分光光度法快速测定液态食品中糖精含量的研究

Study on the rapid spectrophotometric determination of saccharin in liquid food

利用糖精在磷酸缓冲液中与天青Ⅰ反应生成蓝色化合物,二氯甲烷能萃取糖精与天青Ⅰ形成的蓝色复合物而不萃取天青Ⅰ,通过分光光度法可以快速简便地测定液态食品中糖精的含量.糖精与天青Ⅰ形成的蓝色复合物的最大吸收波长为640nm,当样品液取样量为10.0mL、0.2mol/L pH5.0磷酸氢二钠-柠檬酸缓冲液用量为10mL、0.05%天青Ⅰ溶液用量为0.5mL、显色时间为5min、二氯甲烷萃取剂用量为10.0mL时,糖精质量浓度在0～120mg/L范围内与吸光度值呈线性,最低检出限为1.5mg/L.该法应用于四种液态食品中糖精含量的测定,回收率在90%～103%之间,相对标准偏差小于5.0%.

A rapid spectrophotometric method was proposed to determine saccharin in liquid food.The saccharin reacted with azure Ⅰ to form a blue complex to be extracted with dichloromethane.The optimum absorption wavelength of this blue complex was 640 nm.The reaction was performed in 10.0 mL 0.2 mol/L pH5.0 phosphate-citric acid buffer with 10.0 mL sample,0.5 mL 0.05% azure Ⅰ for 5 minutes,and then extracted with 10.0 mL dichloromethane.There existed a linear relationship between the absorbance and saccharin in the range of 0 to 120 mg/L.The detection limit of saccharin was 1.5 mg/L.The recovery rate was in the range of 90% to 103% with RSD less than 5.0% when the method was applied to determine saccharin in four kinds of liquid food.