title: Structural characterization of native high-methoxylated pectin using nuclear magnetic resonance spectroscopy and ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Comparative use of 2,5-dihydroxybenzoic acid and nor-harmane as UV-MALDI matrices.
abstract: The successful analysis by ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (UV-MALDI-TOF MS) of native and hydrolyzed high-methoxylated pectin samples is described. In order to find the optimal conditions for UV-MALDI-TOF MS analysis several experimental variables were studied such as: different UV-MALDI matrices (nor-harmane, 2,5-dihydroxybenzoic acid), sample preparation methods (mixture, sandwich), inorganic salt addition (doping salts, NaCl, KCl, NH(4)Cl), ion mode (positive, negative), linear and reflectron mode, etc. nor-Harmane has never been used as a UV-MALDI matrix for the analysis of pectins but its use avoids pre-treatment of the sample, such as an enzymatic digestion or an acid hydrolysis, and there is no need to add salts, making the analysis easier and faster. This study suggested an alternative way of analyzing native high-methoxylated pectins, with UV-MALDI-TOF MS, by using nor-harmane as the matrix in negative ion mode. The analysis by (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy of the native and hydrolyzed pectin is also briefly described.
authors.affiliation: Instituto de Química Física de Materiales, Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: Monge
authors.forename: R Martín
authors.initials: RM
authors.lastname: Negri
authors.forename: Adriana A
authors.initials: AA
authors.lastname: Kolender
authors.forename: Rosa
authors.initials: R
authors.lastname: Erra-Balsells
mesh_terms: D005841:Gentisates / Q000737:chemistry*; D006247:Harmine / Q000031:analogs & derivatives* / Q000737:chemistry; D006900:Hydroxylation; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D010368:Pectins / Q000032:analysis / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
chemical_list: D005841:Gentisates; D006247:Harmine; C005010:harman; D010368:Pectins; C010925:2,5-dihydroxybenzoic acid