Sulfates are found in many liquid 'soaps' and shampoos. You are making a lye based soap ( I assume) so there are no sulphates. Next time you are in the supermarket, read the ingredients on the back of any liquid soap and you will usually see either sodium lauryl or laureth sulphate or sodium coco sulphate. The front side of the label may say 'natural' or 'plant based' ingredients, which they are, but make no mistake they are man-made detergents that are derived from natural sources.
Sulfates have come under fire in recent years because of a possible link to cancer. I'm not sure of the claims are true - but that's what started all the hype. They can also be quite harsh and drying for those with sensitivities.