AbstractA new simple and sensitive spectrophotometric method for the determination of nicotine is described. The method is based on the bromination of nicotine to form dibromonicotine which reacts with potassium iodide to liberate iodine. The iodine liberated then selectively oxidizes leuco crystal violet, and the crystal violet dye formed shows maximum absorbance at 592 nm. Beer's law is obeyed over the concentration range 0.2 μg–2.2 μg of nicotine in a final solution volume of 25 mL (0.008–0.088 ppm). The molar absorptivity of the colour system is 1.40 × 1061 mol−1cm−1. The method is free from the interference of other major toxicants. The various analytical parameters were optimized, and the method was applied for the determination of nicotine in cigarette smoke, food, and biologic