Determination of 55 Veterinary Antibiotics in Chicken Manure Using Ultra-High-Performance Liquid Chromatography - Tandem Mass Spectrometry (UPLC-MS/MS)

A highly efficient method for the detection and quantification of 55 veterinary antibiotics (VAs) in chicken manure belonging to six drug classes using solid-phase extraction (SPE) and ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed. The mixture of EDTA-McIlvaine buffer (pH 3.0) and the organic extractant (methanol-acetonitrile, 1:3, v/v) was used to isolate the target VAs from freeze-dried chicken manure. The extract was purified by a hydrophile-lipophile balance cartridge. All antibiotics showed excellent linear relationships in the range between 1 and 100 mu g/kg with the coefficients of determination of the standard curves above 0.990. The recoveries of antibiotics were between 35.66% and 103.54% using matrix-matched calibration for quantification. The limits of detection and quantification were from 0.01 to 1.59 mu g/kg and 0.04 to 4.76 mu g/kg, respectively. The method was demployed to determine VAs in chicken manure from 12 farms, revealing contamination in all samples. A total of 13 VAs belonging to six classes were detected with concentrations up to 41.47 mg/kg. The presence of high concentrations of antibiotic residues in poultry manure poses a potential risk for environmental contamination. This work has identified significant differences in the types of VAs compared to literature reports. Additionally, it detected pleuromutilin antibiotics in chicken manure for the first time.