Working on and off on that fungus still. There’s been considerable progress on the US side since the team led by Dr Spalting nailed down the conditions into which Chlorociboria produces xylindein. Not that I didn’t send a hint or two ;)
Since they did the huge work that was needed to understand how this fungus works and how to tame it, I’m the happy bunny who’s now tinkering with the pigment’s chemical part. Not that I’m a chemist, nananaw, but since I’m in a mixed Masters course now, I study both physics and chemistry (to become a college and high school teacher of both). Which gives me many possibilities to access the chem lab hardware, and most importantly, the experts.
Digging on my own side of the ocean I had one of those “whack own’s forehead” moments a few days ago, and made quick tests to check out the reality. Bullseye: xylindein changes color with pH. So my spectra are good to dump and I must do them again. Actually, xylindein is a weak diacid (it can give off two hydrogen atoms per molecule), so it has THREE different colors depending on the pH, and what I took for decay when heated was one of the color changes, which can be reversed in some cases (I’ll study that in deep later this year).
So today I set up a side experiment at the lab and made a pre-wash with ethanol to a very decently saturated sample in sawdust and shaving forms (remember, there is no such thing as scrap wood!). Ethanol washes out the tannins in wood (that’s true for almost all woods) but not xylindein. Not as much as acetone anyway. As my tests confirmed (more on that later next week) ethanol washes out the tannins, which also have color dependency upon pH, but very little xylindein if any at all. So today was laundry day, and I got my sample cleaned up in preparation for the actual extraction.
Cue the Soxhlet apparatus, which is a genius’ work. Let me explain how it works.
There is a round flask at the bottom, attached to the Soxhlet apparatus. Said flask is heated by the blue thingie. Inside the Soxhlet you can see a kinda white-ish cylinder of sorts: that’s the filter cartridge inside of which the sample is located. The Soxhlet is then filled up with the solvent, almost to the top of the little glass tube that can be seen at the left. The round flask also gets its share of solvent (I used a small one, way too small actually). Then a water-circulating condenser is fitted above the Soxhlet and, well, connected to the tap to have cold water circulating inside.
While heating, the solvent evaporates and travels to the top via the glass tube to the right. It rises up to the condenser, where it cools down, liquifies and drips down into the cartridge. This is pure recondensed solvent, whatever it contained stays inside the round flask at the bottom. Now this is where the magic happens: while the solvent drips down, its level rises inside the Soxhlet. Remember the little tube at the left? That’s a siphon. As soon as the solvent level reaches the top of said siphon, WOOSH, gravity takes its duty and everything is sucked down into the round flask, and since this is the solvent that went through the sample, it’s loaded with whatever soluble compound is inside the sample. Once all the solvent has been sucked down, the siphoning action stops, the level of liquid inside the Soxhlet starts to rise slowly again, and so on.
No moving parts. No pumps. Only freaking hydrodynamics and gravity. Really clever stuff.
I hope these explanations were simple enough, I also filmed the siphoning action, which happened every twenty minutes (slow, because of the very small round flask, I’ll aim for a big one next time).
Check that out:
More after the exams… Cheers from the lab.
-- Thomas - Pondering the inclusion of woodworking into physics and chemistry classes...