地沟油中阴离子表面活性剂的测定

Determination of Anionic Surfactants in Drainage Oil by Spectrophotometry

建立地沟油中阴离子表面活性剂十二烷基苯磺酸钠(SDBS)的测定方法.油样中SDBS经水提取、三氯甲烷萃取、亚甲蓝显色后,采用分光光度法进行测定.以亚甲蓝-SDBS显色物吸光度为指标,在单因素试验基础上采用正交试验优化了提取条件.结果表明,SDBS最佳提取条件为:以75 m L水为提取溶剂,220 r/min的振荡速度,在60℃下提取20 min.SDBS在0.5mg/L^5 mg/L浓度范围内呈良好的线性关系,相关系数r2为0.9950,方法检测限为1.0μg/L.加标回收试验测得平均回收率在88.31%~91.37%,相对标准偏差为0.97%~1.32%.经测定,地沟油中SDBS含量明显高于合格食用油.该方法可用于地沟油中SDBS的定量测定.

A method was established for the determination of sodium dodecylbenzene sulfnate （SDBS） in drainage oil by Methylene Blue Spectrophotometry. SDBS was first extracted with water, and then with trichloromethane. The SDBS was determined when methylene blue was coloring. With the absorbance of Methylene Blue-SDBS com- plex as index, the best reaction condition was studied through the single factor and orthogonal test. The optimal conditions were as follows ： the volume of extraction water was 75 mL; the shock speed, 220r/min ; the fermentation temperature, 60 ℃ ; the shock time, 20min with the external standard method. Linearity range was found between 0.5 mg/L and 5 mg/L, with the relevant coefficient as 0.9950, and the detection limit （3S/N） as 1.0 μg/L. The average recovery of SDBS was tested in the range from 88.31% - 91.37% with relative standard deviations （RSD） of 0. 97% - 1.32%. It was determined that the content of SDBS in drainage oil was higher than in edible oil. This method could be used in the quantitative determination of SDBS in drainage oil.