Influenza dei metodi di estrazione e di purificazione sul dosaggio in HPLC degli idrossifenoli

Four different extraction methods were compard, in oder to optimize the HPLC separation and quantitation of hydroxyphenols in «Thymus capitatus». One method was not suitable for HPLC ansly,is, whereas the others partially destroyed the hydroxyphenols extracted from the plant. The Charpentier-Cowles me thod was, found the most effective allowing to analyse, in spite of the losses, most of the free phenolic acids and of those bounded extractable in hot acidic medium but not in ethanol. For the phenolics in free form a method whith recoverier greater than those obtained with Hagerman Nicholson and Horvat-Senter methods was developed.