Camden-Grey also sells nat mixed tocopherols. Here is their blurb regarding the use of T-50 in soaps. I like Pat_D_O's suggestion to use EDTA. A chemistry prof once explained, EDTA is the match maker in chemistry- introduces one molecule to the other, they then have a chemical reaction and form less reactive substances (typically). If memory serves, EDTA is safe, and has a long history of use with no adverse effects. It gets pooh-poohed sometimes though since industry is always trying to keep interests going with "new and improved" products. With the "new & improved" body formulation ingredients you don't get that great usage history that EDTA has already established.
T-50 product description, from Camden-Grey's website:
Sold by weight. T-50 all natural vitamin E. With daily concerns over the safety of synthetic ingredients, why risk the success of your products by using synthetic antioxidants? There are two classes of natural Vitamin E: tocopherols and tocotrienols. We offer you all natural low d-alpha mixed tocopherols or T-50.
Tocopherols: A term used to describe the collection of all the tocopherols in Vitamin E that occur naturally in food. There are 4 types of tocopherols: d-alpha, d-beta, d-gamma and d-delta. Low d-alpha mixed tocopherols are often used to slow the onset of rancidity in fats and oils. Natural oxidants are isolated from vegetable oils and concentrated to contain a mixture of d-alpha (commonly known as Vitamin E), d-beta, d-gamma and d-delta tocopherols.
T-50 is all natural, low d-alpha mixed tocopherols, has 500 mg total tocopherols, and is a brownish-red, clear, viscous oil (color may differ slightly from batch to batch). When you compare prices between the gel caps commonly sold in drugstores and these Tocopherols, pound per pound Tocopherols are a lot less expensive to use, not to mention that you will be using all natural Vitamin E and not synthetic.
At proper usage levels T-50 does not contribute odor, taste or color to the end product. Tocopherols are natures perfect antioxidant. The optimal level of tocopherols in finished products will range from 0.01% to 0.1% of the fat or oil content. Because antioxidants can only prevent oxidation, not reverse it, it is important to add the antioxidant as early in the process as possible.
Tocopherols also slow the onset of rancidity in fats & oils in your soaps & lotions. If you superfat your soaps, then Vitamin E is a must so that your soaps will not develop rancidity in a few months. Tocopherols also help to protect the most vulnerable citrus essential oils.
Recommended usage: 4 drops per one pound of oils in a recipe. T-50 is insoluble in water. Constituents of our T-50 mixture: 50/50 natural mixed tocopherols & partially hydrogenated vegetable oil, mainly soybean oil. May be labeled as natural vitamin E in finished products. Do not refrigerate, store in cool place. Shelf life: 36 months when stored in an unopened container. This product is food grade and is GRAS. INCI: