Simultaneous Determination of Several Classes of Antibiotics in the Activated Sludge of Municipal Sewage Treatment Plants by High Performance Liquid Chromatography-Mass Spectrometry

KeyWord:antibiotics  high performance liquid chromatography- mass spectrometry  municipal sewage treatment plant  activated sludge

Abstract:

      A highly selective and sensitive analytical method was developed for simultaneous determination of three classes of commonly used antibiotics£¬including five sulfonamides£¬three tetracyclines and one macrolide in the activated sludge of municipal sewage treatment plants£¨STPs£© by ultrasonic extraction£¬solid phase extraction and high performance liquid chromatography-mass spectrometry £¨LC-MS£©. The activated sludge sample was ultrasonically extracted with a mixture of methanol and Na2EDTA£¯McIlvaine buffer£¨1¡Ã1£©£¬then concentrated and purified with an HLB cartridge. The separation of targeted compound was performed with a Waters Symmetry C18 column using 0.2% formic acid£¨A£©-acetonitrile£¨B£© as mobile phase. The qualification and quantification of the selected antibiotics were carried out by MS with an electrospray ionization£¨ESI£© under the positive ion mode. The method showed good linearity£¨r2 > 0.99£© for the antibiotics concentration in the range of 0.001-1 mg£¯L. The recoveries at three spiked levels were in the range of 80%-108% for sulfonamides£¨SAs£©£¬91%-112% for tetracyclines£¨TCs£© and 50%-59% for tiamulin£¨TIA£©. The inter day and intra day relative standard deviations were no more than 7.4% and 13.7%£¬respectively. The limits of detection£¨LOD£© were between 1 ¦Ìg/kg and 16 ¦Ìg/kg. The developed method was applied in the detection of the activated sludge samples collected from two STPs located in Beijing and five target antibiotics were detected with concentrations of 124.9-523.3 ¦Ìg/kg for sulfanomindes and 166.5-2 296.4 ¦Ìg/kg for tetracyclines£¬respectively.