Chemical verification of fruit, vegetables, grain, spices, herbs and their extracts is analytically challenging as dozens, or even hundreds of compounds must be identified in a wide variety of matrices. These foods are of interest as they provide an array of phytochemicals, including flavonoids that promote health. Flavonoid composition in plants is dictated by genetics and differs between species and cultivars. Improvements in processed food quality may be achieved by using cultivars with desirable flavonoid profiles and/or through addition of flavonoid rich extracts. Identification of distinguishing flavonoid profiles for cultivar and extract verification is complicated as flavonoids have different patterns of hydroxylation and/or methoxylation and occur as O-glycoside, or less frequently C-glycosides. The sugars of the O-glycosides are generally bound at either C-3 or C-7 positions, whereas C-glycosides are attached at C-6 or C-8. These residues can be further acylated. Herein, LC(ESI+)-Q/TOFMS was used to provide qualitative information on the occurrence of a library of targeted unknown flavonoids in several cultivars of onions. The targeted unknown library was developed using Phenol-Explorer (http://www.phenol-explorer.eu/compound_classes). An exact mass list of the potential flavonoids, including glycosidic and acylated forms, was compiled in Microsoft Excel and imported into MassHunter Software (Agilent Technologies). Extracts were analyzed by scanning TOF/MS for exact mass. Ions corresponding to library hits >70% were then targeted for further MS/MS identification (target unknowns). PCA modeling of targeted unknowns could be used to distinguish cultivars.

Targeted unknown LC(ESI+)-Q/TOFMS approaches for food verification

244th National Meeting (2012)

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