Multiresidue Determination of Sulfonamides, Macrolides, Trimethoprim, and Chloramphenicol in Sewage Sludge and Sediment Using Ultrasonic Extraction Coupled with Solid Phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry

A sensitive and feasible method was developed for the simultaneous determination of 10 trace antibiotic residues including sulfonamides, macrolides, trimethoprim, and chloramphenicol in sewage sludge and sediment. The method involved ultrasonic extraction followed by solid phase extraction cleanup and liquid chromatography-tandem mass spectrometry coupled with electrospray ionization in positive mode. The antibiotics were identified and determined by internal standard method in selected multiple reaction monitoring mode. The detection limits were in a range of 2.2–66.9 ng g−1 dry weight for the investigated antibiotic compounds in sewage sludge. The recoveries ranged from 74.7% to 111.8% with relative standard deviations of 1.2%–10.6%. The method was successfully applied to a primary investigation of the occurrence of antibiotic residues in a sewage sludge sample and a river sediment sample collected from Guangzhou. Sulfamethazine, trimethoprim, azithromycin, clarithromycin, dehydrated erythromycin, and roxithromycin were detected in both the sewage sludge and the river sediment, ranging from 6.8–125.6 ng g−1 dry weight.