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 57: Analytical Method Validation (3)
- TR 33: Rapid Micro Methods (3)
- TR 50: Alt. Methods Mycoplasma Testing (2)
- TR 3: Validation: Dry Heat (2)
- TR 82: Low Endotoxin Recovery (2)
- TR 47: Virus Spikes/Virus Clearance (1)
- TR 49: Validation: Cleaning Biotech (1)
- TR 61: Steam in Place (1)
- TR 69: Bioburden/Biofilm Management (1)
- TR 70: Cleaning/Disinfection Programs (1)
- TR 71: Emerging Methods for Virus Detection (1)
- TR 29: Validation: Cleaning (1)
- TR 41: Virus Filtration (1)
- TR 43: Glass Defects (1)
- TR 45: Depth Filtration (1)
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Latent Virus
Latency is the ability of a virus to be dormant (latent) within a cell (for example, genetic episomes; provirus). Under certain conditions the virus may become active and produce particles. (TR71)
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Leak Rate
Leak rate is the quantity of air leakage over time into the sterilizer chamber obtained while performing a chamber leak test. The leak rate should not exceed a level that will inhibit the sterilization process during air removal or vacuum drying stages. (TR03)
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Leak Test
See System Integrity Test. (TR61)
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Limit
A value for a residue above which a cleaning process would not be acceptable. (TR29) A value for a residue above which a cleaning validation protocol would fail. (TR49)
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Limit Sample
An actual physical unit that is agreed to between the drug manufacturer and the glass manufacturer that defines the approximate maximum degree of acceptability for a specified non-conformance. Creation of limit samples between the user and the manufacturer is optional. (TR43)
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Limit Test
A quantitative test designed to give a positive/negative response. Ideally, a limit test has a high degree of specificity and a low limit of detection. (TR50).
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Limit of Detection (LOD)
The lowest concentration of microorganisms in a test sample that can be detected, but not necessarily quantified, under the stated experimental conditions. (TR33) The lowest amount of analyte in a sample that can be distinguished from the absence of analyte. (TR41) The lowest concentration of analyte that can be unambiguously detected in a sample. For qualitative and for quantitative NAT methods, this value is conventionally expressed as a 95% positive cut-off value, representing the target concentration detected in 95% of repeated tests using a certain assay. (TR50)
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Limit of Quantification
The lowest number of microorganisms in a test sample that can be enumerated with acceptable accuracy and precision under the stated experimental conditions. (TR33)
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Limit, Detection (DL)
The lowest amount of analyte in a sample that can be detected but not necessarily quantitated as an exact value by an individual analytical procedure. [Synonym: Limit of detection (LOD)] (TR57)
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Limit, Quantitation (QL)
The lowest amount of analyte is a sample that can be quantitatively determined with suitable precision and accuracy by an individual analytical procedure. [Synonym: Limit of quantitation (LOQ)] (TR57)
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Limiting Dilution
In the context of this Technical Report the limiting dilution technique is used for virus cloning. The virus suspension is diluted until virus is no longer detectable. The dilution immediately before the dilution where infection of cells is no longer detectable is considered to contain only one virus particle or a very low number of virus particles. (TR47)
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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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Linearity
The ability to elicit results that are proportional to the concentration of microorganisms present in the sample within a given range, where accuracy and precision are demonstrated. (TR33) The linearity of an analytical procedure is its ability (within a given range) to obtain test results that are directly proportional to the concentration (amount) of analyte in the sample. (TR57)
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Lipopolysaccharide
A component of the cell wall of Gram-negative bacteria.(TR3)
Component of the outer cell wall of Gram-negative bacteria that is pyrogenic. (TR69)(TR82)
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Log Reduction
Log reduction is defined as the first log being 90%, the second log being 9% and the third log being 0.09% of the original inoculums. (TR70)
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Low Endotoxin Recovery (LER)
The inability to recover ≥50% activity over time when known amount of endotoxin is added to an undiluted product. LER cannot be overcome by dilution.(TR82)