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Synthetic azo dyes, such as tartrazine, sunset yellow and allura red have sensitive polarographic waves in solution (pH 9.2). However, the dyes polarographic waves are seriously overlapped making their simultaneous determination difficult without previous sample preparation. The aim of this work was to apply partial least squares (PLS) multivariate calibration to such commonplace electrochemical technique as differential pulse polarography (DPP) for the simultaneous determination of the dye's three component mixture at trace levels (0.05–1.00 μmol/L). The method has been applied in the determination of these synthetic dyes in commercial food products.

cInstituto de Ecología, Universidad del Mar, 70902 Puerto Ángel Oax., México 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.

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