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Thread: Certain liquid required

  1. #1 Certain liquid required 
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    I need a liquid that is
    (1) denser than water,
    (2) insoluble in water,
    (3) has a high molecular size so that it cannot permeate through dialysis tubing and
    (4) is relatively non-toxic so that I can easily handle it.

    Perfluorooctane would be good but it is toxic and I have no clue where to get it from.

    Any ideas?


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  3. #2  
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    1. Carbon tetrachloride.
    2. Iodoform.


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  4. #3  
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    but according to:
    http://ptcl.chem.ox.ac.uk/MSDS/IO/iodoform.html

    (Iodoform) is "Harmful by ingestion, inhalation and through skin contact. Eye, skin and respiratory irritant. Readily absorbed through the skin. Typical UK LTEL 8h TWA 0.6 ppm"

    and according to:
    http://www.atsdr.cdc.gov/tfacts30.html

    "High exposure to carbon tetrachloride can cause liver, kidney, and central nervous system damage. These effects can occur after ingestion or breathing.."

    Can I honestly use these chemicals in a home environment?
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  5. #4  
    Forum Sophomore Matt Lacey's Avatar
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    Iodoform and CCl<sub>4</sub> are surely carcinogenic as well.

    Ionic liquids like EMI-TFSI might be a better bet but they're expensive and I have no idea where you'll get them.
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  6. #5  
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    How about Krytox
    http://www.vacuumoil.com/msdspdfs/OI...Krytoxoil.html
    Handling (Personnel)
    Perfluoropolyether oils are considered to be inert and of low toxicity.

    Physical Data
    Solubility in Water : Negligible WT%
    pH : Neutral
    Odor : Odorless
    Form : Liquid, viscous oil
    Color : Colorless
    Specific Gravity : 1.86-1.91 @ 24 deg C (75 deg F)
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  7. #6  
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    Can I honestly use these chemicals in a home environment?
    Yes, absolutely. You are a competent chemist, are you not? Real chemists work daily with far more hazardous substances. Proper technique is what renders such chemicals harmless to the technicians.
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  8. #7  
    Forum Sophomore Matt Lacey's Avatar
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    Quote Originally Posted by SteveF
    Can I honestly use these chemicals in a home environment?
    Yes, absolutely. You are a competent chemist, are you not? Real chemists work daily with far more hazardous substances. Proper technique is what renders such chemicals harmless to the technicians.
    Real chemists wouldn't dare work with chemicals like iodoform without a fume cupboard and a capable air handling system - who has this in the home environment? Iodoform and carbon tetrachloride are pretty volatile chemicals.
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  9. #8  
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    Real chemists wouldn't dare work with chemicals like iodoform without a fume cupboard
    Are we talking about the same substances? Neither one is toxic. A small whiff of vapor is harmless.

    I mentioned proper techniques. That means working at home with an open window, and the more prudent workers might choose wear rubber gloves. (I wouldn't bother for either of these two -- that's how harmless they are.)

    Carbon tet is not particularly volatile; its BP is about 76C, as I recall.

    Iodoform is even less volatile, with a BP of 217C. It was used in medicine as a healing and antiseptic dressing for wounds and sores around the beginning of the 20th century, eventually being replaced by other antiseptics.

    Both are indeed suitable for home use.

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  10. #9  
    Forum Sophomore Matt Lacey's Avatar
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    It occurs to me that iodoform (CHI<sub>3</sub>) is a solid at room temperature, but in case you meant either diiodomethane or methyl iodide, both of those are probable carcinogens due to their reactivity with nucleophiles, as well as being volatile - carbon tetrachloride is (cat 2B carcinogen and definitely toxic).

    Maybe my point of view is just that of a country that regulates its chemicals more strictly, but I really don't consider these chemicals suitable for home use. Not just for their safety issues - maybe you and I could handle them with no issues - but also the fact that responsibility needs to be taken with regards to disposal, carbon tetrachloride especially is a strong environmental pollutant and needs to be disposed of properly.

    Besides, I really think more respect should be given to safety when using chemicals, considering the amount of people I've seen on here recently ask about how to make bombs out of household cleaning products. Chemistry is only a safe profession because of the professional environment in which we do research or whatever, not because the chemicals are 'harmless'.
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  11. #10  
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    Matt, your point is well taken. You get no disagreement from me.

    One key issue (we get it all the time) is that the OP did not initially identify himself as either a professional, advanced student, or a rank beginner.

    This creates a problem for those of us who offer advice. It would be insulting to a professional to demand from him an initial statement of capability. And it could be unwise to recommend certain materials or techniques to a beginner.

    This time I took the OP initially as an experienced chemist. He has since shown this may not be the case. But he does seem to have dialysis equipment, so who can really tell? So the decision to proceed with my suggestion is ultimately his own. He should be far enough along in his studies to make a rational decision. Cheers.

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