Metal ion-mediated degradation of β-lactam antibiotics: kinetics and product identification

• Main Authors: Kuan-YuHsu, 許冠瑜
• Other Authors: Wan-Ru Chen
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/6438ms

碩士 === 國立成功大學 === 環境工程學系 === 102 === Antibiotics recently are considered as potential trace contaminants in the environment. Taiwan continues to import large quantities of antibiotics for medical and agricultural purposes. β-lactam antibiotics account for up to 20 percent of total veterinary drugs usage in Taiwan for past ten years. In addition to the medical treatment, this group of antibiotics also applies to livestock to promote their growth. Many research indicated that the antibiotics would be released to the environment via urine and feces with unchanged parent compounds or metabolites. Metal ions are also common feed additives as trace essential elements in addition to the antibiotics. In previous studies, many authors have reported that β-lactam antibiotics were widely studied in the presence of various metal ions. The objectives of this research are 1. designing batch reactions to examine the degradation of two β-lactam antibiotics (ampicillin and amoxicillin) under different conditions and calculating the kinetic constants; 2. using UV-Vis spectrophotometer and LC-MSMS to elucidate the product generation and reaction mechanism. According to the batch reaction results, in the presence of high Cu2+ concentration under alkaline condition, the reaction is much faster than other conditions. Ca2+ ion and Mg2+ ion are founded that if they coexist in the solution, the reaction will be inhibited. The inhibitory effect was more pronounced in the amoxicillin-Cu2+ system. According to the bathocuproine complexation set up, it was confirmed that Cu2+ ion is reduced to Cu+ ion both in the ampicillin-Cu2+ and amoxicillin-Cu2+ Systems, suggesting the oxidation leads to the degradation of ampicillin and amoxicillin. There are some product peaks observed in the LC chromatograms. However, the details of the product structures and transformation pathway are not proposed in this study. Further qualitative studies are suggested to further elucidate β-lactam antibiotic degradation mechanism and pathway in order to better understand the risk they may pose to human health and ecosystem.