Abstract: Analytical methods for the determination of 29 antibiotic residues including sufonamides, tetracyclines, chloramphenicals and fluoroquinolones in waste waters were developed. Samples were adjusted into pH=6, centrifugated and cleaned\|up through solid phase extraction column. HPLC\|MS/MS with electrospray was used to determine sufonamides, tetracyclines, fluoroquinolones in positive ion scan mode and chloramphenicals in negative scan mode. The fortified recoveries of antibiotic residues in surface water were 68.6%-91.5% at fortification levels ranging from 0.02-1.0 μg·L-1 for sufonamides and fluoroquinolones and 0.04-1.0 μg·L-1 for tetracyclines and chloramphenicals. Relative standard deviations(RSDs) were 2.8%-12.3% (n=5). The limit of quantization(LOQ)were 002-004 μg·L-1. The method was applied to determine residues in 20 waste water samples from livestock and poultry farms or rivers near farms. As a result, five kinds of sufonamides and florfenicol were detected.

Key words: waste water, antibiotics, solid phase extraction, HPLC-MS/MS