Sciencemadness Discussion Board - chromatography column?

chromatography column?

Funkerman23 - 26-10-2012 at 23:34

For the members here who work in Organics: how often do you find a Chromatography column useful for your personal work? That is, outside of class or the company lab how often is a Chrom. column used? Just trying to get a general consensus on this as I may be able to get one soon and I am on a bit of a budget( among other factors). comments, critiques and replies are always appreciated.Thank you.

Endimion17 - 27-10-2012 at 04:08

It's not used exclusively for organic chemistry. Chromatography columns are used a lot in inorganic nuclear chemistry when you have to deal with minute quantities of substances that are easy to detect because they eject subatomic particles.

small columns = small capacity = small quantities = application in analysis

If you want to use such columns for making reagents in useful quantities, you have to use very large columns (and I mean very large indeed) and a lot of solvent. In conclusion, I don't find that neccessary to buy one. If I want to goof around with plant matter analysis, I can use a burette, too. They're basically the same thing.

Nicodem - 27-10-2012 at 05:14

Quote: Originally posted by Funkerman23

For the members here who work in Organics: how often do you find a Chromatography column useful for your personal work?

It depends on what the product is. For crystalline solids you can often get away without chromatography, but if it is an amorphous, resinous, oily or otherwise non-crystalline and non-volatile organic compound, chromatography is the first choice. For amateur chemistry, preparative chromatography is best avoided, because it consumes lots of solvents and lots of silicagel just to get a gram or two of a product (you can easily waste 1 L of solvents and 100 g silicagel for that much of a product). It is expensive and time consuming. And unnecessary, because an amateur can chose the chemistry to do, and so all you need to do, is to chose something that is easily isolable.

On the other hand, analytical chromatography, TLC in particular, is the best friend for an amateur interested in organic chemistry.

BromicAcid - 27-10-2012 at 05:54

It depends on the chemist

In my experience most chemists will shy away from using a column entirely because it does not scale up well, it's labor intensive, and time consuming. Solvents in the industrial world are pretty cheap so that's not a major factor.

Still there are other chemists that use column chromatography as their go-to purification if they're having issues because it can be very effective. And it CAN be scaled if needed, we have a column at work, 25 ft long, 1.5 feet in diameter that we use for those processes that were developed that can only be purified by column chromatography.

Point being you can probably get away without it, but it can be very useful.

Ozone - 27-10-2012 at 11:55

A straight condenser + glass wool + some end-pieces + creativity = jacketted chromatography column. I work out chromatographic conditions on TLC before scaling-up to a column.

Cheers,

O3

chemrox - 30-10-2012 at 00:22

Everybody was right in his own way. The amateur chemist may want to use a column to clean up a messy product before investigating the recrystallization parameters. I like flash for this. I have one 5 cm X 900 mm column for that. I use the cheapest hardware store solvents I can find and distill them when needed. TLC is a good way to check the feasibility of doing that kind of cleanup. TLC is great for working chemists as well as amateurs. I use it all the time. I buy precoated glass plates and have them cut at the window shop. There some expensive software that can be used to quantify spots. I wish someone here would post it somewhere....I'll look it up and post the ref back here so we can all look for it.

[Edited on 30-10-2012 by chemrox]

Funkerman23 - 30-10-2012 at 08:40

Quote: Originally posted by chemrox

Everybody was right in his own way. The amateur chemist may want to use a column to clean up a messy product before investigating the recrystallization parameters. I like flash for this. I have one 5 cm X 900 mm column for that. I use the cheapest hardware store solvents I can find and distill them when needed. TLC is a good way to check the feasibility of doing that kind of cleanup. TLC is great for working chemists as well as amateurs. I use it all the time. I buy precoated glass plates and have them cut at the window shop. There some expensive software that can be used to quantify spots. I wish someone here would post it somewhere....I'll look it up and post the ref back here so we can all look for it.

[Edited on 30-10-2012 by chemrox]

Unless I am very much mistaken flash chromatography requires preloaded "cartridges" and unique columns to use.useful no doubt but not financially appealing( that and I haven't found anyone selling these things to individuals either.. but suggestions here are very much appreciated) I asked as I know chromatography is used to separate organics that otherwise are a pain to purify.. But.. a few grams of product for all that work& supplies needed isn't very appealing.I had hoped that greater yields where possible..hmmmmm

Funkerman23 - 30-10-2012 at 09:14

Pardon the dumb question but in lieu of a C.column what other methods do you recommend for separating organics like the ones mentioned( resinous, non volatile,etc)?

Quote: Originally posted by BromicAcid

It depends on the chemist

Nicodem - 30-10-2012 at 13:00

Quote: Originally posted by Funkerman23

Unless I am very much mistaken flash chromatography requires preloaded "cartridges" and unique columns to use.

Indeed, you are very much mistaken. Flash chromatography is one of the separation techniques that requires the less equipment. All you need is a glass tube with a stopcock at one end. You will also need some cotton, some sand, the stationary phase (most commonly silicagel) and the mobile phase (for example, ethyl acetate and petroleum ether). It is not the glassware that is the problem for the amateur, because it can be improvised and built from other purpose equipment (see Ozone's reply). It is the amount of solvent per gram of isolated product that is the annoying non-amateurish part of the process. Silicagel can eventually be recycled, and so can the solvents be, but then it becomes too much of a fuss for too little product.

Lambda-Eyde - 30-10-2012 at 14:09

You'd also need a source compressed air/nitrogen/argon. Also, columns can be bought on eBay easily, so there's no need to improvise. I agree that the problem lies in the silica gel and massive amounts of solvents used. If one has good routines and equipment for redistilling solvents and silica gel I think it's doable, though.

Dr.Bob - 1-11-2012 at 06:02

For flask chromatography, the general rule of thumb is that you use 10-100 times as much silica gel as crude product. For tough separations or where you need very high purity, 100 is generally good or overkill. But for many separations, especially if the product is not very dirty or the separation is easy (removing baseline material from product), then using 10 x is often sufficient. That may seem like a lot, but for a gram of product, 10-20 gram of silica gel is often enough to get it clean enough to then crystallize, which will then improve the purity even more.

For example, recently I made ~10 grams of a crude material, which would not crystallize, but after running it through a 80 gram silica gel column, I was able to go from about 60% purity to 90% or better, which was enough to allow it to then crystallize, which brought the purity to over 99%. Another example are amide couplings, which often contain acid SM, amine SM, HOBT, TEA, and other coupling agent byproducts. But if the amide is non-polar, it can often be pushed through a "plug" of silica (maybe 4 grams for a 400 mg reaction) to remove the baseline (on TLC) materials to give clean amide product. The main cost is in solvent, but if you can find simple cheap solvents, and/or reuse them by distillation, then the cost is not too bad. And while silica gel is not cheap, you can buy small amounts of it on ebay (even preloaded columns) or elsewhere for prices that are not too bad.

use of c column

wiccanchemist - 1-11-2012 at 10:42

In my lab at University I used a lot of times column croma because is more expensive to use HPLC in cantitative separation.
I use c. croma to separete my product from reactants then send the sample to NMR and x-ray diffraction to confirm the structure. For example I synthetized a product that have 2 close related structures and i separated them with c croma by gradient elution all of the work was done by close analysis of TLC.

Chroma Column for Addition

malford - 4-8-2013 at 15:05

Any reason a chromatography column wouldn't work well for drop addition? They seem to be much more plentiful on the secondary market that addition or dropping funnels.

adamsium - 4-8-2013 at 18:23

Quote: Originally posted by Funkerman23

Unless I am very much mistaken flash chromatography requires preloaded "cartridges" and unique columns to use.

Although this was already addressed, I just wanted to add that it seems you are thinking of automated flash chromatography systems such as the Biotage Isolera and similar. These are horrendously expensive (for an amateur, anyway), as are their pre-loaded cartridges. They are just amazing, though. See: http://www.biotage.com/DynPage.aspx?id=58261

In finding that link, I found that they now make a model with integrated MS.

*I want one*

smaerd - 4-8-2013 at 18:27

Can do flash with an aquarium pump for small diameter columns. Peristaltic pump to add eluent.

If its for basic analysis a pastuer pipet column can be used for a microscale column and eluted with a rubber bulb.

I'm pretty surprised at just how affordable a small isocratic used HPLC system could be had by an amateur. Not for preparative separations but for analysis it'd be fine.

I have yet to master home made TLC plates but thats my next adventure. I think there are simple ways to make the process a lot easier and reproducible. It's an art I'd like to see resurrected.

Preparitive TLC doesn't look too bad for small quantities of compound as well. Applicators can be made relatively easy.

Some people have had good results performing chromatrography with flint glass dust from pottery supply stores of the appropriate mesh size. Probably rinsing it first and drying it. That helps cut the cost but we can't kid ourselves the surface chemistry isn't the same as commercial silica gel.

I like the idea of reverse phase media as it uses polar solvents for elution. Polar solvents in general are cheaper and available in quantity locally. It'd be nice to see a OTC fix for that. Most are modified stationary phases though.

There are all kinds of tricks around running columns it's pretty hard to say which is best or more applicable. I think we have yet to find the best way. In my opinion it really all boils down to work up. Can the compounds be separated with a Liquid Liquid Extraction, crystallization, distillation, solid phase extraction, and or do I need to run a column.

Dr.Bob - 5-8-2013 at 13:13

Quote: Originally posted by smaerd

Can do flash with an aquarium pump for small diameter columns. Peristaltic pump to add eluent.

I will agree with many of your hints, but for most solvents (other than maybe water), an aquarium pump is NOT going to work or be safe (if flammable). A Peristaltic pump may work if right tubing is used, but many of those are not designed for organics either.

If people are looking for columns, I still have a pretty wide variety of glass columns (1/2" - 4+" diameter) as well as a few small pre-loaded silica gel cartridges for various older systems around. I have some photos but not of all of them. But I have them in most every size and style available, plus some accesories for them (reservoirs, flash flow controllers, etc)

smaerd - 5-8-2013 at 16:41

The aquarium pump is for air pressure not moving solvents. Should have been more explicit. I am a proud owner of several of Dr. Bob's columns, definitely a great person to do transactions with.

Dr.Bob - 6-8-2013 at 06:15

So sorry, I just wanted to make sure that someone did not think of using the pump with the solvent.

I mostly use pumped solvent driven columns now, so I am biased towards thinking of the solvent being pumped, not the air. But for pressuring a flash column, an aquarium pump might be ideal, as it won't generate too much pressure.

For home use, I really like the air pressured 2 tank gradient formers, a company called Elution Solutions made a nice, simple, inexpensive, one for a while until they were bought out by a bigger company and closed. You just put A and B into 2 vessels, then pump air into A, which forces it into tank B, where it mixes well, hopefully, and then it is pushed into the column. Very simple way to make a gradient, but dependent on good mixing. Best for small columns.

Chromatography Column Use

Dr Lauren - 10-8-2013 at 07:28

I use the following depending on the scale, cost, and availability:

Liquid, Liquid Extraction, Solid Phase Extraction, TLC, Chromatotron, and then Column Chromatography. Some of those pertain more to product isolation rather than purification.

Best to buy a large top reservoir to fit onto your column, if it is glass. A large separatory funnel (w/stopcock) could be mounted above the column and opened to allow loading of the column and then application of the various eluents/solvents to elute the purified target compound.

I once had an industrial scale stainless steel column for purification of proteins. The thing was 36 inches in diameter and over six feet tall. It had its own packing system otherwise we never would have loaded the thing with an even layer of solid phase material. It took 75 kilograms of silica gel slurry to pack the column. As you can imagine the solvent use cost a small fortune. The yield was 45% of a 99.2% pure product, so that made it all worthwhile!

If i have an old picture I will post it sometime.

<hr width="90%" />
Have you ever heard of a Chromatotron? http://www.harrisonresearch.com/chromatotron/

It can be rigged to recover purified product after it has passed through a separating/purifying layer of solid phase material (silica or alumina depending on how you choose to set yours up). A large chromatography column may well be more trouble than it is worth. Try to explore liquid-liquid extraction methods to pre-isolate as much of your target product as possible and then use only as large of a chromatography column as you can pack manually. Get sand and clean the heck out of it and also buy some glass wool.

Also, the purity of your eluents/solvents is critical and you will use quite a bit if you plan on cleaning and recycling the solid phase material. I know a supplier of bulk silica gel in Morrisville, NC and you can pick your sieve size/porosity. He only communicates via email, but if you decide to buy a column, you can obtain the necessary silica gel in bulk at a fair price. Note that I am not affiliated with that company however I have bought from them many times and have no complaints other than ordering via phone would be convenient.

You probably already do, but before running the product through a prepared column, perform TLC to make sure you have the right eluent mixture to separate and purify your target product. I recommend that you make your own TLC plates and try using a variety of eluents having near-identical polarity and pH to see if a cheaper one will accomplish the separation. For a quick TLC plate I make my own using microscope slides, plaster of paris-silica gel-solvent slurry, and an warm oven. You can find multiple videos or tutorials online for making TLC plates and also preparing and packing a column.

[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: merged sequential posts]

[Edited on 10.8.13 by bfesser]

bfesser - 10-8-2013 at 07:38

Quote: Originally posted by Dr Lauren

Have you ever heard of a Chromatotron? http://www.harrisonresearch.com/chromatotron/

<strong><a href="viewthread.php?tid=10030">Chromatotron - radial chromatography.</a></strong>

Please edit your existing post to append any additional comments, rather than posting another reply. Thank you.

[Still not sure how you posted two in such quick succession (1 min.)—must have been copy-paste.]