Simultaneous Determination of Nonanthocyanin Phenolic Compounds in Red Wines by HPLC-DAD/ESI-MS

The nonanthocyanin phenolic compounds of wines from Vitis vinifera L. cv. Tempranillo, Graciano, Cabernet Sauvignon, and Merlot (vintage 2000, Navarra, Spain), vinified under the same conditions, were extracted with ethyl acetate and diethyl ether and analyzed by high-performance liquid chromatography–diode array detection/electrospray ionization–mass spectrometry (HPLC–DAD/ESI–MS) (negative mode). A total of 47 phenolic compounds were identified in the different wines, including nonflavonoids (hydroxybenzoic and hydroxycinnamic acids and their derivatives, stilbenes, and phenolic alcohols and other related compounds) and flavonoids (flavanols, flavonols, and dihydroflavonols). Novel phenolic acid derivatives, such as the methyl and ethyl esters of gallic acid and some hexose esters of vanillic and p-coumaric acids, were also detected. The concentration of nonflavonoid compounds was higher for Cabernet Sauvignon (62.23 mg/L) and Graciano (57.82 mg/L) wines than for Merlot (47.52 mg/L) and Tempranillo (43.70 mg/L). The concentration of flavonoid compounds was highest for Graciano wine (119.41 mg/L), followed by Cabernet Sauvignon (104.58 mg/L), Merlot (77.54 mg/L), and Tempranillo (50.56 mg/L) wines. Differences between wines were found in the quantified proportion of hydroxybenzoic acids (16.3 to 29.5%), stilbenes (0.3 to 2.9%), phenolic alcohols and other related compounds (9.4 to 17.0%), flavanols (42.9 to 56.1%), and flavonols (10.1 to 15.3%). ESI–MS was confirmed as a valuable tool for obtaining potentially important information on specific phenolic compounds in wine.