Colorimetric determination of nadolol in tablets.

Nadolol was extracted from tablet excipients with an acidic potassium chloride solution. The drug was oxidized with periodic acid, and the resulting aldehyde was reacted with 2,4-dinitrophenylhydrazine to form the corresponding hydrazone. Excess reagent was removed with a cupric chloride solution. The hydrazone was extracted into chloroform, and its absorbance was measured at the 352-nm maximum.