title: Electrostatic charge characteristics of jet nebulized aerosols.
abstract: BACKGROUND
  Liquid droplets can be spontaneously charged in the absence of applied electric fields by spraying. It has been shown by computational simulation that charges may influence particle deposition in the airways. The electrostatic properties of jet nebulized aerosols and their potential effects on lung deposition have hardly been studied. A modified electrical low pressure impactor (ELPI) was employed to characterize the aerosol charges generated from jet nebulized commercial products.
  
  
  METHODS
  The charge and size measurements were conducted at 50% RH and 22 degrees C with a modified ELPI. Ventolin, Bricanyl, and Atrovent were nebulized using PARI LC Plus jet nebulizers coupled to a DeVilbiss Pulmo-Aide compressor. The aerosols were sampled in 30-sec durations. The drug deposits on the impactor stages were assayed chemically using high-performance liquid chromatography (HPLC). The charges of nebulized deionized water, isotonic saline, and the three commercial products diluted with saline were also measured to analyze the contributions of the major nebule ingredients on charging. No mass assays were performed on these runs.
  
  
  RESULTS
  All three commercial nebules generated net negative charges. The magnitude of the charges reduced over the period of nebulization. Ventolin and Bricanyl yielded similar charge profiles. Highly variable charges were produced from deionized water. On the other hand, nebulized saline reproducibly generated net positive charges. Diluted commercial nebules showed charge polarity inversion. The charge profiles of diluted salbutamol and terbutaline solutions resembled those of saline, while the charges from diluted ipratropium solutions fluctuated near neutrality.
  
  
  CONCLUSIONS
  The charge profiles were shown to be influenced by the concentration and physicochemical properties of the drugs, as well as the history of nebulization. The drugs may have unique isoelectric concentrations in saline at which the nebulized droplets would carry near-zero charges. According to results from computational simulation models in the literature, the numbers of elementary charges per droplet estimated from the data were not high enough to potentially affect lung deposition.
authors.affiliation: Advanced Drug Delivery Group, Faculty of Pharmacy, The University of Sydney, NSW, Australia.
authors.forename: Philip Chi Lip
authors.initials: PC
authors.lastname: Kwok
authors.forename: Sebastiaan J
authors.initials: SJ
authors.lastname: Trietsch
authors.forename: Michiko
authors.initials: M
authors.lastname: Kumon
authors.forename: Hak-Kim
authors.initials: HK
authors.lastname: Chan
mesh_terms: D000336:Aerosols; D000420:Albuterol / Q000008:administration & dosage* / Q000737:chemistry; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D016503:Drug Delivery Systems; D009241:Ipratropium / Q000008:administration & dosage* / Q000737:chemistry; D009330:Nebulizers and Vaporizers; D055672:Static Electricity; D013726:Terbutaline / Q000008:administration & dosage* / Q000737:chemistry
chemical_list: D000336:Aerosols; D001993:Bronchodilator Agents; D009241:Ipratropium; D013726:Terbutaline; D000420:Albuterol