Prediction of total phenolic acids contained in plant extracts by PLS-ATR-FTIR

Phenols found in plants are becoming increasingly important. Hydroxybenzoic and hydroxycinnamic acids are the predominant phenolic acids. The main objective of this study is to exploit the experiments carried out for the specific quantification of phenolic acids present in plant extracts by PLS-ATR-FTIR to the determination of total phenolic acids (TPA). Individual phenolic acids were measured between 1566 and 563 cm−1 whereas the common band representative of the total phenolic acids was selected between 1737 and 1624 cm−1. To pass from the quantification of individual-specific phenolic acids to the deduction of the content of total phenolic acids, present in extracts of aromatic plants by PLS-ATR-FTIR, we considered a simple calculation of the concentration of total phenols as being the sum of the concentrations of standard phenols present in the mixtures and the selection of a spectral region common to all the phenolic acids considered. The study developed provides a simple, fast, and precise procedure for the individual simultaneous determination of six phenolic acids (salicylic acid, p-hydroxybenzoic acid, vanillic acid, gallic acid, trans-cinnamic acid, and eugenol) and the estimation of the total phenolic acids present in eighteen extracts of aromatic plants, with the additional advantage of the possibility of examining the plant extracts with a simple plant material extraction by maceration with ethanol which is classified as a green solvent thus providing a green methodology.