FIGURE 1—

The chemistry of freebasing. The tobacco industry has long appreciated the importance of smoke pH for boosting nicotine’s impact. This page, from a 1973 report by Claude E. Teague Jr of RJ Reynolds (Implications and Activities Arising From Correlation of Smoke pH With Nicotine Impact), shows how the freebase form of nicotine in smoke increases with increasing alkalinity. Although pH is a good indicator of relative freebase availability, it tends to underestimate the actual amount available. Other industry methods for measuring free nicotine—such as oil versus water partitioning or studies of nicotine volatility—reveal free nicotine levels much higher than those predicted from pH alone.32