Formation of Diacetyl and Other α-Dicarbonyl Compounds during the Generation of E-Vapor Product aerosols.

Introduction:
This text discusses a study on the formation of diacetyl (Da) and other α-dicarbonyl compounds during the generation of e-vapor product aerosols. The study seeks to determine the potential for the formation of α-dicarbonyl compounds during the aerosol generation process in e-vapor products where no Da or other α-dicarbonyl compounds are added to the e-liquid.

Key Points:

* a novel ultraperformance liquid chromatography-mass spectrometry-based analytical method for the determination of Da, acetyl propionyl, glyoxal, and methylglyoxal was developed and validated.
* Eight commercially available cig-a-like-type EVPs were evaluated for α-dicarbonyl formation.
* Increased levels of α-dicarbonyls were observed in the aerosols of all evaluated EVPs compared to their respective e-liquids.
* Mechanistic studies were conducted using a model microwave reaction system to identify key reaction precursors for Da generated from propylene glycol (PG) and carbon-13-labeled glycerin (GLY).
* The proposed formation pathway is where hydroxyacetone is generated from PG and/or GLY, which then participates in an aldol condensation with formaldehyde to form Da.
* This proposed pathway was further investigated through in situ synthetic organic experiments within the model microwave reactions system.
* The study establishes that Da is formed in the aerosol generation process of the EVPs tested though at levels below toxicological concern.

Main Message:
The study found that Da is formed during the aerosol generation process of e-vapor products, even when no Da is added to the e-liquid. The formation of Da is due to the thermal degradation of PG and GLY, which are the primary components of e-liquids. The levels of Da formed are below toxicological concern, but the study highlights the need for further research on the potential health effects of exposure to α-dicarbonyl compounds in e-vapor product aerosols.

Melvin MS, avery KC, Ballentine RM, et al. Formation of Diacetyl and Other α-Dicarbonyl Compounds during the Generation of E-Vapor Product aerosols. aCS omega. 2020;5(28):17565-17575. doi:10.1021/acsomega.0c02018