title: Combination of off-line solid-phase extraction and on-column sample stacking for sensitive determination of parabens and p-hydroxybenzoic acid in waters by non-aqueous capillary electrophoresis.
abstract: For the first time, a procedure based on solid-phase extraction (SPE) for the simultaneous extraction of a group of parabens (methyl, ethyl, propyl, butyl and benzyl p-hydroxybenzoates) and p-hydroxybenzoic acid (PHBA), from environmental water samples has been developed. Analysis of the extracts was performed by non-aqueous capillary electrophoresis (NACE) coupled with diode array detection (DAD), using large-volume sample stacking (LVSS) based on the electroosmotic flow pump as on-column preconcentration technique. Several water samples, such as tap, river, and wastewater samples, were analyzed using both SPE-NACE-DAD and SPE-LVSS-NACE-DAD methods. It has been observed that in addition to SPE parameters such as sorbent material, sample pH, breakthrough volume, addition of an organic solvent and elution solvent, also sample characteristics, such as organic matter content, have influence on SPE extraction yields, especially in the case of PHBA. The presence of PHBA and some parabens was detected at trace levels in surface water samples. Concentrations up to 8.4 ng mL(-1) were found in raw wastewater, with the highest levels corresponding to methylparaben, propylparaben, and their main degradation product, PHBA.
authors: Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Chemistry, Institute of Research and Food Analysis, University of Santiago de Compostela, Avda. de las Ciencias s/n, E-15782 Santiago de Compostela, Spain.
authors: Eva
authors: E
authors: Blanco
authors: María del Carmen
authors: Mdel C
authors: Casais
authors: María del Carmen
authors: Mdel C
authors: Mejuto
authors: Rafael
authors: R
authors: Cela
mesh_terms: D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods*; D062385:Hydroxybenzoates / Q000032:analysis* / Q000302:isolation & purification; D010226:Parabens / Q000032:analysis* / Q000302:isolation & purification; D052616:Solid Phase Extraction; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000302:isolation & purification
chemical_list: D062385:Hydroxybenzoates; D010226:Parabens; D014874:Water Pollutants, Chemical; D014867:Water