title: Acid-induced phase separation of anionic surfactants for the extraction of 1,4-dichlorobenzene from honey prior to liquid chromatography.
abstract: The acid-induced liquid-liquid phase separation of anionic surfactants in aqueous solutions and its applicability to cloud point extraction methodology were applied as a tool for the extraction of 1,4-dichlorobenzene (p-DCB) from aqueous samples. p-DCB is extracted into the micelles of sodium dodecane sulfonate (SDSA) in a 4.2 M HCl solution. The micellar phase is separated from the bulk aqueous solution after centrifugation and collected from the surface of the suspension. The micellar extracts are injected into a high-performance liquid chromatographic apparatus and quantified at 225 nm with a reference wavelength of 280 nm. Following the proposed methodology, a preconcentration factor of ca. 160 is achieved (starting from 50 mL solutions) allowing for detection limits at the low microg/L level. Application to honey samples produced detection limits of 2.5 microg/kg with quantification limits of 7.5 microg/kg, while the recoveries of the method ranged from 85% at high concentrations to 95% at lower concentrations of p-DCB. The combined uncertainty of the entire analytical procedure was 4.5% at the concentration level of 30 microg/kg allowing for reliable and reproducible results for the determination of p-DCB at the concentration levels considered as thresholds for EU and U.S. legislation (10 microg/kg).
authors.affiliation: Laboratory of Food Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece. me00810@cc.uoi.gr
authors.forename: E K
authors.initials: EK
authors.lastname: Paleologos
authors.forename: S S
authors.initials: SS
authors.lastname: Giannakopoulos
authors.forename: P D
authors.initials: PD
authors.lastname: Zygoura
authors.forename: M G
authors.initials: MG
authors.lastname: Kontominas
mesh_terms: D000704:Analysis of Variance; D000838:Anions; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002722:Chlorobenzenes / Q000302:isolation & purification*; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006722:Honey / Q000032:analysis*; D006851:Hydrochloric Acid; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D000838:Anions; D002722:Chlorobenzenes; D013501:Surface-Active Agents; C018511:4-dichlorobenzene; D006851:Hydrochloric Acid