Bad Mimosa... or Bad Extraction?

[brazilman]

So I've been trying to do a "Lazyman" type extraction. The reason for following that tek is lack of resources and simplicity, I want as little room to mess up as possible, I can learn other teks later. People talk about how simple all this stuff is but then they talk of using magnet stirers... which is great but here it costs like 3x the amazon retail price and I'm far, far from rich. Even something that should be as simple as a turkey baster... I tried to find it only to realize google can't translate the word and I have no idea what these things are called here, if they even exist; I ended up buying a 20ml glass syringe and still have no idea if we have turkey basters in this country. Get some distilled white vinegar they say... apparently this also doesn't "exist" here. Okay, as you can tell, I'm feeling frustrated so back to the point. The results from my attempts have not been good... nothing even remotely close to the 1% yield mentioned in the tek page, more like maybe 0.1%, 0.2% (yes, even a proper scale is 3x the amazon retail price here so I'm going by a 0.01g precision scale that ran out of battery). At first I could spot things I clearly didn't do well and because of some constraints I improvised a little but now I'm wondering if I really am screwing up that badly or if my bark is just not good.

So help me out here, could the following hurt my yield that bad?

On my last attempt I did not do any heating. I used a lot of naphtha (120ml for 60g mhrb) that I mixed for a couple of hours moving the solution from one container to another after the naphtha layer settles; the idea being that I could just do one big pull instead of a bunch of smaller ones. After freeze precipitating, I re-used the naphtha on another batch of 60g mhrb, hoping that even if the solution wasn't saturated enough to precipitate much from the naphtha, the second run through fresh mhrb would just add to it and I could evaporate to see the full content of it. The result of the evaporation was roughly the same volume as the freezing, except darker and more waxy so the hope did not seem to materialize.

 

[pete666]

We can look into it a bit. I don't remember this TEK, but surely read it some time ago.

My first tip is : don't use turkey baster (you can buy it from here). Use 50ml glass pipette (here) with rubber bulb(here). I tried working with turkey baster and it is very bad. Pipette is much more precise, you can get much more non-polar and it is clear. With baster a lot of basic soup gets in.

Second tip : never use result from non-polar evap, always freeze-precip.

Questions :

1. Have you used powderized MHRB?
2. How long have you left basified MHRB standing before adding non-polar solvent?
3. Have you been shaking like crazy for few minutes after non-polar had been added?
4. Have you got any emulsion? Or two clear layers (water/np)?
5. After shaking, have you waited for perfect separation of water and non-polar?
6. After perfect separation, have you removed non-polar or have you repeated shaking? How many times?
7. Have you reduced non-polar before freeze-precip?

 

[null24]

Your poor result may be from performing a single pull. When you're starting out, it's a good practice to follow the TEKS to the letter, building a comprehensive understanding of the process. Once you've done a few with good results and see how the instructions work, then you can start tweaking it a bit.

 

[brazilman]

1. Have you used powderized MHRB?

Yes

2. How long have you left basified MHRB standing before adding non-polar solvent

On this last try, which involved two batches, 24 hours for the first and 48 hours for the second. I had 50g or 60g of MHRB powder in a hdpe container and added 600ml of basified water (60g of lye), doing both batches at once, extracting from the first a day later and from the second a day after that. I mixed it pretty well and it formed a pretty consistent liquid.

3. Have you been shaking like crazy for few minutes after non-polar had been added?

No. From what I understood, you have to be somewhat gentle with the mixing. Because I have no way to close the container (haven't figured out what to use as a lid, compatible with both the naphtha and the strong base) I basically do this: I add the naphtha to an empty erlenmeyer. I then add the mimosa water to the erlenmeyer, the idea being that by starting at the bottom it has to kind of move through all the mimosa water to form the upper layer. After maybe 10 minutes it forms the upper naphtha layer but I let it sit for another 10 minutes and then I pour the entire thing gently into another container. The naphtha being on top tends to move first so it again starts at the bottom and has to move its way up. I do this a bunch of times, 4 or 5. It's hard to really swirl the full erlenmeyer but sometimes I swirl it while it is half-filled.

4. Have you got any emulsion? Or two clear layers (water/np)?

As far as I can tell there is no emulsion, the two layers are clear.

5. After shaking, have you waited for perfect separation of water and non-polar?

What do you mean? I mean how do I measure perfection?

6. After perfect separation, have you removed non-polar or have you repeated shaking? How many times?

As above, I repeated the mixing process 4-5 times after the layers seem to be fully formed.

7. Have you reduced non-polar before freeze-precip?

No but seeing as the full evaporation did not yield more than the freeze precipitation, I don't see how that could be the issue. The precipitation itself seems to have worked perfectly, there just wasn't much in there. EDIT: Which doesn't make much sense to me because my understanding is that if there wasn't much in there, it shouldn't have worked, so I don't know.

 

[brazilman]

Your poor result may be from performing a single pull. When you're starting out, it's a good practice to follow the TEKS to the letter, building a comprehensive understanding of the process. Once you've done a few with good results and see how the instructions work, then you can start tweaking it a bit.

Problem is that the teks make assumptions about time, space and equipment which I can't necessarily match. I do have a sense that the single pull was a bad idea but could it really have been that big of an issue? I sure hope so. That is definitely something I'll try to fix on my next batch but I'm kind of worried it's not the real issue.

 

[brazilman]

My first tip is : don't use turkey baster (you can buy it from here). Use 50ml glass pipette (here) with rubber bulb(here). I tried working with turkey baster and it is very bad. Pipette is much more precise, you can get much more non-polar and it is clear. With baster a lot of basic soup gets in.

As I said, I didn't even find a turkey baster and ended up buying a 20ml glass syringe (the larger ones were too expensive for me). It seems to work pretty well, only problem is it doesn't fit in the bottles I thought of using but whatever. I looked into pipettes but then I realized these things (at least the models I could find locally) are super long, it would be way too clumsy.

 

[pete666]

3. Have you been shaking like crazy for few minutes after non-polar had been added?

No. From what I understood, you have to be somewhat gentle with the mixing. Because I have no way to close the container (haven't figured out what to use as a lid, compatible with both the naphtha and the strong base) I basically do this: I add the naphtha to an empty erlenmeyer. I then add the mimosa water to the erlenmeyer, the idea being that by starting at the bottom it has to kind of move through all the mimosa water to form the upper layer. After maybe 10 minutes it forms the upper naphtha layer but I let it sit for another 10 minutes and then I pour the entire thing gently into another container. The naphtha being on top tends to move first so it again starts at the bottom and has to move its way up. I do this a bunch of times, 4 or 5. It's hard to really swirl the full erlenmeyer but sometimes I swirl it while it is half-filled.

Maybe here can be problem. I suggest trying to find TEK where you can shake without mercy. If you meet emulsion, solve it and next time try something another, but again, with vigorous shaking. I know some people accept the fear of emulsion, but it is not necessary.
If you still fear of emulsion, swirl and mix it carefully, but much longer. It may bring impurities, but I would firstly try to get everything out of the bark and then optimize it for purity.

5. After shaking, have you waited for perfect separation of water and non-polar?

What do you mean? I mean how do I measure perfection?

All entry non-polar solvent is in the upper layer, not less.

Overall, your technique doesn't sound bad. If better mixing won't bring better result, it is likely a bark imho.

 

[brazilman]

All entry non-polar solvent is in the upper layer, not less.

Yea, I had been thinking of checking that more carefuly. I can't answer that with certainty but will seek to do that next time.

Overall, your technique doesn't sound bad. If better mixing won't bring better result, it is likely a bark imho.

What could I use to make a container suitable for vigorous mixing? Would rubber stoppers be tight enough on the erlenmeyer and if yes, what kind (as in, what kind could be used with both the lye water and the naphtha)? I can vigorously shake the mimosa water because I can seal it in a hdpe container with its own properly designed lid but that is not suitable for naphtha (and likely other solvents).

 

[pete666]

What could I use to make a container suitable for vigorous mixing? Would rubber stoppers be tight enough on the erlenmeyer and if yes, what kind (as in, what kind could be used with both the lye water and the naphtha)? I can vigorously shake the mimosa water because I can seal it in a hdpe container with its own properly designed lid but that is not suitable for naphtha (and likely other solvents).

Well, not an easy question. I bought borosilicate glass reagent bottles with ptfe caps. They are perfect, but it may get a bit pricey if you don't find them cheap.
Previously I used ground glassware. It was not bad, but the problem is the glass is etching, not much, but you have to be cautious to not leave it closed with basic solution inside. The ground glass can stick you won't be able to remove the top. But if you tighten it just for shaking and then release it a bit and move it now and then, it is ok. I have done many extractions with it.

I don't think non-ground erlenmeyer flask is good, it is not designed to be used with the rubber stopper. I would suggest ground erlenmeyer definitely.

I have checked compatibility charts and if I used naphtha (I am using toluene), I would use ldpe with KOH.

 

[brazilman]

I have checked compatibility charts and if I used naphtha (I am using toluene), I would use ldpe with KOH.

Wait, wait, wait... I was under the impression I just couldn't use plastic with naphtha but that says "excellent" for ldpe and there is some "good" for hdpe and pp in other charts. Considering the contact is very short term (especially if I only need the lid to be plastic) and I'm not heating the stuff, is my fear of these plastics excessive paranoia? Erlenmeyers with PP lids are easy to find. The ones with glass lids not so much.

if I used naphtha (I am using toluene), I would use ldpe with KOH.

KOH?

 

[pete666]

erlenmeyer flask with PP lid seems to be ok

KOH (potassium hydroxide) is similar to NaOH. They can be swapped in extractions. NaOH is more common though

 

[brazilman]

Well, not an easy question. I bought borosilicate glass reagent bottles with ptfe caps. They are perfect, but it may get a bit pricey if you don't find them cheap.
Previously I used ground glassware. It was not bad, but the problem is the glass is etching, not much, but you have to be cautious to not leave it closed with basic solution inside. The ground glass can stick you won't be able to remove the top. But if you tighten it just for shaking and then release it a bit and move it now and then, it is ok. I have done many extractions with it.

I always struggle to figure out exactly what stuff is called locally. I can find reagant bottles but only with PP caps.

 

[pete666]

There is a cap, but then there can be a gasket in the cap. The cap can be PP, but gasket can be ptfe or another. The gasket is what matters

But as I said, you are ok with PP cap for NaOH and naphtha

 

[brazilman]

There is a cap, but then there can be a gasket in the cap. The cap can be PP, but gasket can be ptfe or another. The gasket is what matters

From what I understood, the standard blue ones are PP, the standard red ones are the more resistant PTFE. The ones I found are all standard blue and clearly labeled as being PP so I'm fairly sure they aren't like what you're using.

But as I said, you are ok with PP cap for NaOH and naphtha

At the very least to test so I know if improper mixing really was the main issue. It's not a perfect "score" so I'm still a little concerned but I need to test it out.

 

[pete666]

STB with closed vessel is always much better/safer than anything else. Buying the flask with top will be worth it even when the reason of low yield is somewhere else.

 

[brazilman]

So I used the new bottle, did a lot of shaking, and used a fair bit of non-iodized salt (that helped massively with quickly separating the layers and avoiding emulsions). I also did more, smaller pulls. The result was much better than what I got in my previous attempts. Only thing I realized is that my freezer is kind of crappy, it lists the lowest temperature as -6 celcius. Despite that, it seems that the naphtha got so saturated with oils that it completely crystalized pretty much all dmt in it, because when I moved it to another container and evaporated it, the glass was almost clean. I'm so relieved to know there is nothing wrong with my MHRB.

 

[pete666]

Good