Analysis Of The Distribution Of Ethylene Oxide Adduct Number Of Polyethoxylated Fatty Alcohol And Alkylphenol Ethoxylates

This research is to establish a method for determination of hydroxyl value of nonionic surfactants by using a parallel synthesizer. The results indicated that there is no significant difference between this method and the national standard method on accuracy and precision, and the parallel synthesizer is simple to operate, with good temperature control,and small systematic error. The hydroxyl value of each sample was determined with this method, and the oxyethylene group content was determined in accordance with GB/T 7385-2012. With both values above,calculate the average polymerization degree of ethylene oxide (EO) of each sample, which can be used to assess the accuracy of component analysis of nonionic surfactants in the absence of standard sample.In addition, the reversed phase liquid chromatography and the normal phase liquid chromatography were established to analyze the component distribution of ethylene oxide(EO) adduct number in polyethoxylated fatty alcohols and alkylphenol ethoxylates.(1) When using the reversed phase high performance liquid chromatograph(RP-HPLC) method to analyze the EO number in polyphenylene ether nonionic surfactants,charged aerosol detector (CAD) with C18 reversed-phase column, as well as the acetonitrile-water solution as the mobile phase. The sample can be separated without derivatization according to the carbon chains and the polymerization degree of EO number. Qualitatively analyze the components of the sample with HPLC-ion trap mass spectrometry under positive ion scanning mode (LC-MS),which is also simple,convenient,efficient and repeatable, and can be used for monitoring the production of products. However,hydrophobic chains in the sample may have a great impact on the separation result.(2) When using the normal phase high performance liquid chromatograph (NP-HPLC)method to analyze the EO number in polyphenylene ether nonionic surfactants. Use a evaporative light scattering detector (ELSD) with NH2 column, as well as the n-hexane-dichloromethane - methanol solution as the mobile phase. The sample can be separated without dervatization according to the polymerization degree of EO number. Use the narrow distributed,single - carbon C12EO7 and C14EO7 as the standard samples to get the retention time of each component, thus to qualitatively identify the components forming the test samples. In contrast to the reversed - phase liquid chromatography method,hydrophobic chains in the sample only have a small impact on the separation result in this method, and the sample components are separated mainly according to the polymerization degree of EO chains with a shorter retention time and higher separation efficiency. Besides the accurate result, this method is sample, convenient, fast and reproducible, which is more suitable for production monitoring.