how long should solvent stay in freezer until no more crystals will form?

[caliwa]

My solvent extraction samples ( one of hexane, one of heptane) have been in my freezer for 48 hours. the hexane has 8 micro cristals formed, id say weighting like .1 mg (it looks like a microscopic yield). the heptane, nothing. should I keep waiting or should I try another thing? both have been partially evaped (80% of the solvent has been evaped before freezing). also, these are acumulative extractions. what I do is, extract - 80% evap - store in a little glass jar, and repeat the proccess till i got a decent amount of concentrated solvent. then I put it in the freezer.

i just though of it that way, hope it doesnt screw up nothing..

 

[tele]

What tek are you using? I recommend trying q21q21's tek and you will not be battling to get more than 1mg out. It's way simple and works like a charm.

Also, I feel like the in the tek you used, it could be possible that you did not let the mix to basify/freebase long enough?

 

[L_Starr]

In hte feezedr for 24hrs plus, filter, than evap down some more and re-freeze. If you have done STB make sure that your aqueous solution is basic as much as can be, and let the np mix and sit for a day or 2.

hih gdluk

 

[caliwa]

I using the lazyman's tek. I let the mimosa basified solution stand for 10 days and then started making pulls. that said, when i make the pulls I warm the solution, add the solvent, turn the bottle up and down like 5 times, let the NP separate, put the mix in the sepparating funnel, get my np back, do a partial evap, and stick to the freezer. i never let the NP more than 30 min on my solution, would it help if I let it stand there for a day or two?

im going to get the materials for q21q21's tek. yesterday I harvest my first precipitation after 2 weeks of hard work, and it was very very, very lame.