Measurement of the size and charge distribution of sodium chloride particles generated by an Aeroneb Pro® pharmaceutical nebulizer

Abstract

The charge distribution of aerosol is an important factor for accurate prediction of aerosol behavior as it influences particle transport, settling, deposition, and coagulation. In the production of aerosol for pulmonary drug delivery, charging of aerosol particles is influenced by both the generation method and chemical properties of the drug. Electrostatic charging of add-on devices such as plastic spacers and holding chambers will reduce the delivery to the lung, while charged particles can also enhance deposition to the respiratory system by inducing an image charge to airway surfaces. Typical target particle size for delivery devices in terms of mass median aerodynamic diameter (MMAD) is 1-5 μm, and therefore up to 50% of the dose includes submicron particles in the fine (100-1000 nm) and ultrafine ( < 100 nm) size range. Measurement of the charge distribution of submicron particles produced using a vibrating mesh nebulizer is presented using a tandem differential mobility analyzer (TDMA). It is found that the charge distribution is not at equilibrium, but instead has an increase in the fraction of charged particles below 200 nm and a decrease in the charged fraction above 200 nm. In general the charge distribution will be dependent on the specific aerosol nebulizer setup being used and the chemical properties of the nebulized solution, and it could be further quantified by using the methods discussed here.

The function and performance of aqueous aerosol devices for inhalation therapy

“…Aerosol charge distribution from active vibrating‐mesh nebulizers has recently been investigated with (TDMA). The results showed that the levels of negatively charged droplets from nebulization of normal saline are superior to that of positively charged particles and that the fraction of charged particles is greater for those below 200 nm in size . Although charge distributions can greatly differ with different nebulizer configurations and formulation compositions, TDMA was successfully used to determine submicron particle charge, which can influence patterns of drug deposition in the lungs.…”

Ultrafine Aerosol Particle Sizer Based on Piezoresistive Microcantilever Resonators with Integrated Air-Flow Channel

“…Instead, in this study, we dispense with an additional charging unit and sample only the naturally positive-charged aerosol fraction. As a quantitative measure of the charging state of a naturally charged aerosol we adopt the size and charge distributions measured in the range of d p = 20 nm to 400 nm with a NaCl aerosol [ 33 ], which we consider as a model system for aerosol charge distributions generated by a nebulizer. We assume that this non-equilibrium charge distribution can describe not only NaCl but also other nebulized aerosols with sufficient accuracy even if, in general, the charge distribution may be dependent on the specific aerosol nebulizer configuration and the chemical composition of the nebulized solution.…”

“…Measured fractions of n -times ( n = 1, 2, 3, 4, 5, 6) positive-charged particles with diameters of d p = 20 nm, 30 nm, 70 nm, 100 nm, 200 nm, and 400 nm are given in reference [ 33 ] for a NaCl aerosol generated by a nebuliser ( Table A1 ). Values for n = 5, 6 are determined by extrapolation.…”