Chromatography Forum

Hello,
I am a student from The Czech Republic and I would like to ask if any of you have ever heard about liquidation of acetonitrile (in waste bottle where mobile phase from detector (HPLC) constantly flows in) using 5% sodium hypochlorite? Could you write me how to do it, please? I mean the volume of 5% sodium hypochlorite with respect to the volume of waste bottle and so on..especially in case of daily routine use.
Thank you very much and please, excuse my bad English.

Kamila,

While I have not tried this approach, you will need to use a lot of 5% NaOCl to accomplish this since this reagent will need to be present in stoichiometric excess (I would guess at least a 50 mole % excess would be required). This would necessitate 54g of 5% NaOCl per gram of acetonitrile! If you want to pusue this, I would suggest base hydrolysis instead. With sodium hydroxide you can achieve quantitatively hydrolyse the acetonitrile to acetate and ammonia (this would only require about 1.5 g of NaOH per gram of acetonitrile with a 50% molar excess).

Bleach is typically used with cyanide salts such as NaCN, KCN. I have no experience using bleach to decompose acetonitrile but as mentioned, hydrolysis (by heating with NaOH or H2SO4) is easier, more reliable and safer.

PM

Dear Kamila, there are two papers of mine about the disposal of acetonitrile / water mixtures:
K. Gilomen, H.P. Stauffer, V.R. Meyer, Detoxification of acetonitrile-water wastes from liquid chromatography, Chromatographia 41 (1995) 488-491.
K. Gilomen, H.P. Stauffer, V.R. Meyer, Management and detoxification of acetontrile wastes from liquid chromatography, LC GC Int. 14 (1996) 56-58.
These publications describe the detoxification with sodium hydroxide. I can send you the reprints if you are interested. In this case, please contact me directly by e-mail: veronika.meyer@empa.ch .

Yours sincerely, Veronika

Have one for TFA?