Completely extracting cactus powder in a Soxhlet apparatus takes at least several hours even if the material is soaked in warm alcohol prior to extraction.

Since I already have an alinh condenser and hotplate stirrer, I was thinking about improving the extraction by boiling the cactus powder in alcohol in a refluxing setup (the alcohol vapors will condense and won't escape the flask.

The alcoholic extract will be then decanted or filtered and fresh alcohol will be poured in. This will be repeated three or four times.

I wonder how effective this would be compared to say 30 Soxhlet cycles or water extraction.

Of course, precautions will be made as this setup needs to be superwised, and the even boiling will be controlled by constant stirring.

I came to this idea since the extract tends to stick to the round bottom flask in Soxhlet and the residue on the walls gets burned and sticks to the flask.

Another option would be washing the cactur powder prior to extraction (removing fats and oils) using acetone, cold MEK or prefferably, cold ethyl acetate. However, I am not sure how any of these methods will be effective.

Any ideas?

Hmm I think a soxhlet would do a better job than the setup you are describing. Sure either one would work. But at least with the soxhlet all the goodies are constantly being extracted, where if you are refluxing in a RB flask, once your liquid reaches a certain concentration nothing more will be pulled out of the plant material.

Interesting topic alcohol extraction though. Someone tried it with cacti once and got a nasty emulsion, though with heat for some time it would have broken down the snot which someone didnt know at the time. Alcohol also pulls more tar than when you use good ole H2O. Generally alkaloid alcohol extractions are meant to skip the boiling step altogether because its a better solvent, but since cacti will form snot if you dont simmer the brew for a while, it seems aqueous is the way to go imho.

Without using heat it does form a "snot" for quite a while but eventually the pulp will settle if the right volume of liquid is used. If it never settles add more alcohol or you could try diluting it with water.

Okay I will probably stick with Soxhlet.

I tried MeOH, EtOH and IPrOH as solvents.

With isopropanol, almost nothing got extracted because when alcohol evaporates from the bottom RBF, the extracted material sticks to the walls and gets burned from the heating mantle. But this happened only with IPrOH which is probably an inferior solvent for cactus.

Water extractions have the snot problem which can be somehow remedied with PC but alcoholic extractions avoids the problem completely and no tedious filtration and cooking is required.

Hence the idea for alcohol refluxing having benefits of both worlds - the simplicity of water-boiling extraction and snot-avoiding and low-volume benefits of alcoholic extraction. Also it can be filtered and refluxed in fresh alcohol few times giving same or higher efficiency than traditional water extractions. The excess amount of alcohol can be distilled off to required amount with filtering while concentrating the extract.

Okay it takes only one piece of glassware to try so maybe I will do it as experiment some time