Simultaneous determination of nitroimidazoles and amphenicol antibiotics in water samples using ultrasound-assisted dispersive liquid–liquid microextraction coupled with ultra-high-performance liquid chromatography with tandem mass spectrometry

Abstract

A rapid, simple and environmentally friendly method involving ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) coupled with ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) was developed for the simultaneous determination of nitroimidazoles (metronidazole and tinidazole) and amphenicol antibiotics (chloramphenicol and thiamphenicol) in water samples. In this work, the effective DLLME parameters such as pH, the type and volume of extraction solvent, the type and volume of dispersive solvent, salt concentration and extraction time were investigated. The significant factors were optimized and selected as follows: pH 4.0 water sample, 300 μL dichloromethane, 600 μL acetonitrile, no salt addition and 4 min of extraction time. Under the optimum conditions, the calibration curves were linear in the range of 2.00–100 ng L⁻¹ (MNZ and TNZ) and 5.00–200 ng L⁻¹(CAP and TAP) with regression coefficients (r) higher than 0.9917. Limits of detection (LODs) and limits of quantification (LOQs) were achieved in the range of 0.39–1.38 ng L⁻¹ and 1.70–4.18 ng L⁻¹, respectively. The relative recoveries of the analytes were from 82.8% to 99.5% with the relative standard deviations between 0.3% and 4.3%. The developed method was successfully applied to analyze the nitroimidazoles and amphenicol antibiotics in water samples with satisfactory results.