DETERMINATION OF ENANTIOMERIC COMPOSITION OF IBUPROFEN IN BULK DRUG BY PROTON NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY WITH A CHIRAL LANTHANIDE CHELATE

The enantiomeric composition of ibuprofen was determined in a simple a nd reliable manner by proton nuclear magnetic resonance spectroscopy w ith a chiral lanthanide chelate. Optimum complexation with the europiu m (III) chelate took place in CCl4 after conversion of the enantiomeri c sample into a mixture of methyl esters. The optimization of the expe rimental conditions in terms of substrate concentration and lanthanide chelate to substrate molar ratio led to two sets of signals of utilit y for quantitative purposes. Analysis of synthetic enantiomeric mixtur es by the proposed method demonstrated excellent agreement between the assay results and the known masses of each enantiomer present in the mixture samples. The average +/- S.D. recovery values were 99.39 +/- 0 .92 and 99.42 +/- 0.68% (n = 10) of (S)-(+)-ibuprofen depending on whe ther the quantitation was based on the a-methyl protons or ester methy l protons, respectively. (C) 1997 Elsevier Science B.V.