哌拉西林的解离常数测定及其在水溶液中的存在形态  

Determination of dissociation constant of piperacillin and its existing speciation in water

作　　者：李国傲 孙成一 雒梅 韦俊伶 刘菲[1] LI Guoao;SUN Chengyi;LUO Mei;WEI Junling;LIU Fei(Beijing Key Laboratoryof Water Resources and Environment Engineering,China University of Geosciences(Beijing),School of Water Resources and Environment,Beijing 100083,China;Beijing Municipal Research Institute of Eco-Environmental Protection,National Engineering Research Center of Urban Environmental Pollution Control,Beijing 100037,China;Institute of International Rivers and Eco-Security,Yunnan University,Kunming 650500,China)

机构地区：[1]中国地质大学(北京)水资源与环境学院,水资源与环境工程北京市重点试验室,北京100083 [2]北京市生态环境保护科学研究院,国家城市环境污染控制工程技术研究中心,北京100037 [3]云南大学国际河流与生态安全研究院,昆明650500

出　　处：《分析试验室》2022年第10期1121-1126,共6页Chinese Journal of Analysis Laboratory

基　　金：国家自然科学基金(41731282);国家重点研发计划(2016YFC0503601);北京市生态环境保护科学研究院院基金(Y2020-014)资助。

摘　　要：哌拉西林(PIP)是一种广泛使用的广谱β-内酰胺类抗生素,其在环境中滞留可能对水生态产生风险。解离常数可以判断其在环境中的稳定性。本文采用自动电位滴定法,并用3种方法处理滴定数据,测定了PIP在25℃时的解离常数(p Ka),其中一阶导数法、二阶导数法和二阶导数对pH作图法测得的p Ka值分别为3.19±0.02,3.20±0.09和3.14±0.18,相对标准偏差分别为0.68%,2.7%和5.8%。根据PIP的解离常数,可初步确定中性条件下,PIP以阴离子形式存在。采用液相色谱仪和分光光度计测定了PIP分子在pH 3~11的形态变化,逐渐碱化过程中,在pH 3~7溶液中PIP分子没有形态变化;在pH 9~11溶液中,PIP分子降解程度随pH升高而升高;pH 11时,PIP瞬间降解。将此溶液体系酸化(pH 11~3)过程中,溶液中存在2种可相互转化的降解产物,含量随pH改变。本研究通过PIP和其它抗生素的对比,预测了PIP的水解行为。Piperacillin(PIP) is a widely used β-lactam antibiotic with broad-spectrum. The retention of piperacillin in the environment may pose a risk to aquatic ecology. The dissociation constant(p Ka)can judge its stability in the environment. In this paper,the dissociation constants of piperacillin at 25℃ were determined by automatic potentiometric titration and the titration data were processed by three methods. The p Ka values measured by the first-order derivative method,second-order derivative method and second-order derivative to pH plot method were 3.19±0.02,3.20±0.09 and 3.14±0.18,with relative standard deviations of 0.68%,2.7% and5.8%,respectively. Based on the dissociation constants of PIP,it could be tentatively determined that PIP existed as the anionic form under neutral conditions. The transform of PIP at pH 3-11 was determined by liquid chromatography and spectrophotometer. During gradual alkalinization,there was no change of PIP molecules at pH 3-7,and the degradation of PIP increased with pH value ranging from 9 to 11. PIP degraded instantly at pH11. During acidification of this solution system(pH 11 to 3),there were two interconvertible degradation products in solution,and their contents change with pH value. The hydrolytic behavior of PIP was predicted by comparing PIP with other antibiotics.

关 键 词：抗生素 哌拉西林 自动电位滴定 解离常数 

分 类 号：O657.31[理学—分析化学] X832[理学—化学]