Validation of a nonaqueous capillary electrophoretic method for the enantiomeric purity determination of R-flurbiprofen using a single-isomer amino cyclodextrin derivative

Nonaqueous capillary electrophoresis (NACE) was successfully applied to the enantiomeric purity determination of R-flurbiprofen using 6-monodeoxy-6-mono(2-hydroxy)propylamino-β-cyclodextrin (IPA-β-CD) as chiral selector. The nonaqueous BGE was made up of 20 mM IPA-β-CD, 20 mM ammonium camphorsulfonate and 40 mM ammonium acetate in methanol. Flufenamic acid was selected as internal standard. The CE method was carefully optimized in order to prevent the adsorption of the cationic CD onto the capillary wall, and therefore, to avoid loss of peak efficiency and enantioresolution. To achieve this goal, the addition of ammonium camphorsulfonate was found to be necessary. In the selected conditions, the determination of 0.1% of S-flurbiprofen in R-flurbiprofen could be performed using the method of standard additions. The NACE method was then fully validated by applying a novel strategy using accuracy profiles.