袋装口含烟样品经自行设计的溶出装置使其中的烟碱溶入于人工唾液中，从所收集的人工唾液中分取试液1.00 mL，加入pH 4.6的柠檬酸-磷酸氢二钠缓冲溶液1.0 mL和饱和甲基橙溶液1.0 mL，混匀，生成黄色络合物。加入二氯甲烷4.0 mL，涡旋1 min，静置15 min，取下层萃取液，于波长420 nm处测量其吸光度。烟碱的质量浓度在1.00~150 mg·L^-1范围内与吸光度呈线性关系，检出限（3s）为0.08 mg·L^-1。按标准加入法进行回收试验，回收率在97.3%~103%之间，测定值的相对标准偏差（n=6）在0.86%~1.2%之间。

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%.