Chiral Separation of Non-Nucleoside Reverse Transcription Inhibitor Efavirenz by HPLC on Cellulose-Based Chiral Stationary Phase

Abstract

A stereospecific HPLC method for the separation of efavirenz (EFZ) enantiomers in bulk drug and formulations was developed and validated on a normal-phase cellulose derivatized chiral column. The effect of organic modifiers, namely, 2-propanol, ethanol and trifluoroacetic acid in mobile phase was optimized to obtain the best enantiomeric separation. The retention times of (R)-EFZ and (S)-EFZ were observed to be 7.5 and 9.2 min, respectively. The calibration curve was found to be linear over the concentration range of 200 - 6210 ng/mL with a determination coefficient (R 2 ) of 0.9999 for the (R)-isomer. The limit of detection (LOD) and limit of quantification (LOQ) were calculated to be 66 ng/mL and 200 ng/mL, respectively. The proposed method was found to be accurate, precise and suitable for the separation and quantification of unwanted (R)-EFZ in active pharmaceutical ingredients (API). The analytical results were supported by statistical parameters. The proposed method could be successfully applied to the enantiomeric purity analysis of EFZ in bulk drug samples and formulations.