The common concept is that a solvent can be used just that many times, after which it becomes "saturated" and does not pull that efficiently. After this point one has to either distil the solvent to a (considerably) cleaner, reusable distillate or simply to discard the solvent somehow and/or evaporate it to collect whatever traces may be left behind. The distillation route is the most reasonable thing to do, but it is a technology to which the vast crushing majority of kitchen chemists do not invest to, for reasons of safety, time, money and what not. Since distillation cannot be widely recommended (on the contrary, it should be suggested to with caution!) there appears to be no much to do other than discarding overused solvents (i.e. the ones that do not evaporate easily like limonene, xylene, toluene, heavy naphthas) or just evaporating them (light naphthas, dcm, chloroform).

Both discarding and evaporating are wasteful processes that seem to be a "necessary evil" amidst lack of distillation apparatus and knowledge to distil safely, but does it need to be so? I will argue here that a solvent can be used a million times without its ability to pull freebases be compromised to any detectable degree. The spark for this thesis comes from a friend who was performing some extraction on mhrb with limonene that had been used to extract at least 500g of mhrb previously as well as roughly 1.3 kilos of cactus powder in a period of a couple of years. After repeated saltings with acidic water, this orangey limonene had been finally washed with salty water and stored till its recent use. Bottom of the line is that this guy's yield using this overused limonene was as expected and comparable to what he'd yielded from using fresh, virgin limonene. It is this apparent lack in efficiency loss between the fresh and the overused limonene that prompted me to re-think about solvents and make this post.

First off, I think that there are not enough (and not reliably enough) hard data regarding any diminishing ability of a used solvent to pull freebases. It all stems from empirical subjective observations and the apparent intuitive predisposition that "the more used a solvent is, the worse it will perform". But given the lack of hard data and measurements, we cannot really make such a conclusion. This is a serious gap but easily filled as people take on experimenting more with their extractions.

Second, what really happens to a solvent after many pulls? From clear transparent it goes to light yellow, then deeper yellow and so on, this coloration coming from plant fats, oils and other lipophilic substances. The more the solvent pulls, the more complex it becomes, but does it become saturated, let along a poorer solvent for freebased alkaloids? Saturated is a poor and misleading term since a solvent can be called saturated with respect to one solute, say dmt freebase or caproic acid or whatever. And does the term saturation apply in our case? Can one saturate olive oil with, say castor oil? Well, no since olive oil and castor oil are miscible in any proportions. Same goes for limonene and acetone. Can you saturate limonene with acetone? Again, not. The remark here is that an overused non-polar solvent just gets enriched with more fats and oils that do not exactly saturate the non-polar solvent used in the extraction, but they merely enrich it. To use other words, they make a complex solvent different from the starting one, e.g. one may state that in his extraction he used "a combination solvent of limonene and cactus fats and oils" to pull dmt. The question is: does this combination solvent perform better, worse or the same regarding its ability to pull the desired freebases compared to the clean solvent? Well, the answer can go either way, but from the incident extraction described above I am more inclined to believe that there is not much difference or in the worst case scenario, there is not going to be a negative impact serious enough that cannot be rectified by doing a couple extra pulls.

Third and last, people already use and report successful extractions of both cactus and mhrb using sunflower oil, canola oil, lard, dog fat etc. These oils are a freaking combination of painfully diverse plant fats and oils. In fact, these oils can be viewed as if one had taken an overused non-polar solvent, distilled off the solvent part then only used the residual oils for his next extraction. Or, it is as if one had used his non-polar solvent so any times that now the ratio of plant oils/fats to limonene is 100000000:1

So, end point thus far is that there is no much rationale on talking about overused, "weak" solvents. Hard data may indicate otherwise (after all, all my points are purely theoretical, stemming nevertheless from a single but convincing observation). Finally people should be encouraged to use the hell out of their solvents instead of throwing them away and if they feel that the yield is lacking behind, then they can do few extra pulls with fresh solvent and see for themselves if anything was really left behind. Any criticisms/discussion/refuting/questions on my points are greatly welcome,


Cheers,
Infun

Awesome post! Ill def add this to the FAQ

Thanks and thanks again for sticking it!

I am also very eager to hear about other people's experiences with heavily used solvents!

I don't have vast experience with re-use, but it seems that I end up pulling less oils and undesirable stuff with saturated solvent.

I have used the same solvent at least 5+ times, and it's a nice deep yellow.

Another useful and fairly simple method, besides distillation, for cleaning up a solvent that has been 'dirtied' with various undesired substances. Is to use a bit of activated charcoal. It adsorbs anything you were unable to get out with water washes, carbonate washes, acidic washes.

Ive gotten practically all of the colour out of solvents with this method, though, mine were not dark dark, opaque yellow coloured.

It can be a bit difficult to filter, but with the addition of one of the most useful substances on earth, DIATOMACEOUS earth, it clumps the carbon enough to make filtering a simple task

I doubt this will be noticed and am not sure if it will work but...Wouldnt rinsing your solvent with a very acidic HCl water solution like ph 2-3? or even vinegar help clean your used solvent out? just curious...

It will work, yes, with basically any acqueous acidic solution. It will clean the solvent of any of the more polar impurities, as well as getting rid of the alkaloids that might have still been in the solvent. But the solvent ill be reusable yes

Very interesting topic indeed! I will say that from my experiences in an actual chemistry lab (not talking about DMT specific extraction here) that the solvents do actually decrease in efficiency with respect to increased saturation, but to what extent is the key here.

There are a few things that the average person may not realize here which is why your friend has had success re-using solvents. This is that organic solvents have a VERY VERY high threshold for dissolving organic molecules. This is why only a small amount of solvent is needed for what appears to be large extractions. Even more so, if hypothetically speaking you are extracting 10 grams of whatever, and lets say you use 25 ml of any given solvent... how many grams of actual organic extracts do you think are in that 10 grams of sample? I can bet you it is not very much and it is likely in the milligram range.

Therefore, you are actually using 25 ml for maybe a few hundred milligrams of organics (the rest of the weight is probably made up of living matter i.e. cellulose, starch, plant tissue, and everything else that gives the plant its life). Using 25 ml of a solvent in this hypothetical situation, where you are only pulling out milligram quantities means that the solvent is NOT EVEN CLOSE to being saturated. This is the reason that you can re-use them and it will probably not effect your yield.


After establishing that.. how many times can you re-use them? Well there is no real answer to that but as you pointed out, the darkness of the yellow color may be a good indication of when to distill your solvent or buy fresh. Even if the solvent turns dark yellow, I would bet you that it can still be used again.


As you pointed out, saturation has to do with respect to each individual analyte. Just because water is saturated with NaCl (regular salt) does not mean it can not dissolve other stuff. Same for organics. I highly doubt anyone will reach the saturation point for any analyte for personal extractions.


Unless you know what you are doing, re-using solvents does pose the risk of contamination. If you re-use the solvent for different plant extractions, you never know what unwanted side reactions could be happening with unknown organics in your solvent. For this reason, I recommend that anyone who re-uses solvents should only re-use it on the same species of plant extraction.

Thank you Powerdana
Great information, much appreciated.

Very nice post indeed, Powderdana. I really like your perspectives.


It is a fair concern, amidst our limited knowledge of what exactly might be happening if one is re-using solvent for cross-extractions.So you're saying that, e.g. some plant oils from mhrb can form something potentially dangerous when combined with (through solvent re-using) a cactus extract? This is definitely worth pondering further.

With solvent re-use, I am mostly concerned that one might get minor cross-contaminations e.g. a minute of mescaline in his dmt prep or vice versa, but the "minute" is so minute that I'd consider it negligible. I'd be interested anyway to analyse such extracts to see if there is really cross-contamination.

i know saturated limo can be salted repeatedly to great success (ime).

it is a bit time consuming to do that many saltings, though.

Thanks! Having a background in chemistry, my thought process always revolves around minimizing all possible contamination and side reactions. I do not necessarily know if the cross contamination can adversely effect your product, or even be toxic. I just know that proper lab techniques would not use the same solvent for different types of extractions. I honestly believe that only negatives can happen from re-using the same solvent for multiple extractions. Whether or not these negatives will be anything noticeable is uncertain, but I would prefer to do things more correctly.


I also have an idea to make an at home distillation apparatus that would essentially do all the work for you involving little more than a warm/hot water bath and a bucket of ice. I am still pondering ideas of how to make the system air tight though which is very important otherwise you will be inhaling the toxic solvents. One of these days when I have time I will try and develop it further and if it works, I will let you all know

About DCM, I was wondering: if I'd want to recycle it, should I distill it?
I own a distillator, is not a problem in itself, but I'm afraid about ruining the yield by warming the solution up. Any idea about it?

Do you mean reduction of combined np solvent extractions? I routinely distill hexane that contains DMT freebase until it gets cloudy. Its bp is ~68C. I did not notice any significant loss of yield (usually over 1%). So DCM with bp ~40C should not be a problem.

But you do not want to distill the solution until it is completely dry, unless you use a rotavap.



I am not a chemist (yet?) but I read and practice a lot. Here are my considerations.

Your distillation apparatus could not be air tight in principle, unless you use a vacuum pump with solvent recovery system.

Under atmospheric pressure standard techniques: tight, well lubricated joints; joint clips; all pieces of glassware secured by clamps to stands, very cold coolant liquid should do it for many solvents. How much solvent escapes will depend on the temperature difference between your solvent bp and you coolant temp, your condenser efficiency and your solvent vapor flow rate.

in preparation of moving, i salted that same limo from my very first extraction (used an inordinate amount of vinegar, but i finally got the limo to look as clear as when i bought it)

i am beginning to question the efficacy of 5% acetic vinegar. i might have to get some glacial acetic and make my own dilute.
is 15% too excessive?

pretty much agree with everything in this post, the only addition i have is my own personal method of re-using limo.

After you've salted out all the alk's you can, wash with acidic distilled water, then basic distilled water, then activated charcoal if you want, then acidic again, and finally a few distilled water washes.

By washes, i mean, put the solvent in a sep funnel, add your basic/acidic/neutral distilled water, and emulsify/separate then drain the wash.

And just to throw it out there, what do any of you chemists think about using a binary alcohol/water solvent to pull some of the impurities out of the np solvent?

Stuff that normally is too NP to move into the water phase without the help of a semi-polar water/np miscible solvent like an alcohol.

Or perhaps theres other solvents that would do that, and are not-miscible with your NP, but not completely immiscible like water and limo/naptha/heptane/etc, etc? Could you use a wash solvent, to clean up your NP for re-use?

Preferably an environmentally friendly solvent that you can re-use many times to "wash" your NP.

.02, just in reference to limonene and san pedro, unless you distill your limonene you will still have a lot of plant oils in your solvent. I don't know if that'll affect your yield but understand that acidic/basic washes aren't going to remove it. That oil in the flask is some revolting smelling shit, incredibly sticky, and dish detergent only kinda removes it.

No! Buy or build yourself a simple distillation setup!

If you use more than a couple gallons per year of solvents you should have distillation setup. To waste any more than that is simply sinful and foolish.

Toothless hillbillies in Arkansas who can't even afford shoes are distilling moonshine all the time, so don't try to claim it's too complicated or expensive for anyone of average intelligence or means to accomplish.


-FF

Steam distil your limonene and you won't end up with burnt on residue like that.

I don't really think my issue with re-using has ever been with solubility. My main concern was with the insolubility during a freeze precip. We all know that plant ooils are used as np solvents, but we also know that they do NOT freeze precip your alkaloids very well. This is why I discard of my re-used solvents after 5-6 trial.

On a side note, I do find that fat/oil saturated naptha seperates from basic solutions A LOT faster than clean naptha. I prefer tospasticly shake my jars like a mad man to ensure that I have removed all freebased alkaloids. And ime the emulsion from theclean naptha being shaken takes 24+ hours to settle, where as the fat/oil saturated naptha settles in 5-30mins(sometimes an hour depending on severity of shake, lol).