I was thinking some more about the sequential extraction numbers I was calculating, and they assume only partitioning the pg/vg.
If you divided up the mineral oil into several batches,
O1, O2, O3, O4, O5 etc,
and the PG into several..
A1, A2, A3, A4, A5 etc.
then mixed a1 with O1, then O2, etc..
then mixed a2 with O1, then O2, etc..
etc... etc..
you get far better extraction. This would be tedious as hell though to do manually, but I just made up an 'experiment' that seems to work well for doing this automatically. It may be possible to get a decent yield with NO acidification of the PG/Glycerine if the freebase alkaloids are soluble in the PG/VG.
I took 4 feet of 3/8inch ID clear vinyl tubing, wrapped it around a 2 inch pipe in a spiral and clamped the bottom closed.
about 30 ml of mineral oil, to which I had added food colouring. It didn't dissolve, but shaking it up well turned the mineral oil blue by holding tiny droplets in suspension.
put this in the tube, and then dripped 0.5 ml of a 75%VG 25% water mixture into the top.
It took a lot of messing around, to get the slope right. too steep and the VG travels quickly, not enough and it 'sticks' to the walls of the tube and doesn't move. (vapour locking is also a concern if you are not careful when adding) 45-50 degrees seemed to work.
once the VG droplet/bubble sank about 1 inch into the mineral oil, I added another .5ml, then another and another so that I had a train of vg bubbles sweeping
through the mineral oil.
You could see how the first bubbles to get to bottom were a deep blue, and the successive bubbles were fainter and fainter.
after about 3 or 4 bubbles, (2ml), they rest were much much clearer, because the food colouring has a much higher (1000:1 ???? guessing here) affinity for the VG, but the principle holds. I believe in the lab this is called "counter-current separation"?
sounds complicated, but was easy to set up and this also makes the separation and final recovery of the VG as simple as slightly loosening the clamp, dripping slowly into your vial.
2$ of tube replaces the flasks, syringes, and or separatory funnels, takes far less 'hands on' time, and should be more efficient as well with what we have to work with.
If I can set this up right, I can have the entire apparatus run 'hands off', mineral oil seeping through the prepared
tobacco, then dripping through an acid
salt bed to dry/neutralize, then dripping directly into the countercurrent tube over night.
Once that is done, then setup a means to automatically drip the VG at the correct rate into the countercurrent tube, and come back in an hour to claim your prize.
Hope that's clear. I should take and post some pictures.