[Emiliosolazzo1993]

Hello everybody, my name is Emilio and I'm a Ph.D. student in immunological oncology.
I've just been struggling with a cell culture which needs pure tetracycline for the selection of transfected cells.
I bought pure tetracycline hydrochloride and I do need the pure tetracycline. Given that my molecule is freely soluble in water, soluble in methanol and ethanol but is insoluble in ether and hydrocarbons, do you have some advice to get pure tetracycline?
Thanks everybody in advance for reading and answering, eventually.

[rolnor]

You can issolve it in EtOH, add 1equ. sodium hydrogen carbonate and sonicate for 30min.
If you se sodium chloride precipitate its working, this precipitate should be more fine then the sodium hydrogencarbonate. Then filter through filter-paper. This is my suggestion, not sure if works.

[AWK]

The solubility of tetracycline in water (true compound, not its derivative) is about ~0.2 g/L. So just neutralize the hydrochloride with a solution of some amine (eg TEA) and filter the precipitate, then wash with a small amount of cold water. The resulting precipitate is a hydrate, it must be dehydrated at a temperature below 60°C, preferably under reduced pressure.

[Emiliosolazzo1993]

Thank you very much for you answers.
Recapping: first I dissolve my tetracycline hydrochloride in water, then I neutralize it with TEA or some other effective amine, then it should form a precipitate whom I have to filter. I should recover the precipitate, eventually, and then dehydrate at a temperature below 60°. It's all right?
Thanks in advance.

[OrganicDan96]

another idea might be to use a basic ion exchange resin, there are many different ones, just stir it and monitor the pH then filter the resin off this prevents the problem of separating salts from polar organic compounds.

[AWK]

Thank you very much for you answers.
Recapping: first I dissolve my tetracycline hydrochloride in water, then I neutralize it with TEA or some other effective amine, then it should form a precipitate whom I have to filter. I should recover the precipitate, eventually, and then dehydrate at a temperature below 60°. It's all right?
Thanks in advance.

You can use even solid hydrochloride. You can use the rather almost exact amount of amine for neutralization since tetracycline is also soluble in an alkaline solution.
This is also a method of isolation in the industry (hydrochloride, filtration of bacteria, precipitation)