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Publications (66)
In the past, many types of researches have been performed to allow multi-element determinations using atomic absorption spectrometry. The first spectrometers developed for this purpose were proposed in the 1970s, using flame and furnace atomizers.
In the early 2000s, a spectrometer equipped with software that allows a fast selection of the hollow c...
This paper proposes a simple, rapid and green ultrasound assisted and ionic liquid dispersive microextraction procedure using pyrocatechol violet (PV) as complexing reagent and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide [C6MIM][Tf2N] as ionic liquid for the detection of tin employing electrothermal atomic absorption spectrometry...
Robustness has been defined as being the capacity of an analytical procedure to produce unbiased results when small changes in the experimental conditions are made voluntarily. The robustness tests are important because sometimes the analyst needs to modify one or a few chemical and/or instrumental parameters of a procedure, and this can only be do...
Carbon black (CB) grafted with 3-mercaptopropyltrimethoxysilane (3-MPTMS) was used as solid phase extractor for Cd²⁺ in a flow injection system coupled to flame atomic absorption spectrometry (FAAS). The influence of pH, buffer concentration, preconcentration flow rate and eluent concentration on preconcentration of Cd²⁺ were investigated by means...
The atemoya is a hybrid fruit obtained by crossing of cherimoya (Annona cherimola Mill.) with sweet sop (Annona squamosa L.). The information about chemical composition of atemoya is scarce. The mineral composition was evaluated employing Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) and the centesimal composition and the physi...
A method was developed for determination of total antimony in hair samples from patients undergoing chemotherapy against Leishmaniasis based on the administration of pentavalent antimonial drugs. The method is based on microwave assisted digestion of the samples in a pressurized system, reduction of Sb5+ to Sb3+ with KI solution (10% w/v) in ascorb...
Mercury is a highly toxic substance that is a health hazard to humans. This study aims to investigate powders obtained from the peel of the fruit of Pachira aquatica Aubl, in its in natura and/or acidified form, as an adsorbent for the removal of mercury ions in aqueous solution. The materials were characterized by Fourier transform infrared spectr...
In this study, the elemental composition of nine medicinal plants and phytomedicines was evaluated by using axial view inductively coupled plasma optical emission spectrometry (ICP OES) after three digestion procedures: dry ashing (DA) and two wet digestions with a mineral acid (HNO3/H2O2) mixture on a conventional hot plate (CD), besides microwave...
The present paper reports advantages, drawbacks and applications of the main techniques of sample preparation employed during determinations of total mercury and methylmercury in food matrices employing analytical methods such as: cold vapor atomic absorption spectrometry (CV AAS), cold vapor atomic fluorescence spectrometry (CV AFS), inductively c...
This paper proposes a direct method for the determination of mercury in vinegar using ultrasound extraction and cold vapor atomic absorption spectrometry (CV AAS). The optimization step was performed using chemometric techniques, a full factorial design and a Box-Behnken matrix, where the factors studied were sodium tetrahydroborate flow rate, isoa...
This work proposes a procedure for the determination of total selenium content in shellfish after digestion of samples in block using cold finger system and detection using atomic fluorescent spectrometry coupled hydride generation (HG AFS). The optimal conditions for HG such as effect and volume of prereduction KBr 10 % (m/v) (1.0 and 2.0 ml) and...
The present paper presents advantages, limitations and applications of a reflux system (cold finger) employed for sample preparation during determination of volatile elements. Also other techniques employed for sample preparation in the determination of volatile elements are discussed and compared. A list of ten papers published reporting use of co...
In the present work, a minicolumn of sisal fiber loaded with tiazolylazo-Resorsinol (TAR) is proposed a preconcentration system for cadmium determination in drinking water samples by flame atomic absorption spectrometry. In the optimization was first of all a full factorial design of two levels (24) was used for preliminary evaluation of four facto...
This article presents a critical evaluation of the analytical procedures used for the determination of lead in seawater, which is important because lead is a good indicator of marine pollution caused by human activities. Sampling, storage, and pretreatment techniques are briefly overviewed, including the significance of systematic errors that canno...
This paper proposes a procedure for the determination of total arsenic in rice using slurry sampling and hydride generation atomic fluorescence spectrometry (HG AFS). During optimization, water, hydrochloric acid, and nitric acid solutions were tested as extractor. Best results were found using 2.0 mol L−1 nitric acid solutions. The slurries are pr...
The present work proposes the photo-oxidation using UV radiation/H2O2 as an alternative procedure for pretreatment of industrialized fruit juice samples for determination of copper by flame atomic absorption spectrometry (FAAS). For optimization of the photo-oxidation procedure the following variables were studied: pH and volume of buffer solution,...
In the present study, a minicolumn of sisal fiber loaded with alizarin fluorine blue is proposed as a preconcentration system for copper determination in tobacco leaf samples by flame atomic absorption spectrometry. During the optimization procedure, a two level full factorial design (2(4)) was used at the preliminary evaluation of four factors, in...
A cloud point extraction procedure for pre-concentration and determination of cadmium and lead in drinking water using sequential multi-element flame atomic absorption spectrometry is described. 4-(2-thiazolylazo)-orcinol (TAO) has been used as complexing agent and the micellar phase was obtained using the non-ionic surfactant octylphenoxypolyethox...
An on-line pre-concentration system for the sequential determination of cadmium and lead in drinking water by using fast sequential flame atomic absorption spectrometry (FS-FAAS) is proposed in this paper. Two minicolums of polyurethane foam loaded with 2-(6-methyl-2-benzothiazolylazo)-orcinol (Me-BTAO) were used as sorptive pre-concentration media...
This paper applies statistical simplex-centroid design to mixture modeling for optimization of the liquid phase composition of cassava slurry leaves in the development of an analytical procedure for iron determination using flame atomic absorption spectrometry (FAAS). This procedure is based on a slurry formation from powdered cassava leaves and a...
The present paper proposes an analytical procedure for speciation analysis of inorganic antimony in airborne particulate matter using slurry sampling and hydride generation atomic absorption spectrometry (HG QT AAS). During the antimony determination, a quartz T tube cell was heated to approximately 900 °C using air–acetylene flame. The optimizatio...
The aim of this work was to evaluate the microemulsification as sample preparation procedure for determination of Cu, Fe, Ni and Zn in vegetable oils samples by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS). Microemulsions were prepared by mixing samples with propan-1-ol and aqueous acid solution, which allowed...
The present work proposes the use of Agave sisalana (sisal fiber) as an natural adsorbent for ions Pb(II) and Cd(II) biosorption from natural waters. The flame atomic absorption spectrometry was used for quantitative determination and study of the ions Pb(II) and Cd(II) adsorption on the solid phase. The Fourier transform infrared spectroscopy (FT...
In this paper is proposed a simultaneous pre-concentration procedure using cloud point extraction for the determination of cadmium and lead in drinking water employing sequential multi-element flame atomic absorption spectrometry. The ligand used is 2-(2-thiazolylazo)-p-cresol (TAC) and the micellar phase is obtained using non-ionic surfactant octy...
In this work, the mineral composition of fresh bovine milk obtained from the milk-producing areas of the Brazilian State of Sergipe was examined. A dry-ashed digestion method and the ICP OES technique were used for the quantification of mineral elements (e.g., Ca, Mg, K, Na, P, Sr and Zn) in 27 samples of milk collected from properties located in m...
This review focuses on the determination of uranium using spectroanalytical techniques that are aimed at total determination such as flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS), inductively coupled plasma optical emission spectrometry (ICP-OES); and inductively coupled plasma mass spectrometry...
This article critically overviews the state-of-the-art of slurry sampling as an approach for the minimization of sample preparation prior to the determination of metals and metalloids in complex matrices by spectroanalytical techniques. Relevant factors involved in the optimization of slurry-based analytical procedures and the dependence of the qua...
In this paper, Brazilian scientific production in analytical chemistry was researched. The work searched 45 international journals that publish research in analytical chemistry. The Web of Science database was used for data collection. The period studied was from 1945 to November, 2009. This search revealed 4461 papers, 3582 being articles (80.3%),...
Cassava, Manihot esculenta crantz, constitutes one of the main foods consumed by most of the population of developing countries, mainly in the population of low income. It is largely used for its low cost and the diversity of its root and leaves products. In this paper, a slurry sampling flame atomic absorption spectrometric method for the determin...
This paper proposes the use of photo-oxidation with UV radiation/H2O2 as sample pretreatment for the determination of iron and manganese in wines by flame atomic absorption spectrometry (FAAS). The optimization involved the study of the following variables: pH and concentration of buffer solution, concentrated hydrogen peroxide volume and irradiati...
The aim of this paper is to give a brief overview of chemometric techniques based on factorial designs and response surface methodologies used in the optimization of electroanalytical methods. Chemometric techniques have several important advantages over one-way optimization for analytical applications, including a relatively low cost, a reduced nu...
, respectively, were obtained using a sample volume of 20 µL. The precision expressed as relative standard deviation (RSD %) was 0.30, 0.37 and 0.49% for wines with cadmium concentrations of 1.286, 0.266 and 0.356 µg L −1 , respectively. The accuracy of the new direct determination methodology applying ET AAS was assessed by comparison with an acid...
A slurry sampling flame atomic absorption spectrometric method is proposed for the determination of copper, manganese and iron in oysters (Crassostrea rhizophora), clams (Anomalocardia brasiliana) and mussels (Mytella guiyanensis; Perna perna). Optimization was carried out using univariate methodology involving the following variables: nature and c...
A procedure is proposed for the direct determination of manganese and iron in wine employing fast sequential flame atomic absorption spectrometry and the reference element technique to correct for matrix effects. Cobalt, silver, nickel and indium have been tested as reference elements. The results demonstrated that cobalt and indium at a concentrat...
The wheat is one of the cereals more consumed in the human food in all worlds. In the form of flour it is used for preparation of breads, cookies, pizzas, cakes, and etc. This way, the knowledge of the mineral content this cereal and its flour is very important. Considering it, methods for determination of metals in these matrices are opportune and...
The present work proposes a direct method based on slurry sampling for the determination of zinc and copper in human hair samples by multi-element sequential flame atomic absorption spectrometry. The slurries were prepared by cryogenic grinding and sonication of the samples. The optimization step was performed using univariate methodology and the f...
A procedure has been developed for the simultaneous determination of trace amounts of cadmium, copper, chromium, nickel and lead in digested vegetable samples. The method involves solid-phase extraction of the metals using a minicolumn of Amberlite XAD-4 modified with dihydroxybenzoic acid (DHB) and detection by Inductively Coupled Plasma Optical E...
The present paper describes fundamentals, advantages and limitations of the Box-Behnken design (BBD) for the optimization of analytical methods. It establishes also a comparison between this design and composite central, three-level full factorial and Doehlert designs. A detailed study on factors and responses involved during the optimization of an...
Spectrometric techniques for the analysis of trace cadmium have developed rapidly due to the increasing need for accurate measurements at extremely low levels of this element in diverse matrices. This review covers separation and preconcentration procedures, such as electrochemical deposition, precipitation, coprecipitation, solid phase extraction,...
This paper describes fundamentals and applications of multivariate statistical techniques for the optimization of chromatographic systems. The surface response methodologies: central composite design, Doehlert matrix and Box-Behnken design are discussed and applications of these techniques for optimization of sample preparation steps (extractions)...
A direct method is proposed for the determination of lead in naphtha and petroleum condensate by electrothermal atomic absorption
spectrometry (ET AAS) using palladium as a permanent modifier. The procedure includes the dilution of 3 mL of sample (naphtha
or petroleum condensate) to a final volume of 10 mL with xylene, and direct injection of 30 µL...
An automatic on-line pre-concentration system is proposed for lead determination in drinking water using flame atomic absorption spectrometry (FAAS). Lead(II) ions are retained as the 1-(2-pyridylazo)-2-naphthol (PAN) complex in the walls of a knotted reactor, followed by an elution step using 0.50molL(-1) hydrochloric acid solution. Optimisation i...
The first publication on the use of polyurethane foam (PUF) for sorption processes dates back to 1970, and soon after the material was applied for separation processes. The application of PUF as a sorbent for solid phase extraction of inorganic analytes for separation and pre-concentration purposes is reviewed. The physical and chemical characteris...
In the present paper, a minicolumn of polyurethane foam loaded with 4-(2-pyridylazo)-resorcinol (PAR) is proposed as pre-concentration system for cadmium determination in drinking water samples by flame atomic absorption spectrometry. The optimization step was performed using two-level full factorial design and Doehlert matrix, involving the variab...
A simple method for mercury determination in petroleum fractions (e.g. naphtha) using electrothermal atomic absorption spectrometry (ETAAS) associated with multiple injection technique for direct preconcentration in the graphite tube has been developed. Oil-in-water micro-emulsions (three-component solutions) were prepared using a mixture of sample...
The present paper proposes a pre-concentration procedure for determination of lead and iron in several samples by flame atomic absorption spectrometry. In it, lead(II) and iron(III) ions are coprecipitated using the violuric acid-copper(II) system as collector. Afterwards, the precipitate is dissolved with 1M HNO3 solution and the metal ions are de...
The literature about direct solid sampling (SS) and slurry sampling atomic absorption spectrometry (AAS) over the past decade has been surveyed critically. It became apparent that a very significant change had occurred, particularly in the relation between the two major techniques used for that purpose. In the 1990s, slurry sampling was typically c...
Iridium and ruthenium, alone and in combination with tungsten, thermally deposited on the platform of a transversely heated graphite tube, were investigated for their suitability as permanent chemical modifiers for the determination of cadmium in coal slurries by electrothermal atomic absorption spectrometry (ET AAS). The conventional mixed palladi...
In the present work, a slurry sampling flame atomic absorption spectrometric method to determine directly manganese and zinc in powdered chocolate samples is proposed. The optimization step was performed using univariate methodology involving the following factors: nature and concentration of the acid solution, sonication time, and particle size. T...
Lead is recognized worldwide as a poisonous metal. Thus, the determination of this element is often required in environmental, biological, food and geological samples. However, these analyses are difficult because such samples contain relatively low concentrations of lead, which fall below the detection limit of conventional analytical techniques s...
It has been observed in previous work using high-resolution continuum-source atomic absorption spectrometry that up to 50% of the nickel and vanadium in crude oil, most likely non-polar nickel and vanadyl porphyrin complexes, was already lost at pyrolysis temperatures 4400 1C, whereas the rest of the analyte was stable up to at least 1200 1C. In th...
A system containing Amberlite XAD 2 (styrene-divinylbenzene copolymers) loaded with 2-(2thiazolylazo)-5-dimethylaminophenol (TAM) reagent is proposed for field sampling, preconcentration and determination of cadmium (II) and nickel (II) ions in fresh water using flame atomic absorption spectrometry (FAAS). The optimisation process was univariate...
Chocolate is a complex sample with a high content of organic compounds and its analysis generally involves digestion procedures that might include the risk of losses and/or contamination. The determination of copper in chocolate is important because copper compounds are extensively used as fungicides in the farming of cocoa. In this paper, a slurry...
The present paper proposes an on-line pre-concentration system for cadmium determination in drinking water using flame atomic absorption spectrometry (FAAS). Cadmium(II) ions are retained as 1-(2-pyridylazo)-2-naphthol (PAN) complex at the walls of a knotted reactor, followed of elution using hydrochloric acid solution. The optimization was perform...
A method has been developed for the direct determination of copper in petroleum condensate using detergentless micro-emulsions (three-component solutions) and graphite furnace atomic absorption spectrometry. The optimization was performed using a three-level full factorial design, resulting in pyrolysis and atomization temperatures of 920 °C and 26...
The present paper describes a flow preconcentration system for copper determination by flame atomic absorption spectrometry (FAAS) based on the sorption of Cu(II) ions onto a mini‐column of polyurethane foam (PUF) loaded with a chromogenic reagent [4‐(2‐pyridylazo)‐resorcinol (PAR)]. The variables associated with flow preconcentration system perfor...
The present paper proposes an on-line pre-concentration procedure for lead determination in drinking water and saline waste from oil refinery by flame atomic absorption spectrometry (FAAS). It is based on the sorption of lead (II) ions in a minicolumn of polyurethane foam loaded with 4-(2-pyridylazo)-resorcinol (PAR) reagent. The optimization step...
A review of the use of the Doehlert matrix as a chemometric tool for the optimization of methods in analytical chemistry and other sciences is presented. The theoretical principles of Doehlert designs are described, including the coded values for the use of this matrix involving two, three, four and five variables. The advantages of this matrix in...
This article describes an on-line pre-concentration system for zinc determination in environmental samples by flame atomic absorption spectrometry (FAAS). It was based on the sorption of zinc(II) ions in a minicolumn of polyurethane foam loaded with 4-(2-pyridylazo)-resorcinol (PAR). The optimisation step was carried out using two-level full factor...
In the present paper, a system for on-line preconcentration and determination of copper by flame atomic absorption spectrometry (FAAS) was developed. It was based on solid phase extraction of copper(II) ions on a minicolumn of Amberlite XAD-2 loaded with 2-(2-thiazolylazo)-5-dimethylaminophenol (TAM). The optimisation process was carried out using...
In the present paper, an on-line system for preconcentration and determination of zinc by Flame Atomic Absorption Spectrometry (FAAS) is proposed. It is based in the sorption of zinc(II) ions on a minicolumn packed with polyurethane foam loaded with 2-[2′-(6-methyl-benzothiazolylazo)]-4-bromophenol (Me-BTABr) reagent. Chemical and flow variables as...
A system for on-line preconcentration and determination of lead by flame atomic absorption spectrometry (FAAS) was proposed. It was based on the sorption of lead(II) ions on a minicolumn of polyurethane foam loaded with 2-(2-thiazolylazo)-5-dimethylaminophenol (TAM). The optimisation step was carried out using two-level full factorial and Doehlert...
An on-line preconcentration system for nickel determination in natural foods has been developed. In it nickel(II) ions are fixed on a minicolumn packed with Amberlite XAD-2 loaded with 2-(2-benzothiazolylazo)-2-p-cresol (BTAC) through complexation process. Afterwards, nickel is eluted with 0.10 mol l−1 hydrochloric acid and determinated by flame at...
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