Digital-image photometry and salting-out assisted liquid-liquid microextraction for determination of flavonols in berries

Author(s)

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

• Document type: Journal article
• Source: Journal of Food Composition and Analysis; v. 123, p. 7-pg., 2023-10-01.

Abstract

The metal-chelating ability of flavonols is exploited in spectrophotometric screening methods, but the content is often overestimated due to interferences by anthocyanins and phenolic acids. In order to circumvent this drawback, liquid-liquid microextraction with acetonitrile is proposed for the separation of flavonols from anthocyanins and further partitioning to the aqueous phase as Al(III) complexes with the working pH adjusted to 3.5 to avoid the interference of phenolic acids. The standard addition method circumvented the matrix effects in photometric measurements by digital-image photometry. A linear response was achieved up to 10 mg L-1 quercetin, with coefficient of variation (n = 10) and limits of detection and quantification estimated at 3.1%, 0.5 and 1.7 mg L-1, respectively. Accurate results were achieved in comparison to the spectrophotometric reference procedure. The proposed procedure is a simple and cost-effective approach, with low reagent and solvent consumption (105 & mu;g of Al(III), 15 mg of NaCl, and 1.2 mL of acetonitrile) and waste generation (1.5 mL) per determination. (AU)

• FAPESP's process: 18/07687-5 - Exploitation of novel calibration strategies, digital images and flow analysis for biodiesel quality control
• Grantee: Samara Soares
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 21/02309-5 - Analytical procedure based on digital images and liquid-liquid microextraction for the determination of flavonoids in fruits
• Grantee: Luís Claudio Martins
• Support Opportunities: Scholarships in Brazil - Master