Determination of Genotoxic Impurities in Escitalopram Oxalate by LC-MS/MS

OBJECTIVE To establish an LC-MS/MS analytical method for the determination of genotoxic impurities in escitalopram oxalate. METHODS The method was achieved on a Zorbax Eclipse XDB C₁₈ column(250 mm×4.6 mm, 5 μm) utilizing a mobile phase of 20 mmol·L^-1 ammonium acetate(A)-acetonitrile(B) with gradient elution at the flow rate of 0.8 mL·min^-1. The temperature of column was set at 35℃. The Ultimate 3000 HPLC-AB Science 4000 QTrap Tripling Four bar LC-MS was used to detect ethyl p-toluenesulfonate and isopropyl p-toluenesulfonate(ESI source, in Multiple Reaction Monitoring positive mode). RESULTS Standard curve was linear in the range of 5-100 ng(r=0.999 9). The limit of quantification of ethyl p-toluenesulfonate and isopropyl p-toluenesulfonate were separately 1 ng and 2 ng. The limit of detection were 2 ng and 4 ng, respectively. The average recovery of ethyl p-toluenesulfonate and isopropyl p-toluenesulfonate were 99.0% and 101.0%, RSD were 3.5% and 4.7%(n=9). CONCLUSION The method is convenient and sensitive for the determination of genotoxic impurities in escitalopram oxalate.