Vitamin C strength

Discussion in 'B&W: Film, Paper, Chemistry' started by psvensson, Apr 1, 2005.

  1. psvensson

    psvensson Member

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    I just ran out of the NOW Foods Vitamin C I've using ever since I started making my own developer last year. The replacement is of The Vitamin Shoppe's house brand, which is also supposed to be pure. It's a finer powder, which means it mixes faster, but I've noticed it's weaker than what I used before. I need 40% more by weight to make the film developer as active as with NOW Foods Vitamin C.

    What does this mean? Is the VS powder getting old, or is it just slightly oxidised from the start because it's a finer powder? Anyone else noticed differences between brands?

    I mix the vitamin in just before development, so there should be no issues of impurities that would cause instability in stored solutions.
     
  2. Tom Hoskinson

    Tom Hoskinson Member

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    It may be weaker. On the other hand, it may be calcium ascorbate or a mix of calcium and sodium ascorbate. Is it described as ascorbic acid or as an ascorbate?

    My personal choice is Trader Joe's 99% pure ascorbic acid (in the vitamins section).
     
  3. psvensson

    psvensson Member

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  4. Tom Hoskinson

    Tom Hoskinson Member

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  5. jim appleyard

    jim appleyard Member

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    I can get ascorbic acid at my health food store for $16/lb; pricey, but convienient. Is Trader Joes an online outfit, or a retail chain or something completely different?
     
  6. Canuck

    Canuck Member

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    I just picked up some ascorbic acid tablets at my local Costco ... in house brand, 500 tablets of 500mg each for $9 (Canadian which is about $7US). Works fine for me ... complete with insoluble inert floaties :D
     
  7. psvensson

    psvensson Member

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    The C-1000 only cost $9 in the store - weird that it's so expensive online.
     
  8. titrisol

    titrisol Member

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    it means 1000 mg of VitC/serving, thus it has been diluted with some filler.

    PS. I'm using Erythorbic acid or D-ascorbic acid, which is an isomer of vitamin C that is used in meat curing and beverages as antioxidant, but it doesn;t have the "vitaminic" action of L-ascorbic acid. So far it exhibited the same properties as L-ascorbic acid for film processing.
     
  9. psvensson

    psvensson Member

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    Titrisol, they're saying its 1000mg of Vitamin C per 1/4 tsp, same as NOW Foods. That doesn't really leave space for filler. 1/4 tsp weighs 1g.

    I thought erythrobic acid was isoascorbic, i.e. an even mix of the enantiomers? Or are you using what's left over after they extracted the L-form?
     
  10. titrisol

    titrisol Member

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    they are "optical" isomers, which means they are chemically the same but our bodies cannot metabolize erythorbic acid.
    isoascorbic = D-ascorbic

    It is used when companies do not want to claim "vitamin C" in their products, but want the anti-oxidant effect, such as in Ham and other meat products. I think it is a lot cheaper than Vit-C
     
  11. Jordan

    Jordan Member

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    It's strange. Ascorbic acid is ascorbic acid. It could be that it lost activitiy on storage, which would be unusual. Otherwise I would guess that it may have absorbed some water.
     
  12. Tom Hoskinson

    Tom Hoskinson Member

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    Trader Joe's is a specialty retail grocery chain that started in Pasadena, Ca, spread over the West Coast and now has locations on the East Coast. I have, on occasion, patronized the one located in Cambridge, MA.
     
  13. titrisol

    titrisol Member

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    Trader Joe's is pretty good, the closest one to me is in the Washington DC area
     
  14. fhovie

    fhovie Subscriber

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    Our Trader Joes has it for 9.99 - I wish it was in larger quantities.
     
  15. dancqu

    dancqu Member

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    Your local Homebrew Beer and Wine supplies outlet will
    likely have ascorbic acid. Many via the WWW do. As a last
    resort Photogaphers' Formulary and others of our specialty
    chemistry suppliers do have it. Dan
     
  16. Zathras

    Zathras Subscriber

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    Which form of Vitamin C did you use previously? If you had Sodium Ascorbate, then you are now making developers that are more acidic than before. Developers containing Ascorbic Acid need to have more alkali added to get them going compared to those containing Sodium Ascorbate. For more info, follow this link to an article on Vitamin C developers by Pat Gainer:
    http://unblinkingeye.com/Articles/VitC/vitc.html

    If you still have your old Vitamin C container, you might want to check the label to see which kind you had.

    Hope this helps...

    Mike Sullivan
     
  17. gainer

    gainer Subscriber

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    Ascorbic acid starts with a 6-carbon sugar. The sugars dextrose and levulose are mirror images of one another. One produces L-ascorbic acid and the other D-ascorbic acid. If you used a mixture of the sugars to make ascorbic acid, I don't think it would be very easy to separate them. The body knows how, but it doesn't tell us.

    I got a big bucket of D-ascorbic acid, also called isoascorbic acid or erythorbic acid. I have not seen any difference in any aspect of developing film or paper. I guess film isn't as smart as our bodies are. If they were really smart, we would be able to make our own vitamin C like gerbils, cats, dogs, and just about everybody but primates do. Then we probably would not have learned that it can develop film. Oh, well.
     
  18. gainer

    gainer Subscriber

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    Ascorbic acid combines with oxygen to make dehydroascorbic acid and water. Dehydroascorbic acid will not develop film. Nothing in our developers can change it back. The hydrogen atoms that are used up are not the one that makes the acid acidic. Chlorine and bromine and a bunch of other things also make dehydroascorbic acid out of ascorbic acid. I think these are things they call "free radicals".

    I don't think there is a color change with this reaction. Sodium ascorbate gets very yellow with exposure to air and moisture and begins to smell like brown sugar.
     
  19. psvensson

    psvensson Member

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    No, it was the acid form.
     
  20. Zathras

    Zathras Subscriber

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    What about your phenidone solution? Could it be headed south?

    Mike
     
  21. Jordan

    Jordan Member

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    Pat, I know about the oxidation chemistry of Vitamin C. I'm just saying that it's unlikely to happen to solid crystalline ascorbic acid unless there has been contamination by an oxidant or the sample is really old.

    Our body doesn't really 'separate' the two possible isomers of ascorbic acid. It just uses one and not the other. The isomer derived from dextrose (glucose) is cofactor for enzymes that are chiral (they have "handedness" and can distinguish between mirror-image molecules the same way our hand can distinguish right- and left-handed gloves).

    For direct photographic purposes the two isomers should be identical since the photographic process doesn't care about chirality. Gelatin is highly chiral, though, but I don't think that its specific interaction with Vitamin C would make a difference.
     
  22. psvensson

    psvensson Member

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    It's fresh and has not changed color, so that seems very unlikely.
     
  23. Lee L

    Lee L Member

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    I have both NOW Foods, which is Sodium Ascorbate, and Vitamin Shoppe, which is ascorbic acid. You might want to try Gainer's method for converting ascorbic acid to sodium ascorbate if that's what you have, and then check to see if it behaves like your NOW Foods did.

    Lee
     
  24. gainer

    gainer Subscriber

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    I think there is another possibility. I saw a container of what was purported to be Vitamin C, but had on the label the formula of dehydroascorbic acid. Our bodies, at least in some circumstances, can use that. The body converts ascorbic acid to dehydroascorbic acid in order to pass the brain-blood barrier (I think that is what it is called) and changes it to ascorbic acid in the brain. When it has been changed to dehydroascorbic acid, it will then pass back. Maybe it is not illegal to sell dehydroascorbic acid alone or in combination with ascorbic acid.