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Sodium Metabisulfite or sodium sulfite as antioxidant
I’m formulating a hydroquinone cream and need help choosing an antioxidant. As the pH is mildly acidic which of the sulfites is preferred?
What percentage of antioxidant is sufficient, without smelling sulfurous?
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6 Replies
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anyone?
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Hydroquinone tends to be most active as a skin bleaching agent at an alkaline pH thus using sulfite in the acid form is a waste, although it is used in commercial products.
From (distant) memory of making skin lighteners for African countries about 0.5% sodium sulfite should suffice but this will depend very much on the other components in the product.
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The reason, possibly, that you’re not getting much feedback is that hydroquinone is not exactly a ‘nice’ ingredient, certainly not something I want to formulate with. I am designing a lightening cream but I won’t use that substance in it.
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Also, many people are allergic to sulfites/sulfates when consumed. Probably not going to go over at all well in a cosmetic product.
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What’s wrong with using BHT, Georgi? Those sulfites can retard the oxidation effect of HQ to some degree. Also, HQ is “more active” just above pH 7.0, where it is less tautomerized, so you can use metabisulfite and adjust your pH to 7.0 - 7.5.
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I really want to use BHT, however, here in Bulgaria there are almost no suppliers for cosmetic ingredients. I have to use whatever I find in lab-supply businesses.
I have quite a lot of difficulties obtaining numerous ingredients.
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