Phenolic fingerprint of peppermint leaves

A reversed-phase high-performance liquid chromatography procedure is proposed for the determination of 10 phenolic compounds (eriodictyol 7-O-rutinoside, eriodictyol 7-O-glucoside, luteolin 7-O-rutinoside, luteolin 7-O-glucoside, hesperetin 7-O-rutinoside, apigenin 7-O-rutinoside, rosmarinic acid, 5,6-dihydroxy-7,8,3′,4′-tetramethoxyflavone, pebrellin and gardenin B) in peppermint. The chromatographic separation was achieved using a reversed-phase Spherisorb ODS 2 (5 μm particle size; 25.0×0.46 cm) column. Of the several extractive solvents tried, ethanol was the best for qualitative and quantitative analysis. Best resolution was obtained using a gradient of water-phosphoric acid (999:1) and acetonitrile. Fourteen samples were subjected to quantification and showed a common composition pattern.