A similar effect was
observed for naproxen between ACN and EtOH. Namely,
R-naproxen eluted as the first peak on ADMPC-based chiral
column in ACN while it eluted as the second peak in
EtOH as the mobile phase (Fig. 6b). EEO of ketorolac also
reverted on the same column when ACN and EtOH were
used as alternative mobile phases (Fig. 6c). The mobile
phase may interact with a particular chiral selector, chiral
analyte, or both and also may affect enantioselective (and
also non-enantioselective) selector–selectand interactions
without entering in point-by-point interactions with any
of the counterparts. Alternatively, the medium may affect
the conformation of the chiral selector [44, 45]. Thus, it
is interesting to learn which of above-mentioned effects is
responsible for the reversal in affinity observed due to the
change in mobile phase in this study.