The stability of biapenem and structural identification of impurities in aqueous solution.

The stability of biapenem in aqueous solution was investigated. Forced degradation of biapenem was carried out under different concentrations, pH values and temperatures. The degradation products were determined by reverse-phase HPLC and identified by LC-MS/MS. One dimeric impurity was obtained by reverse-phase preparative HPLC and characterized by LC-MS/MS and NMR. A possible degradation mechanism has been presented.