Development of a method for trace level determination of antibiotics in drinking water sources by high performance liquid chromatography-tandem mass spectrometry

The presence of antibiotics in drinking water sources is worthy of concern regarding their potentially harmful effects on drinking water quality. In this study, a sensitive and reliable method was developed for the detection of 14 antibiotics in drinking water sources based on solid phase extraction (SPE) and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The primary parameters for the SPE procedure, including different SPE cartridges, pH value of the sample, extraction volume and washing conditions, were optimized to extract the analytes efficiently in a single step with improved recoveries. Chromatographic separation conditions and MS/MS parameters in multiple reaction monitoring (MRM) mode were optimized to improve the sensitivity and specificity of the method. The optimized method provided acceptable recoveries ranging from 60.5% to 103.3%. The validation study indicated that the method detection limits varied from 0.001 to 2.160 ng L-1 and the method quantification limits varied from 0.003 to 6.740 ng L-1. The precision of the method, expressed as relative standard deviation (RSD), ranged from 0.1% to 2.6% and from 0.3% to 3.8% for inter- and intra-day analyses, respectively. Assessment of matrix effects exhibited partial signal suppression from 1.2% to 28.7% for most analytes, but it indicated signal enhancement for tetracycline (15.2%) and oxytracycline (12.6%). The method was successfully applied to the determination of trace levels of antibiotics in drinking water sources in East China. Up to 13 antibiotics were detected at concentrations ranging from 0.16 to 147.05 ng L-1, and the primary antibiotic residues belonged to the groups of fluoroquinolones and tetracyclines.