PDA Technical Glossary

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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Autoclave
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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Batch Process
A process where there are no streams flowing into or out of a controlled volume, as opposed to a continuous process. In a batch filtration process, the feed solution is reduced in volume due to permeation of filtrate through the filter. There is no continuous addition of feed solution to the feed vessel. (TR45)
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Bioburden
The total number of microorganisms per unit of material prior to sterilization. (TR13) Total number of viable microorganisms on or in a health care product prior to sterilization. (TR22)(TR61)(TR62) A population of viable microorganisms in a fluid prior to sterilizing filtration. (TR26) A measure of the contaminating organisms found in or on a given amount of material before it undergoes a sterilization process. (TR45) (TR70) The number of detectable microorganisms (bacteria and fungi) with which an object is contaminated. It is measured in CFU (colony forming units). (TR47) The number of viable, contaminating microorganisms present on a product immediately prior to decontamination. (TR51) Viable microbial contaminants associated with personnel manufacturing environments (air and surfaces), equipment, product packaging, raw materials (including water), in-process materials, and finished products. (TR 67) (TR 69)
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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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Cake
Chemical Compatibility
The relative stability of filter materials and/or filter assembly components when exposed to process fluids and process parameters. (TR45)
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Clarification
The removal of solid particulates from a liquid through filtration, sedimentation, centrifugation or other means. (TR45)
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Colloid
A mixture with properties between those of a solution and a fine suspension. (TR45)
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Compatibility
Proof that no adverse interaction between the filter and the process fluid has occurred. (TR26) A term used in relation to the non-reactivity of filter materials with the substance to be filtered. (TR45)
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Deionized Water
Water treated by passing through both cation- and anion-exchange resin beds, or a mixed-resin bed to remove both positive and negative ions. (TR45)
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Differential Pressure
The difference in pressure between the upstream (feed or influent) and downstream (effluent) sides of the filter. (May be modified with the terms: applied, available differential pressure, clean differential pressure, dirty differential pressure, initial differential pressure, or maximum differential pressure). [Synonym: Delta P (Δ P), PSID, Pressure Drop] (TR45) (TR26)
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Diffusion Flow Test
A test to determine the integrity of a filter. The test is based on the measurement of the diffusive (diffusional) flow of a gas through a wetted filter, along with any bulk flow of gas through open (unwetted) pores. Either the gas flow or the downstream liquid, displaced by the gas flow, may be measured. [Synonym: Forward Flow Test] (TR45)
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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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Extractable
A chemical component that is removed from a material by application of an artificial or exaggerated force (e.g., solvent, temperature, time). The term extractable is often erroneously used to describe a leachable. (TR14) (TR15) (TR26) (TR41) (TR45) Chemical substances that can be extracted from components of material process fluid contact surfaces by exertion of an exaggerated force (e.g., organic solvent, extreme elevated temperature, ionic strength, pH, contact time, etc.) Extractables may represent most but not all of the potential leachables that may be seen in process fluids. (TR66) Extractables are organic and inorganic chemical entities that can be released from a pharmaceutical packaging/delivery system, packaging component, or packaging material of construction under laboratory conditions. (TR54-4) Organic or inorganic chemical entity that is forced out of container closure system materials and components under laboratory experimental conditions. (TR73)
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Fermentation Broth
The fluid and all constituents in a fermentation vessel prior to separation. (TR45)
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Flow Decay Test
An experiment to determine flow rate and throughput of a filter type or combination of filters on a specific liquid, usually by using a small area filter, to determine the sizing of a filter system by extrapolation. (TR45)
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Gauge Pressure
The pressure measured by a pressure gauge. Typically expressed in units of psig, bar or kilopascal. (TR45) Gauge pressure is the difference between a given fluid pressure and that of the atmosphere. (TR26)
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Limulus Amebocyte Lysate (LAL) Test
Endotoxin detection and quantitation can be accomplished at high sensitivity and specificity using reagents manufactured from Limulus Amebocyte Lysate, a biological reagent prepared from horseshoe crabs and offered in a variety of formulations. (TR45)
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Microorganism
Sanitization
Reduction of microbial contaminants to safe levels as judged by public health requirements for the specific country. (TR13) A significant reduction in bioburden, achieved in chromatography by the use of bactericidal agents, such as sodium hydroxide (NaOH), hydrochloric acid (HCl), ethanol (EtOH), and isopropanol (IPA). (TR14) The process of reducing microbial levels by treatment at less than defined sterilizing conditions. Typically water at 80 °C or a chemical treatment is used to perform sanitization of process components. (TR45) A process that reduces the number of viable microorganisms to a defined level. (TR61) (TR69)
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Scalability Studies
Studies used to assess sizing for the appropriate performance of filter media at increased process volumes. (TR45)
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