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Impurities in isopropanol sold as electronics cleaner?

In the US, it's fairly easy to find 70% isopropanol sold for use as a topical antiseptic & such. In the UK, it's harder to find, but I can buy "100%" isopropanol as electronics cleaner & dilute it to 70%. Does anyone know if the latter is likely to contain traces of dangerous impurities that make it unsuitable for topical antiseptic use, sterilizing electric toothbrush heads, etc.?

(I'm aware of the traces of benzene in "nearly 100%" industrial ethanol that make it dangerous; that's what set me on this train of thought.)

--
There's a statute of limitations with the law, but not with  
your wife.              --- Ray Magliozzi, Car Talk 2011-36
Reply to
Adam Funk
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IIRC nowadays ethanol is denatured with kerosene, not benzene, at least over here.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

It's not that. Simple distillation of ethanol in water can't get you a stronger concentration of ethanol than 95.6% (search on "azeotrope" for the full info). Getting ethanol closer to 100% requires some process that involves benzine, but other than the fact that there's residual benzine in the fire-water, I have no idea what that process is.

--

Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com 

I'm looking for work -- see my website!
Reply to
Tim Wescott

I know about the 190 proof problem. ;) Whether there's benzene depends on the feed stock, though. Grain neutral spirit doesn't have benzene in any significant quantity AFAICT.

Even if it did, the actual amount of benzene that's going to be lurking in the OP's toothbrush after it dries would be trivial.

IIRC denatured ethanol used to have benzene added intentionally, before it was discovered to be seriously carcinogenic, at which point they switched to kerosene.

A quick web search reveals that you can dry ethanol by vacuum evaporation (the azeotrope doesn't form below about 70 torr), by reaction with quicklime (CaO), or by sequestration using molecular sieves. Even tapioca works, apparently. !

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

Hmm and apparently you "dry out" IPA with salt.

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(Kinda cool to watch the phase separation, I wonder how long it takes?)

George H.

Reply to
George Herold

Yeah, I know about that! What about the isopropanol?!?

--
Thinking about her this morning, lying in bed, and trying to get my  
thoughts on the right track, I reached into the drawer of the bedstand,  
and found the Gideons' Bible, and I was going for the Psalms, friend, honest 
I was, but I found the Song of Solomon instead.         --- Garrison Keillor
Reply to
Adam Funk

Google is your friend. (it's 91%... which is what we buy for cleaning.)

George H.

Reply to
George Herold

Actually the data sheet for the stuff I've bought says 99.7%, and it just has warnings for flammability, eye irritation, & "may cause drowsiness or dizziness".

--
There?s never enough time to do all the nothing you want. 
                                               --- Calvin
Reply to
Adam Funk

)

Keep the cap tight. I think it will suck water out of the air till it reaches 91%.

George H.

Reply to
George Herold

On Wed, 04 Jan 2017 12:16:52 +0000, Adam Funk quoted:

The tag line says it all... ...Jim Thompson

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Jim Thompson

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