It seems that the answer is no, so I have changed the title of this thread to ………………………………………………
Hi all,
I was just wondering if there is any way to measure the percentage of alcohol in in something like a bottle of rubbing alcohol or hand sanitizer etc. I have heard of using a hydrometer, but I don’t think that is going to work because IIRC do use that you have to take before and after density readings…
Thanks
IR spectroscopy, chromatography and testing with reagents could probably get it done but that is not going to be accessible to you.
Inoculating agar media and culturing the results would be the easiest test, have one as a control, one testing your hands before hand sanitizer and another after using it. While that would not directly test alcohol content, it would test effectiveness.
I thought of fractional distillation but for various reasons I do not think it would work out well.
Use alcoholmeter. Widely available to buy.
For example: https://www.amazon.co.uk/Spirit-Alcoholmeter-Measures-Alcohol-Distilled/dp/B00DSCX4BE
So the density of the gel would make the hydrometer pretty useless. You could distill the alcohol out but a lot of hand sanitizer is a mixture of IPA and ethanol and they form an azeotrope with each other not to mention both form an azeotrope with water so it would be really hard to tell what the original percent used was.
Unless I am missing something. If he wants to test isopropyl alcohol by itself a hydrometer calibrated to the alcohol type used would work. But if he is trying to test the final concentration of ethanol or IPA in hand sanitizer then no. An easier way to test rubbing alcohol IPA content is by “salting it out” with sodium chloride, and measuring the organic top layer. After all salt is cheap and you should have everything you need at home. You can even purify a 70% solution to nearly pure by salting out IPA. If you need it to be almost 100% pure then taking anhydrous magnesium sulfate and using it as a drying agent would work. You can make anhydrous magnesium sulfate from Epsom salts by heating it in an oven for a few hours at around 400 F. You can not salt out ethanol alcohol however.
specific gravity and a chart.
ie what does a quart pint or whatever weigh?
now look that up, given that you know the alcohol type you are interested in.
The main thing I wold be interested in doing this with is hand sanitizer gel.
Gas chromatography is the standard that companies use to test hand sanitizer.
Check if it burns?
The problem with that as a test is that many formulations won’t burn because of additives and it is not quantitative.
Get a spectrometer for alcohol is the best way. A hydrometer works ok but the sample needed is larger. If you are diluting your own you can use a calculator (think there maybe something wrong with this link) these very useful.
Many decades ago vehicles used an alcohol/water mixture before the introduction of ethylene glycol antifreeze. There was a simple tester, an hydrometer, which would measure the alcohol percentage so you knew at what temperature the solution would freeze. You can still buy one of these today calibrated in proof (for alcohol beverages) rather than for vehicles. It’s $8 at Walmart Robot or human?. Since had sanitizer contains other ingredients which may change the specific gravity of the solution (mentioned previously above) this is not going to be as accurate as a lab analysis but that would cost so much it wouldn’t be worth it.
I doubt if most hand sanitizer companies use specific testing equipment to calculate the alcohol content. If you know the proof or % alcohol in the alcohol to begin with it is simple to calculate how much water to add to get the right % alcohol in the final product.
Just read the label?. 
I’ve never bought any yet that doesn’t have the ingredients on, in fact I think it’s illegal not to?
What more do you need beyond “isopropyl alcohol” 70? It is water 30 and isopropyl alcohol 70%. My bottle has a drug fact label on the back that has “active ingredient, isopropyl alcohol 91% by volume” and at the bottom of the label “Inactive ingredient purified water”. Since it is poisonous if drunk it also says “for external use only” and flammable, keep from flames”. It’s not ethyl alcohol but will kill viruses just as well.
@vestureofblood, weigh it!
Pure water will be heavier than pure isopropanol/ethanol, so you can actually calculate it using the weight of your entire solution.
If you have any doubts you just spike it with Everclear 190 proof. I’ve always kept a little bit of soap and water in the vehicle. A roll of paper towels if you can get them. Soap is better than the hand sanitizer. And I don’t think you really need 20 seconds unless you were dipping your hands in the virus
I ordered some hand sanitizer from China. I was hoping to be able to verify the total alchohol content just in case factories treat this product and its measurements the way the do flashlights.
This I think could work with a bottle of alchol but to do this with the sanitizer I would also need to know the weight of the thickening agent.
mix 50-50 with water , and use hydrometer or what ever wine makers use!
Too weak forsh, I believe they recommend 80/20 for corona - I may be wrong though, and it varies from site to site.
I think your right
Most the gel types I see here are 80%
But to get an average reading i think hydrometers or what ever they are called , need a more liquify substance to actually work
Gels I doubt they work at all