Glossary Terms (Simple List)
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Void Volume
See Porosity. (TR45)
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Volatile
Evaporates easily; converts easily from a liquid form to gas. (TR45) (TR26)
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Volumetric Throughput (Vmax)
The maximum volume that can be processed through a filter area. It is the volumetric capacity of the filter for a given process fluid and generally expressed in L/m2. (TR41) (TR47)
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Warning Letters
Type of correspondence that notifies a regulated industry about violations that FDA has documented during its inspections or investigations. (TR67)
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Wash
Step in a chromatography cycle designed to flush the column to remove substances acquired during a previous step (often used between the load and elution steps). (TR14)
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Water Activity (Aw)
Water Activity, Aw is the ratio of the vapor pressure of water in a product (P) to the vapor pressure of water in a product (P) to the vapor pressure of pure water (Po) at the same temperature. It is numerically equal to 1/100 of the RH generated by the product in a closed system. It is a measure of the free or available moisture in the material. Note: Water activity ≠ water content. RH can be calculated from direct measurements partial vapor pressure or dew point, or from indirect measurements by sensors whose physical or electric characteristics are altered by the RH to which they are exposed. Microorganisms need available water within a pharmaceutical product, as well as nutrients and minerals, to proliferate. Water activity, and not water content, is a better measure of the free water, in contrast to bound water that microbial cells require for metabolic activity and osmotic regulation. Effects of reduced Aw on microbial growth include a longer lag phase, slower growth rate, lower numbers of organisms in the stationary phase, and reduced microbial toxin production; below a specified Aw for an organism, microbial growth will not occur. (TR55) (TR67)
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Water for Bacterial Endotoxin Test (BET)
Sterile Water for Injection or other water that shows no reaction with the specific bacterial endotoxin test reagent with which it is to be used, at the limit of sensitivity of such reagent. (TR3)
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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 microorganisms and contains no added substances. (TR45)
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Work Breakdown Structure (WBS)
A hierarchical and incremental decomposition of a project into phases, deliverables, and work packages; commonly a tree structure that shows a subdivision of effort required to achieve an objective. (TR65)
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Working Cell Bank (WCB)
The WCB is derived from one or more vials of cells from the MCB, which are expanded by serial subculture. The pooled cells are dispensed into individual vials and cryopreserved to form the WCB. (TR54-4)
The WCB is derived from one or more vials of cells from the MCB, which are expanded by serial subculture. The pooled cells are dispensed into individual vials and cryopreserved and stored in the vapor phase of liquid nitrogen. (TR83)