Abstract: A method for the analysis of fatty alcohol polyoxyethylene ether sodium sulphate (AES) by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI/MS) was established. The alkyl carbon number distribution, ethylene oxide number and average relative molecular mass in AES were determined by negative ion mode ESI/MS. Nitrogen nebulizer gas temperature was 325 ℃, nitrogen drying gas flow rate was 5.00 L/min, the mass scan range was from m/z 100 to 1000. The free sodium dodecyl sulfate (SDS) in AES was separated on a Zorbax SB-C18 column (150 mm×2.1 mm, 3.5 μm) with methanol-water (70:30, v/v) as the mobile phase at a flow rate of 0.3 mL/min, and then determined at m/z 265 by LC-MS with ESI in negative ion mode. The method has been applied for the determination of the AES samples, and the average ethylene oxide number was verified by nuclear magnetic resonance spectrum.

Key words: alkyl carbon number distribution, average relative molecular mass, ethylene oxide number, fatty alcohol polyoxyethylene ether sodium sulphate (AES) , sodium dodecyl sulfate (SDS), liquid chromatography-electrospray ionization mass spectrometry(LC-ESI/MS)