Determination of fluoroquinolones in water with dispersive liquid-liquid phase microextraction-HPLC

Dispersive liquid-liquid micro-extraction coupled with high performance liquid chromatography ( DLLME-HPLC) was applied to separate and determine six fluoroquinolones ( FQs) in aqueous samples.Before injection into HPLC, the extraction solvent droplet obtained after centrifugation was pulled out, and then dried by nitrogen flow, re-dissolved with dozens of microliters mobile phase at last.Some important parameters, like variety and dosage of extractant and dispersive solvent and pH of extraction solution, which influent the extraction efficiency were investigated. The results showed that after adding 500 μL trichloromethane as extractant solvent, 800 μL acetonitrile as dispersive solvent into extraction system which p H was tuned to7, enrichment factor of 6 FQs was up to 245 and a good linear relationship was obtained in the range of 0.075~0.34 μg/L.The recoveries of 6 FQs in 3 kinds of water from han river, fishpond and running water fell in the range from 88.6% to 109.3% and the relative standard deviation was less than 5.8%. The method had low matrix effect, high enrichment factor and avoids chromatographic peak deformation when direct injection of extraction solvent droplet in the traditional DLLME.It was proven to be sensitive, simple, and accurate in residue analysis of FQs in water.