Determination of Fluoroquinolones in Milk by Ionic Liquid-Mediated two phase extraction followed by Capillary Electrophoresis Analysis

Abstract

We synthesized a surfactant ionic liquid (IL) 1-dodecyl-3-methylimidazolium bromide ([C 12 MIM]Br), and employed it as an additive to the dichloromethane-based liquid-liquid extraction (LLE) of five fluoroquinolones (FQs), namely, gatifloxacin, lomefloxacin, enoxacin, ofloxacin and pazufloxacin, which were subsequently analyzed with capillary electrophoresis-ultraviolet detection (CE-UV). The parameters affecting the IL-mediated LLE efficiency were investigated. It was found that addition of 2.0 g/L [C 12 MIM]Br to the donor phase, which was adjusted to pH 8.2 with 40 mM phosphatetetraborate, could improve the recoveries by 30%-100% for the five model FQs. Incorporated with CE-UV, the method could determine FQs in milk samples with detection limits ranging from 0.003 to 0.024 µg/mL. Our results suggest that the ILmediated LLE method is efficient, fast and easy to operate, and the combinational strategy of IL-mediated LLE-CE can be applied to highly efficient, sensitive, selective detection of trace FQ residues in complicated matrices.