DETERMINATION OF ANTIBIOTICS AND CAFFEINE IN HOSPITAL WASTEWATER AND WASTEWATER TREATMENT PLANTS (WWTPS) IN DOHA, QATAR
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Pharmaceuticals and personal care products (PPCPs) are considered as chemicals of emerging environmental concern in the aquatic environment worldwide. In Qatar, studies concentrating exclusively on wastewater treatment processes for the occurrence of antibiotics and PPCPs are limited. Therefore, there is an urgent need to measure the concentrations of antibiotics residues and PPCPs especially that there are no Hospital Wastewater Treatment Plants in Qatar and Hospital wastewaters are currently discharged directly into the municipal wastewater systems. This study was carried out to optimize an analytical method to investigate and quantify the occurrence of eight selected antibiotics: Penicillin, Amoxicillin, Gentamicin, Ciprofloxacin, Tetracycline, Erythromycin, Metronidazole, Clavulanic acid and Caffeine as an influencing chemical in environmental matrices that are considered to be the most important sources of antibiotic pollution, namely Hospital Wastewater, influents and effluents from wastewater treatment plants (WWTPs). The analytes used belong to different classes of antibiotics: β–Lactam, Aminoglycosides, Macrolides, Tetracyclines, and Fluoroquinolones. The extraction method was based on the automated solid phase extraction (SPE). The analysis of antibiotics in wastewater samples was performed using liquid chromatography - mass spectrometry (LC-MS) with positive ion electrospray ESI (+). Quantification of target compounds were conducted using two isotopically labeled internal standards in order to reduce matrix effects. The method was validated for recovery, accuracy, and reproducibility. Among the nine target compounds tested, the recoveries in the range of 47.5–98% were obtained except for Gentamicin which was excluded from the current study. The method optimized was validated for the analysis of antibiotics in hospital wastewater (HWW), influent and effluent of two wastewater treatment plants (WWTPs) located in Doha for a duration of two months. The results indicated that antibiotics and Caffeine were widespread pollutants in wastewater. The concentration of antibiotics and caffeine were significantly high during the Hajj season, especially Caffeine which exhibited high prevalence above the Method Quantitation Limit (> MQL) in HWW and influent samples collected from both Old (OWWTP) and New (NWWTP) wastewater treatment plants. The highest concentration of Metronidazole and Ciprofloxacin were detected in the HWW at levels of 5.46 ng/ml and 1.99 ng/ml, respectively. In effluent samples of NWWTP, Clavulanic acid was the most prominent compound at concentration as high as 84.74 ng/mL. The highest concentration of Erythromycin (7.20 ng/mL) was detected in the OWWTP influent sample. Tetracycline was spotted at levels of ~ 0.2 ng/ml in most of the samples collected during the study. The levels of Amoxicillin, Penicillin, and Erythromycin were below the MQL or not detected (ND) in most of the samples collected from all collection points. There were a significant interaction between most of the studied compounds. It was observed that Ciprofloxacin was highly interactive with Erythromycin, Clavulanic acid, Metronidazole and Caffeine in all influent samples, whereas the concentration of Erythromycin was highly correlated with those of Amoxicillin, Ciprofloxacin, Tetracycline and Penicillin in all effluent samples. The statistical analysis shows that there is no significant difference (P≥0.05) between OWWTP and NWWTP and the methods used in both of the WWTPs are effective in reducing/removing Caffeine, Penicillin and Metronidazole. NWWTP was effective to remove Caffeine and Penicillin with percent reduction 99.44%, 99.34% on average, furthermore, OWWTP was effective to remove Caffeine and Metronidazole with removal efficiency 95.21%, 90.22% on average. Clavulanic acid and Ciprofloxacin were not removed from NWWTP nor from OWWTP. These findings demonstrated that the LC-MS method optimized in this study is sensitive and selective to detect such low concentrations and the instrument is a robust and reliable tool that can be easily used in the routine analysis of compounds, like antibiotics, in complex matrices (wastewater). However, more research is still needed to investigate the efficacy of different cartridges to be able to detect these selected compounds and their metabolites at much lower levels in wastewater samples, which are known to be an important source of PPCPs pollution in any aquatic environment.
- Biological & Environmental Sciences [26 items ]