Quantitative determination of phenolic compounds in Mentha piperita leaves

A spectrophotometric method using a dual-wavelength Firordt method that enabled simultaneous determination of the flavonoid and phenolic-acid contents was developed for quantitative analysis of phenolic compounds in Mentha piperita L. (Lamiaceae) leaves. Hesperidin and rosmaric acid were used as standards. The optimal extraction parameters of the phenolic compounds were determined. Metrological analysis of the developed method was performed. It was found that the determination error of the analyzed classes of compounds was less than 3%. The studied batches of M. piperita raw material contained flavonoids 3.02–6.32%; phenolic acids, 2.70–5.52%; total phenolic compound content, 5.72–11.51%.