NIR hyperspectral image and MCR-ALS applied in the study of chemical compounds spatial distribution in biodegradable active films

• Ano de defesa: 2018
• Autor(a) principal: Terra, Larissa Rocha
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Quimiometria; Imagem hiperespectral; Embalagens; Acetato de celulose; Métodos Óticos de Análise
• Link de acesso: https://locus.ufv.br//handle/123456789/27623

In this work, it was performed a study involving the use of the hyperspectral image in near infrared region (NIR-HSI) and multivariate curve resolution-alternating least squares (MCR-ALS) for analysis of homogeneity of chemical compounds in cellulose acetate (CA) films. The main advantage of NIR-HSI coupled to MCR-ALS is to provide chemical and spatial information quickly and straightforwardly, without any sample preparation. The film's development was carried out by a full factorial experimental design. Sorbic acid (HS) was used as an antimicrobial agent, and four plasticizers were studied, i.e., triethyl citrate (TEC), glycerol (GLY), polyethylene glycol (PEG), and dioctyl phthalate (DOP). The factors studied were HS/CA and plasticizer/CA ratios. A NIR-hyperspectral image was acquired for each sample. The hypercubes obtained for the films containing the same plasticizer were unfolded in a matrix and then vertically concatenated. The samples data and compounds standard data were preprocessed using image-Despike, the multiplicative scatter correction (MSC), and the Savitzky Golay smoothing. A D matrix was built with the preprocessed samples and standards spectra. The MCR-ALS method was applied. The singular values decomposition (SVD) algorithm showed four components and the standards spectra were used as initial estimative for the spectra of pure components. Constraints were non-negativity concentrations and local rank. The relative concentration matrix (C) columns were reshaped in a spatial distribution matrix for each component. The method was able to recover with accuracy the pure spectra of each film component. The relative concentration vectors obtained by the MCR-ALS were rebuilt in matrices, and it was possible to analyze the homogeneity of the film constituents. Besides, mechanical performance and antimicrobial activity studies of the films were performed. Therefore, the study of the detailed distribution of chemical compounds incorporated into films was possible using NIR hyperspectral imaging combined with the MCR-ALS method. The mechanical test shows that films containing TEC presented the best performances. According to the antimicrobial test, only films with a high level of sorbic acid presented antimicrobial activity.