Keeping water out during freeze precip

[CultiV8]

Hey guys, I've had a really hard time getting crystals as of late. No matter the steps I go through to make the pyrex dish airtight, ice crystals form and then melt, leaving a mix of water and goo instead of nice dry crystals. I've tried covering the dish with multiple layers of plastic wrap secured by a rubber band, plastic wrap with ziplock bags, putting the dish inside a larger plastic dish with an airtight seal, and most recently three ziplock bags with a dessicant packet in one of them. Ice crystals every time.

How do you avoid condensation and ice crystals forming in the freezer? Or what am I doing horribly wrong? Thanks everyone!

 

[Nereus]

Slow cooling the nps. Letting it acclimatise to RT after pulling and collecting, then fridge temp, and only after having it in the fridge for a while it should be moved to the freezer.

Same goes for when the precip is ready.Take it out of the freezer to decant the solvent, back upside down, decant more, back upside down, then fridge temp until it acclimatises to fridge temp, then room temp, and only after it reached a stable temp you proceed with drying it further with a fan.

 

[CultiV8]

Slow cooling the nps. Letting it acclimatise to RT after pulling and collecting, then fridge temp, and only after having it in the fridge for a while it should be moved to the freezer.

Same goes for when the precip is ready.Take it out of the freezer to decant the solvent, back upside down, decant more, back upside down, then fridge temp until it acclimatises to fridge temp, then room temp, and only after it reached a stable temp you proceed with drying it further with a fan.

Thanks. I will test this now with an empty dish and see if there is less condensation.

 

[Nereus]

Maybe providing further infos about your procedure would lead to a better understanding of what you are doing, thus better advise also...

Tek, plant material,chems used... all that can affect the outcome of your end product.

 

[Nope]

I am confused by the "back upside down" part of your advice but had a eureka moment over the part of letting the solvent cool down before it goes in the freezer, so a million points and a thousand thank yous for that

 

[darnell]

we Get the real saran{sp?} wrap.....we like to use round pyrex plates....seems to be easier to get a good seal with round ones....

Oh they gotsta be real clean where the plastic makes contact with the glass....once a good airtight seal is achieved put very slight pressure on the plastic to remove some air if possible creating a bit of vacuum. Then an old drum head makes a nice cover and if you gotta stack em up it helps keep the seal...sometimes.....but sometimes you just get some water in there....

For us it will usually happen at some careless point when doing the pulls.....or heating something in a water bath then there be all this water dripping from the bottom....:?:

But a good mini a\b is prolly the best way to get crystals....for us at least

 

[Nereus]

Inserting the dish upside down back into the freezer.

 

[CultiV8]

Thanks for all the replies, everyone. I am following Cyb's Max Ion with ACRB, distilled water, pickling salt, 100% NaOH, and VM&P Naptha. I have had no trouble getting 2-3% beautiful spice with the same tek and equipment in the past. All of the following methods have resulted in ice crystals forming inside the pyrex dish:

1 layer of saran wrap, pressed tight
3 layers of saran wrap, rubber band to seal
3 layers of sarap wrap, rubber band to seal, inside two ziplock gallon bags
Pyrex lid (no saran wrap) inside two ziplock gallon bags, vacuum sealed w/ dessicant packet
Dish placed inside larger plastic container with rubber seal

I've heard of people having success with some of these, which makes me want to think it's my freezer :?

 

[Nereus]

Different batches of plant material could explain the gooeyness too...with acacia we know that one also gets some NMT in there, and depending on the time of harvest i.e time of year/season etc. some batches might contain more NMT or oils/fats etc.Of course that could be sorted with the mini A/B as stated before, but also slow cooling is important aswell imho.


Edit: Anyway don't panic, these are procedures that go through trial and error until they settle under your belt

 

[1ce]

To dehydrate the solvent, filter it through MgSO4.

 

[fathomlessness]

I get water in my naphtha every time because of the temperature drop.

I just pour off excess water, place under fan and problem solved... :surprised

 

[Nope]

Inserting the dish upside down back into the freezer.

I don't mean to bug you, just asking for some clarification because none of the teks I've looked at mention this

1) Why is it necessary to decant multiple times if you've already poured off the solvent and let the glass sit upside down? There's not going to be any solvent left after that is there?

2) you mean rewrap the glass and put it in upside down? Are you supposed to trust to the crystals natural stickiness to keep it from falling off to the bottom of the freezer/plastic?

 

[Nereus]

Inserting the dish upside down back into the freezer.

I don't mean to bug you, just asking for some clarification because none of the teks I've looked at mention this

1) Why is it necessary to decant multiple times if you've already poured off the solvent and let the glass sit upside down? There's not going to be any solvent left after that is there?

2) you mean rewrap the glass and put it in upside down? Are you supposed to trust to the crystals natural stickiness to keep it from falling off to the bottom of the freezer/plastic?

1) It's not necessary, but on some ocassions after the first decant some solvent will remain trapped between the crystals.It is this last bit of solvent that will melt your crystals into goo upon reaching RT if not carefully dripped out at the right temperature i.e freezing temp.

2) Imho wrap is pretty unpractical.Takes a lot of time to deal with, specially when one has to move fast to avoid condensation.Best to use a dish with lid.But yes, that's what i mean.To make sure the crystals will stick to the bottom of the dish, avoid disturbing the precip dish as much as you can.Patience is a key.

 

[pitubo]

1) It's not necessary, but on some ocassions after the first decant some solvent will remain trapped between the crystals.It is this last bit of solvent that will melt your crystals into goo upon reaching RT if not carefully dripped out at the right temperature i.e freezing temp.

In my experience, quite a lot of solvent is trapped between crystals, especially if rapid cooling caused formation of snowy crystals.

For optimum performance, decant freezing cold solvent rapidly from the crystals, quickly replace lid, tighten well and put back in the freezer upside down. After 15 minutes, take out of freezer while holding upside down and loosen lid while still holding upside down. After last bits of cold solvent have drained, tighten lid again and place upright somewhere to allow warming up to room temperature. Keeping the lid closed while stil below room temperature will prevent condensation of atmospheric moisture onto the inside walls and onto the crystals. After final removal of the lid, it will still take a day before the last bits of solvent have evaporated.

I use a jar instead of a dish. A little harder to scrape, but much easier to handle in all other respects.

 

[downwardsfromzero]

To dehydrate the solvent, filter it through MgSO4.

Anhydrous sodium carbonate works too. Add a level teaspoonful per cup of solvent, swirl, allow to settle and then decant the liquid into your precipitation jar.

The reasoning behind this is also that sodium carbonate is basic whereas magnesium sulfate is very slightly acidic. Whether this is of any practical significance remains to be tested.

 

[CultiV8]

To dehydrate the solvent, filter it through MgSO4.

Anhydrous sodium carbonate works too. Add a level teaspoonful per cup of solvent, swirl, allow to settle and then decant the liquid into your precipitation jar.

The reasoning behind this is also that sodium carbonate is basic whereas magnesium sulfate is very slightly acidic. Whether this is of any practical significance remains to be tested.

Thank you downwards! I have plenty of Na2CO3 but no MgSO4 lying around as 1ce suggested. But I made it myself from baking soda - must it be lab grade / 100% anhydrous to dry properly?

 

[benzyme]

magnesium sulfate (heptahydrate) is epsom salt, and doesn't alter the pH to any significant extent in a nonpolar solvent with residual water. microwave it for 5-10 mins on high to dehydrate, same for baking soda (microwaving or baking decarboxylates it to sodium carbonate). sodium carb is typically used as a 5% solution (5g in 95mL water) to wash the nonpolar phase in the sep funnel, prior to separating and freeze precipitating.

for drying the nonpolar, I always go with epsom salt. calcium sulfate is another effective one

 

[CultiV8]

magnesium sulfate (heptahydrate) is epsom salt, and doesn't alter the pH to any significant extent in a nonpolar solvent with residual water. microwave it for 5-10 mins on high to dehydrate, same for baking soda (microwaving or baking decarboxylates it to sodium carbonate). sodium carb is typically used as a 5% solution (5g in 95mL water) to wash the nonpolar phase in the sep funnel, prior to separating and freeze precipitating.

for drying the nonpolar, I always go with epsom salt. calcium sulfate is another effective one

Thank you very much for the wisdom :thumb_up:

 

[downwardsfromzero]

I was talking Lewis acidity, wherein magnesium ions form coordination complexes with ammonia, and contemplated how this might also occur with alkylamines, leading to yield reduction but this would seem to be a trivial concern.

All I will add is that is possible to use anhydrous sodium carbonate experimentally to dry limonene prior to adding acetone and it works.

And as CultiV8 mentions, if you've soda and no Epsom salts then it is an option, though probably not as universally applicable as the Epsom salts.

But typically the aforementioned sulfates are the standard practice for the most part.