title: Potential of NMR spectroscopy for the study of human amniotic fluid.
abstract: 1D and 2D 800 MHz high-resolution nuclear magnetic resonance spectroscopy of human amniotic fluid (HAF) enabled the identification of approximately 50 metabolites. In addition, liquid chromatography-NMR and diffusion ordered spectroscopy (DOSY) allowed signal overlap to be reduced and the characterization of higher molecular weight (Mw) components, respectively. Indeed, the DOSY spectrum of a Mw >10 kDa HAF fraction enabled three protein families, differing in average Mw, to be detected and may therefore be of potential value in the study of disorder-related variations in HAF protein profiles. The effects of freeze-drying, storage at -20 or -70 degrees C, and freeze-thawing cycles on HAF compositional stability were investigated, as well as stability at room temperature (to account for overnight data acquisition runs). These data are the basis for establishing statistically validated correlations between HAF NMR data and any physiological disorders of the fetus/mother. Freeze-drying caused signal loss for urea, ethanol, and compounds resonating at 2.22 and 1.17 ppm. Storage at -70 degrees C or lower is recommended since only minor compositional changes were observed, affecting mainly acetate and pyruvate. Freeze-thaw cycles did not cause significant compositional changes, and room-temperature stability studies indicated a 4-5 h maximum period of handling/acquisition time to ensure HAF stability.
authors.affiliation: CICECO, Department of Chemistry, Campus UniversitArio de Santiago, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Gonçalo
authors.initials: G
authors.lastname: Graça
authors.forename: Iola F
authors.initials: IF
authors.lastname: Duarte
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Goodfellow
authors.forename: António S
authors.initials: AS
authors.lastname: Barros
authors.forename: Isabel M
authors.initials: IM
authors.lastname: Carreira
authors.forename: Ana Bela
authors.initials: AB
authors.lastname: Couceiro
authors.forename: Manfred
authors.initials: M
authors.lastname: Spraul
authors.forename: Ana M
authors.initials: AM
authors.lastname: Gil
mesh_terms: D000328:Adult; D000653:Amniotic Fluid / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D025341:Principal Component Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity