A sampling and dilution system for droplet aerosols from medical nebulisers developed for use with an optical particle counter

An in-line sampling and dilution system for droplet aerosols from medical nebulisers is described. The device has been designed to interface with a white light aerosol spectrometer (welas® 2070, Palas® GmbH, Germany) that allows measurements of highly concentrated aerosols. The performance of the sampling system in terms of the measured particle size distribution (PSD) is compared to EN 13544-1 approved measurement techniques as well as to techniques proposed for the European Pharmacopoeia (2.9.44). The measured PSD compares favourably to the ones measured by a Next Generation Impactor, cooled prior to measurement, and by laser diffraction analysed by the Mie theory. This study included three nebulisers (Pari LC Plus, Aeroneb Pro, Omron MicroAIR). The measuring system presented in this study offers a time saving alternative for the measurement of PSD as well as quantity of aerosols from medical nebulisers that is of interest for quality control in the pharmaceutical industry.