title: Dispersive liquid-liquid microextraction combined with online preconcentration MEKC for the determination of some phenoxyacetic acids in drinking water.
abstract: A fast and simple technique composed of dispersive liquid-liquid microextraction (DLLME) and online preconcentration MEKC with diode array detection was developed for the determination of four phenoxyacetic acids, 2,4,5-trichlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, 2,6-dichlorophenoxyacetic acid, and 4-chlorophenoxyacetic acid, in drinking water. The four phenoxyacetic acids were separated in reversed-migration MEKC to the baseline. About 145-fold increases in detection sensitivity were observed with online concentration strategy, compared with standard hydrodynamic injection (5 s at 25 mbar pressure). LODs ranged from 0.002 to 0.005 mg/L using only the online preconcentration procedures without any offline concentration of the extract. A DLLME procedure was used in combination with the proposed online preconcentration strategies, which achieved the determination of analytes at limits of quantification ranging from 0.2 to 0.5 μg/kg, which is far lower than the maximum residue limits established by China. The satisfactory recoveries obtained by DLMME spiked at two levels ranged from 67.2 to 99.4% with RSD <15%, making this proposed method suitable for the determination of phenoxyacetic acids in water samples.
authors.affiliation: Citrus Research Institute Southwest University/Laboratory of Citrus Quality and Safety Risk Assessment, Ministry of Agriculture/Key Laboratory of Horticulture Science for Southern Mountainous Regions of Ministry of Education, Southwest University, Chongqing, China.
authors.forename: Yaohai
authors.initials: Y
authors.lastname: Zhang
authors.forename: Bining
authors.initials: B
authors.lastname: Jiao
mesh_terms: D000085:Acetates / Q000032:analysis*; D020374:Chromatography, Micellar Electrokinetic Capillary; D060766:Drinking Water / Q000737:chemistry*; D020407:Internet; D059627:Liquid Phase Microextraction; D015394:Molecular Structure
chemical_list: D000085:Acetates; D060766:Drinking Water; C415326:phenoxyacetic acid
keywords: Dispersive liquid-liquid microextraction; Drinking water; Herbicides; Micellar electrokinetic chromatography; Phenoxyacetic acids