Hydrophobic deep eutectic solvent as a green extractant for high‐performance liquid chromatographic determination of tetracyclines in water samples

Abstract A green extractant, hydrophobic deep eutectic solvent was first introduced for extraction of tetracycline, oxytetracycline, and chlortetracycline from environmental water samples prior to high‐performance liquid chromatography determination. Deep eutectic solvents consist of methyltrioctylammonium chloride and various medium‐chain alcohols/acids, and are easy in preparation, low cost and toxicity, desirably biodegradable, and biocompatible. The overall time required for sample preparation was 6 min and the volume of organic solvent used for extraction was only 400 µL. Under the optimized extraction condition, the present method yielded low limit of detection (0.5–2.0 ng/mL), acceptable precision (relative standard deviations < 9.7%), good linearity from 2.0 to 500 ng/mL ( r 2 ≥ 0.9991). This optimized procedure was applied for determination of tetracyclines in different water samples with desirable spiked recovery ranged from 77.5 to 87.6%. There is, therefore, a great potential to further expand application of the method for investigation of other ultra‐trace analyte(s) in environmental matrixes.