Análise de pimenta-do-reino por espectrometria atômica: diferentes abordagens
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Data
2018-02-19
Autores
Krause, Maiara
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Universidade Federal do Espírito Santo
Resumo
The present study was divided into two chapters. First, it was determined the concentrations of the elements Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, Se, Ti, V and Zn black pepper samples marketed in the State of Espírito Santo. The samples underwent an acidic decomposition procedure assisted by microwave radiation. The Fe and Zn elements were determined by flame atomic absorption spectrometry (F AAS), while the others were determined using the inductively coupled plasma mass spectrometry (ICP-MS) technique. The accuracy of the procedures was evaluated through the analysis of the certified reference material Agro C1003a of tomato leaf. The values measured using the methodology adopted in this study and the certified values did not present significant difference, when Student's t-test with 95% confidence level was applied. After verification of accuracy, the analysis methodology wasapplied to 50 commercial pepper samples. For each manufacturer, denominated as A, B, C, D and E, 5 grain samples and 5 ground samples were obtained to verify a possible supply of trace elements during the processing of the black pepper. Each of the samples was chosen from a different lot, in order to obtain a greater variability of the set of samples that are commercialized in the region. The results show that two of the five analyzed brands showed a great increase in the concentrations of Fe, Pb and V after grinding, suggesting that the increase in the concentration of these elements can be influenced by the milling process. Moreover, for samples where there was a significant increase in Pb, it exceeded safe limits for human consumption according to Brazilian legislation, which is 200 µg kg-1. In the second part of the work a simple and fast methodology for the determination of Pb in pepper samples was developed. The developed method consisted in the use of suspension sampling together with the technique of atomic absorption spectrometry with atomization in graphite furnace. The preparation stage of the suspensions was optimized applying experiment planning. Parameters such as pyrolysis and atomization temperatures, calibration and the necessity of use chemical modifiers were evaluated. The analysis methodology presented simplicity and speed in it experimental stages, and provided low limits of detection and quantification. The method also showed good accuracy and allowed the calibration by aqueous standards. The methodology adopted is presented as an alternative to the traditional procedures of analysis and can be considered adequate for routine analyzes, it also can be extended to other trace elements present in black pepper
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Palavras-chave
Black pepper , Trace elements , Processing , pimenta-do-reino , Elementos traço , Processamento , ICP-MS , Espectrometria de absorção atômica
Citação
KRAUSE, Maiara. Análise de pimenta-do-reino por espectrometria atômica: diferentes abordagens. 2018. Dissertação (Mestrado em Química) – Universidade Federal do Espírito Santo, Vitória, 2018.