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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- TR 15: Validation: TFF in Biopharmaceuticals (9)
- TR 45: Depth Filtration (7)
- TR 41: Virus Filtration (5)
- TR 26: Sterilizing Filtration of Liquids (4)
- TR 62: Manual Aseptic Processes (3)
- TR 50: Alt. Methods Mycoplasma Testing (2)
- TR 69: Bioburden/Biofilm Management (2)
- TR 22: Aseptic Process Simulation (2)
- TR 28: Process Simulation for Bulk API (2)
- TR 77: The Manufacture of Sterile Pharmaceutical Products Using Blow-Fill-Seal Technology (2)
- TR 51: Biological Indicators (1)
- TR 70: Cleaning/Disinfection Programs (1)
- TR 13: Environmental Monitoring (1)
- TR 75: Mycoplasma Filter Rating Method (1)
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Aseptic Processing
Handling sterile materials in a controlled environment, in which the air supply, facility, materials, equipment and personnel are regulated to control microbial and particulate contamination to acceptable levels. (TR28) (TR62) (TR69) Handling of sterile product, containers, and/ or devices in a controlled environment in which the air supply, materials, equipment, and personnel are regulated to maintain (product) sterility. (TR13)
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Aseptic Processing Area (APA)
Controlled environment, consisting of several zones, in which the air supply, facility, materials, equipment and personnel are regulated to control microbial and particulate contamination to acceptable levels. (TR22) (TR28) (TR62) (TR70)
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Aseptic Processing Simulation (APS)
A means for establishing the capability of an aseptic process as performed using a growth medium. (TR22) (TR62)
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Attachment (Adhesion)
Discrete association of a microorganism with an animate or inanimate surface. (TR69)
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Autoclave
A chamber for steam sterilization. (TR45)
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Cross-Flow Rate
Volumetric rate of fluid flow parallel to the membrane surface. (TR15)
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Downstream Side (of Filter)
The effluent side of the process step (filter). (TR45) The filtrate or outlet side of the filter. (TR26)
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Lenticular Filters
A filter made up of a series of biconvex cells that are stacked on top of one another with rings between them to prevent bypass between the cells. End-caps are then placed at the top and bottom of the assembly and are held in place with a central core. [Synonyms: Lenticular Cartridge, Modules, Filter Elements, Filter Devices] (TR45)
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Mandrel
Specialized filling needles on certain BFS machines which also act to form the container. (TR77)
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Media
The part of the filter through which fluid passes that retains particles during filtration. (TR45)
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Microfiltration (MF)
Pressure-driven, membrane-based separation process in which particles and dissolved macromolecules (typically 0.1 &mum or larger) are retained. (TR15)
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Mollicutes
A class of bacteria which lack a cell wall. Mollicutes are small, typically about 0.1-0.5 &mum in size, and vary in form (trivial name: mycoplasma) (TR50)
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Most Probable Number (MPN) Method
A statistical method of estimating the number of viable organisms suspended in a liquid. (TR51)
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Negative Control
A test article used to assess the performance of an assay in the known absence of a targeted microorganism or nucleic acid. Negative controls are used to minimize a risk of false positive results, which could occur due to non-specific signals. (TR50)
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Nominal Molecular-Weight Cutoff (NMWCO)
A manufacturer’s measure of an ultrafiltration membrane based on a defined solute-retention coefficient. (TR15)
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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)
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Parison
The “tube” of polymer extruded by the BFS machine from which the containers are formed. (TR77)
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Permeability
The degree to which a fluid will pass through a permeable substance under specified pressure and temperature conditions. (TR41) (TR26)
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Permeate
The fluid which passes through a membrane. (see also filtrate) (TR41)
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Pore
The channel(s)/path(s) in a membrane through which a fluid or a gas may pass. (TR41) (TR26)
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Pore-Size Distribution
The range of pore sizes in a filter used to determine the filter’s average pore size. (TR15)
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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)
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Porosity (Synonym:Void volume)
The percentage of a membrane’s volume that is occupied by pores. (TR15)
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Positive Control Filter Membrane (Penetration Control)
A control filter membrane with a larger pore size rating than the test filter and used to demonstrate the penetrative ability of the test microorganism. Penetration of this filter by at least one CFU is required to validate a test. (TR75)
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Rejection
The ability of a filter to exclude solutes or particulate matter from passing through. (TR45)
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Screening Studies
Studies used to select a particular type and grade of filter media. (TR45)
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Shear Rate
The velocity gradient in a flowing fluid. This value is proportional to the average linear velocity and is inversely proportional to the channel height or diameter when the recirculation is in the laminar flow regime (most TFF applications). (TR15)
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Sieving
Size-exclusion filtration occurs when a particle is too large to pass through the filter medium and is retained on the surface or within the depth of the filter. (TR45)
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Sieving Coefficient (S0)
The ratio of the filtrate concentration of component i (Ci,f) to the bulk or feed concentration of component i (Ci,b) as in the following equation: S = Ci,f/Ci,b Where S = 1 for a freely passing solute, typically a low molecular weight solute S = 0 for a solute that is fully retained by the membrane [Synonym: transmission; product transmission] (TR15)
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Stirred-Cell Filtration
A surrogate for tangential flow filtration where shear is achieved by rapidly stirring the solution immediately adjacent to the membrane. Typically the stirring is accomplished by mechanical means, such as through the use of a stir bar or impeller. (TR15)
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Transmembrane Pressure (TMP)
The pressure difference equal to the average feed-stream pressure minus the average filtrate-stream pressure. TMP = (Pfeed + Pretentate)/2 - Pfiltrate (TR15)
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Upstream
The influent side of the filter. (TR45) (TR26)