Cigarette manufacturers studied the effects of adding chemicals to influence nicotine delivery.It was found that adding ammonia and other chemicals to tobacco could alter smoke pH and increase the amount of “free nicotine” available in the smoke. Free nicotine makes it easier for smokers to inhale smoke deep into their airways and is more rapidly absorbed into the blood stream.
Ammonia
During the 1960s cigarette manufacturers such as Philip Morris began adding ammonia compounds to their tobacco blends with an observed positive impact on brand sales for Marlboro and other brands.
Manipulation of Smoke pH
Manipulating smoke pH became a major focus of product design by all cigarette manufacturers.
A 1973 R.J. Reynolds document describes various methods that could be used to increase smoke pH and/or nicotine “kick.” These included:
- Increasing the amount of (strong) burley in the blend,
- Reduction of casing sugar used on the burley and/or blend
- Use of alkaline additives, usually ammonia compounds in the blend,
- Addition of nicotine to the blend
- Removal of acids from the blend
- Special filter systems to remove acids from or add alkaline materials to the smoke,
- Use of high air dilution filter systems.
1972, R.J. Reynolds Research Scientist, Claude Teague charted comparative levels on the pH scale.
As the smoke pH increases above about 6 .0, an increasing proportion of the total smoke nicotine occurs in “free” form, which is volatile, rapidly absorbed by the smoker, and believed to be instantly perceived as nicotine “kick.”