title: Direct analysis of Stevia leaves for diterpene glycosides by desorption electrospray ionization mass spectrometry.
abstract: The analysis of Stevia leaves has been demonstrated without any sample preparation using desorption electrospray ionization (DESI) mass spectrometry. Direct rapid analysis was achieved using minimal amounts of sample ( approximately 0.15 cm x 0.15 cm leaf fragment). Characteristic constituents of the Stevia plant are observed in both the positive and negative ion modes including a series of diterpene 'sweet' glycosides. The presence of the glycosides was confirmed via tandem mass spectrometry analysis using collision-induced dissociation and further supported by exact mass measurements using an LTQ-Orbitrap. The analysis of both untreated and hexane-extracted dry leaves proved that DESI can be successfully used to analyze untreated leaf fragments as identical profiles were obtained from both types of samples. Characterization and semi-quantitative determination of the glycosides was achieved based on the glycoside profile within the full mass spectrum. In addition, the presence of characteristic glycosides in an all-natural commercial Stevia dietary supplement was confirmed. This study provides an example of the application of DESI to direct screening of plant materials, in this case diterpene glycosides.
authors.affiliation: Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA.
authors.forename: Ayanna U
authors.initials: AU
authors.lastname: Jackson
authors.forename: Alessandra
authors.initials: A
authors.lastname: Tata
authors.forename: Chunping
authors.initials: C
authors.lastname: Wu
authors.forename: Richard H
authors.initials: RH
authors.lastname: Perry
authors.forename: George
authors.initials: G
authors.lastname: Haas
authors.forename: Leslie
authors.initials: L
authors.lastname: West
authors.forename: R Graham
authors.initials: RG
authors.lastname: Cooks
mesh_terms: D004224:Diterpenes / Q000737:chemistry*; D006027:Glycosides / Q000737:chemistry*; D015394:Molecular Structure; D018515:Plant Leaves / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D036625:Stevia / Q000737:chemistry*; D013549:Sweetening Agents / Q000737:chemistry
chemical_list: D004224:Diterpenes; D006027:Glycosides; D013549:Sweetening Agents