Development and validation of a sensitive and robust chiral method for (R)-propylene oxide: From chiral gas chromatography to chiral liquid chromatography with pre-column derivatization

Propylene oxide (PO) is an important chemical commodity and a chiral building block to prepare pharmaceutical compounds. It is crucial to develop a sensitive and robust chiral method that can be used to assess the enantiomeric purity of PO and safeguard the quality and safety of pharmaceutical products in commercial quality control (QC) laboratories. A chiral gas chromatography (GC) method based on direct enantioseparation of PO enantiomers on a 50-meter Chiraldex™ A-TA open capillary column was successfully developed for determination of enantiomeric impurity (S)-PO in (R)-PO. However, it was revealed that the chiral GC method lacked adequate robustness for routine use. Consequently, a chiral high-performance liquid chromatography (HPLC) method was developed through pre-column derivatization of PO with 2-naphthalenethiol followed by enantioseparation on a Lux Cellulose-1 (250 mm × 4.6 mm, 5 µm) column. The chiral HPLC method has been demonstrated excellent specificity, sensitivity, accuracy and robustness through method validation and robustness evaluation, thus establishing its suitability for routine use in QC laboratories.