Biopharmaceutical manufacturing is divided into two areas: upstream fermentation or cell culture and downstream purification processes. Each area contains multiple unit operations. A unit operation is defined as a step in processing using a particular type of equipment. Here, we focus on downstream process development, which must reliably produce a highly purified drug substance (often >99%). Downstream processing includes recovery, capturing, and polishing steps. The primary downstream unit operation is chromatography because of its simplicity and high resolving…