Determination of fluoroquinolones illegally added in traditional prostate medicines by ultrasonic-assisted dispersive liquid liquid micro-extraction based on deep eutectic solvent combined with quantitative 19F nuclear magnetic resonance method

We optimized the combination of deep eutectic solvent (DES)-based ultrasonic-assisted dispersive liquid-liquid microextraction method and 19F qNMR for quantitation of 5 kinds of fluoroquinolone antibiotics illegally added to drugs for prostatitis treatments (Ciprofloxacin, Levofloxacin, Sparfloxacin, Gatifloxacin, Enrofloxacin). In this study, methyltrioctylammonium bromide and n-capric acid were mixed at a 2:1 M ratio to prepare hydrophobic DES. The newly prepared DES was used as the extract. Fluoroquinolone antibiotics were extracted from saturated ammonium sulfate solution and detected by 19F qNMR. In this study, the effects of extraction conditions such as DES volume, salt dosage, ultrasonic time, centrifugal time, and vortex time on extraction efficiency were systematically investigated. Under the optimal conditions, good linearity (correlation coefficient r: 0.9993–0.9998) was obtained with a detection limit of 0.1 μg mL−1. The extraction reproducibility (RSD) of intra-day and inter-day were below 5.01 and 5.98%, respectively. This study showed feasibility of detection of fluoroquinolone antibiotics illegally added in traditional medicines for prostatitis treatments by DES-based ultrasonic-assisted dispersion-liquid microextraction combined with 19F qNMR method.