Adsorption Retention of solutes, suspended colloidal particles or micro-organisms to fluid contact surfaces
Autoclave Instrument for sterilization by wet steam

Back Pressure Residual pressure opposing the free flow of liquid or gas at the outlet side of the filter

Bioburden Measure of the contaminating organisms found in or on a given amount of material before it undergoes a sterilisation process
Brevendimonas diminuta Formerly Pseudomonas diminuta. Small bacteria used to challenge a sterilizing grade filter during validation testing

Cake Solids deposited on the upstream side of filter

Cartridge Filter device requiring a housing for use
Chemical compatibility Relative stability of filter material when exposed to process fluids
Clarification Removal of solids particulates from a liquid by filtration, sedimentation, centrifugation
Clean in Place (CIP) Process of rinsing or washing process components, as installed without removal, in order to remove or eliminate any contaminants
Colloid Mixture with properties between those of a solution and a fine suspension
Compatibility Term used in relation to the non reactivity of filter materials with the substance to be filtered

Depth Filter
Randomly distributed fibres creating a tortuous path with pores of undefined size and shape. A filter that removes particles by a combination of adsorption and size exclusion within its porous matrix rather than on its frontal surface
Deionized Water
(DI Water) Water treated by passing through both cation and anion exchange resin bed, or a mixed resin-bed to remove both positive and negative ions.
Differential Pressure (Delta P) Difference in pressure between the upstream (feed) and downstream (effluent) sides of the filter

Endotoxin Lipopolysaccharides from the cell walls of the bacteria. When injected they cause a febrile reaction
Extractable Chemical component that is removed from a material by solvent, temperature or time

Feed (influent) Unfiltered liquid stream that is introduced to filter media
Fermentation broth Fluid and all constituents in a fermentation vessel prior to separation
Filter Porous medium used for the separation of process stream components based on size exclusion and / or charge
Filter area Effective surface area of a filter that is available for filtration
Filtrate (Permeate) Fluid that has been passed through a process step
Filtration Process by which particles are removed from a fluid by passing the fluid through a permeable material
Flow rate Volumetric rate of flow of a solution expressed in l/minute

Gauge Pressure Pressure measured by a pressure gauge. It is expressed in units of psig, bar or kilopascal
Hydraulic Pressure Pressure that results from forcing liquid through an orifice, pipe or other channels

Integrity Test Non destructive test used to predict the functional performance of a filter

LAL Test Endotoxin detection and quantification using reagents produced by Limulus Amebocyte Lysate

Media Part of the filter through which fluid passes that retains particles during the filtration process
Micro-organisms Free-living organism too small to be seen by naked eye

Particle, Particulate Discernible mass having observable length, width, thickness, size and shape
Performance Qualification Documented verification that a system is capable of consistently performing or controlling the activities of the processes, according to written and pre-approved specifications
Permeability Degree to which a fluid will pass through a porous substance under specified conditions
Pore size Characteristic of a filter that specifies the size and retention capability of a filter’s pores
(Void Volume) Percentage of a filter’s volume that is occupied by air in the filter’s pores. It is a ratio of the nonsolid volume to the total volume of material
Pressure Force applied per unit area, expressed as psi or mbar

(Yeld) Mass of desired solute in the final product solution divided by the mass of the desired solute in the initial feed solution, expressed as a percentage
Retention efficiency Percentage of particles of a specific size that are removed by a filter
Reverse osmosis
(RO) Process of forcing a solvent from a region of high solute concentration, through a membrane, to a region of low solute concentration by applying a pressure in excess of the osmotic pressure. The membrane is semi-permeable, meaning it allows the passage of solvent but not solute

Sanitization Process of reducing microbial level (e.g.: treatment with water at 80°C or chemical treatment)
Steam in place (SIP) Sterilization of a filter in situ using steam
Sterilization Process used to render a product or an item free of living micro-organisms, including bacterial endospores
(Wetting agent) Soluble compound that reduces the surface tension of a liquid

Total Organic Carbon (TOC) Indirect measure of organic molecules present in water and measured as carbon
Turbidity Dispersed particles causing cloudiness in liquids

Upstream Influent side of a filter

Validation Documented program that provides a high degree of assurance that a specific process, method or system will consistently produce a result meeting pre-determined acceptance criteria
Volatile Easily conversion from a liquid form to gas
Water for Injection
(WFI) Water purified by distillation (or a purification process that is equivalent or superior to distillation) in the removal of chemicals and micro-organisms and contains no added substances
Yield The quantity that would be produced at any appropriate phase of production, based upon the quantity of material to be used.