Pharmaceutical Research

, Volume 33, Issue 4, pp 816–825 | Cite as

Temporally and Spatially Resolved x-ray Fluorescence Measurements of in-situ Drug Concentration in Metered-Dose Inhaler Sprays

  • Daniel J. Duke
  • Alan L. Kastengren
  • Nicholas Mason-Smith
  • Yang Chen
  • Paul M. Young
  • Daniela Traini
  • David Lewis
  • Daniel Edgington-Mitchell
  • Damon Honnery
Research Paper



Drug concentration measurements in MDI sprays are typically performed using particle filtration or laser scattering. These techniques are ineffective in proximity to the nozzle, making it difficult to determine how factors such as nozzle design will affect the precipitation of co-solvent droplets in solution-based MDIs, and the final particle distribution.


In optical measurements, scattering from the constituents is difficult to separate. We present a novel technique to directly measure drug distribution. A focused x-ray beam was used to stimulate x-ray fluorescence from the bromine in a solution containing 85% HFA, 15% ethanol co-solvent, and 1 \( \mu \mathrm{g} \) / \( \mu \kern-.5pt \mathrm{L} \) IPBr.


Instantaneous concentration measurements were obtained with 1 ms temporal resolution and 5 \( \mu \mathrm{m} \) spatial resolution, providing information in a region that is inaccessible to many other diagnostics. The drug remains homogeneously mixed over time, but was found to be higher at the centerline than at the periphery. This may have implications for oropharyngeal deposition in vivo.


Measurements in the dynamic, turbulent region of MDIs allow us to understand the physical links between formulation, inspiration, and geometry on final particle size and distribution. This will ultimately lead to a better understanding of how MDI design can be improved to enhance respirable fraction.


fluorescence pressurized metered dose inhaler synchrotron radiation x-ray 



Full width at half maximum




Ipratropium bromide


Metered dose inhaler


X-ray fluorescence spectroscopy



The authors thank Dr. Christopher Powell and Dr. Andrew Swantek from the Energy Systems Division at Argonne National Laboratory for their assistance. The authors acknowledge funding support from the Australian Research Council. This research was performed at the 7-BM beam line of the Advanced Photon Source at Argonne National Laboratory. Use of the APS is supported by the U.S. Department of Energy (DOE) under Contract No. DE-AC02-06CH11357.

The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.


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Copyright information

© Springer Science+Business Media New York (outside the USA) 2015

Authors and Affiliations

  • Daniel J. Duke
    • 1
  • Alan L. Kastengren
    • 2
  • Nicholas Mason-Smith
    • 3
  • Yang Chen
    • 4
  • Paul M. Young
    • 4
  • Daniela Traini
    • 4
  • David Lewis
    • 5
  • Daniel Edgington-Mitchell
    • 3
  • Damon Honnery
    • 3
  1. 1.Energy Systems DivisionArgonne National LaboratoryLemontUSA
  2. 2.X-ray Science DivisionArgonne National LaboratoryLemontUSA
  3. 3.Laboratory for Turbulence Research in Aerospace & Combustion, Department of Mechanical & Aerospace EngineeringMonash UniversityMelbourneAustralia
  4. 4.Respiratory Technology, Woolcock Institute of Medical ResearchUniversity of SydneySydneyAustralia
  5. 5.Chiesi LimitedChippenhamUK

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