络合萃取分光光度法测定烟草提取液中的烟碱

利用烟碱与甲基橙的络合物在氯仿中的吸光度与其浓度呈正比的原理,建立了测定烟草提取液中烟碱含量的络合萃取分光光度法,即在2.0mL烟草提取液中依次加入2.0mL(pH5.0)柠檬酸/磷酸氢二钠缓冲溶液和2.0mL甲基橙饱和溶液,摇匀,加入20mL氯仿、于室温下振荡萃取2~3min,静置3~5min,取氯仿萃取液于6min内测定其在420nm波长处的吸光度,然后根据工作曲线计算其烟碱含量。该法的线性相关范围是0.0425~0.2550mg/mL,相关系数为0.9994,平均回收率为98.32%,CV<5%。

Determination of Nicotine in Aqueous Tobacco Extract by Complex-Extracting-Spectrophotometry

A method of complex-extracting-spectrophotometric determination of nicotine in an aqueous tobacco extract was developed by virtue of the principle that the light absorptivity of a complex of nicotine and methyl-orange is in proportion to its nicotine concentration while the complex is in chloroform. In this method, 2.0 mL tobacco extract was reacted with 2.0 mL saturated methyl-orange solution in the presence of 2.0 mL (pH5.0) citric acid/sodium hydrogen phosphate buffer solution, extracted with 20mL chloroform at room temperature for 2 to 3 minutes, stood for 3 to 5 minutes, and then determined the light absorptivity at the wavelength of 420 nm within 6 minutes. The content of nicotine was calculated with the calibration curve. The light absorptivity of the complex was linearly correlated with its nicotine concentration in the range of 0.0425-0.2550 mg/mL, correlation coefficient was 0.9994. The average recovery of nicotine was 98.32% and its CV was less than 5%.