Characterization of alcohol ethoxylates as alcohol ethoxy sulfate derivatives by liquid chromatography-mass spectrometry

The characterization of alcohol ethoxylates (AE) to determine ethylene oxide (EO) adduct distribution has been studied in our laboratory for many years by using high-performance liquid chromatography-mass spectrometry (LC-MS). This paper describes the LC-MS approach being used to analyze both nonderivatized and derivatized AE. We conclude that the best way to determine EO adduct distribution is by first converting the AE to alcohol ethoxy sulfates (AES) and then by using LC-MS with electrospray ionization in the negative ion mode. A convenient laboratory technique for converting small-scale samples of AE to AES has been discovered and is reported herein. Several examples of EO adduct distributions determined by this method are presented for both linear and isomeric AE samples.