1.It elaborates the definitions of epimer and epimerization, states the applications of epimerization in medicine and pesticide,and points out its expansive prospect .

1.阐述了差向异差向异化的定义。差向异化技术在医药农药中中应用广泛,前景广阔。

2.RESULTS The chlortetracycline's epimer, tetracycline and its epimer, as impurities in chlortetracycline have been determined by the liquid chromatogram and its first order mass spectrum.

2.结果得到金霉素样品液相色及液相色峰对应的一级质。对进行分析归纳,推测金霉素样品中含有四环素、差向异四环素差向异金霉素杂质组分。