表面活性剂复配体系的分析

介绍了一种使用经典的分析技术定量测定液体皂、皂胶、洗衣皂及香皂中存在的皂类、脂肪酸、非离子表面活性剂及除肥皂以外的阴离子表面活性剂和两性表面活性剂混合物的分析方法。这种方法克服了分析混合表面活性剂系统时常常会碰到的问题。

Analysis of complex surfactant systems a classical approach

This paper describes an analytical method for quantitative estimation of soap, fatty acid, non-ionics, anionics (other than soaps) and amphoterics when present as mixtures in liquid, gel, laundry and toilet soaps using classical analytical techniques. The methodology described overcomes the current problems associated with the analysis of mixed surfactants. Non-ionic surfactant and free fatty acids are separated from soap and amphoteric surfactant as acetone solubles. Part of the acetone solubles is titrated with standard sodium hydroxide solution using phenolphtalein to determine free fatty acids. Another part of acetone soluble is evaporated after neutralising the free fatty acid with alkali, the residue dissolved in water and extracted with ethyl acetate. The residue obtained from ethyl acetate evaporation is weighed as non-ionic surfactant. From the acetone insoluble matter, soap along with amphoteric surfactant and some anionic surfactant (other than soap) is extracted with rectified spirit or absolute alcohol. Rectified spirit extract is partially evaporated, diluted with water to 50 % v/v alcohol content (approximate), split with mineral acid and extracted with petroleum ether. The petroleum ether extract obtained is washed with sodium bicarbonate solution to remove anionic surfactant (other than soap) and amphoteric surfactant and evaporated. The TFM and anhydrous soap are estimated using the conventional methods. Amphoteric surfactant is estimated gravimetrically from the aqueous/alcoholic solution obtained after fatty-acid extraction. Anionic surfactant(other than soap)is determined by two-phase titration with benzethonium chloride (Hyamine 1622) using mixed indicator on a separate sample.