Sinapic acid present in the waste stream of yellow mustard protein isolation was purified by strong base Dowex (1 × 8, Cl−) ion exchange chromatography. The ratio of loading volume to resin bed volume was 19:1. Approximately 80 % of sinapic acid was adsorbed. The column was washed with two bed volumes of water to remove remaining undesirable components. Approximately 75 % of sinapic acid adsorbed by the resins in the column was eluted by ten bed volumes of a solution containing 0.9 M acetic acid and methanol (4:6, v/v). Up to 15 adsorption and regeneration cycles resulted in only a slight, 3–5 %, reduction in ion exchange capacity, indicating that this is a viable approach to the recovery and purification of sinapic acid. The recovery of this valuable nutraceutical ingredient improves the economic viability of an integrated extraction process for this Canadian oilseed crop.