Digital-image eco-friendly spot test with liquid-liquid microextraction for selective determination of flavonols in berries

Autor(es)

Martins, Luis Claudio ; Soares, Samara ; Rocha, Fabio R. P.

• Tipo de documento: Artigo Científico
• Fonte: Microchemical Journal; v. 193, p. 7-pg., 2023-10-01.

Resumo

Spots tests are attractive for food control due to the potential for in situ analysis, quick achievement of results and environmental friendliness. Flavonols, a class of natural compounds with many benefits to human health, are commonly determined by spectrophotometry and chromatography, often generating large amounts of harmful wastes. Besides, the spectrophotometric methods are typically not selective, with interferences from anthocyanins and phenolic acids. To circumvent these drawbacks, this work proposes a cost-effective and environmental friendly spot test associated with liquid-liquid microextraction for determination of flavonols in berries by digital-image photometry. Flavonols were extracted from berries with ethanol and further separated from anthocyanins by ethyl acetate salt-assisted microextraction. After formation of colored Al(III)-flavonol complexes, digital images were obtained in a porcelain plate using a smartphone camera. The RGB values were extracted using ImageJ (R) software, and channel B was taken for photometric measurements. A linear response was achieved within 0.33-5.00 mg/L (1-17 mu mol/L) quercetin equivalent concentration (QE) with r >= 0.997. The coefficient of variation (n = 10) and limit of detection were estimated at 3.9% and 0.1 mg/L QE (0.3 mu mol/L), respectively. The accuracy was assessed by comparison to the spectrophotometric procedure, with results in agreement at the 95% confidence level. The proposed procedure minimized reagent/solvent consumption (70 mu g of Al(III), 142 mg of Na2SO4, equivalent to 9.2 mu L of HCl, and 2.0 mL of ethyl acetate) and the waste generated is mostly composed by water and ethanol. (AU)

• Processo FAPESP: 18/07687-5 - Avaliação de estratégias de calibração, imagens digitais e análises em fluxo para o controle de qualidade de biodiesel
• Beneficiário: Samara Soares
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 21/02309-5 - Procedimento analítico baseado em imagens digitais e microextração líquido-líquido para a determinação de flavonoides em frutas
• Beneficiário: Luís Claudio Martins
• Modalidade de apoio: Bolsas no Brasil - Mestrado