The aim of this work was to develop and validate methodology to reduce the digestion time and reagent consumption in the determination of minerals in maize flour. The standard methodology employed in Brazil is that described by AOAC. It consists of the calcination of the sample at high temperatures for a long period of time, making the process expensive and slow. In this work, a wet sample digestion method using HNO 3 was employed, heating on a block digester with final dissolution in an ultrasonic bath. The validation tests involved linearity and working range studies, and the determination of the detection and quantification limits, accuracy and precision. The sample digestion time was 1:30 h and the percent recoveries for the metals were 93% for Ca, 98% for Cu, 110% for Fe, 97% for Mg, 101% for Mn and 106% for Zn. Keywords: Metals; Maize flour; Acid digestion; Sonification.Resumo O objetivo deste trabalho consiste em desenvolver e validar uma metodologia que reduza o tempo de digestão e o consumo de reagentes para determinar minerais em farinha de milho. No Brasil, a metodologia padrão utilizada é a descrita pelo AOAC, que consiste na calcinação da amostra em altas temperaturas, por longo período, o que torna o processo dispendioso e moroso. Neste trabalho, aplicou-se a digestão por via úmida das amostras usando HNO 3 , aquecimento em bloco digestor e solubilização final em banho ultrassom. Os testes de validação envolveram estudos de linearidade e faixa de trabalho, limites de detecção e de quantificação, precisão e exatidão. O tempo de digestão das amostras foi de 1h30min e as porcentagens de recuperação dos metais foram de 93% para Ca, 98% para Cu, 110% para Fe, 97% para Mg, 101% para Mn e 106% para Zn. Palavras

Usually, the methodologies found in the literature on biological tissue digestion are usually time consuming and use high amounts of reagents. In this study, two methods of preparation of bovine testis samples were evaluated: acid digestion using nitric acid and alkaline solubilization using tetramethylammonium hydroxide. The analytical validation study evaluated the parameters of linearity, limits of detection (acid digestion 0.10; 1.02; 0.16; 0.67 mg kg-1 for Cu, Fe, Mn and Zn, respectively; alkaline solubilization 0.12; 0.74; 0.16; 0.23 mg kg-1 for Cu, Fe, Mn and Zn, respectively) and quantification (acid digestion 0.34; 3.40; 0.53; 2.20 mg kg-1 for Cu, Fe, Mn and Zn, respectively; alkaline solubilization 0.41; 2.50; 0.54; 0.77 mg kg-1 for Cu, Fe, Mn and Zn, respectively), precision (RSD < 7.3% for repeatability and RSD < 15.0% for intermediary precision) and accuracy, being that the percentage of recovery obtained in the acid digestion of 105.50% (Cu), 103.30% (Fe), 94.90% (Mn) and 89.60% (Zn) and in the alkaline solubilization 100.80% (Cu), 98.70% (Fe), 103.70% (Mn) and 95.70% (Zn), therefore, the two procedures were efficient for this type of matrix. The times required for acid digestion and an alkaline solubilization were 1h30min and 1h, respectively.

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Essential metals are important in the normal functioning of the body. However, tissues or organs can be affected when there are inappropriate concentrations of these elements. In the literature, there are works indicating that essential elements may be related to the emergence of neoplasms. Therefore, it is important to determine the metal species in biological samples in order to relate the concentration of these species to the emergence of neoplasms. This study reports the application of the Flame Atomic Absorption Spectroscopy (FAAS) for the quantification of Cu, Fe, Mn and Zn in 31 samples of canine tissue (11 of mammary glands, 4 of pancreas, 3 of skin and 13 of testicles) with and without neoplasms, using alkaline solubilization as sample preparation method. The concentration of these metals was used as co-variables for the construction of models of logistic regression. The concentration of Zn in breast and Fe in pancreas was significant (p < 0.05) in the logistic models. The findings of this study describe that the elements Fe and Zn play a major role in the carcinomas development, since high levels of these metals were observed in neoplastic tissues.

Tea is one of the most consumed non-alcoholic beverages, second only to water. Medicinal plants are commonly used because they are beneficial to health. Among the several plants used whit this aim, Miconia albicans (MA), widely used for joint pain, such as rheumatoid arthritis and other inflammatory processes, and Senna alexandrina (SA), indicated for constipation and even for slimming treatments stand out. However, a little number of researches concerned with the chemical composition of these plants can be found in the literature. Thus, this work aimed to determine metallic ions in MA and SA teas using an atomic absorption spectrometer. In vitro experiments with a simulation of the gastrointestinal digestion processes were also performed (to evaluate bioaccessibility) – after in house validation – using gastric and intestinal juice. Total phenolics and total flavonoids of teas and bioaccessible fractions were also quantified. 3 samples of MA and 5 of SA were analyzed. In all samples, the total and bioaccessible concentrations of Ca, Cu and Mg were quantified. The antioxidant activity of the teas showed that, for the total phenolic content, the concentration ranged from 22 ± 1 to 29 ± 3 mg g-1, the bioaccessible fraction was close to 90% for the two studied plants. For total flavonoids, the bioaccessible fractions range from 60% (MA) to 90% (SA).