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PDA Technical Glossary

PDA Technical Reports are highly valued membership benefits because they offer expert guidance and opinions on important scientific and regulatory topics and are used as essential references by industry and regulatory authorities around the world. These reports include terms which explain the material and enhance the reader’s understanding.

The database presented here includes the glossary terms from all current technical reports. The database is searchable by keyword, topic, or by technical report. Each definition provided includes a link to the source technical report within the  PDA Technical Report Portal.

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Manufacturing Filtration TR 41: Virus Filtration
Tangential or Cross Flow Filtration (TFF or CFF)
Filtration in which a fluid (feed) stream runs tangential to a membrane. A pressure differential causes some fluid to pass through the membrane. (TR41)

Source: TR 41: Virus Filtration

Biotechnology Manufacturing Filtration

Surrogate Fluid
A model process fluid used in a small-scale validation study. The fluid is intended to either match or resemble an actual process fluid as closely as is feasible. (TR41)

Source: TR 41: Virus Filtration

Virus Manufacturing Filtration Validation Technology Transfer

Pore
The channel(s)/path(s) in a membrane through which a fluid or a gas may pass. (TR41) (TR26)

Source: TR 26: Sterilizing Filtration of Liquids

Manufacturing Filtration Sterile Processing

Porosimetry (Gas-Liquid and Liquid-Liquid)
An analytical technique used to determine various quantifiable aspects of a material’s porous nature, such as pore diameter, total pore volume, surface area, and bulk and absolute densities. (TR41)

Source: TR 41: Virus Filtration

Manufacturing Filtration Sterile Processing

Permeate
The fluid which passes through a membrane. (see also filtrate) (TR41)

Source: TR 41: Virus Filtration

Manufacturing Filtration Sterile Processing

Permeability
The degree to which a fluid will pass through a permeable substance under specified pressure and temperature conditions. (TR41) (TR26)

Source: TR 26: Sterilizing Filtration of Liquids

Manufacturing Filtration Sterile Processing

Nominal Pore Size Rating
A filter rating with an arbitrary value, indicating a particulate size range at which the filter manufacturer claims the filter removes some percentage. Nominal ratings vary from manufacturer to manufacturer and may not be suitable to compare filters among manufacturers. Processing conditions, such as operating pressure and concentration of contaminant may have a significant effect on the retention efficiency of the nominally rated filters. (TR41)

Source: TR 41: Virus Filtration

Virus Biotechnology Manufacturing Filtration Microbiology Validation Sterile Processing

Feed (or Load or Feedstock or Feedstream)
The fluid introduced into a process. (TR41)

Source: TR 41: Virus Filtration

Biotechnology Manufacturing Filtration

Filtration
A process of removing particles from a fluid by passing it through a permeable material, such as a membrane film. (TR41) The process by which particles are removed from a fluid by passing the fluid through a porous material. (TR26)

Source: TR 26: Sterilizing Filtration of Liquids

Biotechnology Manufacturing Filtration

Diffusion Test (or Forward Flow Test)
A test for membrane integrity that involves measuring the rate of gas diffusion through a liquid-wetted membrane.(TR15) An integrity test in which a filter is subjected to differential gas pressures below the bubble point and gas molecule migration through the water-filled pores of a wetted membrane is measured. This behavior follows Fick’s Law of Diffusion (i.e., the gas diffusional flow rate for a filter is proportional to the differential pressure and the total surface area of the filter). (TR41)

Source: TR 15: Validation: TFF in Biopharmaceuticals

Biotechnology Manufacturing Filtration

Direct Flow Filtration (DFF) or Normal Flow Filtration (NFF)
In direct flow filtration, all fluid is directed through the membrane in a single pass. (TR41)

Source: TR 41: Virus Filtration

Biotechnology Manufacturing Filtration Validation

Compatibility (Filter)
The ability of a filter to be used with a particular process fluid without a change in the inherent properties of the filter. (TR41)

Source: TR 41: Virus Filtration

Biotechnology Manufacturing Filtration Inspections Packaging Science Validation Quality Risk Management/QRM Supply Chain

Cartridge Filter
Filter elements encased in a housing. Generally, the filter elements are disposable while the housing units are multi-use. In a few cases, both filter and housings are disposable. (TR26) (TR41)

Source: TR 26: Sterilizing Filtration of Liquids

Manufacturing Filtration GMP/Good Manufacturing Processes/cGMP Inspections Validation

Bubble Point
The measured differential gas pressure at which a wetting liquid (e.g., water, alcohol, product) is pushed out of the largest pores of a wetted porous membrane, and a steady stream of gas bubbles or bulk gas flow is detected.(TR15) (TR26) The minimum pressure at which a wetting liquid is pressed out of the pore system of a membrane while forming a steady bubble chain. (TR41)

Source: TR 15: Validation: TFF in Biopharmaceuticals

Biotechnology Manufacturing Filtration

Capsule Filter
Compact, self-contained filter assembly. Generally, the whole assembly is disposable. (TR26) (TR41)

Source: TR 26: Sterilizing Filtration of Liquids

Manufacturing Filtration GMP/Good Manufacturing Processes/cGMP Inspections Validation