ABSTRACT
Este estudo teve como objetivo analisar os teores de flúor na água de abastecimento público do município de Uberlândia (MG) e, adicionalmente, comparar os valores encontrados com os dados do controle operacional e de um laboratório de referência. Durante seis meses coletaram-se 126 amostras, as quais foram analisadas pela técnica eletrométrica, inicialmente na Universidade Federal de Uberlândia e depois pelo laboratório de referência. Por meio do teste Generalized Estimating Equations, os dados foram comparados entre si e com os de controle ope-racional. Observou-se diferença estatística entre os laboratórios, entre os momentos avaliados e na interação entre laboratório e tempo. Mesmo com variabilidade entre os resultados, pôde-se concluir que o flúor está presente na água de abastecimento de Uberlândia com teores dentro dos padrões recomendados pelo Centro Colaborador do Ministério da Saúde em Vigilância da Saúde Bucal quanto à concentração de fluoretos e que a população tem sido assistida de forma segura.
This study aimed to analyze the fluoride levels in the public water supply in Uberlândia, State of Minas Gerais, and, in addition, to compare the values with data from the operational control and from a reference laboratory. A total of 126 samples were collected over 6 months. Samples were analyzed using the electrometric technique, initially at the Federal University of Uberlândia and later at the reference laboratory. With the Generalized Estimating Equations, data were compared to each other and to the operational control data. A statistical difference was detected between the laboratories, between the moments evaluated and in the interaction between the laboratory and the time of sample collection. Even with variability in the results, it can be concluded that fluoride is present in the water supply in the municipality of Uberlândia, at levels within the range recommended by the Collaborating Center of the Ministry of Health in Oral Health Surveillance regarding the concentration of fluorides, and the population has been served with safe water.
ABSTRACT
A methodology was developed to monitor the content of crambe biodiesel in mixtures with conventional diesel using hydrogen nuclear magnetic resonance (1H NMR) spectroscopy combined with the orthogonal projections on the latent structure-discrimination analysis (OPLS-DA). The efficiency of the developed OPLS-DA model was analyzed based on the criteria of true response statistics: false positive and false negative rate, sensitivity, specificity, efficiency and Matthew's correlation coefficient, where the sensitivity (true positive rate) and specificity (true negative rate) were both equal to 1 and the false positive and false negative rates were both equal to 0, which means that all samples to be predicted as belonging to the diesel class of interest, B10 (containing 10% biodiesel and 90% pure diesel), were predicted in class 1, and all samples to be considered as belonging to the diesel class, not of interest, BX (biodiesel content less and greater than in B10), were predicted in class 0. These results showed 100% correct classification of the training and test set samples for B10 and BX, demonstrating a high efficiency of the OPLS-DA model in the monitoring of crambe methyl biodiesel content when mixed with diesel in various proportions. The excellent results in the application of this model suggest that this analytical methodology is feasible, efficient and suitable for use by inspection agencies to control the quality of this fuel.