PDA Technical Glossary
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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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Microbiology Manufacturing Filtration
Anaerobic Microorganism
A microorganism that does not utilize oxygen as the final electron acceptor during metabolism; microorganism that will grow only in the absence of oxygen. (TR62)(TR22)
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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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Back Pressure
Residual pressure opposing the free flow of liquid or gas at the outlet side of the filter. (TR45) Pressure applied downstream of a filter or other piece of equipment. (TR26)
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Breakthrough Limited
A filtration operation resulting in a significant rise in filtrate turbidity accompanied by a small increase in differential pressure. This occurs when the adsorptive capacity of the filter is reached, resulting in the passage of particles smaller than the pore size of the filter that would normally be removed by adsorption. (TR45)
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Brevundimonas Diminuta (B. diminuta)
Small bacteria (0.3–0.4 &mum in diameter by 0.6–0.1 &mum long) used to challenge a sterilizing grade filter during validation testing. [Formerly Pseudomonas diminuta](TR45)
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Column Load
The solute that is passed through the column for separation. (TR14)
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Column Packing
Preparation of a column that includes the addition of resin slurry into a column to create a bed suitable for its intended use. Characteristics of a packed column bed include bed height and diameter, backpressure, and number of theoretical plates. (TR14)
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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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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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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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Psid
Pound-force per square-inch differential is the difference in pressure; for example, the pressure differential between the upstream (influent) and downstream (effluent) sides of a filter. (TR75)
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Screening Studies
Studies used to select a particular type and grade of filter media. (TR45)
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Upstream
The influent side of the filter. (TR45) (TR26)
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