Analysis Of Typical Antibiotics In Water Environment And Investigation Of Their Ecological Toxicity

The residual of Pharmaceutical and Personal Care Products (PPCPs) in aquatic environment has received wide concern. Incompletely absorbed antibiotics are discharged through urine and excreta into municipal and hospital waste water. They can not be removed effectively in waste water treatment plants (WWTPs) in the current stage. In China, antibiotics especially cephalosporins are produced and consumed in a large scale. So the long-term, large amount and continous emission of cephalosporins antibiotics will cause "pseudo-persistent" pollution, and lead to the damages on ecological environment and human health.Firstly, this study developed a robust and reliable determination method for simultaneous analysis of a variety of cephalosporin antibiotics in water samples based on the solid-phase extraction (SPE) and high performance liquid chromatography (HPLC), through improving the previously established technology. By optimizing the conditions of gradient elution (detection and reference wavelength in respectively 254 and 270 nm), 7 cephalosporin antibiotics were completely separated in 20 min. By selecting and optimizing the solid-phase extraction conditions, after pretreated by the HLB column for SPE, adjusted pH value to 3, NaCl dosage of 6.0 g / L, the water sample was determinated by HPLC. he regression equation coefficient of determination of the 7 kinds of cephalosporin antibiotics were all greater than 0.99, the detection limit (LOD) ranges in 0.05 ~ 0.39μg / L. The average recoveries of this method were 87 to 105% and 68 ~ 105% for ultrapure water and tap water respectively. The method has good recovery, repeatability, accuracy and sensitivity for simultaneous determination of 7 cephalosporin antibiotics in water.Additionally, level III model was applied to preliminarily forecast the distribution of cephalosporin antibiotics in the environment. It can provide the basis for ecological risk assessment of the cephalosporin antibiotics in large scale environments. It was found the model simulation results and experimental results were comparable. The 10 selected cephalosporin antibiotics are enriched mainly in water and soil. The distribution ratio in the two phases totally accounts for more than 90%. In this study, two cephalosporins (cephalexin, cephradine) with high concerntrations in aquatic environment, and two main degradiation products of cephalosporins (7-ACA, 7-ADCA) were selected as the target analysts to determine their toxicity on Selenastrum capricornutum and Daphnia magna. Moreover, several tetracycline antibiotics (tetracycline, chlortetracycline and oxytetracycline) were also tested for the comparisons. 72h growth inhibition test, measurements of chlorophyll-a (Chla) and IC50 were performed on Selenastrum capricornutum under different concentrations of antibiotics. The results showed that the degradiation products of cephalosporins had greater toxicity than the cephalosporins, although the latter had relatively weaker inhibition effects on Selenastrum capricornutum compared with tetracycline antibiotics.The results of joint action experiments showed that, except of the binary mixture of tetracycline and 7-ACA had antagonistic effect, the other binary mixtures showed simple additive effect. In addition, the 24h immobilisations assay on Daphnia magna of different drugs at different concentrations was studied. The results indicated the potential ecological risks of the long-term large-scale emissions of cephalosporins and its degradation products should be seriously concerned. This study provides an important reference for further research in environmental and ecological risk assessment and management policies of cephalosporins.