title: On-line characterisation of apple polyphenols by liquid chromatography coupled with mass spectrometry and ultraviolet absorbance detection.
abstract: Apple polyphenols were characterised by means of hyphenated techniques such as HPLC coupled to UV photodiode array detection (LC-DAD) and to mass spectrometry (LC-MS). LC-MS using atmospheric pressure ionisation (APCI) in the positive ion mode provided the molecular weight, the number of hydroxyl groups, the number of sugars and an idea about the substitution pattern of the polyphenols. LC-DAD with postcolumn addition of UV shift reagents afforded precise structural information about the position of the free hydroxyl groups in the polyphenolic nucleus. Five isorhamnetin glycosides, two hydroxyphloretin glycosides and quercetin were reported in apple peel for the first time. Postcolumn addition of UV shift reagents in LC-DAD analysis confirmed the presence of isorhamnetin glycosides and not the isomeric glycosides of rhamnetin. Moreover, isorhamnetin-3-O-rhamnoglucoside was identified unambiguously by comparison with a standard. These results are relevant not only from a chemotaxonomic point of view, but also in the control of authenticity of fruit derived products in order to detect fraudulent admixtures.
authors.affiliation: Departamento de Química Analítica, Facultad de Ciencias, Universidad del País Vasco/Euskal Herriko Unibertsitatea E-48080 Bilbao, Spain.
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Alonso-Salces
authors.forename: Karine
authors.initials: K
authors.lastname: Ndjoko
authors.forename: Emerson F
authors.initials: EF
authors.lastname: Queiroz
authors.forename: Jean R
authors.initials: JR
authors.lastname: Ioset
authors.forename: Kurt
authors.initials: K
authors.lastname: Hostettmann
authors.forename: Luis A
authors.initials: LA
authors.lastname: Berrueta
authors.forename: Blanca
authors.initials: B
authors.lastname: Gallo
authors.forename: Francisca
authors.initials: F
authors.lastname: Vicente
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005419:Flavonoids / Q000032:analysis*; D027845:Malus / Q000737:chemistry*; D010636:Phenols / Q000032:analysis*; D059808:Polyphenols; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
chemical_list: D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols