Banca de DEFESA: FABIANA ROBERTA SEGURA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : FABIANA ROBERTA SEGURA
DATA : 29/07/2019
HORA: 09:30
LOCAL: Auditório, 8º andar, Bloco B, Campus SA da Fundação Universidade Federal do ABC, localizada na Avenida dos Estados, 5001, Santa Terezinha, Santo André, SP
TÍTULO:

Arsenic and rice: analytical tools for monitoring and methods for (bio)remediation

PÁGINAS: 77
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Analítica
ESPECIALIDADE: Análise de Traços e Química Ambiental
RESUMO:

Arsenic is one of the most toxic chemicals and known carcinogen. It can be found in food basically in 5 different forms: arsenobetaine (AsB), dimethyl arsenic (DMA), monomethyl arsenic (MMA), arsenate (As⁵⁺) and arsenite (As³⁺), the latter two forms (i-As) are the most toxic. Thus, it is of extreme importance the use of chemical speciation for the evaluation of the real risks associated to arsenic intake from contaminated food. In this sense, this study aimed develop a simple method for separation of arsenic species by LC and detection by ICP-MS, quantitative extraction of arsenic species from animal tissues and rice grains, the application of the proposed method in the analysis of food samples commercialized in Brazilian markets, and the study of arsenic metabolism in different rice cultivars. The method developed for the extraction of arsenic species in animal tissues (egg, muscle of chicken, fish and cattle, etc.) used only methanol (10%v/v) and nitric acid (2%v/v) as extractant and 2 minutes of sonication, showing quantitative recovery of the analyte (>88%, n=3) when analyzing reference materials (CE278, DOLT-3, DORM-3 e SRM NIST 1577). However, for the analysis of rice grains, only nitric acid (2%v/v) was used as extractant, allowing a quantitative recovery (>94%, n=6), when analyzing the reference material (NIST Rice Flour 1568a). For the chromatographic separation several columns were evaluated and an anion exchange column (Hamilton PRP X-100) was used in all experiments. The analysis of several foods consumed in Brazil, showed a wide variation in the concentrations of different arsenic species in muscle, eggs, and especially in rice. Due to the high concentrations of arsenic found in rice samples (in several cases with predominance of more toxic species, As³⁺ and As⁵⁺) and the large consumption of this food in the country and abroad, it was also carried out a study on arsenic metabolism in 6 different rice cultivars. The focus of this study was the synthesis of phytochelatins (PCs), non-peptide compounds produced by plants exposed to toxic elements, and its influence on the transfer factor (TF) soil-grains. The TF of arsenic as well as the concentration of PCs varied in relation to the cultivars (genotype) studied. Furthermore, the PCs have shown a strong positive correlation between themselves and with the concentration of i-As in the grains, and a negative correlation with TF roots-grains. Therefore, the developed method demonstrated feasibility for routine use in toxicological studies of arsenic species in food samples and, finally, the study of arsenic metabolism in rice plant can contribute to the selection of cultivars that absorb less arsenic, thereby reducing the intake of this toxic element by rice consumption.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 2046361 - BRUNO LEMOS BATISTA
Membro Titular - Examinador(a) Externo ao Programa - 1844792 - AMEDEA BAROZZI SEABRA
Membro Titular - Examinador(a) Externo à Instituição - LEANDRO AUGUSTO CALIXTO - UNIFESP
Membro Titular - Examinador(a) Externo à Instituição - JULIANA IKEBE OTOMO - UNINOVE
Membro Titular - Examinador(a) Externo à Instituição - RODRIGO MENDES PEREIRA - UFABC
Membro Suplente - Examinador(a) Externo à Instituição - RODRIGO PAPAI DE SOUZA - IPT-SP
Membro Suplente - Examinador(a) Externo à Instituição - BRUNO ALVES ROCHA - USP
Membro Suplente - Examinador(a) Externo à Instituição - MÔNICA HELENA MONTEIRO DO NASCIMENTO - UFABC