An improved HPLC method for investigating selective filtration
Selective filtration is an important part of optimizing cigarette filter performance to meet potential regulatory requirements. Phenolic compounds are frequently used for selective filtration studies because there is general interest in enhancing their removal. Since they are known to be selectively removed by cellulose acetate filters, they provide a useful model for semi-volatile filtration mechanisms.For such studies at Eastman, phenolic compounds are determined by HPLC after extraction of Cambridge pads or filters in an alcohol solution. Direct analysis of extracts enables the phenolic compounds to be determined from the same smoking session as used to determine NFDPM, nicotine, and CO. Efficient extraction of cellulose acetate filters enables the direct determination of filtration efficiency for these compounds. Recent improvements to the method retains these advantages while improving resolution of the LC peaks and adding additional compounds which can be measured simultaneously. Conveniently including additional smoke components enhances the potential learnings from a selective filtration study.Among the added compounds are some that are known to be non-volatile, particulate-phase smoke components. Selective filtration is usually indicated by comparing the removal efficiency of a specific smoke component to the removal efficiency for NFDPM. However, NFDPM contains many semi-volatile smoke components that may also be influenced by the factors being investigated in a selective filtration study. The availability of a particulate phase smoke component offers a more appropriate reference for understanding the mechanisms of selective filtration.