Process for making sulfonated fatty acid alkyl ester surfactant

An improved process for the production of sulfonated fatty acid alkyl ester surfactants containing low levels of impurities including disalt and dimethyl sulfate (DMS) impurities, said process comprising sulfonating fatty acid alkyl esters, forming a substantially anhydrous alkoxide solution, over-neutralizing to a pH of at least about 10 with the alkoxide solution, and re-neutralizing to a pH of about 5 to about 9. The substantially anhydrous alkoxide solution is formed by combining an alkoxide solution containing an alkoxide of the formula (RO-)nMn+, a C1 to C8 alcohol, and no more than 1% by weight water with a sacrificial ester of the formula R1COOR2, wherein the molar ratio of the sacrificial ester to water is from about 0.5:1 to about 2:1.