Determination of reference ultrasound parameters for model and hydrofluoroalkane propellants using high-resolution ultrasonic spectroscopy

Susan Hoe, Paul M. Young, Philippe Rogueda, Daniela Traini

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

The aim of this research was to determine the reference ultrasonic velocity (v) and attenuation coefficient (α) for 2H, 3H-perfluoropentane (HPFP), 1,1,1,2-tetrafluoroethane (HFA-134a) and 1,1,1,2,3,3,3-tetrafluoroethane (HFA-227) propellants, for the future purpose of characterising pressurised metered dose inhaler (pMDI) formulations using high-resolution ultrasonic spectroscopy (HRUS). Perfluoroheptane (PFH) was used as a reference material for HPFP. With its velocity and attenuation coefficient determined at 25 °C, HPFP was subsequently used as a reference for HFA-134a and HFA-227. It was found that there is a linear decline in ultrasonic velocity with an increase in temperature. As with HPFP, the ultrasonic velocity of HFA-134a and HFA-227 were successfully calculated at 25 °C. However, the difference in density and viscosity between reference and sample prevented accurate determination of reference attenuation coefficient for the hydrofluoroalkanes. With ultrasonic velocity alone, dispersion concentration and stability monitoring for experimental pMDI formulations is possible using HRUS. However, at this point in time measurement of particle size is not feasible.
Original languageEnglish
Pages (from-to)605-611
Number of pages7
JournalAAPS PharmSciTech
Volume9
Issue number2
DOIs
Publication statusPublished - Jun 2008
Externally publishedYes

Keywords

  • aerosols
  • pMDIs
  • suspension formulation
  • ultrasonic spectroscopy

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