title: Over-evaluation of total flavonoids in grape skin extracts containing sulphur dioxide.
abstract: Sulphur dioxide (SO2) proved to increase absorbance at 280 nm of grape skin and seed extracts containing it, diluted with ethanol-HCl to assess total flavonoids and anthocyanins in the same analysis. Additional absorbance at 280 nm was also observed in acetone:H2O extracts, if the acetone had not completely evaporated before the extracts were diluted with a solvent. Flavonoids were correctly quantified in the extracts when SO2 or acetone were removed by solid-phase extraction with a C18 RP as sorbent and methanol as eluting solvent.
authors.affiliation: Dipartimento Scienze Agrarie e Forestali, Università di Palermo, Viale delle Scienze 4, 90128 Palermo, Italy. Electronic address: onofrio.corona@unipa.it.
authors.forename: Onofrio
authors.initials: O
authors.lastname: Corona
authors.affiliation: Centro per l'Innovazione della Filiera Vitivinicola, Assessorato Agricoltura e Foreste, Regione Siciliana, C.da Bosco 421, 91025 Marsala (TP), Italy.
authors.forename: Margherita
authors.initials: M
authors.lastname: Squadrito
authors.affiliation: Corso di Laurea in Viticoltura ed Enologia, Università di Palermo, Via Dante Alighieri 120, 91025 Marsala (TP), Italy.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Vento
authors.affiliation: Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, Università di Milano, Via Celoria 2, 20133 Milano, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Tirelli
authors.affiliation: Università di Palermo, 90128 Palermo, Italy.
authors.forename: Rocco
authors.initials: R
authors.lastname: Di Stefano
mesh_terms: D000096:Acetone / Q000737:chemistry; D000872:Anthocyanins / Q000032:analysis / Q000302:isolation & purification; D005419:Flavonoids / Q000032:analysis* / Q000302:isolation & purification; D010636:Phenols / Q000737:chemistry / Q000302:isolation & purification; D010936:Plant Extracts / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry / Q000378:metabolism; D052616:Solid Phase Extraction; D013053:Spectrophotometry; D013458:Sulfur Dioxide / Q000737:chemistry*; D027843:Vitis / Q000737:chemistry* / Q000378:metabolism; D014867:Water / Q000737:chemistry
chemical_list: D000872:Anthocyanins; D005419:Flavonoids; D010636:Phenols; D010936:Plant Extracts; D014867:Water; D013458:Sulfur Dioxide; D000096:Acetone
keywords: Anthocyanins; Anthocyanins (PubChem CID: 5318979); Flavonoids; Polyphenols; Proanthocyanidins; Proanthocyanidins (PubChem CID: 108065); Sulphur dioxide; Sulphur dioxide (PubChem CID: 1119)