sodium thiosulphate....looking to reduce browning (oxidation) with Vanillin

A cursory glance through old discussions did not shed much light on browning reduction (vehicle is a pretty natural lotion) caused by inclusion of Vanillin.  
Background:  I am creating a mosquito lotion that includes a large amount of vanillin (3%) as a fixative.  I am already using Vitamin E, Rosemary Oil extract and EDTA, each of which has helped....but not to the level I would like to achieve.

Sidebar...I have also noted considerable variation based on which emulsifier is used.

A few hours on the net last night, and I learned that sodium thiosulphate is the go to product for reducing/slowing the vanillin effect.
So question is....Is sodium thiosulphate the best chemistry to use in browning reduction?  My cursory study also uncovered: Sodium bisulfite, aka sodium hydrogen sulfite as an option, as well as sodium metabisulfite.
My chemistry background is not strong enough for me to sort through these three options.  
So I guess I am looking for input as follows.... Which would be the most effective.....which might pose a problem with other common lotion ingredients....and which one would or wouldn't you want on your skin? :)

Thanx in advance.

Comments

  • PharmaPharma Member, Pharmacist
    The proposed compounds are all very similar regarding chemistry and pros and cons. Sodium metabisulfite is the most commonly used one for cosmetics and builds sodium hydrogen sulfite in solution. Sodium thiosulfate is also used as pharmaceutical drugs but its reactions may result in the formation of sulfur which could be undesirable (not dangerous, just annoying).
    I'd use metabisulfite.
  • GraillotionGraillotion Member
    edited May 1
    Pharma said:
    The proposed compounds are all very similar regarding chemistry and pros and cons. Sodium metabisulfite is the most commonly used one for cosmetics and builds sodium hydrogen sulfite in solution. Sodium thiosulfate is also used as pharmaceutical drugs but its reactions may result in the formation of sulfur which could be undesirable (not dangerous, just annoying).
    I'd use metabisulfite.
    Thank You....that is exactly the type of information I am looking for.
    Any chance you could tell me inclusion rate?
    Note: I have tons of Vanillin in the formula....3%.....and it smells....GOOD!  Never gotten so many complements in my life....on my 'cologne'....(also has 13 EO's in the formula)… So a herbal vanilla scent.
  • PharmaPharma Member, Pharmacist
    You'll have to try it out. Thiosulfate, metabisulfite and sulfite aren't expensive and you could try all three to see A: how much each really requires, B: which one has the lowest overall cost, and C: which, at it's optimal concentration, does show the least effect on the product. Even if all are similar, they aren't identical. And if you were to feel experimental, there's not just sodium salts but also potassium and ammonium salts of all three available ;) .
    It would be advised to stay below 0.5%. We don't know how much vanillin really degrades because it colours quite well. At 3% vanillin, 0.5% should be way more than enough. Hence, I'd start at ~0.05%.
    Further things regarding stability:
    Check pH: Vanillin is more stable under slightly acidic conditions.
    Avoid amines such as amino acids and aqueous herbal extracts.
  • PharmaPharma Member, Pharmacist
    BTW if you were to use a dark airless dispenser, a pinch of ascorbic acid or ascorbyl palmitate should also do the trick because you worst enemy or the real problem is oxygen and sunlight (UV). A pH above 6 simply speeds up the reaction and amines are probably not present in your product.
  • GraillotionGraillotion Member
    edited May 1
    Pharma said:
    BTW if you were to use a dark airless dispenser, a pinch of ascorbic acid or ascorbyl palmitate should also do the trick because you worst enemy or the real problem is oxygen and sunlight (UV). A pH above 6 simply speeds up the reaction and amines are probably not present in your product.
    Thank you.  I always use colored PET bottles...except when I am testing...then I use clear...and leave them in a warm sunny window...to aggravate the situation, and so I can observe.  I have discussed pumps vs flip tops...and will use pumps on this formula...I know...not the same as airless....but I think better than flip tops... :)  No Amines.


    Thanx again for your insightful comments.
  • Pharma said:


    One last question....the re-packers that are selling Browning reducers (metabisulfite) and listing it as.... 'Fragrance'.  (INCL)

    Can I do this also?  And the reason I ask...is two fold... I doubt I will ever come across a customer that says....Wow...finally found a lotion with metabisulfite in it!!!!

    and

    I am looking to minimize ingredient list....and since I will already be using 'fragrance'....it kills two birds with one stone.

    I am sure they (the re-packers) are using 'fragrance'....so people like me don't discover how easy and cheap that ingredient is to work with.

    Thank You 
  • PharmaPharma Member, Pharmacist
    Here around it's not a fragrance and I don't think it is in the US either...
    Yea, sulfite ain't that loved on ingredient lists ;( .
  • Pharma said:
    Here around it's not a fragrance and I don't think it is in the US either...
    Yea, sulfite ain't that loved on ingredient lists ;( .
    Of course I know it is not a 'fragrance'.... but the vendors are using some 'loophole' to market it as fragrance, so they can sell a cheap ingredient for a high price.  I was just curious as to what that loophole was! :) 
  • PharmaPharma Member, Pharmacist
    Maybe it's a fragrance additive, there's no real regulation, or they just don't care?
    The only 'hole' I can think of right now doesn't start with an L but a P... :smiley:
  • ozgirlozgirl Member, PCF student
    The loophole is probably to do with the IFRA Transparency List.

    IFRA describes two types of ingredients used in fragrances - Fragrance ingredients and Functional ingredients.

    Functional ingredients are substances that are not used to provide odor or malodor coverage, but which are essential for the functionality or durability of a fragrance compound – such as an antioxidant, preservative, diluent, solvent or color.

    Sodium thiosulfate is listed as being used in fragrances as a functional ingredient so if it is added to your fragrance to stop oxidation you can probably get away with listing the combination (fragrance + sodium thiosulfate) as "fragrance".

  • ozgirl said:

    Functional ingredients  – such as an antioxidant, preservative, diluent, solvent or color.

    Sodium thiosulfate is listed as being used in fragrances as a functional ingredient so if it is added to your fragrance to stop oxidation you can probably get away with listing the combination (fragrance + sodium thiosulfate) as "fragrance".

    Ahh...I'm sure that is it....an antioxidant for the fragrance.
    I knew the practice was widespread.
    I like that! :) 
  • Pharma said:
    BTW if you were to use a dark airless dispenser, a pinch of ascorbic acid or ascorbyl palmitate should also do the trick because you worst enemy or the real problem is oxygen and sunlight (UV). A pH above 6 simply speeds up the reaction and amines are probably not present in your product.
    Can you explain to me...what the purpose/function of the ascorbic acid, or ascorbyl palmitate will do?
    Thank You.
  • PharmaPharma Member, Pharmacist
    It catches oxygen which isn't obvious although it's an antioxidant. Unlike phenolics such as tocopherol, it also reacts with oxygen to create water whereas phenolics only neutralise reactive products formed when oxygen reacts with 'stuff' such as unsaturated fatty acids. Thiosulfate and bisulfides do the same, they react with oxygen and not just degraded stuff.
  • Pharma said:
    You'll have to try it out. Thiosulfate, metabisulfite and sulfite aren't expensive and you could try all three to see A: how much each really requires, B: which one has the lowest overall cost, and C: which, at it's optimal concentration, does show the least effect on the product. Even if all are similar, they aren't identical. And if you were to feel experimental, there's not just sodium salts but also potassium and ammonium salts of all three available ;) .
    It would be advised to stay below 0.5%. We don't know how much vanillin really degrades because it colours quite well. At 3% vanillin, 0.5% should be way more than enough. Hence, I'd start at ~0.05%.
    Further things regarding stability:
    Check pH: Vanillin is more stable under slightly acidic conditions.

    The Sodium Metabisulfite...definitely helped, but did not solve the issue.  pH is running 5.5....so good.  I am getting a little brown smoke ring in the lotion....in as little as a week....but then it doesn't seem to progress much.  I am using the meta at .3%

    Should I just try the Thiosulfate instead....or try and tweak something.

    I think the industry is using Thiosulfate....HOWEVER.... I think they choose that one...because they can hide it under the 'Fragrance' label...and don't have to disclose it....  Metabisulfite is not on the list of ingredients I can hide....under 'fragrance'.  :) 

    Do you have any additional thoughts....on how to get that 'smoke ring' out of my Vanillin lotion....hehehehe.
  • PharmaPharma Member, Pharmacist
    You'll have to try it. Sometimes it's equal, sometimes better (regarding antioxidation).
    Smoke ring? You mean just at the top edge where product/air/jar meet?
    If so, get the air out of your bottle! You can't chemically remove it in head space but only in your product and then it's too late because, statistically, oxygen will hit vanillin always first (you can't add thiosulfate at 5% or so). You could flush and seal your product under nitrogen or argon... but seriously, that's overkill. Fill your bottles brim-full (however, the ring will appear once the bottle gets emptier) or go with an adequate airless system or a non-transparent one wherein you guarantee that the top layer never leaves the bottle (waste and cheating the customers, I know, but not a completely new idea either).
  • Pharma said:
    You'll have to try it. Sometimes it's equal, sometimes better (regarding antioxidation).
    Smoke ring? You mean just at the top edge where product/air/jar meet?

    A pound of that stuff...cost like $3....hehehe....so I can afford to try it! :)  
    I should have clarified.... I am putting it through my torture test....clear bottle, only filled 2/3, in a warm sunny window....opening the bottle once a week to allow fresh O2 in...etc... (what I call the torture test) I was trying to see if I could make it bulletproof...hehehe.   NOPE!
    When it goes to market...it will be in a colored bottle...with a pump.  I am just trying to make it crazy good....to begin with.


    The smoke ring....is a off colored ring...that appears just below the surface of the lotion...somewhere between a soft orange, and soft tan.  Might only be visible at this stage....to someone looking for it. :) 
  • Pharma said:
    It catches oxygen which isn't obvious although it's an antioxidant. Unlike phenolics such as tocopherol, it also reacts with oxygen to create water whereas phenolics only neutralise reactive products formed when oxygen reacts with 'stuff' such as unsaturated fatty acids. Thiosulfate and bisulfides do the same, they react with oxygen and not just degraded stuff.
    So do I understand you correctly.....to add ascorbic acid, or ascorbyl palmitate, as well as using one of the sulfites/sulfates....hehehe...I didn't know if the have 3 or 4 O2 atoms. :) 
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