JBCS

19:39, Sun Jul 23

Open Access/APCs

vol. 25, No. 2, 2014, p. 183-388

 

Measurement Errors in Multivariate Chemical Data

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.

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Cover Article
J. Braz. Chem. Soc. 2014, 25(2), 183-196

Measurement Errors in Multivariate Chemical Data

Peter D. Wentzell

How 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.

http://dx.doi.org/10.5935/0103-5053.20130293

Published online: December 10, 2013

Account J. Braz. Chem. Soc. 2014, 25(2), 183-196

Measurement Errors in Multivariate Chemical Data

Peter D. Wentzell

How 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.

http://dx.doi.org/10.5935/0103-5053.20130293

Published online: December 10, 2013

Articles J. Braz. Chem. Soc. 2014, 25(2), 197-207

A New Functionalized MCM-41 Mesoporous Material for Use in Environmental Applications

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. Romão

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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.

http://dx.doi.org/10.5935/0103-5053.20130284

Published online: December 3, 2013

J. Braz. Chem. Soc. 2014, 25(2), 208-218

Application of a Multivariate Exploratory Analysis Technique in the Study of Dissolved Organic Matter and Metal Ions in Waters from the Eastern Quadrilátero Ferrífero, Brazil

Erik S. J. Gontijo; Francysmary S. D. Oliveira; Mariana L. Fernandes; Gilmare A. da Silva; Hubert M. P. Roeser; Kurt Friese

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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.

http://dx.doi.org/10.5935/0103-5053.20130285

Published online: December 3, 2013


J. Braz. Chem. Soc. 2014, 25(2), 219-228

Using Chemometric Techniques to Characterize Gluten-Free Cookies Containing the Whole Flour of a New Quinoa Cultivar

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 Matsushita

How 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.

http://dx.doi.org/10.5935/0103-5053.20130286

Published online: December 3, 2013

J. Braz. Chem. Soc. 2014, 25(2), 229-237

Dispersive Liquid-Liquid Microextraction-Solidified Floating Organic Drop Combined with Spectrophotometry for the Speciation and Determination of Ultratrace Amounts of Selenium

Shayessteh Dadfarnia; Ali M. Haji Shabani; Mahnaz Nozohor

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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.

http://dx.doi.org/10.5935/0103-5053.20130287

Published online: December 10, 2013

J. Braz. Chem. Soc. 2014, 25(2), 238-245

Characterization and Quantification by Gas Chromatography of Free Steroids in Unsaponifiable Matter of Vegetable Oils

Kelly da S. Bezerra; Nelson R. Antoniosi Filho

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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.

http://dx.doi.org/10.5935/0103-5053.20130288

Published online: December 10, 2013


J. Braz. Chem. Soc. 2014, 25(2), 246-252

Trace Determination of Cadmium Ions by Flame Atomic Absorption Spectrometry after Pre-Concentration Using Temperature-Controlled Ionic Liquid Dispersive‑Liquid Phase Microextraction

Farzad Bamdad; Mehdi Ardalani; Mohammad R. Sangi

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[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.

http://dx.doi.org/10.5935/0103-5053.20130290

Published online: December 10, 2013

J. Braz. Chem. Soc. 2014, 25(2), 253-263

Direct, Rapid and Convenient Synthesis of Esters and Thioesters Using PPh3/N-Chlorobenzotriazole System

Hamed Rouhi-Saadabad; Batool Akhlaghinia

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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.

http://dx.doi.org/10.5935/0103-5053.20130291

Published online: December 10, 2013


J. Braz. Chem. Soc. 2014, 25(2), 264-270

Determination of Metal Associated with Proteins of Wheat Seed Samples After Sequential Extraction Procedure

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. Costa

How to cite this article

 

This paper describes a procedure to evaluate metals associated to proteins in wheat seed samples using a sequential extraction procedure.

http://dx.doi.org/10.5935/0103-5053.20130292

Published online: December 10, 2013

J. Braz. Chem. Soc. 2014, 25(2), 271-281

A Validation Method Development for Simultaneous LC-ESI-TOF/MS Analysis of Some Pharmaceuticals in Tangkas River-Malaysia

Fouad F. Al-Qaim; Md P. Abdullah; Mohamed R. Othman; Jalifah Latipa; Wan Afiq

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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.

http://dx.doi.org/10.5935/0103-5053.20130294

Published online: December 13, 2013

J. Braz. Chem. Soc. 2014, 25(2), 282-289

Variable-Temperature NMR and Conformational Analysis of Oenothein B

Suzana C. Santos; Ariadne G. Carvalho; Gilmara A. C. Fortes; Pedro H. Ferri; Anselmo E. de Oliveira

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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.

http://dx.doi.org/10.5935/0103-5053.20130295

Published online: December 13, 2013


J. Braz. Chem. Soc. 2014, 25(2), 290-297

Electrochemical Evidences of Linalyl Acetate (LA) Adsorption on Low-Carbon Steel in Aqueous and Ethanol Medium

Fabiana N. Grosser; Tainá I. T. Barros; Reinaldo S. Gonçalves

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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.

http://dx.doi.org/10.5935/0103-5053.20130296

Published online: December 13, 2013

J. Braz. Chem. Soc. 2014, 25(2), 298-312

Determination of Endocrine Disrupters and Pharmaceuticals in Sewage Samples by Tandem Solid Phase Clean up/Extraction and High Performance Liquid Chromatography-Negative and Positive Electrospray High-Resolution Mass Spectrometry

Fernanda B. Queiroz; Júlio C. Silva; Sérgio F. Aquino; Maurício X. Coutrim; Robson J. C. F. Afonso

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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.

http://dx.doi.org/10.5935/0103-5053.20130297

Published online: December 13, 2013

J. Braz. Chem. Soc. 2014, 25(2), 313-319

A Novel, Donor-Active Solvent-Assisted Liquid-Phase Microextraction Procedure for Spectrometric Determination of Zinc

Lívia Kocúrová; Ioseph S. Balogh; Martina Fatľová; Yaroslav Bazeľ; András Simon; Rastislav Serbin; Miroslav Badida; Radoslav Rusnák; Vasil Andruch

How 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.

http://dx.doi.org/10.5935/0103-5053.20130299

Published online: December 17, 2013


J. Braz. Chem. Soc. 2014, 25(2), 320-330

Biopolymer-Clay Nanocomposites: Cassava Starch and Synthetic Clay Cast Films

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. Constantino

How 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.

http://dx.doi.org/10.5935/0103-5053.20130300

Published online: December 17, 2013

J. Braz. Chem. Soc. 2014, 25(2), 331-339

Pre-Concentration of Traces of Cadmium, Cobalt, Nickel and Lead in Natural Honeys by Solid Phase Extraction Followed by Their Determination Using Flame Atomic Absorption Spectrometry

Helena Stecka; Dominika Jedryczko; Pawel Pohl; Maja Welna

How 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)

http://dx.doi.org/10.5935/0103-5053.20130301

Published online: December 17, 2013

J. Braz. Chem. Soc. 2014, 25(2), 340-350

Ab Initio and CVTST Investigation of the Gas Phase Nucleophilic Substitution CH3Cl + OH- → CH3OH + Cl-

Ana C. B. de Souza; Glauco F. Bauerfeldt

How 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.

http://dx.doi.org/10.5935/0103-5053.20130302

Published online: December 19, 2013


J. Braz. Chem. Soc. 2014, 25(2), 351-360

Certified Reference Material for Traceability in Environmental Analysis: PAHs in Toluene

Evelyn de F. Guimarães; Eliane C. P. do Rego; Helen C. M. Cunha; Janaína M. Rodrigues; José Daniel Figueroa-Villar

How to cite this article

 

First Brazilian development of toxic polyaromatic compounds (PAHs) certified reference material, with quality assurance, reliability and traceability for environmental analysis.

http://dx.doi.org/10.5935/0103-5053.20130303

Published online: December 19, 2013


J. Braz. Chem. Soc. 2014, 25(2), 361-364

Solvent-Free Oxidation of Secondary Alcohols to Carbonyl Compounds by 1, 3-Dibromo-5, 5-Dimethylhydantoin (DBDMH) and 1, 3-Dichloro-5, 5-Dimethylhydantoin (DCDMH)

Ardeshir Khazaei; Fatemeh Abbasi; Maryam Kianiborazjani; Shahnaz Saednia

How 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.

http://dx.doi.org/10.5935/0103-5053.20130304

Published online: December 19, 2013


J. Braz. Chem. Soc. 2014, 25(2), 365-371

Synthesis of New 3-(2-Chloroquinolin-3-yl)-5-Phenylisoxazole Derivatives via Click-Chemistry Approach

Carlos Fernández-Galleguillos; Luis A. Saavedra; Margarita Gutierrez

How 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.

http://dx.doi.org/10.5935/0103-5053.20140002

Published online: January 10, 2014


J. Braz. Chem. Soc. 2014, 25(2), 372-379

The Influence of Plastic Deformation on the Structure of Passive Films on Carbon Steel in Simulated Pore Solution

Xingguo Feng; Xiangyu Lu; Yu Zuo; Da Chen

How 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.

http://dx.doi.org/10.5935/0103-5053.20140003

Published online: January 10, 2014

Short Report J. Braz. Chem. Soc. 2014, 25(2), 380-388

First Appraisal of Water Contamination by Antifouling Booster Biocide of 3rd Generation at Itaqui Harbor (São Luiz - Maranhão - Brazil)

Lia Gracy R. Diniz; Marcelle S. Jesus; Luis Alberto E. Dominguez; Gilberto Fillmann; Eny M. Vieira; Teresa Cristina R. S. Franco

How 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.

http://dx.doi.org/10.5935/0103-5053.20130289

Published online: December 10, 2013

Online version ISSN 1678-4790 Printed version ISSN 0103-5053
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