Determine Multiple Classes of Veterinary Antibiotics in Soil: Comparing Dispersive and Solid-Phase Extraction for Sample Cleanup

Veterinary antibiotics in agricultural soil are a growing concern, as they pose risks to soil quality and food safety. An analysis approach that covers a broad spectrum of target substances and has low detection limits is required for a comprehensive risk assessment. In this study, we developed a method for simultaneously analyzing 34 antibiotics (tetracyclines, sulfonamides, macrolides, and quinolones) in agricultural soil. The soil was extracted using an organic solution of acetonitrile and methanol (v:v, 1:1) with 0.2% formic acid followed by the addition of Na(2)EDTA-McIlvaine buffer. Dispersive and solid-phase extractions (SPE) were compared for cleanup. Ultra-performance liquid chromatography-tandem mass spectrometry with matrix-matched calibration was used for quantification. The results of this study showed that SPE was more appropriate for determining multi-class antibiotics. The SPE approach proved better recoveries (56-98%) than dispersive SPE (d-SPE) (28-121%). The matrix effects obtained by SPE (46-299%) were more reasonable than that by d-SPE (3-4036%). The method detection limits by SPE were in the range of 0.007-1.400 mu g/kg with relative standard deviations < 18%. This optimized method was then applied to 55 agricultural soil samples. The total concentrations of veterinary antibiotics ranged from blow method detection limits to 1448 mu g/kg. Tetracyclines were the dominant antibiotics, particularly in soil applied with swine manure. This method can be used to screen for and accurately determine the presence of veterinary antibiotics in soil, which will aid their risk assessment and regulation of these antibiotics in the agroecosystem.

Automated summary

Veterinary antibiotics in agricultural soil are a growing concern due to their risks to soil quality and food safety. This study developed a method for simultaneously analyzing 34 antibiotics in soil, with solid-phase extraction proving to be more suitable for determining multi-class antibiotics. The optimized method can be used to screen for and accurately determine the presence of veterinary antibiotics in soil for risk assessment and regulation in the agroecosystem.