title: Design of a device for simultaneous particle size and electrostatic charge measurement of inhalation drugs.
abstract: OBJECTIVE
  To develop a device for simultaneous measurement of particle aerodynamic diameter and electrostatic charge of inhalation aerosols.
  
  
  METHODS
  An integrated system consisting of an add-on charge measurement device and a liquid impinger was developed to simultaneously determine particle aerodynamic diameter and electrostatic charge. The accuracy in charge measurement and fine particle fraction characterization of the new system was evaluated. The integrated system was then applied to analyze the electrostatic charges of a DPI formulation composed of salbutamol sulphate-Inhalac 230 dispersed using a Rotahaler.
  
  
  RESULTS
  The charge measurement accuracy was comparable with the Faraday cage method, and incorporation of the charge measurement module had no effect on the performance of the liquid impinger. Salbutamol sulphate carried negative charges while the net charge of Inhalac 230 and un-dispersed salbutamol sulphate was found to be positive after being aerosolized from the inhaler. The instantaneous current signal was strong with small noise to signal ratio, and good reproducibility of charge to mass ratio was obtained for the DPI system investigated.
  
  
  CONCLUSIONS
  A system for simultaneously measuring particle aerodynamic diameter and aerosol electrostatic charges has been developed, and the system provides a non-intrusive and reliable electrostatic charge characterization method for inhalation dosage forms.
authors.affiliation: Institute of Chemical and Engineering Sciences, A STAR (Agency for Science, Technology and Research), 1, Pesek Road, Jurong Island, Singapore 627833, Singapore. Zhu_Kewu@ices.a-star.edu.sg
authors.forename: Kewu
authors.initials: K
authors.lastname: Zhu
authors.forename: Wai Kiong
authors.initials: WK
authors.lastname: Ng
authors.forename: Shoucang
authors.initials: S
authors.lastname: Shen
authors.forename: Reginald B H
authors.initials: RB
authors.lastname: Tan
authors.forename: Paul W S
authors.initials: PW
authors.lastname: Heng
mesh_terms: D000336:Aerosols / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D004867:Equipment Design; D010316:Particle Size; D055672:Static Electricity
chemical_list: D000336:Aerosols