Multivariate optimization of microwave-assisted digestion of copper and zinc from powder milk

Abstract

Neste trabalho, um método fácil e rápido de digestão assistida por micro-ondas combinado com espectrometria de absorção atômica por chama (FAAS) foi desenvolvido para determinações de zinco e cobre em amostras de leite. A potência da irradiação, o volume de ácido nítrico, a temperatura e o tempo de digestão foram selecionados para a otimização deste trabalho. Os resultados do planejamento fatorial completo de 2 níveis (2 4 ) baseado em análise de variância (ANOVA) e diagrama de Pareto mostraram que todos os fatores são estatisticamente significantes. As condições ideais das extrações dos analitos em amostras de leite foram obtidas por metodologia de superfície de resposta (RSM) baseada no planejamento experimental Box-Behnken. Uma condição de compromisso entre as melhores condições para cada analito foi selecionada para a aplicação do método proposto, na determinação de zinco e cobre em amostras de leite. Estes valores foram 110 °C, 450 W, 4,0 mL e 21,0 min, para temperatura, potência da irradiação, volume de ácido nítrico e tempo de digestão, respectivamente.In the present study, an easy and fast microwave-assisted digestion method combined with flame atomic absorption spectrometry (FAAS) was developed for zinc and copper determinations in milk samples. The irradiation power, volume of nitric acid, temperature and digestion time were selected for optimization in this work study. The results of 2-level full factorial (2 4 ) design based on analysis of variance (ANOVA) and Pareto chart showed that all of factors were statistically significant. The optimal conditions for the analytes extraction in milk samples were obtained by response surface methodology (RSM) based on Box-Behnken experimental design. The conditions of work were accepted as an agreement between optimal values that were found for the analytes. These values were 110 °C, 450 W, 4.0 mL and 21.0 min for temperature, irradiation power, volume of nitric acid and digestion time, respectively. This procedure was applied to the zinc and copper determinations in milk samples.

Factorial Design Optimization of Microwave Digestion for Macro and Microelements in Pregnant Women and Diabetics Multivitamin/Multielement Preparations by Inductive Coupled Plasma Mass Spectrometry (ICPMS)

“…Besides, ANOVA results show the p-value (probability value) which indicates the significant differences in multiple responses with each factor. When the p-value is lower than 0.05, it demonstrates that the model is statistically significant [23]. Additionally, the interactions of acid volume with radiation period model, and interaction of temperature with radiation period model are statistical significant with p-value 0.047 and 0.02, respectively, as shown in Table 4.…”

“…Several previous studies have focused on optimization of microwave assistant digestion using multivariate techniques to assess the relationship between experimental condition factors and obtain statistically acceptable results for optimization method for quantification analysis of organic and inorganic species [20]. The factorial design is a good tool for finding the critical conditions of the factors (maximum and minimum) with lower consumption of reagents, decreased time spent during the optimization steps [20], and the pareto chart shows the statistical significance of the factors [21][22][23]. Anjos and colleagues [22] optimized a sample preparation procedure using microwave-assisted digestion for the determination of nickel and vanadium in crude oil employing inductively coupled plasma optical emission spectrometry (ICP OES).…”

“…The optimization step was performed utilizing a two-level full factorial design (2 3 ). Khajeh [23] optimized an easy and fast microwave-assisted digestion method combined with flame atomic absorption spectrometry (FAAS) for zinc and copper determinations in milk samples, and this method was performed by 2-level full factorial (2 4 ) design based on analysis of variance (ANOVA). In addition to these advantages, the limited works had been done reporting the use of factorial techniques for elemental determination in multivitamin/multielement.…”

Niveles de cobre y zinc en diferentes etapas de la leche materna y la influencia del estado nutricional de madres lactantes

“…Además, la alimentación complementaria suele iniciarse de manera precoz o de forma tardía, y con frecuencia se introducen alimentos de muy bajo aporte nutricional. Como consecuencia, los niños que padecen malnutrición por déficit presentan índices de supervivencia bajos y frecuentemente sufren a lo largo de su vida las consecuencias de un retraso en su desarrollo 9,10,11,12 . Entre las razones más comunes por las que las madres no siguen la recomendación de la lactancia materna son: (i) consideran que ellas no producen suficiente leche, o que tienen algún otro problema para lactar; (ii) tienen un empleo fuera de su casa y desconocen cómo amamantar y al mismo tiempo continuar trabajando; (iii) pocos conocimientos en lo que se refiere a los beneficios que ofrece la lactancia materna; y (iv) la falta de actividades educativas y de concientización por parte de las instancias educativas gubernamentales y los organismos de salud 10 .…”