Determination of Tetracycline Using Ultrasound–Assisted Dispersive Liquid–Liquid Microextraction Based on Solidification of Floating Organic Droplet Followed by HPLC-UV System

Background Tetracyclines are a group of broad-spectrum antibiotics that used to controls bacterial diseases in humans or are applied as feed additives to enhance growth in farm animals. Tetracyclines are released into the aquatic environment in different pathways. Many analytical methods combined with a preconcentration step have been introduced for the determination of tetracycline in various environmental samples. Objective The objective this paper is developing reliable analytical methods for determination of tetracycline trace in various environmental samples. Method In present work, combine ultrasound-assisted and dispersive liquid–liquid microextraction according to the solidification of floating organic drop as a sample preconcentration procedure for determining tetracycline hydrochloride HPLC in water and serum samples was used. Results A series of parameters, including the type and volume of disperser and extraction solvents, salt effect, extraction time, and pH of solution influencing the extraction efficiency of UA-DLLME-SFO, was examined. Enrichment factors (EFs) were in the range of 125–137 for tetracycline hydrochloride under optimum conditions. The linear range was calculated from 0.005–3 mg/L and LOD 0.002 mg/L. Relative standard deviations (RSD) were in the range of 2.7 to 3.2 (n = 5). The UA-DLLME-SFO method used in water and serum samples revealed good extraction recoveries with RSD of 2.7–4.3%. Conclusion This method significantly decreased the organic solvent volume from 3 mL to 90 µL, also LOD and linear ranges were lower than or almost close to levels obtained in other research studies. In this procedure, ultrasound bath enhanced the mixing and contact between the sample solution and the extraction solvent.