Estudo visando a obtenção de sensores baseados em filmes poliméricos ultrafinos para detecção de toxinas em castanha-do-brasil

Abstract

Brazil nuts is a seed of the nut tree fruit, being most of it located in the Amazon region. The nuts presents health benefits due to its macro and micronutrients, for example, the selenium, that is an important antioxidant can be found in high tield. The seed has significant importance in Brazilian shiping market. However, it’s suceptable to fungi produced toxin contamination, wich can lead diseases or even death in animals and humans. The most concerning fungi in Brazil nuts are Aspergillus type, responsible for the production of the aflatoxin mycotoxin. The maximum range of aflatoxin permitted overseas is 10 to 20 μg/kg. The methods to measure aflatoxin are usually expensive and complex chromatographic methods. Therefore, electrochemical sensors cheap and simple use may be the logical repleacment. The ain of this work was to carachterize an electrochemical tongue sensor suitable to detects aflatoxins. Benefits as lightness, reuse, portability and cheap cost of manufacturing can be obtained if this type of sensor. In addition, low cost electrodes such as phenolite and fiberglass based electrodes were tested in comparison with high cost interdigited gold electrodes. The electrode construction method was based on Layer-by-Layer deposition, in which cationic and anionic substances are deposited in a substrate in order to form a double electric layer. As the double layers are deposited a film is formed. In order to develop the electric tongue, analyzes were first performed on glass substrate, with different films compositions, so the best films could be used in electrode composition. Six phenolite sensors and three fiber glass sensors were used, being tested first in the construction of the calibration curve using furaric acid toxin and then aflatoxin concentrations were analyzed.