Navegando por Autor "SALDANHA, Teresa Cristina Bezerra"

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Acesso aberto (Open Access)
Flow-batch analyser for preparation of calibration standard mixtures in simultaneous multicomponent spectrometric analysis
(2009) VISANI, Valeria; BARROS, Sara Regina Ribeiro Carneiro de; DANTAS FILHO, Heronides Adonias; ALMEIDA, Luciano Farias; LIMA, Ricardo Alexandre Cavalcanti de; FRAGOSO, Wallace Duarte; SALDANHA, Teresa Cristina Bezerra; ARAÚJO, Mário César Ugulino de
The application of multivariate calibration techniques to multicomponent analysis by UV-VIS molecular absorption spectrometry is a powerful tool for simultaneous determination of several chemical species. However, when this methodology is accomplished manually, it is slow and laborious, consumes high amounts of reagents and samples, is susceptible to contaminations and presents a high operational cost. To overcome these drawbacks, a flow-batch analyser is proposed in this work. This analyser was developed for automatic preparation of standard calibration and test (or validation) mixtures. It was applied to the simultaneous determination of Cu2+, Mn2+ and Zn2+ in polyvitaminic and polymineral pharmaceutical formulations, using 4-(2-piridilazo) resorcinol as reagent and a UV-VIS spectrophotometer with a photodiode array detector. The results obtained with the proposed system are in good agreement with those obtained by flame atomic absorption spectrometry, which was employed as reference method. With the proposed analyser, the preparation of calibration and test mixtures can be accomplished about four hours, while the manual procedure requires at least two days. Moreover, it consumes smaller amounts of reagents and samples than the manual procedure. After the preparation of calibration and test mixtures, 60 samples-1 can be carried out with the proposed flow-batch analyser.
Acesso aberto (Open Access)
Simultaneous spectrometric determination of Cu2+, Mn2+ and Zn2+ in polivitaminic/polimineral drug using SPA and GA algorithms for variable selection
(2005-02) DANTAS FILHO, Heronides Adonias; SOUZA, Ênio Sartre Oliveira Nunes de; VISANI, Valeria; BARROS, Sara Regina Ribeiro Carneiro de; SALDANHA, Teresa Cristina Bezerra; ARAÚJO, Mário César Ugulino de; GALVÃO, Roberto Kawakami Harrop
The application of the method for the simultaneous spectrophotometric determination of the divalent ions of copper, manganese and zinc for analysis of a pharmaceutical formulation of polivitaminic/polimineral is reported. This method uses 4-(2-pyridylazo) resorcinol (PAR) and multivariate calibration and was optimized using the successive projections algorithm (SPA) and a genetic algorithm (GA) for choosing the best series of wavelengths for analysis. Thus the construction of calibration models based on multiple linear regression (MLR-SPA and MLR-GA respectively) was made possible. The results obtained were compared with models based on latent variables, principal component regression (PCR) and partial least square regression (PLS) through the criterion of the root mean square error of prediction (RMSEP). All the methods presented even performance but the RLM methods are simpler since they require a smaller number of wavelengths and are easier to interpret than those based on latent variables.