Advances in mammalian cell line engineering, DNA transfer vector and cell culture media have increased protein yields in mammalian cell cultures by a factor of 10 over the last decade, due in part to the increased cell titers at harvest. Thus, the biopharmaceutical industry has encountered a new challenge to improve primary cell clarification while minimizing protein loss and we designed Zeta Plus EXT series filter cartridges with SP media to help fulfill this need.

Zeta Plus SP Series filter products are a family of advanced depth filters designed for general purpose clarification of various bioprocess, biological and pharmaceutical fluids. Zeta Plus SP Series filter media contains a mixture of inorganic filter aids, cellulose and a crosslinking polymer binder resin. The EXT version of SP Series has dual layer or dual zone filter media. The upstream zone is more open than the downstream zone. This structure enhances the contaminant holding capacity of the filter media, since larger particles are trapped in the upper zone and smaller particles are trapped in the lower zone, reducing premature plugging and extending service life. Zeta Plus SP series filter media is available in a broad range of grades to meet coarse, medium or fine clarification applications. The two filter “zones” can be independently selected and combined to optimize performance.

The Zeta Plus SP media used in the Zeta Plus EXT Series Filter Cartridges offers a combination of mechanical and electrokinetic particulate removal mechanisms as a result of its physical and chemical attributes. The polymer binding resin used in these product families contains a balance of tertiary and quaternary amines resulting in an intermediate charge level relative to other 3M Zeta Plus media offerings. The surface charge enhances the filtration effectiveness by attracting negatively charged contaminants too small for removal by mechanical sieving. This intermediate charge level is recommended for fluid challenges containing a highly negatively charged product that has a potential to bind to the positively charged amine polymer.

Zeta Plus Construction
The lenticular cells of cartridges are comprised of dual opposing layers of the filter media and an inner cell separator with a polymeric molded edge seal. The lenticular cells are sealed to one another by ring seals that are aligned to the inner fluid effluent core and held together with three stainless bands. Each cartridge has two gaskets one at the top and one at the bottom. Filter cartridges are available in 8", 12" and 16" nominal diameters, with surface areas ranging from 0.26 m2 to 3.9 m2 per cartridge.