It looks like the folks at analtech need to put that cyclograph in a hood where they won't breath the solvent fumes.
As a disclaimer, the fine folks at Analtech had nothing to do with my posting this, other than making me laugh with their ad. I could use a couple 4 mm cyclograph plates though.
What is your view of the cyclograph? I am very interested in this device, especially as a grad student who would like to live outside the lab a little. It seems like a very good idea, just a high initial investment. Plates can be made by hand. No high pressures and easy to visualize if there are chromophores. Since you have 18 years experience what do you think?
ReplyDeleteThanks Felix for reminding me how ancient I am. I actually have 25 years of experience with this technique.
ReplyDeleteLet me start with the technique itself. It is also sometimes call a Chromatotron (Harrison Research's name for it).
I believe it was originally designed to replace Prep TLC for isolating materials. I doubt the most in the younger crowd has ever used this technique.
It is rather flexible. I have only used silica but you can use alumina, cellulose and an number of other stationary phases.
You don't need a chromophore per se. If you can see the spots on TLC with a UV lamp you will be fine. If not, collect in tubes and use the same method to visualize that you would use otherwise. Many of my compounds are very difficult to see but can be seen on the "tron" and because they have poor chromaphores can't be seen on the ISCO flash system I have back in my lab.
I have never used a plate bigger than 4 mm thick. I have separated material from 50 mg to 2 g scale. I believe that some people use plates up to 8 mm.
It uses less solvent than flash, which is a plus for those of us on tight budgets. You can also do manual gradients to speed up the elution.
Done well it is about as fast as flash. If it is taking longer, you need to reconsider your solvent choice, or use a gradient.
One nice thing is that if I have a clean band, I just collect straight into a round bottom and then throw it on the rotovap.
It is great for teaching since you can see the bands separate and broaden. Use the tron for a while and you will be a better chromatographer.
You can reuse the plates, if you are careful to remove the baseline crap that does not move on TLC.
The initial cost can be mitigated. With all due respect to the Analtech folks, Harrison Research did this technique first and does it for lower cost. I don't want to get into trouble for advertising, so I will let you find the Harrison Research Site.
My students always have difficulty making 4 mm plates, so I buy them from Analtech. We make the 1 and 2 mm ones ourselves.
I how this helps.
T. S. Hall
This comment has been removed by the author.
ReplyDeleteI come from a CSU campus so resources are tight. Column chromatography is very expensive for a small campus, especially since there are no PhD students with lots of years to spend running columns. It's even more difficult when we don't have a good vacuum available and a cooled trap, especially with all that solvent. Students often grow very tired of columns and skip out on synthesis completely and go for an analytical chemistry background instead.
ReplyDeleteThe cyclograph seems like a good fix for routine chromatography. I was wondering if it makes life any easier for your students. I want to teach at a CSU but I see this as a major problem, especially since many students just quit synthesis because of all the time it takes. I've seen it happen.
Making chromatography a little simpler may go a long way or I may be just to optimistic about the chromatotron/cyclograph idea.
I originally found the Harrison model since a fellow grad student knew the inventor's son. But the Analtech brand sticks in my head a lot, especially because of the commercial and the fact that it is a little prettier than the chromatotron.
ReplyDeleteWe have a flash chromatograph with fraction collector and UV display. That makes my students lives easier. If that is not available they go the the tron. They only run columns by hand if they have no choice.
ReplyDeleteI assume CSU is the California State University System and not Colorado State University. For those that don't know the CSU is the non-RO1 state "supported" system in California.
I will pick up the, How do you keep them in the hood when they have seen analytical?, issue in a future in a future post.
I do mean California State, sorry about that. Those machines do make life a lot easier, I have access to those since coming to grad school. Keeps students interested and gives them valuable experience for industry positions where time is money, and I'm not kidding at all. I interned at a company, hand columns are still common but are used when it fits the job. All hand techniques are there and it's a valuable skill since machines break a lot.
ReplyDelete