Collaborative study of a spectrophotometric determination of ferric, ferrous, and total iron in drugs by reaction with alpha,alpha'-dipyridyl.

A spectrophotometric method for determining Fe2+, Fe3+, and total Fe in drugs has been developed, using alpha,alpha'-dipyridyl as the colorimetric reagent. The method is applicable to tablets elixirs, injectables, and bulk powder. Eight collaborates analyzed a synthetic iron preparation and 7 commercial samples. For the synthetic iron preparation, the average recovery was 100.3% and the coefficient of variation was 1.02%. For 7 commercial samples, the average coefficient of variation was 1.44%. The method has been adopted as official first action.