Simultaneous determination of four classes of antibiotics in sediments of the Pearl Rivers using RRLC-MS/MS.

A simultaneous extraction and analysis method was developed for four classes of antibiotics: sulfonamides (SAs), macrolides (MLs), fluoroquinolones (FQs) and tetracyclines (TCs) in sediment. The antibiotics in the sediment were extracted by using an optimized mixed solution (citric buffer: acetonitrile, 50:50 v/v), and analyzed by rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS) equipped with electrospray ionization source in the positive mode. The recoveries for the antibiotics in the spiked sediment were: 66.3-123.5%, 48.2-72.0%, 61.8-160.4% and 60.6-151.9% for the SAs, TCs, FQs and MLs, respectively. The LOD ranged from 0.08 microg/kg to 4.2 microg/kg and LOQ from 0.26 microg/kg (erythromycin-H(2)O) to 14.01 microg/kg (norfloxacin). The developed analytical method was applied in the determination of the antibiotics in sediment samples collected from the Pearl Rivers, China. The antibiotics were found at the levels of microg/kg in the sediments of the three rivers. Ofloxacin was found to have the highest concentration of 1560 microg/kg in sediment. However, no significant seasonal variation could be found for the antibiotics in the sediments between wet season and dry season.