Measurement Errors in Multivariate Chemical Data
Peter D. WentzellHow to cite this article
Characterization of errors in multichannel analytical measurement vectors, in particular instrument noise, is important for understanding and improving experimental measurements and for the optimization of multivariate data analysis methods. This article reviews some of the techniques used to describe the interdependence of multivariate measurement errors, including error covariance/correlation matrices and frequency domain methods. Details are presented in the Account Measurement Errors in Multivariate Chemical Data by Peter D. Wentzell on page 183.
Peter D. WentzellHow to cite this article
Graphical abstract illustrating the conversion of IR spectra of ink samples to a scores plot by making use of the error covariance matrix and maximum likelihood principal components analysis.
José A. S. Costa; Anuska C. F. S. Garcia; Danilo O. Santos; Victor H. V. Sarmento; André L. M. Porto; Maria E. de Mesquita; Luciane P. C. RomãoHow to cite this article
PABA-MCM-41 synthesis procedure. Anew functionalized MCM-41-based mesoporous material was synthesized using a hydrothermal/co-condensation method. The CTAB surfactant was removed by refluxing in a solution of CH3CH2OH/HCl.
Erik S. J. Gontijo; Francysmary S. D. Oliveira; Mariana L. Fernandes; Gilmare A. da Silva; Hubert M. P. Roeser; Kurt FrieseHow to cite this article
Some physico-chemical parameters and dissolved organic carbon data of waters of a mining region in southeast of Brazil were analysed using the multivariate technique Kohonen neural network. It provided a better visualisation and easier interpretation of the results.
Lilian M. Pagamunici; Aline K. Gohara; Aloisio H. P. Souza; Paulo R. S. Bittencourt; Alex S. Torquato; Weliton P. Batiston; Sandra T. M. Gomes; Nilson E. Souza; Jesuí V. Visentainer; Makoto MatsushitaHow to cite this article
This study developed gluten-free cookies containing the whole flour of quinoa and linseed as source of essential fatty acids and minerals. The Principal Component Analysis (PCA) is a useful chemometric tool to facilitate the visualization of the best formulation.
Shayessteh Dadfarnia; Ali M. Haji Shabani; Mahnaz NozohorHow to cite this article
A DLLME-SFOD method based on the formation of the yellow Se(IV) complex with the 3,3'-diaminobenzidine (DAB) ligand combined with the spectrophotometry method was developed for the preconcentration, separation and determination of the inorganic selenium species.
Kelly da S. Bezerra; Nelson R. Antoniosi FilhoHow to cite this article
The steroids composition is not the same for different oils. Free steroids were extracted from unsaponifiable oil using the saponification reaction adapted micro-scale, and after extraction steroids were analyzed by gas chromatography (GC) for separation, characterization and quantification of the steroids contained in this fraction.
Farzad Bamdad; Mehdi Ardalani; Mohammad R. SangiHow to cite this article
[C4MIM][PF6] was used as an extracting solvent for pre-concentration of cadmium ions from aqueous solution by temperature controlled ionic liquid dispersive-liquid phase microextraction.
Hamed Rouhi-Saadabad; Batool AkhlaghiniaHow to cite this article
We have developed an efficient method for esterification and thioesterification of various carboxylic acids with different alcohols and thiols using PPh3/N-chlorobenzotriazole mixed reagent in CH2Cl2 at room temperature.
Leila M. Bittencourt; Diogo A. P. D. Lana; Adriano M. de C. Pimenta; Agenor V. dos Santos; Ana Paula F. Gonçalves; Rodinei Augusti; Letícia M. CostaHow to cite this article
This paper describes a procedure to evaluate metals associated to proteins in wheat seed samples using a sequential extraction procedure.
Fouad F. Al-Qaim; Md P. Abdullah; Mohamed R. Othman; Jalifah Latipa; Wan AfiqHow to cite this article
The occurrence of residues of pharmaceuticals in aquatic environments is considered an emerging environmental issue. In Malaysia, this is the first report to identify these compounds in the Tangkas River. Six pharmaceutically active compounds were detected using LC-ESI-TOF/MS instrument.
Suzana C. Santos; Ariadne G. Carvalho; Gilmara A. C. Fortes; Pedro H. Ferri; Anselmo E. de OliveiraHow to cite this article
NMR experiments at lower temperatures and DFT(B3LYP/6-31G)/PCM methods were used to determine the 3D geometry of the favoured conformer of the macrocyclic ellagitannin oenothein B.
Fabiana N. Grosser; Tainá I. T. Barros; Reinaldo S. GonçalvesHow to cite this article
Linalyl acetate (LA): a chemical compound extracted from biomass and used as green corrosion inhibitor. Adsorbed species formed from LA adsorption on the metal surface inhibits the mechanism associated with the oxidation processes of the metal.
Fernanda B. Queiroz; Júlio C. Silva; Sérgio F. Aquino; Maurício X. Coutrim; Robson J. C. F. AfonsoHow to cite this article
Linear alkylbenzene sulphonates (LAS) occur in high concentration in raw sewage, thereof interfering with the analysis of micropollutants by mass spectromety. This paper proposes a tandem solid phase extraction procedure that combines two distinct solid phase extraction cartridges to reduce LAS concentration in the extracts, thereby enhancing the sensitivity of the analytical method for the quantification of five pharmaceutical compounds and three endocrine disrupting chemicals in samples of raw and treated sewage.
Lívia Kocúrová; Ioseph S. Balogh; Martina Fatľová; Yaroslav Bazeľ; András Simon; Rastislav Serbin; Miroslav Badida; Radoslav Rusnák; Vasil AndruchHow to cite this article
A donor-active solvent-assisted liquid-phase microextraction procedure followed by spectrophotometric determination of zinc was developed. The method is based on the ion associate formation between Zn(II), thiocyanate and 2-[2-(5-dimethylamino-thiophen-2-yl)-vinyl]-1,3,3-trimethyl-3H-indolium bromide (DTVTI) reagent which is extractable by the mixture of toluene and tributylphosphate.
Gustavo F. Perotti; Jairo Tronto; Marcos A. Bizeto; Celly M. S. Izumi; Marcia L. A. Temperini; Ademar B. Lugão; Duclerc F. Parra; Vera R. L. ConstantinoHow to cite this article
Polymer-clayfilms based on cassava starch and synthetic Laponite were prepared. Exfoliated nanocomposites are producedat low clay loadings. Starch crystallinitydecreases as the amount of Laponite is increased. Thermal decomposition profile is sensitive to the clay quantity in the hybrid material.
Helena Stecka; Dominika Jedryczko; Pawel Pohl; Maja WelnaHow to cite this article
A simple and fast solid phase extraction sample preparation procedure for the flame atomic absorption spectrometry determination of traces of Cd, Co, Ni and Pb in honeys was proposed. The method provided the precision and the accuracy better than 4.5% and detection limits of 0.005 µg g-1 (Cd), 0.015 µg g-1 (Co, Ni) and 0.073 µg g-1 (Pb)
Ana C. B. de Souza; Glauco F. BauerfeldtHow to cite this article
In this work, the CH3Cl + OH CH3OH + Cl reaction is investigated at the MP2/6-31+G(d) level and by the CVTST method. Final results for rate coefficients (1.94 × 10-9 cm3 molecule-1 s-1 at 298.15K) are found in agreement with the experimental data.
Evelyn de F. Guimarães; Eliane C. P. do Rego; Helen C. M. Cunha; Janaína M. Rodrigues; José Daniel Figueroa-VillarHow to cite this article
First Brazilian development of toxic polyaromatic compounds (PAHs) certified reference material, with quality assurance, reliability and traceability for environmental analysis.
Ardeshir Khazaei; Fatemeh Abbasi; Maryam Kianiborazjani; Shahnaz SaedniaHow to cite this article
In this research, the application of dibromo dimethylhydantoin (DBDMH) and dichloro dimethylhydantoin (DCDMH) in oxidation of secondary alcohols under solvent free condition in the range of temperature 70-80 ºC has been investigated. This method offers some of the advantages as following: simplicity of the reaction conditions and work-up, short reaction times and high yields.
Carlos Fernández-Galleguillos; Luis A. Saavedra; Margarita GutierrezHow to cite this article
Herein, we report the synthesis of new substituted 3-(2-chloroquinolin-3-yl)-5-phenylisoxazole derivatives by click chemistry on good to moderate yields.
Xingguo Feng; Xiangyu Lu; Yu Zuo; Da ChenHow to cite this article
When carbon steel was subjected to constant plastic deformation in a cement extract solution, the thickness of the space charge layers significantly decreased as the deformation magnitude increased.
Lia Gracy R. Diniz; Marcelle S. Jesus; Luis Alberto E. Dominguez; Gilberto Fillmann; Eny M. Vieira; Teresa Cristina R. S. FrancoHow to cite this article
The Port of Itaqui (São Luís, Maranhão State, Northeast Brazil) stands out for heavy flow of vessels. Irgarol and Diuron are booster biocides present in antifouling paints and they were identified in such region that, jointly with north of Pará State, is located in the largest continuous mangrove area worldwide.
Online version ISSN 1678-4790 Printed version ISSN 0103-5053
Journal of the Brazilian Chemical Society
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University of Campinas - UNICAMP
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