A type UVM-7 mesoporous silica with γ-cyclodextrin for the isolation of three veterinary antibiotics (ofloxacin, norfloxacin, and ciprofloxacin) from different fat-rate milk samples

Abstract

An analytical method based on the solid-phase extraction of three veterinary fluoroquinolones (ofloxacin, norfloxacin, and ciprofloxacin) from milk samples followed by their quantification with liquid chromatography coupled to fluorescence detection is described here. The sorbent used is a novel type UVM-7 mesoporous silica modified with analyte-accessible γ-cyclodextrin, which is useful for isolating these analytes through the selective host-guest interactions carried out between them. The whole extraction procedure has been optimized and the recoveries obtained range from 83 % to 92 % in water and from 60 % to 70 % in real milk samples spiked with the studied compounds at μg L−1. The complexity of the milk matrix is overcome through a high selectivity obtained due to the presence of γ-cyclodextrin in the silica structure of the material and thanks to the type of quantification technique used. Indeed, no interfering effect is observed during the chromatographic separation. Besides, the good precision of the method is shown through variations lower than 10 % for intra-day and inter-day repeatability, and the detection limits have been established at the ng L−1 level. To end, a comparison with an alternative extraction method of veterinary drugs from milk has been carried out and the results obtained are comparable with those achieved using the developed method. The method described here can play an outstanding effect in the target fluoroquinolones separation and purification, which are nowadays substances of high concern in food safety.