Manifold blocks in chromatography systems for bioprocessing

In the manufacture of chemical fluid handling equipment, it is often necessary to machine parts that act as junctions between components in the fluid handling system in order to regulate fluid flow. These “junction parts” are usually referred to as manifold blocks, and can often be seen in chromatography systems for bioprocessing. Ideally they are transparent in order to verify fluid flow. They must have excellent chemical resistance, so as to not modify or introduce any leachable compound or chemical into the fluids they are handling. Special additional performance needs within the medical or biopharmaceutical industries may also require the material to be gamma stable for sterilisation purposes. Polycarbonates and acrylics have been the staple materials for years, however, chemical resistance is often lacking at times. Polyetherimides (PEI), provide the additional chemical resistance needed, but they also tend to sacrifice clarity due to the deep amber coloration of the polymer.  

In this application in the bio pharmaceutical processing industry, there was an additional need for the manifold block to be clear as well as gamma stable after exposure to 45 kGy of radiation. Previous polymers the manufacturer had tried suffered the negative response of cross linking in the presence of certain chemicals, and further changed on a molecular level, causing the exposed material to physically change in appearance, as well as in chemical and mechanical properties, thus reducing part functionality and life. There was also concern for what leachable materials in the plastic such as bisphenol A might transfer into the process solutions.  Picking a material that was stable when exposed to processing fluids, plus maintaining chemical stability after gamma exposure was extremely important.