DIRECT HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY RESOLUTION ON CHIRAL COLUMNS OF TIAPROFENIC ACID AND RELATED-COMPOUNDS IN BULK POWDER AND PHARMACEUTICAL FORMULATIONS

High-performance liquid chromatography (HPLC) was employed for the sep aration and determination of impurities [5-benzoyl-2-acetylthiophene ( BAT), 5-benzoyl-2-ethylthiophene (BET) and (RS)-5-benzoyl-alpha-methyl -3-thiopheneacetic acid (3-isomer of tiaprofenic acid) contained in bu lk racemic tiaprofenic acid and pharmaceutical formulations. Chiral co lumns containing the 3,5-dimethylphenylcarbamate of cellulose and amyl ose were used. The effect of the organic modifier, 2-propanol, in the mobile phase was studied. The HPLC method gave good performances from qualitative and a quantitative standpoints, allowing the enantiomeric ratios of tiaprofenic acid and its 3-isomer to be determined together with the related impurities BAT and BET.