Low levels of thermal degradation products such as carbonyls (formaldehyde, acetaldehyde, acrolein, and crotonaldehyde) have been reported in e-cigarette aerosols. The collection techniques and analytical methodologies used for the quantification of carbonyls in e-cigarette aerosols have been adapted from methods developed for tobacco cigarettes. These methodologies typically use HPLC-UV and are often not sensitive enough to detect the low levels of carbonyls found in e-cigarette aerosols (e.g., LOQ ~0.3 µg/puff). These methods are also subject to interference from e-cigarette flavor systems resulting in a potential for false positive identifications or incorrect quantification of carbonyls. Therefore, the objective of this work was to develop and validate a rapid, selective and sensitive method optimized for the analysis of carbonyls in e-cigarette aerosols using UPLC-MS. For this work, e-cigarette aerosols were trapped in sequential 20-puff collections following a puff regimen of 4 second duration, 55 mL volume, 30 second interval and square wave profile. The collection apparatus involved a 5-port linear smoking machine fitted with a 44 mm Cambridge filter pad followed by an impinger containing acidified 2,4-Dinitrophenylhydrazine. This optimized method showed high trapping efficiency, an LOQ of 0.016 µg/puff and an instrument run-time of only four minutes. Six leading commercially available e-cigarettes were evaluated (five devices each) to confirm that the method was fit-for-purpose. All commercial products tested contained formaldehyde and in most cases, the levels were well below those observed in conventional tobacco cigarettes (less than 3 µg/puff). However, for some commercial products, levels above tobacco cigarettes were detected with the highest at 14.1 µg/puff.