Analysis of Impurity Spectrum and Degradation of Impurities in Oseltamivir Phosphate Oral Suspension

OBJECTIVE To identify, synthesize and analyze the structure of an unknown impurity exceeding the identification threshold in oseltamivir phosphate oral suspension. Set the impurity as known impurity control. METHODS The unknown impurity structure was proposed based on the data of two-dimensional liquid chromatography-mass spectrometry(2D-LC- MS/MS). According to the proposed impurity structure, it was attributed to the formulation process of the product. The impurity reference standard was synthesized successfully, and confirmed by using 2D-LC-MS/MS, NMR, IR, UV and TGA. Finally, the impurity analytical method was established with HPLC. RESULTS It was confirmed that the impurity was produced in a reaction between oseltamivir and the sorbitol. The impurity's correction factor was 1.5. CONCLUSION The impurity is set as a known impurity into the quality control and is named as impurity I. The impurity assay is calculated by the self-control associated with correction factor method.