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Easy way to test for Fusel Alcohols in ethanols

  1. Aug 1, 2017 #1
    I know fusel alcohol is not an official term, and my chemistry is rusty, but is there an easy way to test for fusel alcohols in a primarily ethanol/water mixture? Basically, any alcohol that isn't ethanol?

  2. jcsd
  3. Aug 1, 2017 #2
    If you are not sure what the term 'fusal alcohol' means, (and I don't), then it's unlikely you will find much information about it.
    I did a quick search, it seems to refer to brewing of drinks which did not work out well, and most people would not drink it.
    Fusal is a German word related to 'refuse' in English
    Last edited: Aug 1, 2017
  4. Aug 1, 2017 #3


    Staff: Mentor

    Why ever you want to test it, you know that methanol is highly toxic with a small ##LD_{Lo}## (far less than a gram per kg body weight; ##0.14\,g/kg## in a case)? Not to mention the extreme high risk to your optical nerve. One could certainly test it in a laboratory by several methods, but I doubt there is an easy way outside a lab. The difference between ethanol and methanol is a small discrepancy in the boiling point, which is not always accurately controlled. Really many people lost their lives or became blind due to badly made moonshiners. In any case this doesn't affect the fusel alcohols which develop in the distillation process due to bad temperature handling.

    So whatever you want to test there: DO NOT DRINK IT.
  5. Aug 1, 2017 #4

    jim mcnamara

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    Staff: Mentor

    https://en.wikipedia.org/wiki/Fusel_alcohol These are usually alcohols with more than 2 carbons that are found in small amounts in alcohols derived from fermenation.

    What the thread is about: primarily butyl, amyl, and methyl alcohol. And yes it is possible to test for these and other secondary and tertiary alcohols.
    Organic chem101 lab:

    Easy - no.

    If you are trying to separate samples of drinkable alcohol (Ethanol) , forget it. We will read your obituary in a few days. I am not being funny.

    Fermented alcohols ( mostly ethanol ) can and are often denatured with non-drinkable alcohols like methanol. Methanol is very toxic, can cause blindness and death and - In small quantities.

    What exactly are you trying to do?

    An answer: ethanol and some longer chain polyalcohols are edible or drinkable. Some are not.
    Amyl alcohol (5 carbons) is edible. It does not have any of the effects ethanol has, and is considered a source of minor toxicity - hangovers. On the other hand the primary flavor agent in bananas is amyl acetate - acetic acid ester of amyl alcohol. It present in small quantities.

    So unless you have had organic chemistry and did well in the labs, forget whatever you are after.

    PS: this thread seems on the edge of a likely dangerous pursuit. We do not permit or want that kind of thread here.
    Last edited: Aug 1, 2017
  6. Aug 1, 2017 #5


    Staff: Mentor

    Not according to the German standard dictionary. But Germans do say Fusel to bad (cheap) liquors and other alcoholic drinks as wine, which likely originates from Fusel-Alkohole or Fusel-Öle (fusel oils), which are basically the same words as in English.
  7. Aug 1, 2017 #6
    Well Ok, I expect the Visigoths were the first to actually give a name to bad but drinkable beer,
  8. Aug 1, 2017 #7
    Jesus christ guys way to go off a cliff.

    Here's what i know:

    There are approximately 10 "fusel" alchohols that are produced during distillation and fermentation in addition to ethanol. The FDA has PPM limits on each one of these all relating to their levels of toxicity (yes, methanol too. You're still drinking methanol in your baily's and coffee). What i'd like to do is to TEST the liquid to determine the levels of alcohols present aside from ethanol. I'm not trying to drink it and i sure as hell aren't trying to manufacture it.

    Outside of buying a spectroscopy machine, is there a device out there that will allow me to test samples to determine quantities of alcohols other than ethanol?

    Does ethanol have some sort of wavelength sensitivity that i can shine a narrow band LED at said wavelength and measure the drop in intensity in a test sample and determine ethanol concentration in said sample?
  9. Aug 1, 2017 #8
    Sure, there are tests which can determine if a person has consumed ethanol beyond the legal limit in that country when driving say.
    I think they have not yet got an equivalent roadside test of whether someone may have smoked weed or taken LSD.
    Both of them involve stuff which generically could be classified as a form of alcohol'
  10. Aug 2, 2017 #9
    Am i taking crazy pills or are people just not paying attention?
  11. Aug 2, 2017 #10


    Staff: Mentor

    i.e. a cheap and easy way, due to the high chemical similarity of the substances in question.

    No need to get rude. The number of moonshine producers among our members isn't really high. In general you can only test substances you're especially looking for. In this case ethanol vs. all others. Now you can look up the properties of ##C_2H_6O## and see if there is one, which discrepancy to unknown others is large enough to be tested by limited resources: boiling point, color during burn, or whatever. As long as "all others" is unknown it will be difficult to develop a criterion. If "all others" are just other alcohols, then you run into the narrow margins that distinguish them.

    So my bet is: No.
  12. Aug 2, 2017 #11
    I had figured it might be difficult to determine due to the chemical similarity. I just wasn't sure if anyone was familiar with the methods by which they do this in a laboratory, or even if they knew exactly which machines had been developed specifically for this task. Maybe i should just place a call to fischer scientific and ask a sales rep?

    Again, i do not intend to manufacture ethanol. What i was after was the characterization of different alcohols sold to the public in liquor stores. As an example, using corn as main ingredient to distill vs Rye and the fusel alcohols created by their different starch contents. Of course this will vary batch to bach and distillery to distillery, but the effects of fermentation and temperature in fusel oil production has already been established in previous published studies, so i was going to use those as a baseline. This area of research is insufficiently paved in my opinion and i just wanted to add to it.
  13. Aug 9, 2017 #12
    As an amateur zymergist and distiller, I can tell you there are a lot of variables leading to fusel oils in fermentation broths. Using starch/glucose gives the cleanest fermentations. Also you need to control the temp during fermentation. Too warm yield bad actors. Also, the type of yeast used is important. Time is another variable; slow fermentations are preferable to fast fermentations. The distillation process should separate out most of the bad actors, but a few ppms of fusel oils will co-distill. These are enough to give the liquor a non-neutral flavor. Subsequent filtration through activated charcoal will remove most of these for a palatable liquor. I know of several ways to analyze for fusel oils, but all involve sophisticated sample prep and equipment. BP is an excellent indicator of purity, which you can monitor during distillation.
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