So I always used the old school phenol:chloroform:isoamyl alcohol (25:24:1) technique. It's from Current protocols but I've attempted to attach below my write up of the protocol from grad school. You would start around step 15. Make sure whatever protocol you use has the isoamyl alcohol as this is a substantial improvement over even older protocols. As you're on buccal brushes, most people I know soak the brush in TE buffer and then you can proceed as described but other protocols I've done, for the buccal swab (I wasn't actually using a buccal swab) would mean add your TE, then add phenol:chloroform:iso to the TE with the brush still in and mix, vortex, or soak. Then proceed as described. As in this written protocol, you'll definitely get higher yields of DNA if you precipitate over night at -80. Glycogen will reduce the odds of you losing your pellet. And I've done this same protocol on the 200 uL scale which was probably more consistent with what your DNA yields are going to be, but you have the problem of the large buccal brush that you need to sufficiently wash. Note in the below protocol, it's just the ratios of reagents to the starting amount of buffer that the DNA is contained that matters. If you want to soak your brush in 1 mL you can adjust everything accordingly. The least amount of DNA I've purified reliably and consistently with this technique is just below the nanogram levels, so 100s of pg. I've simply not tried even lower, but it does take a little bit of finesse. Hope this helps.

Do you want to extract DNA from human cells or bacterial cells? The following may not work for certain recalcitrant bacteria but might be relevant for buccal cells: https://www.med.umich.edu/tamc/HotShotDNA.pdf. It may require some tests or improvements to deal with the brush/swab matrix though. HTH

 Great thoughts David! I'm trying to look up but I had at one time found a paper from very long ago that proposed mixing phenol and chloroform and my memory is that the argument was the chloroform gives better separation of the aqueous phase from the phenol. Otherwise, a significant amount of the water will remain mixed into the phenol layer and presumably some of the nucleic acids too. The isoamyl helps make sure chloroform contamination of your aqueous phase is also minimized. But it was never clear to me whether or how mixing phenol and chloroform was any different or better from just doing the chloroform extraction after the phenol one.

Also, Bob, I've purified my fair share of pellets that were monitored more by faith than by sight and they can work out in the end if you're careful. Just need to plan out some steps where you can check the presence and fidelity of your DNA you're looking for. 

Oi 

Deixa o cotonete mergulhado no tampão TE, Durante uns minutos, DEPOIS tente uma técnica de lise térmica POR TE,