Determination of Calcium Carbonate in Cigarette Paper and Reclaimed Tobacco Leaves Made by the Paper-Making Process by Continuous Flow Method

The sample (0.500 g) of strips (about 0.5 cm×2.5 cm) of cigarette paper or reclaimed tobacco leaves made by the paper-making process was taken and reacted completely with 4.5 mL of 0.5 mol·L^-1 HCl solution. Water (95.5 mL) was added, and the mixture was mixed well and filtered. Granulated active carbon (5 g) was added to the filtrate, and the mixture was mixed thoroughly for 30 min and filtered again. The filtrate was collected and its content of calcium carbonate was determined by continuous flow method through the color reaction among KIO₃, KI and H⁺ remained in the sample solution, and based on the content of H⁺ found, calcium carbonate was calculated. It was found that:① linearity range of calcium carbonate was 5.007-30.042 mg; ② detection limit (3s) of the method was 0.11 mg; ③ RSDs (n=6) for the results were found between 0.34% and 0.86%; ④ values of recovery found by standard addition method ranged from 96.6% to 103%. The results found by the present method were as a whole in consistency with those found by potentiometric titration, but obvious deviations were found as compared with the results given by ion chromatography.