A Comprehensive Study on the Acidic Compounds in Gas and Particle Phases of Mainstream Cigarette Smoke

Acidic compounds constitute a group of chemicals present in mainstream cigarette smoke, among which organic acids contribute to flavoring. In order to obtain a comprehensive understanding of the constituents of acidic compounds in both the particulate and gaseous phases of the mainstream smoke of commercial cigarettes, and to delineate the difference between two types of cigarettes, the yields of acidic constituents from nine cigarettes of two commercial brands (L- and M-types) were collected and analyzed in detail by gas chromatography-mass spectrometry (GC-MS). The results identified and quantitatively analyzed 46 compounds, grouped according to the substituent groups. Compositional differences between the two cigarette types were evaluated with statistical approaches. Comparison between individual, grouped, and total acid contents, between the particulate and the gaseous phases, and between the commercial L- and M-type tobaccos were conducted and characterized by the p values obtained from Student's t-test. Multivariate analysis was performed using principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA) models to identify the acids that enable a reliable differentiation of the two types. Seventeen acidic compounds whose p < 0.05 and variable importance in projection (VIP) > 1 were identified as key components that could discriminate between the two groups of commercial cigarettes. This study may be beneficial for the development of non-combusted tobacco products, which could serve as alternatives to traditional cigarettes.