Determination of Composition Distribution of Fatty Alcohol Ethoxylates by Normal-Phase High-Performance Liquid Chromatography

The sample (0.100 0 g) was dissolved and made up its volume to 50 mL with a mixture of n-hexane and dichloromethane (90+10). The solution was filtered through 0.45 μm filter membrane, and separated by normal-phase high-performance liquid chromatography using Hypersil NH₂ chromatographic column as stationary phase, and a mixture of n-hexane, dichloromethane and methanol in various ratios as mobile phase in gradient elution. As shown by the results, no derivatization was necessary, and the composition of fatty alcohol ethoxylates (AEO) could be well separated according to the degree of polymerization of ethylene oxide (EO) and the carbon chain. Self-prepared C12EO7 and C14EO7 were used as standard samples for qualitative analysis and the area normalization method was used for quantification. A sample of AEO-7 was analyzed by the above method, giving value of RSD (n=6) of 2.7%.