An Efficient HPLC–MS Method for Impurity Profile of Ertapenem

A mass spectrometer compatible, reverse-phase high-performance liquid chromatography method capable to resolve twenty-six impurities and degradation products (DPs) in Ertapenem (ERT) has been developed. Eight dimer impurities (m/z 951) and two dehydrated dimers (m/z 933) were baseline resolved. Out of eight dimers, four dimers are reported the first time. The impurities and DPs were identified using LC–MS/MS. The chromatographic separation was achieved on X-Terra RP 18 (150 × 4.6 mm, 3.5 µm) column using gradient elution. The separation was dependent on the pH of the mobile phase, optimum separation was achieved using the mobile phase of pH 8. Mobile phase-A comprised of a mixture of ammonium formate buffer (pH 8.0), water and acetonitrile in a ratio of 40:60:01; v/v/v. Mobile phase-B comprised of a mixture of ammonium formate buffer (pH 8.0), acetonitrile and methanol in a ratio of 40:50:10; v/v/v. The flow rate was 1.0 mL min−1 and column was maintained at 40 °C. Considering the fragility of ERT and demand of faster analysis method, the method was further transformed on rapid resolution column with a run time of 10 min. The later method also produced the same kind of selectivity with enhanced sensitivity.