Trace analysis of quinolone and fluoroquinolone antibiotics from wastewaters by liquid chromatography–electrospray tandem mass spectrometry

A sensitive liquid chromatography–electrospray tandem mass spectrometry method, combined with solid-phase extraction and a weak cation exchange cartridge cleanup, was established for twenty quinolone and fluoroquinolone antibiotics (pipemidic acid, flerofloxacin, ofloxacin, pefloxacin, enoxacin, norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin, lomefloxacin, difloxacin, sarafloxacin, gatifloxacin, sparfloxacin, moxifloxacin, cinoxacin, oxolinic acid, nalidixic acid, flumequine, and piromidic acid) in influent, effluent, and river waters. For the various water matrices considered, the overall recoveries were from 64% to 127% except for piromidic acid (27–33%), and no obvious matrix effect was observed. The method detection limits for the twenty target antibiotics in the influent, effluent, and surface water samples were 1.6–50 ng/L, 0.6–50 ng/L, and 0.8–50 ng/L, respectively. This method was applied to analyze residual quinolone and fluoroquinolone antibiotics in wastewater and surface water samples from Beijing, China. Eight antibiotics (12 (pipemidic acid)–1208 ng/L (ofloxacin)) were detected in wastewater, and seven (1.3 (lomefloxacin)–535 ng/L (ofloxacin)) were detected in surface water samples. Gatifloxacin, a 4th generation fluoroquinolone antibiotic, was detected for the first time in influent (111 ng/L), effluent (56 ng/L), and river water (16–42 ng/L).