Development of an impurity test for 3-tropanyl-3,5-dichlorobenzoate using capillary gas chromatography

Summary A simple, accurate and sensitive capillary gas chromatographic test procedure was developed for the detection and quantification of impurities in bulk 3-tropanyl-3,5-dichlorobenzoate, a drug which is a neural serotonin 5HT₃ receptor antagonist. The drug substance was dissolved in acetonitrile and chromatographed on a 30 m×0.32 mm 0.25 μm film DB-5 column operated with a temperature program of 80 to 230°C. A flame ionization detector was used, and the impurities detected in the drug were estimated from peak areas on a percent basis compared to the parent peak. Validation of this procedure included a recovery study of spiked impurities from 0.1 to 1.2% (w/w) and a repeatability study using two different synthesized batch lots of the drug.