Brownish precipitate in 100% (w/v) TCA solution?

08 November 2018 0 7K Report

I'm doing a protein precipitation protocol using TCA (trichloroacetic acid) for the first time. My protocol says to dissolve 500g TCA into 350ml dH20 (and store at room temp) for a 100% (w/v) solution.

I've done my first protein precipitation and it seems to have worked nicely, but now I've noticed that my 100% TCA stock has a brownish precipitation in it that is concerning. I'm worried it might be contamination of some sort, or that I haven't properly stored the solution.

Has anyone else seen this and is it ok/normal??

Thanks for the help!

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