Porphyra sp., and Enteromorpha sp.). AsT was determined by dry-ashing flow injection hydride generation atomic absorption spectrometry. AsI was determined by acid digestion, solvent extraction, and flow injection hydride generation atomic absorp…