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Ledesma, Claudia Martins; Krepsky, Larissa Mascarenhas; Borges, Endler Marcel – Journal of Chemical Education, 2019
Here, students determine the total phenolic content in beers using the Folin-Ciocalteu assay. The Folin-Ciocalteu reagent is a yellow complex, in an alkaline medium; it reacts with phenols and non-phenolic reducing substances to form a blue complex. Quantitative analysis was carried out using absorbance measured at 765 nm (standard method) and…
Descriptors: Science Instruction, Science Experiments, Chemistry, College Science
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Filgueiras, Matheus Fernandes; de Jesus, Paulo Cesar; Borges, Endler Marcel – Journal of Chemical Education, 2021
The Griess assay is widely used by regulation agencies as an official method for nitrite quantification in water and food samples. In Brazil, the official method, which has been used to determine nitrite in food, was described by Instituto Adolfo Lutz (283/IV) in 1984. It uses 8 mL of reactants and provides 50 mL (reactants plus sample) of waste…
Descriptors: Science Instruction, Water, Food, Science Experiments