Determination and quantification of phenolic acids in raw propolis by reversed phase high performance liquid chromatography. Feasibility study for the use of near infrared spectroscopy

In this study we analyzed the phenolic composition of 50 propolis extracts from Spain and Chile by high performance liquid chromatography (HPLC). Ten compounds were identified and quantified: caffeic acid; p-coumaric acid; cinnamic acid; ferulic acid; isoferulic acid and 3,4-dimethyl-caffeic acid (DMCA); caffeic acid benzyl ester; p-coumaric cinnamyl ester; p-methoxy cinnamic acid cinnamyl ester; and caffeic acid phenylethyl ester (CAPE). The amounts of phenolic acids found ranged from 20.1–156.4 mg/g for Spanish propolis to 1.7–37.4 mg/g for Chilean propolis. Higher amounts were found for phenolic acid derivatives in all samples analyzed with values between 23.5–132.2 mg/g in Spanish propolis and 21.0–123.0 mg/g in Chilean propolis. A new method based on Near-Infrared Spectroscopy (NIR) is used to estimate the phenolic composition of acids and acid derivatives. The results obtained show that there are no differences between the results obtained by NIR spectroscopy and the chromatographic data.