Some cigarettes may deliver a 20 times more powerful nicotine "kick" than others, according to researchers.
Some cigarettes could be more addictive
On first inspection, the bulk of different cigarette brands have roughly the same amount of nicotine in them.
However, it does not mean that the habit-forming chemical is delivered to the smoker in the same way.
Some produce a far higher amount of nicotine in a "free-base" form, which is more quickly absorbed by the smoker and produces the characteristic "kick".
The research, by a team at Oregon Health and Science University, tested smoke from 11 brands of cigarettes purchased across the US.
They were tested against what is described as a "standard" cigarette - a cigarette manufactured to exact standards and used only in smoking research.
Their results could help rate the "addictiveness" of various cigarette brands.
Nicotine is carried into the smoker's body on the billions of particles in cigarette smoke.
The chemical can appear in two forms - free-base and non free-base.
The free-base form of nicotine is better able to be vaporised into a gas during smoking.
This means it can be more easily absorbed by the lungs, from where it is transported to the brain.
The first three "puffs" from each cigarette on test were measured.
The "standard" cigarette only had approximately 1% of the nicotine in the first few puffs in the free-base form.
The highest brand - a speciality cigarette - had a massive 36%.
One type of Marlboro had 10% free-base nicotine, and the levels varied widely between all the brands tested.
Professor James Pankow, who led the study, said: "We believe that this study is a major step forward in understanding how addictive nicotine is delivered by tobacco smoke.
"We found big differences in the percentages of free-base nicotine among the 11 brands."
The findings, if repeated, could provide ammunition for action against the brands of cigarette which might prove most addictive.
The tobacco industry has been resisting efforts by governments - in particular the Netherlands - to make them disclose the exact formulation of their cigarettes.
The head of the Cancer Institute at the University, Dr Grover Bagby, said: "Cigarette smoking is the single most preventable cause of morbidity and mortality in the United States.
"Understanding the chemical elements that form the basis of addiction is an important step forward in developing ways of conquering this problem in our society today."
The research was published in the journal Chemical Research.