Solvent-free extraction method for in vitro testing with tobacco vapor products
Since extracts made with emissions from ENDS and tobacco vapor products (TVP) generally exhibit weak biological responses in commonly used in vitro tests compared to those from conventional cigarettes, it is essential to generate very high concentration extracts. However, concentration of extracts made with the historical method using Cambridge filter pad (CFP) with dimethyl sulfoxides (DMSO) is limited from a technical perspective. We therefore developed an extraction method without using an extraction solvent. The vapor of a TVP was trapped on multiple CFPs, and all the CFPs were compressed together without any solvents using an originally designed device, and then shaken with a shaker. Although pressure was applied to the CFPs, the temperature of the extract remained unchanged. The extract was then collected by centrifuge. The recovery rate of the condensate and the ratio of the major constituents were comparable to those obtained by the historical method with DMSO. The maximum concentration of the extract was approximately 1,000 mg/mL; it was at least 10 times higher compared to the maximum concentration obtained by the historical method for conventional products. This new method prevents interaction between the solvent and test systems and enables preparation of high concentration extracts. The new method can be useful for various in vitro tests with products exhibiting very weak toxicities.