Collaborative study of a semiautomated colorimetric analysis of digoxin tablets

A semiautomated thiobarbituric acid colorimetric analysis for digoxin was collaboratively studied by 6 laboratories. Collaborators were supplied with 3 composites of tablets of different dosage levels. Results agreed with the USP method. The coefficients of variation ranged from 0.46 to 2.73%. The method has been adopted as official first action.