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Thread: Any suggestions?

  1. #1 Any suggestions? 
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    Hey guys,

    A friend of mine is doing an investigative report on whether local nightclubs are watering down their vodka and asked for my help as she knows nothing about chemistry (she's doing a journalism course so it's not a homework question!).

    She wanted to know what the easiest way to detect this phenomenon is; and the first thing that popped into my head was fractional distillation, i.e. see how much ethanol comes out of the vodka at 78*C compared to a control. Taste and smell are obvious but not concrete enough. Can anyone else suggest a simple technique? As I said it's not a chemistry report so it doesn't have to be something ridiculously accurate, just conclusive.


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  3. #2  
    Forum Masters Degree thyristor's Avatar
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    I don't know, maybe it woud be easier to freeze it. Since ethanol freezez at
    -114,3 C, you could freeze the vodka to let's say a few grades below zero, to make sura all water is ice, and then just pick away the ice.


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  4. #3  
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    I would think that the best way would be gas chromatography or high-pressure liquid chromatography, if you're trying to actually get results that you could publish. Any university chemistry department should be able to help you out with either of those. If you're determined to do it yourself with no real equipment, I guess distillation would be the way to go, using "pure" vodkas as controls.
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  5. #4  
    Forum Masters Degree organic god's Avatar
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    could go totally non-chemistry, get a large group of people to drink a lot.

    50% drink the control vodka, 50% drink the nightclub vodka,

    see how long it takes for them to pass out,
    if you use enough people and make sure weights and "drink holding" are evenly distributed. then a noticable difference in the time will indicate the vodka has been tampered with.
    everything is mathematical.
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  6. #5  
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    Quote Originally Posted by organic god
    could go totally non-chemistry, get a large group of people to drink a lot.

    50% drink the control vodka, 50% drink the nightclub vodka,

    see how long it takes for them to pass out,
    if you use enough people and make sure weights and "drink holding" are evenly distributed. then a noticable difference in the time will indicate the vodka has been tampered with.
    It shouldn't be done this way since while it may be repeatable, it won't be reproducible.

    And what Scifor said. HPLC is a good method.
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  7. #6  
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    I had considered using people as guinea pigs but like Georginho said I don't think it's reliable as there's too much variance in people's tolerance towards alcohol... not to say that it wouldn't be a kick-ass experiment

    I currently don't have access to my university's lab so gas chromatography/ HPLC are out of the question unfortunately, I asked one of the lab techs and he suggested a device (the name of which he couldn't remember) which measured the density of liquids, which could possibly be bought in a shop that sells home brewing materials. Does anyone know what it's called?

    I like the freezing idea, it's rudimentary enough to do at home but it should be enough to discern if there's a difference between a large enough sample and some shop bought vodka, thanks thyristor.

    I don't think the report is actually going to be published, it's just part of the course she's doing and there's much more to it than the section that I'm working on so I'm fairly sure that you won't be reading it in the tabloids any time soon...
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  8. #7  
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    I think an alcohol hydrometer is the thing you need.
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  9. #8  
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    Brilliant, thanks a million!
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