Determination of Flavonoid Content in Brazilian Propolis Extracts by UV-Vis Spectroscopy and PLS Regression
Ariane Araujo Assimos, Cristina Donizeti Bernardes, Helga Gabriela Aleme, Paulo Jorge Sanches BarbeiraBackground:
The determination of flavonoid content in propolis is very important because these substances are assigned various biological properties present in propolis and their content is regulated by Brazilian legislation. The spectrophotometric method, based on the formation of a yellow complex between Al(III) and carbonyl and hydroxyl groups of flavonoids, is the most used to determine flavonoid content but is time-consuming (only after one hour the absorbance of the solutions can be read) and reagents.
Objective:
This work proposes a simple method to determine flavonoid content using UV-Vis and Partial Least Squares (PLS) regression.
Methods:
A robust PLS spectrophotometric method for the quantification of flavonoids in propolis, based on spectra of ethanol-diluted samples, was developed and a complete validation was done in this model, estimating several figures of merit.
Results:
The model built proved to be very effective, showing good results for flavonoid content, with a range of 0.06 to 1.50 %mass, providing root mean square error of prediction (RMSEP) of 0.05 %mass.
Conclusion:
This proposed model has the advantage of being less laborious and faster, involves a small amount of solvents, is an alternative to routine analysis, and can be used as a screening method.