Product manufacture in AZ’s Large Scale Lab encountered a significant negative trend in yield and increased impurity for a particular product. A three-hour Britest session identified 14 potential corrective actions covering chemistry, engineering and analysis. By systematic testing, the root cause (oxygen ingress) was identified. By improving vessel purging AZ were able to reduce impurity to 2% and increase the yield from 50% to 70%. Successful manufacture corresponded to $250K of cost deferred.