Particle Size Measurements in Aerosols

  • Regina ScherließEmail author
Part of the Advances in Delivery Science and Technology book series (ADST)


Pharmaceutical aerosols comprise a wide range of drug products which all are dispersed as droplets (wet aerosol) or particles (dry aerosol) in a gas for application. Hence, the device being used for dispersion plays a very important role as it impacts the dispersion efficiency and significantly influences the resulting aerosol particle size. For an aerosol’s therapeutic effect it is important how the particles behave in the gas they are dispersed in, i.e. how they distribute and deposit. Therefore, aerodynamic particle size is important in addition to a geometrical particle size—unlike many other formulations where only geometrical particle size is looked at. The chapter defines the differences in particle sizes and gives an overview of measurement techniques to determine aerodynamic particle size as well as other sizing techniques in use for aerosol particle sizing. Pharmacopoeial requirements are summarized and physiological implications as well as ideas to closer mimic the in vivo situation are discussed.


Accessories to mimic in vivo situation Aerodynamic particle size Cascade impaction Geometric particle size Particle deposition mechanisms Pharmacopoeial requirements Sample dispersion 


  1. Byron PR, Hindle M, Lange CF, Longest PW, McRobbie D, Oldham MJ, Olsson B, Thiel CG, Wachtel H, Finlay WH (2010) In vivo–in vitro correlations: predicting pulmonary drug deposition from pharmaceutical aerosols. J Aerosol Med Pulm Drug Delivery 23:S59–S69CrossRefGoogle Scholar
  2. Byron PR, Wei X, Delvadia RR, Longest PW (2013) Standardizing in vitro test methods to support aerosol drug evaluation in the clinic. Respir Drug Deliv 1:85–92Google Scholar
  3. Carvalho TC, Peters JI, Williams RO III (2011) Influence of particle size on regional lung deposition—what evidence is there? Int J Pharm 406:1–10CrossRefPubMedGoogle Scholar
  4. de Backer J (2012) Novel imaging in assessing small airway disease and therapy. In: Proceedings of DDL 23. Edinburgh, ScotlandGoogle Scholar
  5. de Boer AH, Gjaltema D, Hagedoorn P, Frijlink HW (2002) Characterization of inhalation aerosols: a critical evaluation of cascade impactor analysis and laser diffraction technique. Int J Pharm 249:219–231CrossRefPubMedGoogle Scholar
  6. Dekati (2010) Dekati ELPI: electrical low pressure impactor. TampereGoogle Scholar
  7. Glover W, Chan H-K (2004) Electrostatic charge characterization of pharmaceutical aerosols using electrical low-pressure impaction (ELPI). Aerosol Sci 35:755–764CrossRefGoogle Scholar
  8. Heim M, Mullins BJ, Umhauer H, Kasper G (2008) Performance evaluation of three optical particle counters with an efficient "multimodal" calibration method. J Aerosol Sci 39:1019–1031CrossRefGoogle Scholar
  9. Hickey AJ, Martonen TB, Yang Y (1996) Theoretical relationship of lung deposition to the fine particle fraction of inhalation aerosols. Pharm Acta Helv 71(3):185–190CrossRefPubMedGoogle Scholar
  10. Hinds WC (1999) Aerosol technology—properties, behavior and measurement of airborne particles. John Wiley & SonsGoogle Scholar
  11. Hoe S, Young PM, Chan H-K, Traini D (2009) Introduction of the electrical next generation impactor (eNGI) and investigation of its capabilities for the study of pressurized metered dose inhalers. Pharm Res 26(2):431–437CrossRefPubMedGoogle Scholar
  12. Kippax P, Fracassi J (2003) Particle size characterisation in nasal sprays and aerosols. LabPlus InternationalGoogle Scholar
  13. Kotian R, Peart J, Bryner J, Byron PR (2009) Calibration of the modified electrical low-pressure impactor (ELPI) for use with pressurized pharmaceutical aerosols. J Aerosol Med Pulm Drug Deliv 22(1):55–66CrossRefPubMedGoogle Scholar
  14. Marjamäki M, Keskinen J, Chen D-R, Pui DYH (2000) Performance evaluation of the electrical low-pressure impactor (ELPI). J Aerosol Sci 31(2):249–261CrossRefGoogle Scholar
  15. Marple VA, Olson BA, Santhanakrishnan K, Mitchell JP, Murray SC, Hudson-Curtis BL (2003a) Next generation pharmaceutical impactor (a new impactor for pharmaceutical inhaler testing). Part II: archival calibration. J Aerosol Med 16(3):301–324CrossRefPubMedGoogle Scholar
  16. Marple VA, Roberts DL, Romay FJ, Miller NC, Truman KG, Van Oort M, Olsson B, Holroyd MJ, Mitchell JP, Hochrainer D (2003b) Next generation pharmaceutical impactor (a new impactor for pharmaceutical inhaler testing). Part I: design. J Aerosol Med 16(3):283–299CrossRefPubMedGoogle Scholar
  17. Marple VA, Olson BA, Santhanakrishnan K, Roberts DL, Mitchell JP, Hudson-Curtis BL (2004) Next generation pharmaceutical impactor: a New impactor for pharmaceutical inhaler testing. Part III. Extension of archival calibration to 15 L/min. J Aerosol Med 17(4):335–343CrossRefPubMedGoogle Scholar
  18. Mitchell JP, Nagel MW (1999) Time-of-flight aerodynamic particle size analyzers: their use and limitations for the evaluation of medical aerosols. J Aerosol Med 12(4):217–240CrossRefPubMedGoogle Scholar
  19. Olsson B, Borgström L, Lundbäck H, Svensson M (2013) Validation of a general in vitro approach for prediction of total lung deposition in healthy adults for pharmaceutical inhalation products. J Aerosol Med Pulm Drug Delivery 26(6):355–369CrossRefGoogle Scholar
  20. Stapleton KW, Guentsch E, Hoskinson MK, Finlay WH (2000) On the suitability of k–ε turbulence modeling for aerosol deposition in the mouth and throat: a comparison with experiment. J Aerosol Sci 31(6):739–749CrossRefGoogle Scholar
  21. Steckel H, Bolzen N (2004) Alternative sugars as potential carriers for dry powder inhalations. Int J Pharm 270(1–2):297–306CrossRefPubMedGoogle Scholar
  22. Stein SW, Myrdal PB, Gabrio BJ, Obereit D, Beck TJ (2003) Evaluation of a new aerodynamic particle sizer spectrometer for size distribution measurements of solution metered dose inhalers. J Aerosol Med 16(2):107–119CrossRefPubMedGoogle Scholar

Copyright information

© Controlled Release Society 2016

Authors and Affiliations

  1. 1.Department of Pharmaceutics and BiopharmaceuticsKiel UniversityKielGermany

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