Parenteral pharmaceuticals must be “essentially free” from visible particulate matter (1). In the production of biopharmaceuticals with single-use systems (SUS), biocompatibility requires controlling interactions between drug substances/products and SUS surfaces to ensure drug product quality and patient safety with regard to extractables/leachables and particulate matter. Any particulate matter stuck to fluid-contacting surfaces of process components could wash off and contaminate process fluids. Depending on system configuration, a final drug product could be at risk for particulate matter from SUS. Risk…