title: [Ground and first singlet excited dissociation constants of 4-methylumbelliferone: application for indirect spectrofluorimetry of nitriles and nitrosamines].
abstract: The light adsorption process provides important changes in the electronic configuration of molecules. For phenolic derivatives, light adsorption contributes to acidity in the excited state. In aqueous medium, excitation of the molecular form (ArOH) undergoes dissociation at the first singlet excited state and subsequent fluorescence emission occurs from the excited ionized form (ArO-*). The emission is higher than from the molecular form and exhibits a shift to the red. The combination of these two phenomena allowed simultaneous increase in selectivity and sensitivity. In addition this method allowed an easy quantification of 4-methylumbelliferone at the nanomolar level and consequently trace levels of nitrates and N-nitrosamines after diazotization and/or denitrozation.
authors.affiliation: Laboratoire de Chimie Analytique, Faculté de Pharmacie Paris XI, 5, rue J.-B. Clément, F92290 Châtenay-Malabry.
authors.forename: S
authors.initials: S
authors.lastname: Diallo
authors.forename: P
authors.initials: P
authors.lastname: Prognon
authors.forename: M
authors.initials: M
authors.lastname: Hamon
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D006923:Hymecromone / Q000737:chemistry*; D007202:Indicators and Reagents; D009573:Nitrites / Q000032:analysis*; D009602:Nitrosamines / Q000032:analysis*; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence
chemical_list: D007202:Indicators and Reagents; D009573:Nitrites; D009602:Nitrosamines; D006923:Hymecromone
vernacular_title: Différence d'ionisation de la 4-méthylombelliférone aux états fondamental et excité. Intérêt pour sa détection spectrofluorimétrique dans le dosage indirect des nitrites et nitrosamines.