Lab Grade ethanol versus ABSOLUTE ALCOHOL

[Guest guest]

Hi All, & Thomas,

 

I wrote:

> Lab grade ethanol (NOT METHANOL] is 99.9% pure alcohol. If one

> takes 700ml of ethanol and adds 300ml triple-distilled deionised

> lab grade distilled water, one will have 1 litre of 70% pure

> alcohol.

 

replied:

> Actually Phil, " lab grade ethanol " is right around 95% pure as

> anything more than that is quite unstable.

 

Thomas, you are correct. I meant to say ABSOLUTE ALCOHOL.

 

> It is most likely if you are getting 99.9% pure alcohol it is

> methanol or rubbing alcohol, which is fine for external

> preparations but I avoid it just in case someone decides to drink

> one of my liniments. thomas

 

Agreed, but I was not referring to methanol! Other than in

homeopathic dilutions, methanol would be dangerous in

preparations for oral use.

 

Your comment prompted me to double-check with a senior analyst

in the Grange Blood Analysis Lab. My colleague consulted the

label on a bottle of absolute alcohol. ETHANOL (not METHANOL]

is the reagent in absolute alcohol that we use for chemical

analysis.

 

We expect our reagents to be >99.5% (often >99.8%) pure. Merck

(Germany) manufactures the reagent. The label states that it is

99.8% pure.

 

The highest grade ethanol available is used in some aspects of lab-

and histopath- work. For example, see:

http://ajp.amjpathol.org/cgi/content/full/154/1/83

 

It says: " H & E-Stained Tissue Sections: Sections of colonic

carcinoma tissue 5 µm thick, fixed approximately 24 hours in

phosphate-buffered saline buffered formalin (3.7%) and embedded

in paraffin, were deparaffinized by incubating the slides in xylene for

2 x 15 minutes, in 99.9% ethanol for 2 x 10 minutes, in 96%

ethanol for 2 x 10 minutes, and in 70% ethanol for 2 x 10 minutes

and stained with H & E. ... "

 

That said, many labs use " Lab grade ethanol " , a lower grade of

ethanol (circa 95%, as you said) in less critical work.

 

Thank you for alerting me to the error. I should have used the term

" absolute alcohol " .

 

 

Best regards,

 

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