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.
J Sep Sci. 2013 Sep;36(18):3067-74. doi: 10.1002/jssc.201300290. Epub 2013 Jul 30.
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.
建立了一种快速、简单的技术，包括分散液-液微萃取（DLLME）和在线浓缩 MEKC 与二极管阵列检测，用于测定饮用水中的四种苯氧乙酸，即 2,4,5-三氯苯氧乙酸、2,4-二氯苯氧乙酸、2,6-二氯苯氧乙酸和 4-氯苯氧乙酸。这四种苯氧乙酸在反迁移 MEKC 中基线分离。与标准的水力注射（25 mbar 压力下 5 s）相比，在线浓缩策略可将检测灵敏度提高约 145 倍。仅使用在线浓缩程序，无需对提取物进行任何离线浓缩，LOD 范围为 0.002 至 0.005 mg/L。结合提出的在线浓缩策略，使用 DLLME 程序，可实现定量限在 0.2 至 0.5 μg/kg 的范围内测定分析物，远低于中国规定的最大残留限量。通过在两个水平上进行 DLLMME 加标，获得的回收率在 67.2%至 99.4%之间，RSD<15%，这使得该方法适用于水样中苯氧乙酸的测定。
