Antibiotic residue determination in environmental waters by LC-MS

Pharmaceuticals, identified as emerging contaminants, are used in large quantities in human and veterinary medicine for treatment of different diseases. Among pharmaceuticals, antibiotics in the aquatic environment are of great concern as prolonged exposure to low doses may promote antibiotic resistance. The rapid development of liquid chromatography (LC) coupled to mass spectrometry (MS) and tandem MS (MS2) in the environmental field has transformed this combined technique into a valuable tool for the determination of antibiotics in water samples. To be of real value from the environmental and public health point of view, the analysis performed should meet the scientific standards established to assure data quality. These require not only accurate quantitative methods but also reliable confirmative methods, at the low concentration levels expected for antibiotics in water. We present a critical review of published methods based on LC-MS or LC-MS2 for the determination of antibiotic residues in environmental waters. We evaluate different approaches for screening, quantification and confirmation of these compounds, giving special attention to dealing with the intrinsic difficulties of confirming analytes with confidence at low-ng/L levels.