Selective removal of a pharmaceutical process impurity using a reactive resin

A low-level (0.5%), but troublesome, aldehyde impurity in a pharmaceutical product was conveniently removed from an existing process stream by employing a reactive, polystyrene-based sulfonylhydrazine resin. Selection of this resin resulted from screening a number of adsorbents and reactive resins using a high throughput LC-MS approach. The sulfonylhydrazine resin was able to quickly remove an impurity from an existing, highly concentrated, product stream in DMF at a level of 20 mg resin for each gram of product. The material obtained from such treatment showed a greatly improved impurity profile, with an 85% reduction in the level of the aldehyde impurity and without introduction of additional impurities.