Banca de DEFESA: ÍCARO SACRAMENTO DE ALMEIDA PORTO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : ÍCARO SACRAMENTO DE ALMEIDA PORTO
DATA : 11/12/2020
HORA: 09:00
LOCAL: Instituto de Química
TÍTULO:

ANALYTICAL STRATEGIES USING DIGITAL IMAGES FOR DETERMINATION OF ASCORBIC ACID IN FRUIT JUICES

PALAVRAS-CHAVES:

Digital Image, Ascorbic Acid, RGB, Fruit.

PÁGINAS: 89
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Analítica
ESPECIALIDADE: Métodos Óticos de Análise
RESUMO:

In recent years, several spectrophotometric methods consolidated in the literature have been adapted for digital images (DI), offering an alternative for fast, portable and low-cost analysis. In this context, the present work proposed the development of analytical strategies based on digital images for quantification of ascorbic acid in samples of natural fruit juices using the chromogenic reagents 1,10-phenatroline and Br-PADAP (- (5-bromo-2- pyridylazo) -5-diethylaminophenol). In an acidic environment, ascorbic acid reduces Fe (III) to Fe (II) and this new oxidation state forms colored complexes with the proposed reagents. To establish the best analysis conditions, multivariate and univariate optimization techniques were applied. The images were obtained through a webcam coupled with a CMOS detector (Complementary Metal-Oxide Semiconductor) and stored in .jpg format and submitted to specific software for data extraction. The construction of the analytical signal was performed using the additive model of RGB colors corresponding to the colors red, green and blue. Two forms of processing were investigated: one is analogous to Beer's law and the other was defined as the result of the expression: S = 255 - (R, G or B), where R, G or B, refers to intensity of radiation emitted by the standard or sample solution in a color component. The precision of the method was assessed in terms of relative standard deviation (% RSD) using samples chosen arbitrarily (n = 10), with values ranging between 1.2% and 8.2%. The limits of detection (LD) varied between 0.004 and 0.857 mg/100g and those of quantification (LQ) between 0.012 and 2.857 mg/100g. Accuracy is assessed using the results of the corresponding molecular technique. The ascorbic acid concentrations in a total of 13 fruit samples were evaluated, namely: lemon, orange, grape, lime, pineapple, tangerine, mango, mangosteen, plum, passion fruit, genipap, melon and watermelon, purchased in the city of Salvador. The concentrations obtained varied between 3.8 mg/100g and 38.1 mg/100g. The analysis of digital images produced satisfactory results and proved to be a promising alternative to replace the use of expensive equipment.

 

 

MEMBROS DA BANCA:
Interno - 268481 - SERGIO LUIS COSTA FERREIRA
Interno - 670.936.635-91 - VALFREDO AZEVEDO LEMOS - UFBA
Interno - 318.201.155-34 - WALTER NEI LOPES DOS SANTOS - UFBA
Externo à Instituição - CLEBER GALVAO NOVAES - UESB
Externo à Instituição - RITA MARIA WESTE NANO CARVALHO - IFBA