纸上吸光光度法研究——水中阴离子表面活性剂的测定

Paper Absorption Spectrophotometric Determination of Anionic Surfactant in Environmental Water by Methylene Blue Method

本方法采用阳离子显色剂亚甲基蓝试剂,与阴离子表面活性剂形成不溶于水的离子对沉淀,将沉淀吸滤在滤纸上,直接置于721型分光光度计中,用双波长吸光度差值法定量,操作简单、快速,选择性好,灵敏度高。对于0.5μg阴离子表面活性剂13次测定变异系数为2.2％。样品测试回收率在96-102％之间,以取样体积为20ml计,最小检出浓度为7.5×10^(-8)g/ml。

The anionic surfactant was precipitated with methylene blue agent. The ionpair precipitate through a filtering pipette was collected on a small piece of filter paper as a blue fleck of which the absorbance was determined at 670nm and 730nm with a spectrophotometer of Model 721. The system obeys Beer's law in the range of 0-1.75μg/ml of anionics. The precision generally varies for 0.50μg anionics within ?2.2%. The detection limit and recovery of this method are 7.5 × 10 -8g/ ml and 96-102% respectively.