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Acid-Induced Phase Separation of Anionic Surfactants for the Extraction of 1,4-Dichlorobenzene from Honey Prior to Liquid Chromatography

Paleologos, E.K., Giannakopoulos, S.S., Zygoura, P.D., Kontominas, M.G.
Journal of agricultural and food chemistry 2006 v.54 no.15 pp. 5236-5240
honey, food contamination, insect repellents, chemical residues, organochlorine compounds, acid treatment, separation, extraction, nonionic surfactants, chemical analysis, high performance liquid chromatography
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 micrograms/L level. Application to honey samples produced detection limits of 2.5 g/kg with quantification limits of 7.5 g/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 micrograms/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 micrograms/kg).