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TLC of pharmacueticals

Adrenochrome

Adrenochrome

Ex-Bluelighter
Joined
Dec 3, 2004
Messages
979
Has anyone here ever extracted pharmacueticals using thin-layer chromatography with a large plate (as a means to isolate ?
If so, which and any comments about it?
If not any comments?
I believe you'd have to protonate drugs with carboxyl groups by using an eluent with .5% glacial acetic acid, thereby discharging (my intentional pun;)) them to traverse the adsorbent; what would be an appropriate eluent mixture for drugs with amine groups?
Cool thanks :)
(We're a regular TLC (small plates so for extraction) with lame pills like Aspirin, Anacin, Bufferin, Cope, Excedrin, Tylenol, B.C. Tablets, Advil, Aleve, & Orudis)
 
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preparative TLC is pretty limited in terms of quantities produced.
however TLC of LSD in blotter or liquid is a useful purification technique, because the quantities are very small and the pure LSD area can be simply cut out. the solvent of choice is a non polar solvent mixed with a small quantity of polar solvent and ammonia. so toluene, IPA, and concentrated ammonia (10:1:1) is a good starting point. Dichloromethane in the presence of ammonia vapour works well too but dichloromethane is a bit too volatile, chloroform is the best but has its own serious problems.The plate should be silica on aluminium rather than glass so it can be cut though the coating could always be scraped off glass plates. Alumina probably works well too. UV light to reveal the spots.

solvent choices for mixtures of products are a bit of a black art, and often a 2D run using different solvent mixtures is required, so mostly non polar in one direction and a polar run at right angles to it.
Generally with amines, a non polar solvent mixture with ammonia or other base works. the silica or alumina is the polar phase.
carboxylic acids tend to smear whatever solvent mixture is used.

maybe reverse phase TLC is possible too for prep purposes, however it is much more handy to use reverse phase TLC to pick the solvents for a proper prep or semiprep HPLC run.

as for quantities TLC is good up to about 100mg I guess it could be pushed into grams.
hplc up to a couple of grams, unless you have a serious HPLC machine >20-30 ml a minute and large bore columns.
if the products/impurities have highly differing rf values than flash chromatography through a short wide column is really good for hudreds of grams.

centrifugal chromatography is an interesting one too, and the machine has a cool 1950's name, the chromatron, a bit like the orgasmotron, though I think PuroRama would have better.
 
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What? Am I the only bluelighter to ever use cellulose or hydroxyethylcellulose solid phases? :)

Has anyone ever used the radial compression systems? Waters (at least) used to make them. Short fat little columns that were in a plastic tube instead of steel - you put them in a holder that applied radial compression to the cartridge. They were pretty good for doing semi-prep scale HPLC on a regular HPLC system.
 
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retired_chemist said:
What? Am I the only bluelighter to ever use cellulose or hydroxyethylcellulose solid phases? :)

Has anyone ever used the radial compression systems? Waters (at least) used to make them. Short fat little columns that were in a plastic tube instead of steel - you put them in a holder that applied radial compression to the cartridge. They were pretty good for doing semi-prep scale HPLC on a regular HPLC system.
Click to expand...

cellulose....not since separating felt tip pen ink at school....:)
its kind of inconsistent..
 
retired_chemist said:
What? Am I the only bluelighter to ever use cellulose or hydroxyethylcellulose solid phases? :)
Click to expand...

I'm still a student of orgo, would this technically be considered that be called paper chromatogrpahy?

If it is then probably saying its one or the other is trivial, but its those trivial questions that get me on my tests ;)
 
vecktor said:
cellulose....not since separating felt tip pen ink at school....:)
its kind of inconsistent..
Click to expand...

Oh I actually did real paper chromatography too, LOL. Talk about old school. Paper strips, then spraying them with p-Dimethylaminobenzaldehyde, Rhodamine B, Bromocresol Green etc to visualize them. God that sucked.

But they actually make regular TLC plates, quan and prep sizes with cellulosic phases. I doubt they are used much outside of the dyestuff industry. Good for polysulphonic acids - those things stick like glue to silica, tend to not stick at all to C18 silica...
 
Adrenochrome said:
I'm still a student of orgo, would this technically be considered that be called paper chromatogrpahy?

If it is then probably saying its one or the other is trivial, but its those trivial questions that get me on my tests ;)
Click to expand...

See the above, but like I say, they are pretty specialized plates. If you get a question in basic org it's probably gonna refer to paper chromatography.
 
fastandbulbous said:
Try biochem where you're spraying known mutagens like ethidium bromide (used for DNA)
Click to expand...

OK since we are down to war stories, and F&B's box is too full to accept PMs ...

I guess you poured a lot of acrylamide EP gels too?

I had to scale up a polyacrylamide production from lab to 2000 gal glass lined reactor. We did not have tank space for a proper line so we had to buy acrylamide monomer as 50% solution in 55 gallon drums.

Never had a serious accident, but between plant life and research - sulfur hemimustards, vinyl sulfones, aziridines, bis(2-Bromoethyl)amine, you name it - I don't expect to be in the old folks home for long. :\
 
Ive poured some acrylamide gels lately, for wesern Blots. Also using some TLC to quantfy the lipid content in Arabidopsis plants

We have an imager that determines every thing from charts on the concentration to the Rf vaues
 
I've done simple TLCs with OTC analgesics. I've used both silica and alumina (usually best) plates with 5% acetic acid in Ethanol for extraction. Solvent was varying mixtures of ethyl acetate/ n-hexane, mostly 50:50 and 80:20 ratios.

Edit: Also had some experience with column chromatography; mixtures and diastereomer separation etc...
 
I love doing column chromatography, I purify Antibodies in a study of Calcium Dpendent Protein Kinases, With a sulfo link resin that binds that reduce disulfide bridges. I run 10 samples of my elution in the spec and take the 3 most concentraated and concentrate them further in dialysis tubing with TBS.

drip drip drip drip drip dripdrip drip dripdrip drip dripdrip drip dripdrip drip dripdrip drip dripdrip drip drip!


on topic Ive used TLC to half ass positive test for LSD, Someone in the LSD testing thread said to put it in EtOH (and atmosphere) and use a UV lamp to look for two spots distinct spots for iso-LSD and LSD. At work we use a Iodine developing chamber tobring out the color. Im a tad skeptical as to how accurate it the acid test was
 
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