Yesterday an old argument reemerged in the lab. On discussing the use of an auto-column and the ways in which we can implement it in the lab and the ways in which time will be saved one of us mentioned that an auto-column MPLC would never be as good as a good ol' hand worked flash column.
Well, this discussion, I am sure, has been brought up in a number of scientific circles since the emergence of these new-fangled contraptions. Most notably, the Biotage Isolera (Image 1) and the Teledyne CombiFlash (Image 2) as well as the Kyle Finchsigmate's MPLC for the people (Image 3). But, are they as good as the good ol' hand column.
Well, here are the pros and cons that I can think of and I am sure some equally chemically minded person will come through with many more.
MPLCs
Pros:
- Set it up and walk away (do another experiment in the time it takes to run)
- Set up a solvent gradient to allow for greater separation.
- In the case of the Industrial machines, use of software to duplicate Rf separation from TLC plates is reportedly possible.
- Ready-made cartridge columns mean you don't have to worry about packing your column.
- Loading the column requires little to no time and doesn't require you to reach high up in the hood under the sash and try load your column without disturbing the silica.
- Small scale to large scale, it doesn't matter.
- Auto collection of samples with ELSD tech to let you know where your compounds are and in which fractions.
- Reusable columns (simply flush with methanol)
- Reverse phase simply requires a different column pack.
- Column can be set to not collect until it identifies a compound.
- Can be networked and allow for notification of completion.
- Higher pressure means faster run columns.
Cons:
- Some setup time required to start the column.(Probably simply comes with time and use of the machine the user should get faster.)
- Works better with small Rf separations rather than large.
- ELSD doesn't work without a chromaphore in your compound (duh).
- TLC mimic tech doesn't always work.
- Churns through a lot of solvent (but can be optimized with Isolera "Gradient Optimization").
- Any blockage may cause detrimental effects and lots-o-mess.
- One column at a time for the basic apparatus and this can cause lab fights (grrr)
- Someone's gotta look after the bloody thing or else it'll turn to sh!t.
Ol' Faithful Pros:
- Usually able to be run fairly quickly once you are proficient.
- Can usually get a good separation especially with large Rf differences
- Close to hand and no wait time in the lab.
- Can be relaxing and give you some time to reflect on some of the finer points in your thesis.
Cons:
- Time consuming running a big column and no free hands to do other work.
- Silica is often not recycled and discarded.
- TLCing your fractions only to find it hasn't come off yet is such a biatch.
- No automatically made solvent gradients means you pretty much make up a solution of a certain polarity and run it like that.
- Loose silica is bad for your lungs (like Cancer bad)
- Loading columns can be tedious
- Packing columns can be tedious
- Exploding glass columns, rare but can happen
- Ground joints on goose necks fusing to the joint on the column, so annoying
- Tubes flying off from too much pressure
Posts
I'm a big fan of getting a Multi Purpose Lab Companion. I think the biggest problem with the MPLC is this: it tempts people to use the automated features of the machine and throw their brains out the window. Eg if you can't get good separation on TLC, go back and do some solvent system optimisation first on TLC before whacking it on the MPLC... it's not going to magically separate it for you just because it's a computer.
ReplyDeleteIf good chemical sense is applied, an MPLC can be a real time saver.
Wow, fancy!
ReplyDeleteIn my opinion, it may be a time saver, but would probably cost a lot of money to buy it and to fix it. I like the old fashion way.. with sand :)
That's true. These save a plenty of time and consume less solvents, but costs a lot (starting price $ 19k for academic people).
DeleteI like to point out that ELSD (evaporative light scattering)does not depend on chromophore - UV does, so ELS is a more universal detection mode than UV.
ReplyDeleteHas anyone used the Revelleris (Grace Davison)? Would like comments on the ease of use and efficacy of separation.
ReplyDeleteOur lab has had the Grace Reveleris system installed for a couple of months now, it's great - very easy to use and means I spend less time doing tlc of fractions and washing tubes. You do still need to employ your neurons and do the leg work before you stick anything in the system as with hand-run columns. It comes with both uv-vis and els detection. There is software available form Grace that will do the tlc conversion but we don't have this function. I'm very proficient at columns (10+ years of practice....) and the Reveleris is much faster and has much less clean up. There are a few minor issues but generally it is quicker and cleaner than running columns by hand but still has some of the same issues such as not being able to directly transfer whats on your tlc plate to the column, but the system is interactive while the column is running so you can change your solvent gradient basically immediately. The silica particle size used is smaller than that used in normal flash but you get used to the corrections you need to employ - or you can purchase the conversion software I guess. And hey OrganicOverdose if you can't run a gradient flash column you're not trying hard enough.
ReplyDelete