APPLICATION OF EXTRACTION DISKS IN DISSOLUTION TESTS OF CLENBUTEROL AND LEVOTHYROXINE TABLETS BY CAPILLARY ELECTROPHORESIS

Sample preparation procedures using octadecyl (C-18) extraction disks were developed to obtain accurate and reproducible results for determi nations of clenbuterol (20 mu g per dose) and levothyroxine (100 mu g per dose) in dissolution media of solid oral dosage forms. Preconcentr ation of samples allowed final concentrations of 1.1 mu g/ml of clenbu terol and 4.0 mu g/ml of levothyroxine to be reached prior to CE analy sis. The results obtained by CE were in good agreement with those of H PLC. The precision of the migration time, peak area, peak height and a ccuracy were determined in both intra-day (n = 6) and inter-day (n = 1 8) assays. Linearity was demonstrated over the ranges 0.5-80.0 mu g/ml of clenbuterol and 1.0-30.0 mu g/ml of levothyroxine. The mean recove ries were higher than 94.0%, ranging from 50 to 125% levels with respe ct to dose potencies. The proposed methodology may be generally applie d to determine drugs at ng/ml concentrations.