Analysis of organic acids in e-vapor products by ion chromatography
Organic acids (formic acid, acetic acid, propionic acid and lactic acid) are of interest for e-vapor products testing, especially propionic acid which is included in guidance from US Food and Drug Administration Center for Tobacco Products (FDA-CTP). Herein we wish to present a method for the analysis of these organic acids in e-cigarette aerosols and e-liquids by ion chromatography. The trapping efficiency study indicated that one glass fiber filter pad (Cambridge Filter Pad) is sufficient for aerosol collection without the use of impingers. A Cerulean SM 450 smoking machine has been utilized to collect aerosol under the ISO regime, while a Cerulean CETI-8 e-cigarette testing instrument can be used for either ISO or intense regimes. The filter pad after the aerosol collection or an e-liquid aliquot is extracted with deionised (DI) water in a 50 mL polypropylene vial using a shaker for 30 min. The extracts are analyzed by ion chromatography. The run time is 19 minutes (including equilibrating time) with baseline separations between these analytes. The calibration range is 0.05 µg/mL to 5 µg/mL for all of these organic acids. The method limit of quantitation (LOQ) is defined as the lowest spiking level used during the validation, which is 0.05 µg/mL, 0.036 µg/puff for 50 puffs of aerosols, or 5 µg/g for 0.36 g of e-liquids. The new method has been validated on two Dionex ion chromatography systems (ICS 5000 and ICS 6000) with good recoveries on e-cigarette aerosols (80-109 %) and e-liquids (89-123 %).