INVESTIGADORES
WUILLOUD Rodolfo German
congresos y reuniones científicas
Título:
Separation and determination of selenium species in food and beverages by ionic liquid-assisted reversed-phase liquid chromatography
Autor/es:
CASTRO GRIJALBA, ALEXANDER; FIORENTINI, EMILIANO; WUILLOUD, RODOLFO G.
Lugar:
Santos
Reunión:
Congreso; 5th IBEROAMERICAN MEETING ON IONIC LIQUIDS (IMIL 2017); 2017
Institución organizadora:
Universidade Estadual Paulista (UNESP)
Resumen:
Ionic liquids (ILs) were studied as modifiers in reverse phase high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry detection (RP-HPLC-HG-AFS) for selenite Se(IV), selenate Se(VI), selenomethionine (SeMet) and Se-methyl selenocysteine (SeMeSeCys) separation and determination in wine, beer, yeast and enriched garlic samples. The separation was performed on a C8 column in gradient elution mode with a mobile phase containing 1-hexyl-3-methylimidazolium chloride ([C6mim]Cl) at 0.1% (v/v) with 5% (v/v) of methanol at pH 6.0. A study of the influence of the ILs on the fluorescence signal of the Se species was performed. A multivariate methodology was applied to optimize AFS signals of each Se species. The separation was obtained in 12 min with a resolution higher than 0.98 for all Se species studied. The inorganic Se species could be separated with the aid of ILs in comparison with common ion-pair reagents which do not accomplish this approach. The ILs showed a similar behavior to other ion pair reagents used in RP-HPLC. The limits of detection for Se species were 0.92, 0.86, 1.41 and 1.19 µg L-1 for Se(IV), Se(VI), SeMet and SeMeSeCys, respectively. This method used one only IL and at a very low concentration for the complete Se speciation analysis. The different separation mechanisms are discussed in this work and might include anion exchange in addition to ion pairs formation between Se species and IL molecules. Both processes contributing to the retention of Se species on the C8 column. Moreover, retention times and resolution of Se species were dependant on the length of alkyl chains in imidazolium-type ILs. The method developed in this work showed detection limits that were comparable or even better than those reported in the literature using RP-HPLC coupled to more expensive detectors such as ICPMS. The significant improvements achieved on the separation of both organic and inorganic Se species when ILs were used as mobile phase modifiers, allowed the successful application of the method for Se speciation analysis in highly complex samples such as wines, beers, yeast and garlic.