Determination of Nicotine in Simulated Saliva Dissolved from Bagged Smokeless Sucking Tobacco by UV-Vis Spectrophotometry

By the self-made installation, the main constituents of the bagged smokeless sucking tobacco (BST), including nicotine were dissolved into simulated saliva, which was collected as described. An aliquot of 1.00 mL was taken from it for analysis, and 1.0 mL of citric acid-disodium hydrogen phospate buffer solution (pH 4.6) together with 1.0 mL of saturated methyl orange solution was added and mixed thoroughly to form a yellow colored complex with nicotine. 4.0 mL of dichloromethane was added to the solution, and the mixture was swirled for 1 min and stood for 15 min to have the nicotine-methylorange complex transferred into the organic phase. The lower organic phase was separated and its absorbance was measured at the wavelength of 420 nm. Linear relationship between values of absorbance and mass concentration of nicotine was found in the range of 1.00-150 mg·L^-1 with detection limit (3s) of 0.08 mg·L^-1. Test for recovery was made by standard addition method, giving results in the range of 97.3%-103%, with RSDs (n=6) in the range of 0.86%-1.2%.