Determining Alcoholic Content without SG?

How would you determine the alcohol content of a liquid or solid without the use of a hydrometer? Basically I'm trying to find out what sort of instruments or methods could be used to find out how much ethyl alcohol a substance had... but just ethyl alcohol and not similar molecules.

One way would be boiling off the ethyl alcohol and measuring the volume lost. If you have other similar molecules in the mixture and none are toxic if inhaled, measure the volume of your original mixture, then bring to just under 78C and measure the volume, then raise to 79C, wait 30 minutes, then measure again. The volume lost during the rest at 79C should be ethyl alcohol. You will need to correct temperature for altitude (don't under estimate this if you are looking for accurate temperature measurement) and correct volume measurements for temperature due to expansion (assuming H2O is the major component of your mixture, it gains around 2 or 3 percent volume from room temp to 79C).

There are refractometers that can measure the potential, as well as the actual alcohol.

One example;
http://www.misco.com/products/PA203-003-128-129-194-195.html

KwaiLo said:

There are refractometers that can measure the potential, as well as the actual alcohol.

One example;
http://www.misco.com/products/PA203-003-128-129-194-195.html

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Seems like it still requires you to do a distillation if you don't know the SG:

The actual Alcohol by Volume of a particular finished wine may also be established following procedures and methods recognized by international bodies. After distilling a small volume of wine, the ethanol distillate is measured on the Palm Abbe Digital Wine/Alcohol Refractometer and the actual alcoholic strength (percent by volume) or specific gravity is displayed.

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You could probably use GC/mass spec, but that could get pricey and hard to come by

Bike N Brew said:

Seems like it still requires you to do a distillation if you don't know the SG:

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It does, but it is a hydrometer alternative...

Breathalizer... Drink 4 commercial beers with a known ABV on an empty stomach, then take the breathalizer test. Then, 24 hours later, drink 4 of your homebrews on an empty stomach and take another breathalizer. Simple algebra should give you your ABV.

cant you jsut use a vinometer..?? I have heard people at the LHBS tal kabout these...

http://pivo.northernbrewer.com/nbstore/action/search-do?searchTerm=VINOMETER

menschmaschine said:

Breathalizer... Drink 4 commercial beers with a known ABV on an empty stomach, then take the breathalizer test. Then, 24 hours later, drink 4 of your homebrews on an empty stomach and take another breathalizer. Simple algebra should give you your ABV.

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Thanks for all the great replies, I think this one is my favorite...although probably the least accurate.

The Vin-O-Meter sounds quite interesting as well!

gyrfalcon said:

Thanks for all the great replies, I think this one is my favorites...although probably the least accurate.

The Vin-O-Meter sounds quite interesting as well!

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I've been wanting to pick one up sometime, but I always forget when I'm ordering my supplies... let us know if you get one and how it works out...

Jester said:

I've been wanting to pick one up sometime, but I always forget when I'm ordering my supplies... let us know if you get one and how it works out...

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Well I picked up a Vinometer today after work (don't hate me...but I live about 5 minutes from midwest brewing supplies)...

I used it with water and it gave me a close to 0 reading. I blew out the water cleaned it...blew out the water again and then used it to test a hard cider I'm making.

It read 10% alcohol... The SG tests I did today say it's at 6% alcohol right now, but it started at a SG of 1.075 which can yield about 10% alcohol.

So basically it seems if you didn't get a starting SG, or want to calculate how much sugar is still left, the Vinometer be a great tool!

menschmaschine said:

Breathalizer... Drink 4 commercial beers with a known ABV on an empty stomach, then take the breathalizer test. Then, 24 hours later, drink 4 of your homebrews on an empty stomach and take another breathalizer. Simple algebra should give you your ABV.

Click to expand...

This sounds like a fun test.... now to get one without the cop attached!!!