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Anyone else get the black dot in their nucleic acid precipitate? - (Jul/18/2005 )

Despite which method I use to extract nucleic acids, and regardless of whether I'm working with RNA or DNA, I always get a small black dot in the center of my pellet. Anyone else run into this? My spec readings are still good, so it's not really detrimental to my work. I'm just curious.



for my maxipreps i do too. But i've never encounter a problem due to this point...


I have had this too. I have always thought it was rubber dust off the vortex that gets on your hands/gloves and ends up in your tubes.

-Daniel Tillett-

At least I'm not the only one getting this! I always see it when I spin down bacteria too. I assumed it was just charred cells from flaming the innoculating loop, but if I'm seeing it in any type of pellet then it must be something else.


I also get this with some cells, normally in cells grown a bit longer than a few hours (lag phase).
I was told this precipitate is iron taken up by the cells and incorporated in the lagphase.
Should not cause any problems though.