Fluorescence quenching effects of antibiotics on the main components of dissolved organic matter

Dissolved organic matter (DOM) in wastewater can be characterized using fluorescence excitation-emission matrix and parallel factor (EEM-PARAFAC) analysis. Wastewater from animal farms or pharmaceutical plants usually contains high concentration of antibiotics. In this study, the quenching effect of antibiotics on the typical components of DOM was explored using fluorescence EEM-PARAFAC analysis. Four antibiotics (roxarsone, sulfaquinoxaline sodium, oxytetracycline, and erythromycin) at the concentration of 0.5 similar to 4.0 mg/L and three typical components of DOM (tyrosine, tryptophan, and humic acid) were selected. Fluorescence quenching effects were observed with the addition of antibiotics. Among these four antibiotics, roxarsone (2.9 similar to 20.2 %), sulfaquinoxaline sodium (0 similar to 32.0 %), and oxytetracycline (0 similar to 41.8 %) led to a stronger quenching effect than erythromycin (0 similar to 8.0 %). From the side of DOM, tyrosine and tryptophan (0.5 similar to 41.8 %) exhibited a similar quenching effect, but they were higher than humic acids (0 similar to 20.2 %) at the same concentration of antibiotics. For humic acid, a significant quenching effect was observed only with the addition of roxarsone. This might be the first report about the fluorescence quenching effect caused by antibiotics. The results from this study confirmed the interference of antibiotics on the fluorescence intensity of the main components of DOM and highlighted the importance of correcting fluorescence data in the wastewater containing antibiotics.