SIMULTANEOUS DETERMINATION OF CLOPAMIDE-PINDOLOL COMBINATION IN TABLETS BY ZERO-CROSSING DERIVATIVE SPECTROPHOTOMETRY

A first-derivative spectrophotometric method, using a 'zero-crossing' technique of measurement has been used for determining clopamide-pindo lol mixture in tablets. In the first-derivative mode the zero-crossing points of clopamide and pindolol occur at 272.6 and 262.4 nm, respect ively. The relative ease offered by this technique for the quantificat ion of these drugs with closely overlapping bands was demonstrated. Th e linearity of the calibration curves was satisfactory (r = 0.9998) an d the precision (RSD%) better than 1.89. Detection limits were 0.50 an d 0.44 mug ml-1 for pindolol and clopamide, respectively. No spectral interferences from tablet excipients were found. Applications are give n for the assay of commercial tablets and content uniformity test. The procedures proved to be suitable for rapid and reliable quality contr ol.