Application of salting-out assisted liquid-liquid extraction for the determination of oxytetracycline, tetracycline, tilmicosin, and tylosin in cow milk by liquid chromatography with photodiode array detection.

ABSTRACT

This paper introduces a novel, sensitive, and rapid method for the quantification of oxytetracycline, tetracycline, tilmicosin, and tylosin residues in cow's milk. The method involves a two-step process of extraction and detection. The extraction process uses acetonitrile and salting-out assisted liquid-liquid extraction to isolate the antibiotics from the milk. The detection process employs Liquid Chromatography coupled with photo-diode array detector (PDA) to quantify the antibiotics. The method has been successfully applied to milk samples, demonstrating its effectiveness and potential for widespread use in residue analysis.•The calibration curves for the antibiotics were found to be linear within the range of 0.06-3.0 µg/mL to 0.1-3.0 µg/mL.•The limits of detection for oxytetracycline, tetracycline, tilmicosin, and tylosin were 0.03 µg/mL, 0.02 µg/mL, 0.04 µg/mL, and 0.02 µg/mL respectively.•The method demonstrated an average recovery rate of over 90% from milk samples with peak values reaching up to 0.100-0.200 µg/mL.