Water in ethanol?
Peter Jason
ethanol. A routine rapid-test method is needed.
Is it possible:
1/ To buy test strips to detect between 2% to 0.1% water in
ethanol?
2/ To add some reagent to the ethanol which will change
colour if the water content exceeds 2%?
Please help, PJ
terry
I am not aware of any simple test strips or color test, but there are
certainly instrumental methods that can be rapid and routine, but the
equipment could be quite expensive.
Coulometric Karl Fisher ( I think these are about $10K but will give
you a result in about 1 minute.
NIR not sure of the cost of these but not cheap , again very quick
GC with TCD detector probably 5 min test but $50K instrument
You might want to look up variation of density vs composition. 2% may
be detectable by density difference. Karl Fisher and GC will get you
down to ppm levels.
Good luck
Terry
Salmon Egg
"Peter Jason" <p...@jostle.com> wrote:
There is much you do not say about the requirements. Is a sampling
technique OK or is there a process that requires monitoring? Have you
tried a consultant at a university or commercial laboratory? (I am not a
chemist looking for a gig.)
I would think that adding an appropriate acid or base insoluble in
ethanol and measuring pH with a meter or pH paper might work. But if you
cannot do that yourself, or be willing to pay someone means that you are
not yet desperate enough.
Bill
--
An old man would be better off never having been born.
Martin Brown
You probably want to add a sample of the ethanol to the reagent, but
anhydrous copper sulphate ought to do it. It is its own indicator.
You may have to work out how much to add to a test tube full to get best
sensitivity for water content.
Regards,
Martin Brown
Dirk Bruere at NeoPax
Conductivity?
--
Dirk
http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.blogtalkradio.com/onetribe - Occult Talk Show
Peter Jason
"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in
message news:57_%m.297$nR4...@newsfe01.iad...
Tried this already (dried CuSO4 on a plastic strip) but not
good enough.
Carl Ijames
a little checking and I think that the limit of accuracy even with a $2000
instrument is going to be about +/- 1-2%, sigh. I think either conductivity
or dielectric constant may be your best bet for lowest cost, followed by NIR
(near infra red).
-----
Regards,
Carl Ijames
"Peter Jason" <p...@jostle.com> wrote in message
news:l5WdneJY7ffnvNzW...@netspace.net.au...
Anonymous
> ethanol. A routine rapid-test method is needed.
As another responder noted, you don't provide enough context.
Nevertheless, David R. Burfield published a series of papers
on the preparation of "super-dry" (less than 1 ppm H2O)
solvents. Which means he had analytical methods down to 1 ppm
and below.
In SOME cases, he would spike his samples with tritiated
water and measure the residual tritium, post-drying.
Leading ref: J. Org. Chem., 1977, 42(18), 3660.
Burfield, Lee, and Smithers. "Desiccant Efficiency in
Solvent Drying. A Reappraisal by Application of a Novel
Method for Solvent Water Assay".
Also: D. R. Burfield, Anal. Chem., 48, 2285 (1976).
Using modern beta-counting (e.g., HPLC radiation detectors?
sensitivity?), you can probably get the info rapidly.
J. Chem. Tech. Biotechnol. 1984, 34A, 187-194
Desiccant Efficiency in Solvent and Reagent Drying 8. Molecular
Sieve Column Drying of 95% Ethanol: An Application of
Hygrometry to the Assay of Solvent Water Content
David R. Burfield, Glenn T. Hefter" and Donald S. P. Koh
He describes the design and use of a hygrometer.
The thesis you mention in the other thread ("Dehydrating ethanol.
New method.") does not cite or mention Burfield at all.
Anonymous
> ethanol. A routine rapid-test method is needed.
As another responder noted, you don't provide enough context.
Nevertheless, David R. Burfield published a series of papers
on the preparation of "super-dry" (less than 1 ppm H2O)
solvents. Which means he had analytical methods down to
below 1 ppm.
In SOME cases, he would spike his samples with tritiated
water and measure the residual tritium, post-drying.
Leading ref: J. Org. Chem., 1977, 42(18), 3660.
Burfield, Lee, and Smithers. "Desiccant Efficiency in
Solvent Drying. A Reappraisal by Application of a Novel
Method for Solvent Water Assay".
Also: D. R. Burfield, Anal. Chem., 48, 2285 (1976).
Using modern beta-counting (e.g., HPLC radiation detectors?
sensitivity?), you can probably get the info rapidly.
Specifically:
J. Chem. Tech. Biotechnol. 1984, 34A, 187-194
Desiccant Efficiency in Solvent and Reagent Drying 8. Molecular
Sieve Column Drying of 95% Ethanol: An Application of
Hygrometry to the Assay of Solvent Water Content
David R. Burfield, Glenn T. Hefter" and Donald S. P. Koh
He describes the design and use of a hygrometer.
The thesis you mention in the other thread ("Dehydrating ethanol.
New method.") does not refer to Burfield or these methods.
Autymn D. C.
> I remember using a refractometer to cover 0-100% ethanol in water but I did
> a little checking and I think that the limit of accuracy even with a $2000
> instrument is going to be about +/- 1-2%, sigh. I think either conductivity
> or dielectric constant may be your best bet for lowest cost, followed by NIR
> (near infra red).
Why is a refractometer $2000?
Carl Ijames
in the VWR catalog. The whole range of 0-100% ethanol in water is a span of
1.333 to 1.361 so if it is completely linear (it isn't :-)) then 0-2%
ethanol changes the refractive index from 1.333 to 1.3336, so one of those
little hand-held ones doesn't stand a chance.
We used this method to cover 0-100% in a pchem lab but I had to look up the
numbers to see if it would work over this narrow range, and I probably
shouldn't have posted it since it really isn't a good way to do this. I
think Karl-Fischer titration with an automated system would be the most cost
effective method in a testing lab.
-----
Regards,
Carl Ijames
"Autymn D. C." <lysd...@sbcglobal.net> wrote in message
news:3d8250ed-1cdc-4a8e...@q4g2000yqm.googlegroups.com...
Bernhard Kuemel
> Peter Jason wrote:
>> Desperately seeking a way to determine traces of water in ethanol. A
>> routine rapid-test method is needed.
>>
>> Is it possible:
>>
>> 1/ To buy test strips to detect between 2% to 0.1% water in ethanol?
>>
>> 2/ To add some reagent to the ethanol which will change colour if the
>> water content exceeds 2%?
>>
>> Please help, PJ
>
> Conductivity?
You mean the conductivity of the ethanol/water mixture itself?
Saturating it e.g. with NaCl should greatly increase the sensitivity.
Bernhard
Autymn D. C.
> One that can do +/- 0.00025 is, at least that was the spec on one I checked
> in the VWR catalog. The whole range of 0-100% ethanol in water is a span of
> 1.333 to 1.361 so if it is completely linear (it isn't :-)) then 0-2%
> ethanol changes the refractive index from 1.333 to 1.3336, so one of those
> little hand-held ones doesn't stand a chance.
>
> We used this method to cover 0-100% in a pchem lab but I had to look up the
> numbers to see if it would work over this narrow range, and I probably
> shouldn't have posted it since it really isn't a good way to do this. I
> think Karl-Fischer titration with an automated system would be the most cost
> effective method in a testing lab.
>
> -----
> Regards,
> Carl Ijames
>
> On Jan 4, 4:47 pm, "Carl Ijames" <x...@yyy.zzz> wrote:
>
> > I remember using a refractometer to cover 0-100% ethanol in water but I
> > did
> > a little checking and I think that the limit of accuracy even with a $2000
> > instrument is going to be about +/- 1-2%, sigh. I think either
> > conductivity
> > or dielectric constant may be your best bet for lowest cost, followed by
> > NIR
> > (near infra red).
>
> Why is a refractometer $2000?
Argh, you top-poster. I can see down to 15 microns, so resolution of
any sliver isn't much of a problem. Could one not whip up a cheap kit
with compound parabolic (uniaxial) reflectors.. or a laser or pinpoint
liht beam guide?
-Aut