Measuring The Bipolar Charge Distributions of Fine Particle Aerosol Clouds of Commercial PMDI Suspensions Using a Bipolar Next Generation Impactor (bp-NGI)

Purpose To measure the charge to mass (Q/M) ratios of the impactor stage masses (ISM) from commercial Flixotide™ 250 μg Evohaler, containing fluticasone propionate (FP), Serevent™ 25 μg Evohaler, containing salmeterol xinafoate (SX), and a combination Seretide™ 250/25 μg (FP/SX) Evohaler metered dose inhalers (MDIs). Measurements were performed with a purpose built bipolar charge measurement apparatus (bp-NGI) based on an electrostatic precipitator, which was directly connected below Stage 2 of a Next Generation Impactor (NGI).