Quantification of human and veterinary antibiotics in water and sediment using SPE/LC/MS/MS

An analytical method was developed and tested for four different groups of veterinary antibiotics in both river water and sediment matrices. Solid phase extraction (SPE) was used to enrich and to clean up the aqueous sample. Also, Mcllvaine and ammonium hydroxide buffer solutions were used to extract the compounds from the sediment matrix. High performance liquid chromatography (HPLC) equipped with tandem mass spectrometry (MS/MS) was used to separate and quantify the samples. The range of recoveries (in percent) for tetracyclines (TCs), sulfonamides (SAs), macrolides (MLs), and ionophore polyethers (IPs) in the water matrix were 102.2-124.8, 76.6-124.3, 89.5-114.7, 82.7-117.5 with 1-13 (%) of relative standard deviation respectively with three different concentrations. For sediment, the percent recovery ranges were 32.8-114.8, 62.4-108.9, 53.4-128.4 and 51.3-105.4 for TCs, SAs, MLs and IPs, respectively. The relative standard deviation ranged from 16 - 27 (%) over three different concentrations. The limit of quantification (LOQ) was determined by two different methods and calculated to be in the range of 0.01-0.04 microg/l and 0.3-2.5 microg/kg for TCs, SAs, and MLs in water and sediment, respectively. For IPs, the LOQ was 0.001-0.003 microg/l in river water and 0.4-3.6 microg/kg for sediment. The sediment concentration measured in an agriculture-influenced river was much higher than in the overlying water matrix, indicating a high degree of sediment partitioning for these compounds.