IBAM   22618
INSTITUTO DE BIOLOGIA AGRICOLA DE MENDOZA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
UHPLC-(+)ESI-MS/MS Monitoring of Melatonin and its Isomers from grape to wines
Autor/es:
FEDERICO JOSÉ VICENTE GOMEZ; ISMAEL GATICA HERNANDEZ; JULIO RABA; SOLEDAD E. CERUTTI; MARIA FERNANDA SILVA
Lugar:
Baltimore
Reunión:
Simposio; ITP 2012—19th International Symposium, Exhibit & Workshops on Electro- and Liquid Phase-separation Techniques; 2012
Resumen:
Melatonin (MT, N-acetyl-5-methoxitryptamine) is a neurohormone discovered more than 50 years ago in the mammalian pineal gland. This molecule, a biogenic indolamine, performs an important role in the regulation of both circadian and seasonal rhythms. Furthermore, melatonin is a “suicide” antioxidant, which is not regenerated and does not promote further oxidation reactions. Its presence in higher plants was recently discovered and the knowledge of its function in vivo is very limited. Several studies have shown the occurrence of melatonin and related compounds in grapes and wines. The latter provides evidence of the opportunity to enhance the nutraceutical properties of premium wines. The analysis of MT in foods represents a highly challenging task due to its low concentration range, the difficulty in the selection of the extraction solvents because of its amphipathic nature, and the fact that it reacts quickly with other food components. In this work, the development of a methodology for the analysis of melatonin and its isomers in plant tissues, grape skins, musts and finished wines based on ultra-high performance liquid chromatography (UHPLC) coupled with electrospray ionization in positive mode ((+)ESI) and associated with tandem mass detection (MS/MS) is proposed. Sample processing factors, preparation/cleanup procedures and chromatographic/detection parameters were evaluated. Thus, C8 cartridges were chosen for the extraction of the analytes. Because of their chemical properties, a hydrophilic interaction liquid chromatography (HILIC) column was selected, being water (A) and acetonitrile (B), both with 0.1% formic acid, the chosen mobile phases for the elution gradient (6 min run cycle). As for mass detection, two transitions from the fragmentation of both MT and the isomer´s pseudomolecular ion ([M+H]+ = 233) were selected: 233 > 216 (higher abundance for the isomer) and 233> 174 (higher abundance for MT), which correspond to the losses of the NH3 and CH3CONH2 groups of the aliphatic portion of the molecule. The limits of detection (LoD) and quantitation (LoQ) were in the low ng/L range. Recovery, repeatability, reproducibility, and matrix effect studies were performed. Melatonin was detected in plant and grape extracts while its isomer was found in musts and finished wines. From the studies mentioned, it was possible to conclude that there were many external factors influencing the levels of MT and its isomer in the different samples, including saccharomyces strain during the fermentation process, harvest schedule and biotic/abiotic stress.