Analysis of carbon number and ethylene oxide number distribution in alcohol ethoxylates by HPLC/electrospray ionization mass spectrometry]
高效液相色谱质谱法分析脂肪醇聚氧乙烯醚中的碳数及环氧乙烷加成数的分布

Alcohol ethoxylates (AEO) of the formula RO(CH2CH2O)nH are an increasingly important class of nonionic surfactants. They are not single component but a complex mixture with a distribution of alkyl and ethoxylate groups. The average number of ethoxylate groups can greatly influence the characteristics of surfactants. High performance liquid chromatography (HPLC) was applied to separate alcohol ethoxylates(AEO) by alkyl and ethoxylate groups. Coupled with on line electrospray mass spectrometry, chromatographic peaks were assigned according to their mass spectra. Using this method, we succeeded in determining the distribution of LION AEO3 (Dobanox25c), which has an alkyl chain with 12, 13, 14 and 15 carbon atoms. Its ethylene oxide numbers vary from 1 to 12. The reason of distortion of the pseudo-molecule-ion intensity is also explained. The response of the MS detector for AEO species increased exponentially as the EO number increased from 1 to 6, after that, the increasing trend became moderate.