ONLINE HPLC PHOTODIODE-ARRAY DETECTION AND OPA DERIVATIZATION FOR PARTIAL IDENTIFICATION OF SMALL PEPTIDES FROM WHITE WINE

This paper reports the possibilities of on-line reversed-phase HPLC wi th photodiode array detection (PDAD) and derivatization with o-phthald ialdehyde (OPA) far identification of small peptides. The methodology was initially applied to a wide range of standard peptides. Spectral p arameters (wavelengths of the spectrum maxima, convexity interval, and wavelengths of the second-derivative spectrum maxima) obtained by PDA D allow identification of the aromatic amino acid residues (tyrosine, tryptophan, and phenylalanine) contained in the peptides as well as id entification of other compounds from wine that can coelute with peptid es (i.e. phenolic compounds). Postcolumn OPA derivatization allows con firmation of the peptidic nature of chromatographic peaks. The methodo logy has been successfully applied to peptide fractions (<700 Da) from eavas (Spanish sparkling wines). Peptides not containing aromatic ami no acids and peptides containing only phenylalanine, tryptophan, or ty rosine as aromatic amino acids, as well as two coeluted cinnamic deriv atives, were detected. To the authors' knowledge, these are the most d etailed data reported to date about the composition of individual pept ides from wine.