Validation of a method using an achiral liquid chromatography sorbent and a circular dichroism detector. Analysis of the efaroxan enantiomers.

Abstract The known HPLC method using an achiral C 8 silica sorbent and a circular dichroism (CD) detector for the determination of efaroxan enantiomeric excess has been validated. After optimization of the mobile phase, the enantiomers were detected at 278 nm offering maximum ellipticity between two optically active forms. The calibration curve of the anisotropy factor ( g ) versus the enantiomeric excess was linear with a correlation coefficient ( r 2 ) of 0.9985. The accuracy of the method was assessed by comparing the enantiomeric excess obtained by measuring the g factor (C 8 column, CD and UV detections) with those determined by enantioselective HPLC (Chiralpak AD-H column, UV detection). Statistical tests (level of confidence of 95%) were assessed to compare the two orthogonal methods. The straight line gave a correlation coefficient of 0.9995, an intercept not significantly different from zero (0.0549) and a slope of 1.026. The precision evaluated on retention time (RSD  g factor (RSD