A novel method for determining relative response factors using high-performance liquid chromatography with photodiode array detector and evaporative light scattering detection

Abstract

Objectives: Because the purity of the two impurities reference standard (RS) of cefathiamidine is not easy to obtain, HPLC-PDA-ELSD were used to determin the RRFs of cefathiamidine impurities.

Methods: Peak area correction was applied to calculate RRFs to eliminate the influence of different responses caused by the difference in pH between the two mobile phases of HPLC-PDA and HPLC-PDA-ELSD. The resulting RRF values have been verified by qNMR.

Conclusion: The new calcution method described in this article provides a reliable research idea for determintion the RRFs by HPLC-PDA-ELSD, especially when the purity of RS is unknown and the mobile phase of HPLC-PDA and HPLC-PDA-ELSD have difference. This method can be mutually verified with qNMR to ensure the accuracy of RRFs. It is also promingsing replace determination RRF by qNMR becausing economical, simple and low cost.

Keywords: HPLC-DAD-ELSD; area correction; drug; impurity; relative response factors.