Determination of 1-benzo[b]thien-2-ylethanone and related impurities by high performance liquid chromatography

1-Benzo[b]thien-2-ylethanone (2-acetylbenzothiophene, 2-ABT) and related impurities were determined using a reverse-phase high performance liquid chromatography system and UV detection at 254 nm. Separation was achieved isocratically on a 4.6 mm x 25 cm, 5 microns Zorbax Rx-C8 column using an eluent which is 0.2% perchloric acid/THF in a ratio of 60:40 (v/v). The chromatographic system resolved 2-ABT and known impurities in less than 45 min with near baseline resolution. Known impurities were quantitated versus 2-ABT with corrections made for differences in detector response at the specified wavelength. Linearity for 2-ABT was demonstrated with a correlation coefficient > 0.9999. Assay precision (RSD values) for impurities at 0.5% ranged from +/- 1.8% to +/- 14%, while precision (RSD values) for the 2-ABT determination ranged from +/- 0.81% to +/- 1.1%. A variety of different chromatographic columns and conditions are discussed for the application.