A SIMPLE SPE-UPLC-MS/MS METHOD FOR DETERMINATION OF 9 ANTIBIOTICS IN SURFACE WATER

Abstract

The overuse of antibiotics is losing their effectiveness due to increased antibiotic resistance in bacteria. Over the past two decades, the evaluation of antibiotic residues in the environment has received considerable attention. In this work, a combined SPE-UPLC-MS/MS method was developed and validated for the simultaneous determination of 9 antibiotic compounds belonging to 3 different groups which are tetracyclines (tetracycline, chlortetracycline, oxytetracycline), fluoroquinolones (ciprofloxacin, norfloxacin, ofloxacin), and macrolides (azithromycin, erythromycin, clarithromycin) in surface water. All target analytes were separated on a reversed-phase column (Water BEH C18 column, 1.7 µm particle size, 100 mm in length × 2.1 mm in diameter) coupled with a tandem mass spectrometer employing positive electrospray ionization (+ESI). All target analytes were well separated with an overall run time of 16 minutes. The limit of detection of antibiotics ranged from 0.2 to 10 µg L-1. The extraction process was successfully optimized using an HLB column (Oasis, 6 mL, 200 mg, Waters) with recoveries from 71 to 125 %. The optimized method was finally applied to analyze ten surface water samples (from lake and river). Ofloxacin, clarithromycin and erythromycin were the most frequently detected compounds in lake water samples at concentrations ranging from 35 to 570.3 ng L-1, while only CIP was found in river samples. The other compounds were also detected in both types of samples, but in concentrations below the limit of quantification.