Ana Rita Araujo Nogueira - Academia.edu (original) (raw)

Papers by Ana Rita Araujo Nogueira

Research paper thumbnail of FIA-FAAS method for tannin determination based on a precipitation reaction with hemoglobin

Journal of the Brazilian Chemical Society, Apr 1, 2003

Um sistema em fluxo acoplado a espectrômetro de absorção atômica com chama (FIA-FAAS) foi desenvo... more Um sistema em fluxo acoplado a espectrômetro de absorção atômica com chama (FIA-FAAS) foi desenvolvido para determinação de taninos em amostras de feijão guandu, explorando a reação de precipitação entre os taninos e proteínas. Extratos obtidos pela sonicação das amostras com solução de metanol 50% (v/v), foram introduzidos no sistema e induzidos à reação com hemoglobina, sendo o precipitado produzido pela reação retido em um filtro localizado no percurso analítico. Solução 1% (m/v) dodecil sulfato de sódio, fluindo em sentido inverso ao fluxo de filtração, foi empregado para solubilizar e conduzir o complexo tanino-hemoglobina ao detector, espectrômetro de absorção atômica com chama, para quantificação dos íons ferro presentes na estrutura da hemoglobina. Uma solução de ácido tânico foi utilizada para construção da curva analítica. O método proposto apresentou freqüência analítica de 30 amostras por hora, desvio padrão relativo de 9,7 % (n=10) e limite de quantificação 0,27 mg L-1 de ácido tânico. A flow system, coupled with flame atomic absorption spectrometry (FIA-FAAS), was developed for tannin determination in pigeon pea samples, exploring the precipitation reaction between tannins and proteins. Sample extracts obtained by sonication with a 50% (v/v) methanol solution were introduced into the system and induced to react with a hemoglobin solution. The precipitate produced was retained on a filter located in the analytical flow. A reversed flow of 1% (w/v) sodium dodecyl sulfate solution was used for solubilization of the precipitate from the filter and to conduct the tanninhemoglobin complex to the FAAS, to quantify the iron ions present in the hemoglobin structure. A tannic acid solution was used to prepare the analytical curve. The proposed method allowed determination of 30 samples per hour, a standard deviation of 9.7% (n=10), and a quantification limit of 0.27 mg L-1 for tannic acid.

Research paper thumbnail of Bioaccessibility Assessment of Cu, Fe, K, Mg, P, and Zn in Thermally Treated Lamb Meat

A bioaccessibility test with raw and cooked lamb meat samples was performed. The evaluated cookin... more A bioaccessibility test with raw and cooked lamb meat samples was performed. The evaluated cooking devices were grill, microwave oven, air fryer, pressure cooker, and electric oven. Physicochemical parameters and the total mass fraction of Cu, Fe, K, Mg, P, and Zn were determined in raw and cooked samples by inductively coupled plasma optical emission spectrometry (ICP OES). The trueness was evaluated using certified reference materials, with recoveries from 87 to 101%. The pressure cooking presented the major changes, including the highest values of internal temperature, loss of inorganic elements after cooking, and the lowest values of moisture and analyte mass fractions. An in vitro gastrointestinal simulation was performed, and the method was validated by an addition and recovery test, in which the trueness varied from 87 to 115%. The bioaccessibility ranged between 28-56, 4-19, 68-76, 41-54, 48-57, and 1-21% for Cu, Fe, K, Mg, P, and Zn, respectively. The cooking methods promot...

Research paper thumbnail of Alternative Approaches Applied to Inductively Coupled Plasma Techniques: Multi‑Flow and Two-Flow Calibration

Journal of the Brazilian Chemical Society, 2021

Multi-flow calibration (MFC) is based on monitoring the analytical signal from a single calibrati... more Multi-flow calibration (MFC) is based on monitoring the analytical signal from a single calibration standard solution at several different nebulization gas flow rates (Q), which normalizes plasma conditions and minimizes matrix effects. In the present study, MFC was evaluated, for the first time, applied to inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) to analyze different and complexmatrix samples. Al, As, Cd, Cr, Cu, Mn, Pb, and Zn were determined by ICP OES, while As, Cd, Co, Cu, Hg, Mo, Mn, Ni, Se, Sb, Pb, and V were determined by ICP-MS. MFC results were compared with those obtained using external standard calibration (EC) for both techniques and in all cases, MFC showed equal or superior accuracy (recoveries between 80-120%) compared to EC, and lower relative standard deviation (RSDs ≤ 10%). Several tests were also performed using only two nebulization gas flows to build linear models for calibratio...

Research paper thumbnail of Bioacessibilidade De Zinco, Cálcio e Fósforo Em Extrato De Soja e Amostras De Leite Bovino, Caprino e Ovino

Química Nova, 2020

Recebido em 14/01/2020; aceito em 25/03/2020; publicado na web em 05/05/2020 BIOACESSIBILITY OF Z... more Recebido em 14/01/2020; aceito em 25/03/2020; publicado na web em 05/05/2020 BIOACESSIBILITY OF ZINC, CALCIUM AND PHOSPHORUS IN SOYBEAN EXTRACT AND COW, GOAT, SHEEP MILK SAMPLES. This work describes the bioaccessibility in vitro simulated gastric digestion for levels of Zn, Ca, and P in milk and soybean extract samples. Total and dialyzed levels were determined by ICP OES. According to results of the dialyzed samples, it can be concluded that in 250 mL of milk (a glass) the body can be absorb about 1.

Research paper thumbnail of Genetic regulators of mineral amount in Nelore cattle muscle predicted by a new co-expression and regulatory impact factor approach

Mineral amount in bovine muscle affect meat quality, growth, health and reproductive traits in be... more Mineral amount in bovine muscle affect meat quality, growth, health and reproductive traits in beef cattle. To better understand the genetic basis of this phenotype, we implemented new applications of use for two complementary algorithms: the partial correlation and information theory (PCIT) and the regulatory impact factor (RIF), by including GEBVs as part of the input. We used PCIT to determine putative regulatory relationships based on significant associations between gene expression and mineral amount. Then, RIF was used to determine the regulatory impact of genes and miRNA expression over mineral amount. We also investigated over-represented pathways, as well as evidences from previous studies carried in the same population, to determine regulatory genes for mineral amount e.g. NOX1, whose expression was positively correlated to Zn and was described as regulated by this mineral in humans. With this methodology, we were able to identify genes, miRNAs and pathways not yet describ...

Research paper thumbnail of Strategy of Sample Preparation for Arsenic Determination in Mineral Fertilizers

Journal of the Brazilian Chemical Society, 2016

A method for determination of arsenic in mineral fertilizers by continuous flow hydride generatio... more A method for determination of arsenic in mineral fertilizers by continuous flow hydride generation atomic absorption spectrometry (CF-HG-AAS) was developed by using diluted acid and digester block with perfluoroalkoxy (PFA) tubes to sample preparation. An additional sample preparation procedure using microwave-assisted digestion was evaluated and compared with the proposed procedure. A full factorial design was applied to investigate the effect of the variables and the best conditions found were 7 mol L −1 HNO 3 + 30% (m/m) H 2 O 2 as reagents, 4 h of digestion and concentration of reagents diluted 1:1. The effect of concomitants on the analytical signal of arsenic was investigated and no one significant interference was observed, with recoveries ranged from 97 to 103%. The accuracy of proposed method was evaluated by certified reference material (NIST SRM 695) and recovery of 95% was obtained. The arsenic concentration (8.9 ± 0.2 mg kg −1) found in the fertilizer is below of maximum concentration established by Brazilian legislation.

Research paper thumbnail of Evaluation of Decomposition Procedure to Determine Ba, Co, Cr, Cu, Ni, Mn, V, and Zn Total Content in Soil Samples

Communications in Soil Science and Plant Analysis, 2014

ABSTRACT

Research paper thumbnail of Análise exploratória dos teores de constituintes inorgânicos em sucos e refrigerantes de uva

Eclética Química, 2002

Os teores de Ca, Cu, K, Mg, Na, P e S foram determinados simultaneamente em sucos e refrigerantes... more Os teores de Ca, Cu, K, Mg, Na, P e S foram determinados simultaneamente em sucos e refrigerantes de uva utilizando espectrometria de emissão ótica com plasma de argônio induzido (ICP-OES) como técnica analítica. Os dados obtidos foram submetidos a dois métodos de análise exploratória: análise de componentes principais (PCA) e análise hierárquica de agrupamentos (HCA). Os resultados mostraram que o Na foi o principal elemento para discriminação entre as amostras, diferenciando principalmente sucos e refrigerantes. A adição de conservantes e o teor de sais minerais também foram aspectos relevantes para a discriminação dos grupos. A análise exploratória mostrou-se útil para o tratamento dos dados em questão, produzindo informações que dificilmente seriam visualizadas diretamente na matriz de dados.

Research paper thumbnail of Soil Calcium and pH Monitoring Sensor System

Journal of Agricultural and Food Chemistry, 2007

An agrarian sensorial system based on temperature, moisture, and all solid-state ion-selective po... more An agrarian sensorial system based on temperature, moisture, and all solid-state ion-selective potentiometric sensors was developed with the objective of monitoring the behavior of H + and Ca 2+ ions in soil and in real conditions, contributing with a new tool that tries to complement the current precision agriculture technology. The evaluation of the sensorial system to pH monitoring presented a good correlation between the results obtained by the system and the standard methodology, allowing us to notice the soil buffer capacity at different soil depths. With regard to calcium, the sensor system also presented an agreement between its results and those obtained by flame atomic absorption spectrometry, using a calibration model based on multiple linear regressions that allows the correct determination of Ca 2+ concentrations in soil depths where the relative moisture is different. In this way, using well-known potentiometric sensors in a complex, discontinued, and heterogeneous matrix, such as soil, the sensorial system proved to be a useful task for agrochemical field applications.

Research paper thumbnail of Effect of drying method and length of storage on tannin and total phenol concentrations in Pigeon pea seeds

Food Chemistry, 2004

Total phenols and condensed tannins in Pigeon pea seeds were determined by flow injection spectro... more Total phenols and condensed tannins in Pigeon pea seeds were determined by flow injection spectrophotometry. Folin-Denis and vanillin assays were used for total phenol and condensed tannin, respectively. Three Pigeon pea accessions were cultivated in a greenhouse. After harvesting, one access was separated into two aliquots. One aliquot was freeze-dried ()196°C), and the other was dried in a forced air oven at 50°C, like the other access samples, to evaluate drying temperature interference. The seeds were initially analyzed and then stored at around)10°C, 16°C or at ambient temperature (25 AE 10°C). The stored samples were analysed every 30 days, for a 90 day period. A significant difference ðP < 0:05Þ occurred between the drying methods for condensed tannin as well as for total phenols, regardless of the storage conditions. The experiments for comparing total phenols, obtained at different storage times, showed significant differences ðP < 0:05Þ for total phenols, indicating that tannin quantification has to be done immediately after harvesting to avoid formation of protein complexes or polymerisation, which lead to erroneous results. In accordance with results, freeze-drying proved to be best for preserving the characteristics of the sample. In order to compare the tannin and phenol contents within accessions, fresh seeds should be used.

Research paper thumbnail of Multivariate Classification of Cigarettes According to Their Elemental Content Determined by Inductively Coupled Plasma Optical Emission Spectrometry

Analytical Sciences, 2007

In this paper we describe our study on the characterization of cigarette samples according to the... more In this paper we describe our study on the characterization of cigarette samples according to their mineral content. Acid digestion assisted by microwaves was employed, and inductively coupled plasma optical emission spectrometry was the analytical technique used for the determination of Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, P and Sr in conventional, light, and flavorized cigarettes. Multivariate techniques, such as hierarchical clusters analysis (HCA) and principal-component analysis (PCA), were applied to discriminate among different types of cigarettes. Cluster analysis and principalcomponent analysis showed differences in cigarettes according to the type and mineral composition. The cigarette samples were divided within the 3 groups according to their mineral composition. Ca, Sr, Cu, K and Na were the most important elements for cigarette classification, and only these 5 variables were sufficient for the classification and discrimination of the evaluated types of cigarettes.

Research paper thumbnail of Evaluation of Distribution and Bioaccumulation of Arsenic by ICP-MS in Tilapia (Oreochromis niloticus) Cultivated in Different Environments

Journal of the Brazilian Chemical Society, 2017

The concentration of arsenic in tissues of tilapia was evaluated and an estimation of the risks a... more The concentration of arsenic in tissues of tilapia was evaluated and an estimation of the risks associated with the consumption of this fish was done, taking into account the guidelines established by FAO/WHO. The inductively coupled plasma mass spectrometry (ICP-MS) technique in kinetic energy discrimination (KED) mode was employed and certified reference materials were analyzed with recoveries of 101, 110, and 80% from NIST 1640a (trace elements in water), NIST 1566b (oyster tissue), and DORM-3 (fish protein). In the consumable portion (the muscle fish tissue), the average concentration found was 0.030 ± 0.008 µg g-1 , which is below the arsenic maximum level established by international regulatory agencies. The average concentration found in the viscera (stomach, gills, and liver) was 0.485 ± 0.225 µg g-1 , concluding that the viscera had greater capacity for the bioaccumulation of arsenic. From this study was possible to monitor the arsenic element in different tilapia specimens evidencing its accumulation throughout the body of the fish.

Research paper thumbnail of Fast method for the determination of copper, manganese and iron in seafood samples

Journal of Food Composition and Analysis, 2008

This article was published in an Elsevier journal. The attached copy is furnished to the author f... more This article was published in an Elsevier journal. The attached copy is furnished to the author for non-commercial research and education use, including for instruction at the author's institution, sharing with colleagues and providing to institution administration. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:

Research paper thumbnail of Embrapa's experience in the production and development of agriculture reference materials

Journal of Physics: Conference Series

The main challenge of Embrapa is to develop a model of genuine Brazilian tropical agriculture and... more The main challenge of Embrapa is to develop a model of genuine Brazilian tropical agriculture and livestock. To get this task, the quality of laboratories results is mandatory, increasing the demand for reference materials. Projects were proposed to produce reference materials to support the national agriculture laboratories and consolidate a network able to perform reliable and reproducible analytical testing laboratory within the internationally standards required. Reference materials were produced and available to interested laboratories and collaborative tests were conducted to obtain consensus values. The results and statistical evaluations were performed with the use of software developed by Embrapa Pecuária Sudeste.

Research paper thumbnail of Determination of Al, Ba, Cd, Cr, Cu, Fe, Sr, and Ti in Sparkler Candles by MIP OES

Research paper thumbnail of Chromium speciation in organic fertilizer by cloud point extraction and optimization through experimental Doehlert design as support for legislative aspects

Research paper thumbnail of Internal Standardization as a strategy to overcome non-spectral interferences in the determination of As, Cd and Pb in mineral fertilizers by synchronous vertical dual view (SVDV) ICP OES

Analytical Methods

Elemental determination for fertilizer analysis by optical spectrometric techniques is often pron... more Elemental determination for fertilizer analysis by optical spectrometric techniques is often prone to non-spectral interferences due to the high contents of easily ionizable elements (EIE’s). Here, we verify the use...

Research paper thumbnail of Determination of Trace Elements in Meat and Fish Samples by MIP OES Using Solid-Phase Extraction

Research paper thumbnail of Production and characterization of a bovine liver candidate reference material

Journal of Physics: Conference Series

The preparation of a bovine liver candidate reference material and the steps are taken to confirm... more The preparation of a bovine liver candidate reference material and the steps are taken to confirm its homogeneity, long and short term stabilities, and consensus values are described. Details of the sample preparation and the final collaborative exercise are presented. The material elemental composition was characterized by 17 elements (As,

Research paper thumbnail of Multi-Energy Calibration: A Practical Method for Determination of Macro and Micro Nutrients in Meat by ICP OES

Journal of the Brazilian Chemical Society

The multi-energy calibration (MEC) was evaluated for the determination of Ca, Cu, Fe, K, Mg, Na, ... more The multi-energy calibration (MEC) was evaluated for the determination of Ca, Cu, Fe, K, Mg, Na, P, S, and Zn in meat samples by inductively coupled plasma optical spectrometry (ICP OES). This calibration method consists of using only two calibration standards and several atomic and ionic emission wavelengths with different sensitivities to determine the analyte concentration in the sample. Both calibration mixtures are prepared using the same amount of sample, which contributes to minimize matrix effects. The accuracy was evaluated using two certified reference materials, bovine liver (SRM 1577c) and bovine muscle (SRM 8414), with recoveries within 87-107% range. The method was applied for the determination of the analytes in meats of chicken, sheep loin, sheep carcass and bovine, and prove to be usable in samples with different characteristics.

Research paper thumbnail of FIA-FAAS method for tannin determination based on a precipitation reaction with hemoglobin

Journal of the Brazilian Chemical Society, Apr 1, 2003

Um sistema em fluxo acoplado a espectrômetro de absorção atômica com chama (FIA-FAAS) foi desenvo... more Um sistema em fluxo acoplado a espectrômetro de absorção atômica com chama (FIA-FAAS) foi desenvolvido para determinação de taninos em amostras de feijão guandu, explorando a reação de precipitação entre os taninos e proteínas. Extratos obtidos pela sonicação das amostras com solução de metanol 50% (v/v), foram introduzidos no sistema e induzidos à reação com hemoglobina, sendo o precipitado produzido pela reação retido em um filtro localizado no percurso analítico. Solução 1% (m/v) dodecil sulfato de sódio, fluindo em sentido inverso ao fluxo de filtração, foi empregado para solubilizar e conduzir o complexo tanino-hemoglobina ao detector, espectrômetro de absorção atômica com chama, para quantificação dos íons ferro presentes na estrutura da hemoglobina. Uma solução de ácido tânico foi utilizada para construção da curva analítica. O método proposto apresentou freqüência analítica de 30 amostras por hora, desvio padrão relativo de 9,7 % (n=10) e limite de quantificação 0,27 mg L-1 de ácido tânico. A flow system, coupled with flame atomic absorption spectrometry (FIA-FAAS), was developed for tannin determination in pigeon pea samples, exploring the precipitation reaction between tannins and proteins. Sample extracts obtained by sonication with a 50% (v/v) methanol solution were introduced into the system and induced to react with a hemoglobin solution. The precipitate produced was retained on a filter located in the analytical flow. A reversed flow of 1% (w/v) sodium dodecyl sulfate solution was used for solubilization of the precipitate from the filter and to conduct the tanninhemoglobin complex to the FAAS, to quantify the iron ions present in the hemoglobin structure. A tannic acid solution was used to prepare the analytical curve. The proposed method allowed determination of 30 samples per hour, a standard deviation of 9.7% (n=10), and a quantification limit of 0.27 mg L-1 for tannic acid.

Research paper thumbnail of Bioaccessibility Assessment of Cu, Fe, K, Mg, P, and Zn in Thermally Treated Lamb Meat

A bioaccessibility test with raw and cooked lamb meat samples was performed. The evaluated cookin... more A bioaccessibility test with raw and cooked lamb meat samples was performed. The evaluated cooking devices were grill, microwave oven, air fryer, pressure cooker, and electric oven. Physicochemical parameters and the total mass fraction of Cu, Fe, K, Mg, P, and Zn were determined in raw and cooked samples by inductively coupled plasma optical emission spectrometry (ICP OES). The trueness was evaluated using certified reference materials, with recoveries from 87 to 101%. The pressure cooking presented the major changes, including the highest values of internal temperature, loss of inorganic elements after cooking, and the lowest values of moisture and analyte mass fractions. An in vitro gastrointestinal simulation was performed, and the method was validated by an addition and recovery test, in which the trueness varied from 87 to 115%. The bioaccessibility ranged between 28-56, 4-19, 68-76, 41-54, 48-57, and 1-21% for Cu, Fe, K, Mg, P, and Zn, respectively. The cooking methods promot...

Research paper thumbnail of Alternative Approaches Applied to Inductively Coupled Plasma Techniques: Multi‑Flow and Two-Flow Calibration

Journal of the Brazilian Chemical Society, 2021

Multi-flow calibration (MFC) is based on monitoring the analytical signal from a single calibrati... more Multi-flow calibration (MFC) is based on monitoring the analytical signal from a single calibration standard solution at several different nebulization gas flow rates (Q), which normalizes plasma conditions and minimizes matrix effects. In the present study, MFC was evaluated, for the first time, applied to inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) to analyze different and complexmatrix samples. Al, As, Cd, Cr, Cu, Mn, Pb, and Zn were determined by ICP OES, while As, Cd, Co, Cu, Hg, Mo, Mn, Ni, Se, Sb, Pb, and V were determined by ICP-MS. MFC results were compared with those obtained using external standard calibration (EC) for both techniques and in all cases, MFC showed equal or superior accuracy (recoveries between 80-120%) compared to EC, and lower relative standard deviation (RSDs ≤ 10%). Several tests were also performed using only two nebulization gas flows to build linear models for calibratio...

Research paper thumbnail of Bioacessibilidade De Zinco, Cálcio e Fósforo Em Extrato De Soja e Amostras De Leite Bovino, Caprino e Ovino

Química Nova, 2020

Recebido em 14/01/2020; aceito em 25/03/2020; publicado na web em 05/05/2020 BIOACESSIBILITY OF Z... more Recebido em 14/01/2020; aceito em 25/03/2020; publicado na web em 05/05/2020 BIOACESSIBILITY OF ZINC, CALCIUM AND PHOSPHORUS IN SOYBEAN EXTRACT AND COW, GOAT, SHEEP MILK SAMPLES. This work describes the bioaccessibility in vitro simulated gastric digestion for levels of Zn, Ca, and P in milk and soybean extract samples. Total and dialyzed levels were determined by ICP OES. According to results of the dialyzed samples, it can be concluded that in 250 mL of milk (a glass) the body can be absorb about 1.

Research paper thumbnail of Genetic regulators of mineral amount in Nelore cattle muscle predicted by a new co-expression and regulatory impact factor approach

Mineral amount in bovine muscle affect meat quality, growth, health and reproductive traits in be... more Mineral amount in bovine muscle affect meat quality, growth, health and reproductive traits in beef cattle. To better understand the genetic basis of this phenotype, we implemented new applications of use for two complementary algorithms: the partial correlation and information theory (PCIT) and the regulatory impact factor (RIF), by including GEBVs as part of the input. We used PCIT to determine putative regulatory relationships based on significant associations between gene expression and mineral amount. Then, RIF was used to determine the regulatory impact of genes and miRNA expression over mineral amount. We also investigated over-represented pathways, as well as evidences from previous studies carried in the same population, to determine regulatory genes for mineral amount e.g. NOX1, whose expression was positively correlated to Zn and was described as regulated by this mineral in humans. With this methodology, we were able to identify genes, miRNAs and pathways not yet describ...

Research paper thumbnail of Strategy of Sample Preparation for Arsenic Determination in Mineral Fertilizers

Journal of the Brazilian Chemical Society, 2016

A method for determination of arsenic in mineral fertilizers by continuous flow hydride generatio... more A method for determination of arsenic in mineral fertilizers by continuous flow hydride generation atomic absorption spectrometry (CF-HG-AAS) was developed by using diluted acid and digester block with perfluoroalkoxy (PFA) tubes to sample preparation. An additional sample preparation procedure using microwave-assisted digestion was evaluated and compared with the proposed procedure. A full factorial design was applied to investigate the effect of the variables and the best conditions found were 7 mol L −1 HNO 3 + 30% (m/m) H 2 O 2 as reagents, 4 h of digestion and concentration of reagents diluted 1:1. The effect of concomitants on the analytical signal of arsenic was investigated and no one significant interference was observed, with recoveries ranged from 97 to 103%. The accuracy of proposed method was evaluated by certified reference material (NIST SRM 695) and recovery of 95% was obtained. The arsenic concentration (8.9 ± 0.2 mg kg −1) found in the fertilizer is below of maximum concentration established by Brazilian legislation.

Research paper thumbnail of Evaluation of Decomposition Procedure to Determine Ba, Co, Cr, Cu, Ni, Mn, V, and Zn Total Content in Soil Samples

Communications in Soil Science and Plant Analysis, 2014

ABSTRACT

Research paper thumbnail of Análise exploratória dos teores de constituintes inorgânicos em sucos e refrigerantes de uva

Eclética Química, 2002

Os teores de Ca, Cu, K, Mg, Na, P e S foram determinados simultaneamente em sucos e refrigerantes... more Os teores de Ca, Cu, K, Mg, Na, P e S foram determinados simultaneamente em sucos e refrigerantes de uva utilizando espectrometria de emissão ótica com plasma de argônio induzido (ICP-OES) como técnica analítica. Os dados obtidos foram submetidos a dois métodos de análise exploratória: análise de componentes principais (PCA) e análise hierárquica de agrupamentos (HCA). Os resultados mostraram que o Na foi o principal elemento para discriminação entre as amostras, diferenciando principalmente sucos e refrigerantes. A adição de conservantes e o teor de sais minerais também foram aspectos relevantes para a discriminação dos grupos. A análise exploratória mostrou-se útil para o tratamento dos dados em questão, produzindo informações que dificilmente seriam visualizadas diretamente na matriz de dados.

Research paper thumbnail of Soil Calcium and pH Monitoring Sensor System

Journal of Agricultural and Food Chemistry, 2007

An agrarian sensorial system based on temperature, moisture, and all solid-state ion-selective po... more An agrarian sensorial system based on temperature, moisture, and all solid-state ion-selective potentiometric sensors was developed with the objective of monitoring the behavior of H + and Ca 2+ ions in soil and in real conditions, contributing with a new tool that tries to complement the current precision agriculture technology. The evaluation of the sensorial system to pH monitoring presented a good correlation between the results obtained by the system and the standard methodology, allowing us to notice the soil buffer capacity at different soil depths. With regard to calcium, the sensor system also presented an agreement between its results and those obtained by flame atomic absorption spectrometry, using a calibration model based on multiple linear regressions that allows the correct determination of Ca 2+ concentrations in soil depths where the relative moisture is different. In this way, using well-known potentiometric sensors in a complex, discontinued, and heterogeneous matrix, such as soil, the sensorial system proved to be a useful task for agrochemical field applications.

Research paper thumbnail of Effect of drying method and length of storage on tannin and total phenol concentrations in Pigeon pea seeds

Food Chemistry, 2004

Total phenols and condensed tannins in Pigeon pea seeds were determined by flow injection spectro... more Total phenols and condensed tannins in Pigeon pea seeds were determined by flow injection spectrophotometry. Folin-Denis and vanillin assays were used for total phenol and condensed tannin, respectively. Three Pigeon pea accessions were cultivated in a greenhouse. After harvesting, one access was separated into two aliquots. One aliquot was freeze-dried ()196°C), and the other was dried in a forced air oven at 50°C, like the other access samples, to evaluate drying temperature interference. The seeds were initially analyzed and then stored at around)10°C, 16°C or at ambient temperature (25 AE 10°C). The stored samples were analysed every 30 days, for a 90 day period. A significant difference ðP < 0:05Þ occurred between the drying methods for condensed tannin as well as for total phenols, regardless of the storage conditions. The experiments for comparing total phenols, obtained at different storage times, showed significant differences ðP < 0:05Þ for total phenols, indicating that tannin quantification has to be done immediately after harvesting to avoid formation of protein complexes or polymerisation, which lead to erroneous results. In accordance with results, freeze-drying proved to be best for preserving the characteristics of the sample. In order to compare the tannin and phenol contents within accessions, fresh seeds should be used.

Research paper thumbnail of Multivariate Classification of Cigarettes According to Their Elemental Content Determined by Inductively Coupled Plasma Optical Emission Spectrometry

Analytical Sciences, 2007

In this paper we describe our study on the characterization of cigarette samples according to the... more In this paper we describe our study on the characterization of cigarette samples according to their mineral content. Acid digestion assisted by microwaves was employed, and inductively coupled plasma optical emission spectrometry was the analytical technique used for the determination of Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, P and Sr in conventional, light, and flavorized cigarettes. Multivariate techniques, such as hierarchical clusters analysis (HCA) and principal-component analysis (PCA), were applied to discriminate among different types of cigarettes. Cluster analysis and principalcomponent analysis showed differences in cigarettes according to the type and mineral composition. The cigarette samples were divided within the 3 groups according to their mineral composition. Ca, Sr, Cu, K and Na were the most important elements for cigarette classification, and only these 5 variables were sufficient for the classification and discrimination of the evaluated types of cigarettes.

Research paper thumbnail of Evaluation of Distribution and Bioaccumulation of Arsenic by ICP-MS in Tilapia (Oreochromis niloticus) Cultivated in Different Environments

Journal of the Brazilian Chemical Society, 2017

The concentration of arsenic in tissues of tilapia was evaluated and an estimation of the risks a... more The concentration of arsenic in tissues of tilapia was evaluated and an estimation of the risks associated with the consumption of this fish was done, taking into account the guidelines established by FAO/WHO. The inductively coupled plasma mass spectrometry (ICP-MS) technique in kinetic energy discrimination (KED) mode was employed and certified reference materials were analyzed with recoveries of 101, 110, and 80% from NIST 1640a (trace elements in water), NIST 1566b (oyster tissue), and DORM-3 (fish protein). In the consumable portion (the muscle fish tissue), the average concentration found was 0.030 ± 0.008 µg g-1 , which is below the arsenic maximum level established by international regulatory agencies. The average concentration found in the viscera (stomach, gills, and liver) was 0.485 ± 0.225 µg g-1 , concluding that the viscera had greater capacity for the bioaccumulation of arsenic. From this study was possible to monitor the arsenic element in different tilapia specimens evidencing its accumulation throughout the body of the fish.

Research paper thumbnail of Fast method for the determination of copper, manganese and iron in seafood samples

Journal of Food Composition and Analysis, 2008

This article was published in an Elsevier journal. The attached copy is furnished to the author f... more This article was published in an Elsevier journal. The attached copy is furnished to the author for non-commercial research and education use, including for instruction at the author's institution, sharing with colleagues and providing to institution administration. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:

Research paper thumbnail of Embrapa's experience in the production and development of agriculture reference materials

Journal of Physics: Conference Series

The main challenge of Embrapa is to develop a model of genuine Brazilian tropical agriculture and... more The main challenge of Embrapa is to develop a model of genuine Brazilian tropical agriculture and livestock. To get this task, the quality of laboratories results is mandatory, increasing the demand for reference materials. Projects were proposed to produce reference materials to support the national agriculture laboratories and consolidate a network able to perform reliable and reproducible analytical testing laboratory within the internationally standards required. Reference materials were produced and available to interested laboratories and collaborative tests were conducted to obtain consensus values. The results and statistical evaluations were performed with the use of software developed by Embrapa Pecuária Sudeste.

Research paper thumbnail of Determination of Al, Ba, Cd, Cr, Cu, Fe, Sr, and Ti in Sparkler Candles by MIP OES

Research paper thumbnail of Chromium speciation in organic fertilizer by cloud point extraction and optimization through experimental Doehlert design as support for legislative aspects

Research paper thumbnail of Internal Standardization as a strategy to overcome non-spectral interferences in the determination of As, Cd and Pb in mineral fertilizers by synchronous vertical dual view (SVDV) ICP OES

Analytical Methods

Elemental determination for fertilizer analysis by optical spectrometric techniques is often pron... more Elemental determination for fertilizer analysis by optical spectrometric techniques is often prone to non-spectral interferences due to the high contents of easily ionizable elements (EIE’s). Here, we verify the use...

Research paper thumbnail of Determination of Trace Elements in Meat and Fish Samples by MIP OES Using Solid-Phase Extraction

Research paper thumbnail of Production and characterization of a bovine liver candidate reference material

Journal of Physics: Conference Series

The preparation of a bovine liver candidate reference material and the steps are taken to confirm... more The preparation of a bovine liver candidate reference material and the steps are taken to confirm its homogeneity, long and short term stabilities, and consensus values are described. Details of the sample preparation and the final collaborative exercise are presented. The material elemental composition was characterized by 17 elements (As,

Research paper thumbnail of Multi-Energy Calibration: A Practical Method for Determination of Macro and Micro Nutrients in Meat by ICP OES

Journal of the Brazilian Chemical Society

The multi-energy calibration (MEC) was evaluated for the determination of Ca, Cu, Fe, K, Mg, Na, ... more The multi-energy calibration (MEC) was evaluated for the determination of Ca, Cu, Fe, K, Mg, Na, P, S, and Zn in meat samples by inductively coupled plasma optical spectrometry (ICP OES). This calibration method consists of using only two calibration standards and several atomic and ionic emission wavelengths with different sensitivities to determine the analyte concentration in the sample. Both calibration mixtures are prepared using the same amount of sample, which contributes to minimize matrix effects. The accuracy was evaluated using two certified reference materials, bovine liver (SRM 1577c) and bovine muscle (SRM 8414), with recoveries within 87-107% range. The method was applied for the determination of the analytes in meats of chicken, sheep loin, sheep carcass and bovine, and prove to be usable in samples with different characteristics.