A new, simple and cost-effective
method for the synthesis of sulfated beta-cyclodextrin (S-β-CD), one of the
most widely used chiral mobile phase additive, using sulfamic acid as
sulfonating agent has been described. The method was optimized and the acquired
product was characterized and compared with a marketed Sigma Aldrich sulfated
beta-cyclodextrin (S-β-CD1). Beta cyclodextrin (β-CD), hydroxypropyl beta-cyclodextrin
(HP-β-CD), S-β-CD1 and S-β-CD2 were evaluated as chiral mobile phase additives
(CMPAs) for the enantiomeric separation of cloperastine, an antitussive agent,
using reversed-phase HPLC. Under the optimized conditions, a resolution of 3.14
was achieved within 15 minutes on an achiral Kromasil C<sub>8</sub> (150 x 4.6
mm, 5 µ) column with a mobile phase of 5mM monopotassium phosphate containing
10mM S-β-CD3 pH 3 and 45% methanol with a run time of 15 min. The method
utilizing S-β-CD3 as CMPA was validated as per ICH guidelines and applied for the
quantitative determination of cloperastine enantiomers in active pharmaceutical
ingredients and pharmaceutical formulations. The selectivity changes imparted
by S-β-CD were proven to be beneficial for chiral separation. The chiral recognition mechanism and elution order
of the reported enantiomers were determined by simulation studies. It was
observed that inclusion complex formation and hydrogen bonding are the major
forces for the chiral resolution.
