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  1. #1

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    Stability of ascorbic acid in powder form?

    Does anyone know the expected life of ascorbic acid in powder form stored in a partially full plastic bottle?

    And would there be any visual signs that it was going bad?

    Sandy King

  2. #2
    edz
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    Quote Originally Posted by sanking
    Does anyone know the expected life of ascorbic acid in powder form stored in a partially full plastic bottle?
    Measured in years if its stored dry. The problem is water and/or mositure. Is the acid dry, clump-free and white powder or colourless crystals?
    Edward C. Zimmermann
    BSn R&D // http://www.nonmonotonic.net

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    Pretty much what edz said, if it is dry L-ascorbic acid with no filler material and is stored in a sealed container.

    Here is the JT Baker MSDS: http://www.jtbaker.com/msds/englishhtml/a7608.htm
    Vitamin C - L ascorbic acid
    Tom Hoskinson
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  4. #4

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    Quote Originally Posted by edz
    Measured in years if its stored dry. The problem is water and/or mositure. Is the acid dry, clump-free and white powder or colourless crystals?
    It is dry, clump-free and mostly white, with just a few yellow crystals scattered in the powder.

    Sandy

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    If the jar is opened frequently, and if the air is somewhat humid, there will be more of the yellowing. I assume that is some kind of deterioration.

    I ingest some ascorbic acid every day (deliberately: it's the only developing agent that I eat) and I've noticed this deterioration particularly when I travel in the tropics.

  6. #6
    edz
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    Quote Originally Posted by sanking
    It is dry, clump-free and mostly white, with just a few yellow crystals scattered in the powder.
    Sounds fine. The powder sold in the drugstores sometimes contain a little bit of light yellow crystals. For your uses in developers I'd not give it much more thought.
    Edward C. Zimmermann
    BSn R&D // http://www.nonmonotonic.net

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    Ascorbic acid is usually packed under nitrogen but some containers are really not suitable for long term storage once they have been opened. This is particularly true for those with snap type caps. I would suggest transferring to a glass container with a screw cap.

  8. #8
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    Quote Originally Posted by john_s
    I ingest some ascorbic acid every day (deliberately: it's the only developing agent that I eat) and I've noticed this deterioration particularly when I travel in the tropics.

    I routinely ingest enough L-ascorbic acid each day to develop two rolls of film. However, it's not the only developing agent I routinely and intentionally ingest (nor, I'd guess, is that the case for you): I also routinely consume about half a roll worth of caffeic acid, as found in coffee, and a similar capacity of tannic acid as found in tea -- both are developing agents of the staining/tanning type.

    If I increase my onion consumption a bit, I might be able to make my blood into a monobath...
    Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.

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    Quote Originally Posted by Gerald Koch
    Ascorbic acid is usually packed under nitrogen but some containers are really not suitable for long term storage once they have been opened. This is particularly true for those with snap type caps. I would suggest transferring to a glass container with a screw cap.
    I wonder if virtually all photographic chemicals in poweder form would not also benefit from storage in glass containers?

    Sandy King

  10. #10
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    Quote Originally Posted by sanking
    I wonder if virtually all photographic chemicals in poweder form would not also benefit from storage in glass containers?

    Sandy King
    I've wondered the same thing, and I've wondered if Mason jars would work. If kept in a cabinet, they would be away from most sunlight. That leaves the question of whether the coating on the inside of the cap is sufficient to keep the metal from affecting the chemicals. Anyone know?
    juan

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