Optimization of a phase separation based magnetic-stirring salt-induced liquid–liquid microextraction method for determination of fluoroquinolones in food

Herein, we developed a novel integrated apparatus to perform phase separation based on magnetic-stirring, salt-induced, liquid–liquid microextraction for determination of five fluoroquinolones in animal-based foods by HPLC analysis. The novel integrated apparatus consisted of three simple HDPE (high density polyethylene) parts that were used to separate the solvent from the aqueous solution prior to retrieving the extractant. The extraction parameters were optimized using the response surface method based on central composite design: 791 μL of acetone solvent, 2.5 g of Na2SO4, pH 1.7, 3.0 min of stir time, and 5.5 min centrifugation. The limits of detection were 0.07–0.53 μg kg−1 and recoveries were 91.6–105.0% for the five fluoroquinolones from milk, eggs and honey. This method is easily constructed from inexpensive materials, extraction efficiency is high, and the approach is compatible with HPLC analysis. Thus, it has excellent prospects for sample pre-treatment and analysis of fluoroquinolones in animal-based foods.