Integration of phase separation with ultrasound-assisted salt-induced liquid–liquid microextraction for analyzing the fluoroquinones in human body fluids by liquid chromatography

• An integrated apparatus was developed using three simple high-density polyethylene components.
• The apparatus quickly separates the extractant from the aqueous phase prior to retrieving.
• The novel device can be easily integrated with the PS-MSLM method.
• The LODs of this method are low (0.12–0.67 μg L−1) for biological fluids.
• The extraction time of this method is short (ca. 11.1 min).

Herein, we developed a novel integrated device to perform phase separation based on ultrasound-assisted salt-induced liquid–liquid microextraction for determination of five fluoroquinones (FQs) in human body fluids. The integrated device consisted of three simple HDPE components used to separate the extraction solvent from the aqueous phase prior to retrieving the extractant. A series of extraction parameters were optimized using the response surface method based on central composite design. Optimal conditions consisted of 945 μL acetone extraction solvent, pH 2.1, 4.1 min stir time, 5.9 g Na2SO4, and 4.0 min centrifugation. Under optimized conditions, the limits of detection (at S/N = 3) were 0.12–0.66 μg L−1, the linear range was 0.5–500 μg L−1 and recoveries were 92.6–110.9% for the five FQs extracted from plasma and urine. The proposed method has several advantages, such as easy construction from inexpensive materials, high extraction efficiency, short extraction time, and compatibility with HPLC analysis. Thus, this method shows excellent prospects for sample pretreatment and analysis of FQs in human body fluids.