Departament de Química Analítica, Facultat de Química, Universitat de València, Dr. Moliner 50, 46100 Burjassot, Spain.
J Chromatogr A. 2011 Nov 25;1218(47):8511-8. doi: 10.1016/j.chroma.2011.09.059. Epub 2011 Sep 29.
A method for the separation, characterization and determination of fatty alcohol ethoxylates (FAE) and alkylether sulfates (AES) in industrial and environmental samples is described. Separation of the two surfactant classes was achieved in a 50:50 methanol-water medium by retaining AES on a strong anionic exchanger (SAX) whereas most FAE were eluted. After washing the SAX cartridges to remove cations, the residual hydrophobic FAE were eluted by increasing methanol to 80%. Finally, AES were eluted using 80:20 and 95:5 methanol-concentrated aqueous HCl mixtures. Methanol and water were removed from the FAE and AES fractions, and the residues were dissolved in 1,4-dioxane. In this medium, esterification of FAE and transesterification of AES with a cyclic anhydride was performed. Phthalic and diphenic anhydrides were used to derivatizate the surfactants in industrial samples and seawater extracts, respectively. Separation of the derivatized oligomers was achieved by gradient elution on a C8 column with acetonitrile/water in the presence of 0.1% acetic acid. Good resolution between both the hydrocarbon series and the successive oligomers within the series was achieved. Cross-contamination of FAE with AES and vice versa was not observed. Using dodecyl alcohol as calibration standard, and correction of the peak areas of the derivatized oligomers by their respective UV-vis response factors, both FAE and AES were evaluated. After solid-phase extraction on C18, the proposed method was successfully applied to the characterization and determination of the two surfactant classes in industrial samples and in seawater.
描述了一种用于分离、表征和测定工业和环境样品中脂肪醇乙氧基化物（FAE）和烷基醚硫酸盐（AES）的方法。通过在 50:50 甲醇-水介质中保留 AES 在强阴离子交换剂（SAX）上，实现了两种表面活性剂类别的分离，而大多数 FAE 被洗脱。在洗涤 SAX 柱以去除阳离子后，通过增加甲醇至 80%来洗脱残留的疏水性 FAE。最后，使用 80:20 和 95:5 甲醇-浓盐酸混合液洗脱 AES。从 FAE 和 AES 馏分中去除甲醇和水，并将残留物溶解在 1,4-二恶烷中。在该介质中，FAE 进行酯化反应，AES 与环状酸酐进行酯交换反应。邻苯二甲酸酐和二苯甲酮酐分别用于衍生化工业样品和海水提取物中的表面活性剂。通过在 C8 柱上用乙腈/水在 0.1%乙酸存在下进行梯度洗脱，实现了衍生化低聚物的分离。在烃系列和系列内的连续低聚物之间实现了良好的分辨率。未观察到 FAE 与 AES 之间的交叉污染。使用十二醇作为校准标准，并通过衍生化低聚物各自的 UV-vis 响应因子校正峰面积，对 FAE 和 AES 进行了评估。在 C18 上进行固相萃取后，该方法成功应用于工业样品和海水中两种表面活性剂类别的表征和测定。
