Abstract: Oleic acid methyl ester ethoxylate (OMEE) was characterized by FT-IR.The acid and alkali resistance of fatty acid methyl ester ethoxylate (FMEE) and OMEE were measured qualitatively and quantitatively by national standard method and mass method,respectively.The experimental results show that,the structure of OMEE is different from that of conventional saturated FMEE because of the presence of carbon-carbon double bond.The national standard method is not suitable for the determination of acid or alkali resistance of FMEE.The hydrolysis rate of OMEE is always higher than that of FMEE at any pH.The hydrolysis of both FMEE and OMEE are the fastest at pH 13,and OMEE has been hydrolyzed completely at 170 h.At pH 2~9,the hydrolysis rate of FMEE is still less than 20% during the period of 500 h.In additon,the hydrolysis rate of OMEE has been little affected by either pH or time when the pH is less than 13.

Key words: fatty acid methyl ester ethoxylate, acid resistance, alkali resistance, national standard method, hydrolysis rate, qualitative analysis