乙基紫吸光光度法测定水样中阴离子表面活性剂

SPECTROPHOTOMETRIC DETERMINATION OF ANIONIC SURFACTANTS IN ENVIRONMENTAL WATER SAMPLES WITH ETHYL VIOLET

在pH 2.2—2.8的邻苯二甲酸氢钾-盐酸缓冲体系中,在聚乙烯醇存在下,乙基紫可与阴离子表面活性剂生成离子缔合物,并可用于水相直接光度法测定阴离子表面活性剂,对于十二烷基苯磺酸钠、十二烷基硫酸钠和十二烷基磺酸钠摩尔吸光系数分别为1.99×10~5、1.93×10~5和1.07×10~5L·mol^(-1)·cm^(-1),完全可用于环境水样中微量阴离子表面活性剂的光度测定。

A highly sensitive and direct Spectrophotometric method for determination of anionic surfactants in water was developed. The optimal conditions for the colour reaction of the ion-associate of anionic surfactant with ethyl violet in the presence of polyvinyl alcohol was described. The suitable pH range is between 2.2 and 2.8 with C8H5O4K-HC1 buffer solution. The wavelength of maximum absorbance of the ion-associates is at 550nm and the molar absorptivity are 1.99×105 L.mol-1.cm-1 for dodecylbenzene sulfonate, 1.93×105 L.mol-1.cm-1 for dodecylsulfate, 1.07×105 L.mol-1.cm-1 for dodecylsulfonate, respectively. The method has high sensitivity and fairly good selectivity and so it can be applied to the Spectrophotometric determination of micro amounts of anionic surfactants in environmemtal water samples.