Enantiomeric purity determination of ketoprofen by capillary electrophoresis:: development and validation of the method

A simple, fast capillary electrophoresis method for determining the total ketoprofen content in an oral pharmaceutical formulation is proposed. The addition of 75 mM of heptakis(tri-O-methyl)-beta-cyclodextrin to the background electrolyte allows the quantitation of the enantiomeric impurity of (R)-(-)-ketoprofen contained in the formulation. A relative limit of detection is proposed as a measure of the lowest detectable enantiomeric impurity and the results show that the method can detect the minor enantiomer at levels as low as 0.04% in (S)-(+)-ketoprofen. The chiral method was validated following ICH recommendations and the quality parameters obtained show the suitability of the proposed method. The analysis of samples examined during the course of a stability study under chiral and achiral conditions revealed that the total ketoprofen content did not change significantly with time and the enantiomeric impurity range was 0.1-0.4%.