Spectrophotometric method for the determination of total tobacco alkaloids and nicotine

Abstract

A spectrophotometric method for the determination of total tobacco alkaloids and nicotine is described. The method is based on the bromination of nicotine to form dibromonicotine which reacts with potassium iodide in the presence of starch to form a water-soluble blue complex. The complex shows maximum absorbance at 580 nm. Beer's law is obeyed over the concentration range 3.7–29.6 µg of total tobacco alkaloids in a final solution volume of 25 ml. The molar absorptivity of the colour system is 9.4 × 10⁴ l mol^–1 cm^–1. The reproducibility was assessed by carrying out seven replicate analyses of a solution containing 14.8 µg of total alkaloids in a final solution volume of 25 ml. The standard deviation and relative standard deviation for the absorbance values were found to be 0.01 µg ml^–1 and 2.7%, respectively. The method is free from the interference of other major toxicants. The analytical parameters were optimized and the method was applied to the determination of total alkaloids and nicotine in tobacco leaves, cigarette smoke and biological samples. The method is highly sensitive and was compared with other reported methods.