| Good Cascade Impactor Practice (GCIP) and Considerations for "In-Use" Specifications. | |
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MedLine Citation:
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PMID: 23344853 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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The multi-stage cascade impactor (CI) is widely used to determine aerodynamic particle size distributions (APSDs) of orally inhaled products. Its size-fractionating capability depends primarily on the size of nozzles of each stage. Good Cascade Impactor Practice (GCIP) requires that these critical dimensions are linked to the accuracy of the APSD measurement based on the aerodynamic diameter size scale. Effective diameter (D (eff)) is the critical dimension describing any nozzle array, as it is directly related to stage cut-point size (d (50)). d (50) can in turn be determined by calibration using particles of known aerodynamic diameter, providing traceability to the international length standard. Movements in D (eff) within manufacturer tolerances for compendial CIs result in the worst case in shifts in d (50) of <±10%. Stage mensuration therefore provides satisfactory control of measurement accuracy. The accurate relationship of D (eff) to d (50) requires the CI system to be leak-free, which can be checked by sealing the apparatus at the entry to the induction port and isolating it from the vacuum source and measuring the rate of pressure rise before each use. Mensuration takes place on an infrequent basis compared with the typical interval between individual APSD determinations. Measurement of stage flow resistance (pressure drop; ΔP (stage)) could enable the user to know that the CI stages are fit for use before every APSD measurement, by yielding an accurate measure of D (eff). However, more data are needed to assess the effects of wear and blockage before this approach can be advocated as part of GCIP. |
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Authors:
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S C Nichols; J P Mitchell; C M Shelton; D L Roberts |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2013-1-24 |
Journal Detail:
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Title: AAPS PharmSciTech Volume: - ISSN: 1530-9932 ISO Abbreviation: AAPS PharmSciTech Publication Date: 2013 Jan |
Date Detail:
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Created Date: 2013-1-24 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100960111 Medline TA: AAPS PharmSciTech Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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OINDP Consultancy, Rugby, UK. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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