Estudo sístematico da síntese de polímeros molecularmente impressos obtidos pelo método de precipitação e do tipo core@shell para determinação de tartrazina (yellow acid 23) visando desenvolvimento de novos métodos de análise
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Data
2019-03-01
Autores
Ruiz Córdova, Gerson Alessandro
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A tartrazina é um corante amplamente usado na indústria alimentícia que pode ocasionar doenças na pele e doenças neurológicas. O presente trabalho explora diferentes sínteses de polímeros impressos para o corante alimentício Tartrazina, incluídos o método convencional por precipitação e no formato core@shell. Para isso, foram avaliadas sínteses com o monômero funcional, acrilamida, e monômero estrutural, N-N’ metileno-bis-acrilamida, e os núcleos (core) de sílica (SiO2) e sílica funcionalizada com agente vinil-silanizante (SiO2-C=C), os quais foram empregados em diferentes proporções molares para a polimerização. Obtendo-se três materiais, MIP convencional por precipitação, SiO2-C=C@MIP e SiO2@MIP estes últimos foram obtidos pelo método core@shell usando diferentes suportes. Se avaliaram as propriedades de adsorção dos materiais. O primeiro material não foi eficiente, nem seletivo. O material híbrido SiO2-C=C@MIP apresentou uma boa porcentagem de adsorção, 91,5% e manifestou interferência do corante Amarelo Direto 50. Porém, manteve a cor amarela de fundo intensa, devido à alta adsorção do corante pela sílica funcionalizada. O seguinte material híbrido sintetizado foi o SiO2@MIP, o qual apresentou os melhores resultados e usando a refletância total atenuada diretamente nos sólidos adsorvidos. Para a síntese usou-se a proporção molar 1:2:100 (analito: monômero funcional: monômero estrutural) usando 300 mg de SiO2. Este material mostrou uma porcentagem de adsorção próxima a 93%. Nos estudos de adsorção do analito, as isotermas de adsorção foram plotadas no intervalo de concentração de 0,1 a 100 µmol L-1, se ajustando a um perfil de Langmuir-Freundlich. Nos estudos de seletividade, o SiO2@MIP demostrou um reconhecimento seletivo do analito, ao não adsorver, ou adsorver em menor grau, os corantes estudados, inclusive o Amarelo Direto 50. Após obtidos os materiais otimizados, estes foram caracterizados por MEV e espectroscopia Raman, encontrando partículas esféricas de diâmetro de 203, 213 e 229 nm para o suporte SiO2, SiO2@NIP e SiO2@MIP, respectivamente para o material em core@shell. Finalmente, os materiais sintetizados foram aplicados em amostras de refrigerantes, e os valores encontrados foram comparáveis com os obtidos pelo método de referência por HPLC. Com estas informações, foram realizados estudos preliminares para a síntese diretamente em tips de fibras ópticas mostrando a viabilidade de desenhar um sensor óptico usando o material descrito neste trabalho.
Tartrazina is a dye widely used in food industry, which can cause skin neurological diseases. The present work explores different syntheses of imprinted polymers for food dye Tartrazine, including the conventional method by precipitation and the core@shell format. For this, diverse syntheses with functional monomer, acrylamide, and structural monomer, N-N'-methylenebisacrylamide, and cores of silica (SiO2) and vinyl-functionalized silica (SiO2-C=C), which were employed in different molar ratios for polymerization. Obtaining three materials, conventional MIP by precipitation, SiO2-C=C@MIP and SiO2@MIP by core@shell method using different cores. Evaluating adsorption properties of the materials, the first material was not efficient, nor selective. The hybrid material SiO2-C=C@MIP showed a good adsorption percentage, 91.5% and an interfering dye, Direct Yellow 50. However, the material presented an intense yellow coloration given by the high adsorption of dye on the used core. Synthesized SiO2@MIP hybrid material showed better results and attenuated total reflection was directly used on adsorbed solids. For the syntheses was used 1:2:100 molar proportion (analyte: functional monomer: structural monomer) using 300 mg of SiO2. This material showed an adsorption percentage near to 93%. In the adsorption studies of the analyte, the adsorption isotherms were plotted in the concentration range of 0.1 to 100 μmol L-1, adjusting to a Langmuir-Freundlich profile. In the study of selectivity, SiO2@MIP showed selective recognition of the analyte by not adsorbing or adsorbing on less proportion the studied dyes, including Direct Yellow 50, the main interfering on this work. After obtaining the optimized materials, they were characterized by SEM and Raman spectroscopy, finding spherical particles of diameter 203, 213 and 229 nm for SiO2, SiO2@NIP and SiO2@MIP, respectively, for the core shell material. Finally, the synthesized materials were applied to soda samples, and the values found were comparable to those obtained by the reference method by HPLC. With this information, preliminary studies were made synthetizing directly on optical tip-fibers showing the feasibility of designing an optical sensor using the material described in this work.
Tartrazina is a dye widely used in food industry, which can cause skin neurological diseases. The present work explores different syntheses of imprinted polymers for food dye Tartrazine, including the conventional method by precipitation and the core@shell format. For this, diverse syntheses with functional monomer, acrylamide, and structural monomer, N-N'-methylenebisacrylamide, and cores of silica (SiO2) and vinyl-functionalized silica (SiO2-C=C), which were employed in different molar ratios for polymerization. Obtaining three materials, conventional MIP by precipitation, SiO2-C=C@MIP and SiO2@MIP by core@shell method using different cores. Evaluating adsorption properties of the materials, the first material was not efficient, nor selective. The hybrid material SiO2-C=C@MIP showed a good adsorption percentage, 91.5% and an interfering dye, Direct Yellow 50. However, the material presented an intense yellow coloration given by the high adsorption of dye on the used core. Synthesized SiO2@MIP hybrid material showed better results and attenuated total reflection was directly used on adsorbed solids. For the syntheses was used 1:2:100 molar proportion (analyte: functional monomer: structural monomer) using 300 mg of SiO2. This material showed an adsorption percentage near to 93%. In the adsorption studies of the analyte, the adsorption isotherms were plotted in the concentration range of 0.1 to 100 μmol L-1, adjusting to a Langmuir-Freundlich profile. In the study of selectivity, SiO2@MIP showed selective recognition of the analyte by not adsorbing or adsorbing on less proportion the studied dyes, including Direct Yellow 50, the main interfering on this work. After obtaining the optimized materials, they were characterized by SEM and Raman spectroscopy, finding spherical particles of diameter 203, 213 and 229 nm for SiO2, SiO2@NIP and SiO2@MIP, respectively, for the core shell material. Finally, the synthesized materials were applied to soda samples, and the values found were comparable to those obtained by the reference method by HPLC. With this information, preliminary studies were made synthetizing directly on optical tip-fibers showing the feasibility of designing an optical sensor using the material described in this work.
Descrição
Palavras-chave
Tartrazina, MIP core@shell, Refletância difusa, Tartrazine, Diffuse reflectance