Resumen En este trabajo, se caracterizó el color de lacas acrílicas blancas utilizadas para retocar pintura automotriz, mediante el espacio de color CIELab y el índice de blancura, utilizando el iluminante estándar D65 y el observador estándar a diez grados. A partir de tal información, fue posible reconocer las tendencias del color usado en este tipo de productos en el mercado nacional. Por otra parte, la aplicación de las técnicas quimiométricas de Análisis de Componentes Principales, Análisis de Grupos y Análisis Jerárquico, permitió reconocer semejanzas entre los colores observados, encontrando, entre otros, la mayor diferencia visual en la laca de blanco aperlado. Por otro lado, la laca de blanco Alaska de Mazda y la de blanco universal de Nissan fueron las más parecidas. También se concluye que el análisis cromático y el quimiométrico de datos espectrales fueron complementarios, por lo que se recomiendan ambos en el nivel de control de calidad.

Resumo Neste trabalho, caracterizou-se a cor de lacas acrílicas brancas utilizadas para retocar pintura automotriz, através do espaço de cor CIELab e o índice de brancura, utilizando o iluminador padrão D65 e o observador padrão a 10 graus. A partir dessa informação, foi possível reconhecer as tendências da cor usada neste tipo de produtos no mercado nacional. Por outro lado, a aplicação das técnicas quimiométricas de Análise de Componentes Principais, Análise de Grupos e Análise Hierárquica permitiu reconhecer semelhanças entre as cores observadas, encontrando, entre outras, a maior diferença visual na laca de branco perolizado. Por sua vez, a laca do branco Alaska da MAZDA e a do branco universal da NISSAN foram as mais parecidas. Conclui-se, também, que a análise cromática e a quimiométrica de dados espectrais foram complementárias, razão pela qual, em nível de controle de qualidade, ambas são recomendadas.

Abstract The color of white acrylic lacquers utilized to touch up automotive paint was characterized in this paper using the CIELab color space and the whiteness index, with standard illuminant D65 and the standard observer at ten degrees. Based on this information, the color trends used in this type of product in the national market were recognized. In addition, the chemometric techniques of the Principal Component Analysis, Cluster Analysis, and Hierarchical Analysis allowed for recognition of similarities between the observed colors, which found, among other aspects, the greatest visual difference in the pearl white lacquer. On the other hand, the Alaskan white lacquer from Mazda and the universal white lacquer from Nissan were the most similar. It is also concluded that the chromatic and chemometric analyses of spectral data complemented each other; therefore, both are recommended for quality control purposes.

In this work, chemometric tools were applied to establish correlations between biomarkers for identifying the most significant ones in relation to acute exposure of Wistar rats to Pb. The metal content in biological matrices (serum, urine, liver, brain, and kidney), biochemical parameters (protein content, activity of the Glutathione S-Transferase enzymes, and urinalysis), apart from morphological measurements of organisms, were estimated in both the exposed and the control groups and submitted to Significance tests, Principal Component Analysis, Hierarchical Cluster Analysis, and Generalized Procrustean Analysis. It could be observed that Pb in serum, but not in erythrocytes, was the biomarker associated with the Pb content in kidney and other parameters related to this organ. In the same way, Pearson correlation coefficients emphasized the relation between Pb in serum and these variables, with the exception of kidney weight. Additionally, Pb in serum was found to be the biomarker with the greatest difference between the control and the exposed groups, which converts it into the most sensitive biomarker in the present study

En el presente trabajo, se aplicaron herramientas quimiométricas para establecer las correlaciones entre biomarcadores e identificar los más significativos en relación a la exposición aguda de ratas Wistar a Pb. El contenido del metal en matrices biológicas (suero, orina, hígado, cerebro y riñón), parámetros bioquímicos (contenido de proteína, la actividad de enzimas Glutatión S-Transferasas y análisis de orina), además de mediciones morfológicas a los organismos, se estimaron en los grupos control y expuesto y fueron sometidos a Contrastes de Significación, Análisis de Componentes Principales, Análisis Jerárquico de Conglomerados y Análisis de Procrustes Generalizado. Pudo observarse que el Pb en suero y no en eritrocitos fue el biomarcador asociado con el Pb en riñón y otros parámetros relacionados con este organismo, lo que pudo corroborarse a través de los coeficientes de correlación de Pearson, a excepción de Pb en suero y peso del riñón. Además, el contenido de Pb en suero fue el biomarcador con la mayor diferencia entre el grupo control y el expuesto, lo que lo convierte en el biomarcador más sensible en el presente estudio.

The electrochemical behavior of the metamitron herbicide at the water|1,2-dichloroethane interface was studied by means of cyclic voltammetry and Electrochemical Impedance Spectroscopy. The results show that metamitron extraction across the interface was pH dependent. The curves capacitance-potential shown that the presence of a lipid monolayer inhibits the metamitrone transport across the interface. In this paper the equilibrium partition of metamitron across the interface of two immiscible electrolyte solutions is discussed

Se estudió el comportamiento electroquímico del herbicida metamitrona en la interface agua|1,2-dicloroetano mediante voltamperometría cíclica y Espectroscopía de Impedancia Electroquímica. Se encontró que la extracción de la metamitrona es dependiente del pH. Los estudios a través de las curvas capacitancia-potencial muestran que la presencia de una monocapa de lípidos en la interfase, bloquea el transporte de este herbicida. En el presente articulo se discute el equilibrio de partición de la metamitrona en el sistema de interfases de dos soluciones electrolíticas inmiscibles.

Soft Independent Modeling of Class Analogy (SIMCA) e Regressão por Mínimos Quadrados Parciais foram usados nesse trabalho para a identificação e quantificação de tiamina, riboflavina, nicotinamida e piridoxina, por espectrofotometria UV-Vis, sem realizar os procedimentos analíticos de separação e pré-concentração. Para a quantificação, os intervalos de trabalho estabelecidos foram 1-14 mg L-1 para riboflavina, 2-26 mg L-1 para tiamina, 2-30 mg L-1 para nicotinamida, e 2-22 mg L-1 para piridoxina. Os resultados de recuperação obtidos foram superiores a 95% em todos os casos, para a análise de amostras sintéticas e comerciais. Na busca de cada vitamina alvo, foi construído um modelo de classificação com duas categorias: (i) com a vitamina de interesse e (ii) sem a vitamina de interesse. A capacidade discriminatória de cada modelo de classificação foi avaliada para aprendizagem, para um conjunto de amostras teste e para amostras comerciais, com resultados satisfatórios, com exceção da riboflavina. Assim, um método simples e confiável é proposto para a estimativa simultânea desses compostos.

Soft Independent Modeling of Class Analogy and Partial Least Squares Regression were used in this work for the identification and quantification of thiamine, riboflavin, nicotinamide and pyridoxine by UV-Vis spectrophotometry, without separation or preconcentration steps in the analytical procedure. For quantitative purposes, the working range established was 1-14 mg L-1 for riboflavin, 2-26 mg L-1 for thiamine, 2-30 mg L-1 for nicotinamide, and 2-22 mg L-1 for pyridoxine. Recovery results higher than 95% were obtained in all cases during the analysis of synthetic and commercial samples. In the screening of each target vitamin, a classification model was built with two classes: (i) with the vitamin of interest, and (ii) without it. The discriminate capability of each classification model was evaluated for learning, independent testing and commercial samples, resulting in satisfactory findings with exception of riboflavin. Thus, a simple and reliable method is proposed for the simultaneous estimation of these compounds.

It is presented the development of a new and easy analytical method for the simultaneous determination of atrazine and dicamba in water. Under the experimental conditions proposed, atrazine showed a linear dynamic range of 0.3 to 4.9 µg mL-1, a limit of detection of 0.1 µg mL-1 and a limit of quantification of 0.3 µg mL-1; similarly, dicamba showed a linear dynamic range of 0.8 to 8.8 µg mL-1, a limit of detection of 0.2 µg mL-1 and a limit of quantification of 0.8 µ mL-1. Partial Least Squares Regression (Type 1) was applied for the resolution of spectral interferences between analytes, obtaining recovery percentages higher than 95 % for both compounds in synthetic mixtures. Finally, quantitative determination of both herbicides in tap, well and sea water samples, was carried out successfully by the proposed method, previous preconcentration of the analytes by solid phase extraction