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Rotary evaporation

aaron_33767

Hey guys- working on my home rig,a buchi r124 with vaccubrand diaphram pump with conrtoller (able to get down to 2 torr) and a thermo-scientific circulating chiller connected to the condenser.

My question pertains to what is optimal or ideal temp to run the chiller at for the coil condenser? The chiller can go down to -5C and I usually run it at 0C. Is there, or should ever be, a variance in in cooling temp for the condenser? I should also say that I do not go above 80C in the water bath. Here is a pic of the set up. With the older controller I am running test in timing for extractions of the volatiles to find the best results. I'm playing with nasturtium a lot right with it. Thanks in advance for any input.

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Chris_Young_80640

The colder the temperature of the condensing coil and the more of the most volatiles you'll recapture. Colder also lets you run the bath hotter so that you can go faster. In practice, I don't like to see the condensation line more than about 3/4 of the way up the coil. If it's higher than that, you're definitely removing too many volatiles.

aaron_33767

Thanks Chris!

aaron_33767

Chris,

What are your thought's on Dave Arnold's approach to the addition of the peristaltic pump? Do you have any experience with that?

jesper_echardt

I would really like to know what circulating chiller you use? I have spent MANY weeks trying to figure out what chiller to go with but I am really confused. Buchi do basically not have any circulating chiller (regardless of price...) specified below -10 C (and I have also discussed this with them and they think -10 C should be fine BUT the applications they are targeting are seldom not interested in the distillate itself as is the case for many (but not all) culinary applications). However, Dave recommends (urge...) to run the condenser at -20 C. Equally important is of course also the power at a given temperature (e.g. what is the power of the chiller at -20 C). So it would be interesting to have you opinion on this topic (with some "hard" fact, for instance power ratings for specific temperatures of the chiller you use). Your response is highly appreciated though I am in the process of investing in a chiller (now)!