Relationship between Free Nicotine in Tobacco and its pH Value

The extraction conditions of free nicotine in tobacco were studied.The methods for extracting free nicotine in tobacco successively with water and chloroform and measuring the same by GC equipped with FID were determined.The recoveries of nicotine were from 95.1% to 99.8% and the RSD of these methods were from 1.21% to 1.70%.Meanwhile, the accuracies of the measurement methods for whole tobacco pH and total nicotine in tobacco were also tested.The free nicotine, total nicotine and whole tobacco pH value of 47 brands of cigarettes were measured and the correlative analysis was conducted.The results indicated that the correlations between free nicotine content, ratio of free nicotine to total nicotine and the pH value of tobacco were significantly positive linear, and no correlation between free nicotine and total nicotine was found, and so was total nicotine and the pH value of tobacco.