Liquid chromatographic determination of thalidomide in tablets, capsules, and raw materials

A simple, isocratic liquid chromatographic method for assay of thalidomide in tablets, capsules, and raw materials was developed. The method uses a Nova-Pak octadecylsilane bonded-phase column (150 x 3.9 mm, 4 microns particle size), a mobile phase of acetonitrile-water (15 + 85), a flow rate of 1 mL/min, detection at 237 nm, and phenacetin as internal standard. Phosphoric acid was used in preparation of sample solutions to inhibit thalidomide hydrolysis. Assays ranged from 99.3 to 100.4% in raw materials from 4 manufacturers, from 79.7 to 104.8% in tablets from 7 manufacturers, and from 75.3 to 102.6% in capsules from 4 manufacturers. Assay method precisions for triplicate analyses on 5 days were 0.30% for tablets, 0.22% for capsules, and 0.22% for raw materials. Recovery from simulated tablet formulations was 100%. The method has been used to analyze individual tablets and capsules for determination of content uniformity.