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Author: Subject: How to purify a chemical to analytical grade
Quantum
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[*] posted on 6-6-2005 at 12:19
How to purify a chemical to analytical grade


This is of course all thinking as I don't have the money to buy such purification equipment nor any chemicals I wish to purify to such a high standard.

My question is what equipment would one need to purify a somewhat unstable bioactive chemical to medical grade(for ingestion) to say 99.99% clean all one isomer ext. The starting product would be somewhat dirty - perhaps not even clean crystals but just a gunk depending on the chemists skill.

The chemist might have say about a gram and want to be able to purify it batch or all at once with such equipment. It would later be split into say 100 microgram units so a machine that can only handle chunks of microgram mass ( say for MS) would not be good.

After all its not much point to make such a chemical if one can not purify it.

[Edited on 6-6-2005 by Quantum]




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vulture
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[*] posted on 6-6-2005 at 12:36


The problem is that the purification process itselfs inserts further impurities. Glassware that's not 100% clean, contaminated solvents, etc.

Impurities are best excluded from the start as every purification step is just a compromise unless done with very pure reagents and you'll lose massive amounts of yield.




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[*] posted on 6-6-2005 at 13:16


It rather depends on what you want to purify and what the impurities are. For some materials a couple of recrystalisations will get to 99.99%
For some mixtures your only hope is something like preparative HPLC or CG.
In general, working with small quantities is fiddly, and so it's less efficient.
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[*] posted on 6-6-2005 at 15:20


Quote:
Originally posted by vulture
The problem is that the purification process itselfs inserts further impurities. Glassware that's not 100% clean, contaminated solvents, etc.

Impurities are best excluded from the start as every purification step is just a compromise unless done with very pure reagents and you'll lose massive amounts of yield.


Vulture you couldn't be more right. But consider high purity chemicals come from somewhere. On that note Quantum you should investigate thoroughly the properties of the compound you are interested and become an authority on that compound and related products.

Most manufacturers specialize. Maybe company A is great at making reagent grade Hydrobromic acid so they carry this expertise toward compounds like ammonium bromide, cupric bromide, ethyl bromide, etc etc. Get the idea? Why not apply the same philosophy to hobbyist chemistry?

[Edited on 6/6/2005 by chloric1]




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Quantum
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[*] posted on 12-6-2005 at 14:39


Hmm. I have done research and flash or gravity chromotography is a good choice. I have got a supplier(UGT) that sells the columns for not to much.

I read about them and how to use them and such and it seems your 'efluent' drips out the bottom with the compound inside it. The question is how do you know when to catch the drips that have just what you want in them?

I have ordered a Organic Lab Manuel so soon all these stupid questions I have will be answered I guess.

Who here has column chromotography?




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Lambda
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[*] posted on 12-6-2005 at 17:04
Stupid questions ?????


Quote:
Originally posted by Quantum
I have ordered a Organic Lab Manuel so soon all these stupid questions I have will be answered I guess.


Quantum, nothing is as stupid as not to ask in the first place. It is easy to stay ignorant, as most people are, for they rather avoid the "shame" of asking.
Please check these books out on eMule, they may be of great benefit to you, and they are free !!!!

Purification of Laboratory Chemicals (Fifth Edition).pdf (20.15 mb)
http://rapidshare.de/files/2375720/Purification_of_Laborator...
Purification of Laboratory Chemicals_4th ed.pdf (37.29 mb)
http://rapidshare.de/files/2369172/Purification_of_Laborator...
Academic Press, Encyclopedia of Biological Chemistry Vol. 1 (2004); BM OCR 7.0-2.5.pdf (23.21 mb)
http://rapidshare.de/files/2350280/Academic_Press__Encyclope...
Academic Press, Encyclopedia of Biological Chemistry Vol. 2 (2004); BM OCR 7.0-2.5.pdf (19.43 mb)
http://rapidshare.de/files/2349890/Academic_Press__Encyclope...
Academic Press, Encyclopedia of Biological Chemistry Vol. 3 (2004); BM OCR 7.0-2.5.pdf (18.99 mb)
http://rapidshare.de/files/2350280/Academic_Press__Encyclope...

"The Total Bio-Chemical Laboratory Manual" is also available.

Allso search "chromatography", "Biological", "Bio-Chemical", "Purification" and "Chemistry".
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[Edited on 14-6-2005 by Lambda]
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[*] posted on 13-6-2005 at 00:00


Quote:

I read about them and how to use them and such and it seems your 'efluent' drips out the bottom with the compound inside it. The question is how do you know when to catch the drips that have just what you want in them?

If you compound is invisible, so it doesn't have a colour, TLC might be an option.
So you eluate every 5 minutes in a different vial, do TLC on all of them, and then look in which vail(s) your compound is.

Before you indest anything, I would search someone with some spare time and an analytical instrument to see what's actually in there...




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[*] posted on 16-6-2005 at 09:47


Am I mistaken or is the link for Encyclopedia of Biological Chemistry Vol. 3 identical to the link for volume 1?
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Lambda
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[*] posted on 16-6-2005 at 11:09
Volume 3 is wrong, and will be uploaded again


Sorry about this IrC. strang that it is only now noticed, for this file has been downloaded 9 times.

I don't seem to be able to edit my post, but this will be corrected as soon as I can find volume 3, and uploade it again.

Thank you for observing this error !

[Edited on 16-6-2005 by Lambda]
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[*] posted on 16-6-2005 at 12:33


buying it pure might be cheaper.
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Lambda
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[*] posted on 18-6-2005 at 21:23
ERRATA ! Academic Press, Encyclopedia of Biological Chemistry Vol. 3 (2004)


IrC had rightly remarked about the erroneouse link that I had given to:
Academic Press, Encyclopedia of Biological Chemistry Vol. 3 (2004)

I have uploaded this book again to Rapid Share.

Academic Press, Encyclopedia of Biological Chemistry Vol. 3 (2004); BM OCR 7.0-2.5.pdf (18.99 mb)
http://rapidshare.de/files/2475331/Academic_Press__Encyclope...

I apologise for this mistake.
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[*] posted on 26-7-2005 at 21:13


When you are talking micrograms, tlc is not always the best bet, especially if it is hard to detect, if it has color it would make it somewhat more easy. And usually crystalizations work better if you have more products because you would filter away your junk. Sounds like a tough one if you dont have alot of the product. say 5grams at the least.
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[*] posted on 27-7-2005 at 01:09


Im trying to build a verticle zone melting/refinement device, As a alternative to recrystalisations. Along with a few other things.

Ive found that Analytical chem texts all have "sample preparation/purification" chapters, its worth looking into....
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neutrino
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[*] posted on 27-7-2005 at 06:08


I was thinking that too, but I don't think an unstable chemical would survive too many meltings.
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[*] posted on 14-12-2005 at 21:37


Quote:
Purification of Laboratory Chemicals (Fifth Edition).pdf (20.15 mb)
http://rapidshare.de/files/2375720/Purification_of_Laborator...
Purification of Laboratory Chemicals_4th ed.pdf (37.29 mb)
http://rapidshare.de/files/2369172/Purification_of_Laborator...




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[*] posted on 14-12-2005 at 21:53


Well, it is over 5 months old...
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[*] posted on 15-12-2005 at 05:31


Quote:
Originally posted by jqwhy
Quote:
Purification of Laboratory Chemicals (Fifth Edition).pdf (20.15 mb)
http://rapidshare.de/files/2375720/Purification_of_Laborator...
Purification of Laboratory Chemicals_4th ed.pdf (37.29 mb)
http://rapidshare.de/files/2369172/Purification_of_Laborator...




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kazaa81
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[*] posted on 10-8-2007 at 06:45


I'm sorry to bring up such an old thread but...

wouldn't be better to upload "Purification of Laboratory Chemicals (Fifth Edition)"
on another web hosting, instead of rapid sha re?

I couldn't find a working link about these books all trough the forum !

thank you

[Edited on by kazaa81]
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[*] posted on 10-8-2007 at 07:10


VoilĂ  ici:
http://www.megaupload.com/de/?d=MPCOHWJE
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kazaa81
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[*] posted on 10-8-2007 at 07:48


thank you!

is it just me, or that wasn't OCRed ?

being tired of rapidshare and/or megaupload for obvious reasons,
I've uploaded it on uploading.com

http://www.uploading.com/files/W1NJMAO4/Purification_of_Labo...
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[*] posted on 11-8-2007 at 04:38


If you mean ACS AR grade then you need the large and costly ACS book of specifications to start with. These are unique for every listed substance.

One of the major purification techniques is chromatography, so you are likely looking at prep scale ion chromatography, size exclusion, gel filtration, HPLC, etc. Ion exchange resins.

In many instances, unless you are equipped to do the job already, there will be no cost effective way to get to AR grade that will compete with buying the requisite compound in that grade. It's a matter of economy of scale. The capital expense might be the same to make 25 g or a ton, you see.
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