Particle size distribution of nicotine in mainstream smoke from 2R4F, Marlboro Medium, and Quest1 cigarettes under different puffing regimens.

Nicotine's dose and rate of delivery to the brain play an important role in its addiction and cardiovascular effects. Nicotine is mainly present in the particulate phase of cigarette smoke, and since particle size distribution controls the deposition behavior of particles in the respiratory tract, changes in the particle size distribution can produce variations in its regional and total dose to the lung. These variations can change its absorption rate and delivery to the brain. The particle size distribution of mainstream smoke (MS) varies with changes in puffing regimen and cigarette design and composition. This study examined nicotine in different particle size fractions of MS generated from 2R4F, Marlboro Medium, and Quest1 cigarettes using 3 puffing regimens: (1) FTC-like puff, 35 ml over 2 s; (2) short puff, 50 ml over 2 s; and (3) long puff, 100 ml over 10 s. MS was generated in a chamber at 37 degrees C and >95% relative humidity (RH), and size-segregated particles were collected using RJR cascade impactors. Particle size distribution was determined by spectrophotometry. Nicotine was analyzed using gas chromatography and mass spectrometry. Results showed that nicotine speciates in larger particles (1.1-1.9 microm diameter) under the long puffing regimen and in smaller particles (0.4-1.1 microm diameter) under the short puffing regimen, while mass median aerodynamic diameter of mainstream smoke particles was found to be approximately constant (0.9-1.0 microm) for the three puffing regimens. Overall, changes in puffing regimen have a significant effect on particle size distribution of nicotine and its deposited dose.