Chromatography Forum

Hi everyone!

I am trying to analyze piperidine as a residual solvent in an API by GC-HS. I have found out that somehow it reacts with the API in the headspace vial (I see piperidine perfectly as a standard solution of 67 ppm but not when spiking the API)

Now I am trying to derivatize it with MBTFA, which in Literature appears to be a good derivatizing agent for primary and secondary amines, but i have not succeed until now. I am adding MBTFA in a molar ratio of 2:1 (MBTFA:piperidine) but reaction seems not to progress too much, even incubating vials 20 minutes at 90ºC

Does anyone have a method that would like to share with me? Or any tips to help me to progress with the derivatization reaction, wich is something I had never done until now...

Any help would be highly appreciated!
Thank you very much in advance
jotapee

You can avoid the derivatization and use known addition headspace. It means you have to burn 4 vials, but man, oh, man will it ever save you time and heartache! Assuming that the reaction with your analyze is not 100%, you spike with differing concentration of piperidine and then derive the concentration from the slope. This technique is well handled in many analytical texts.

If you suspect that the analyte is reacting with the matrix, then standard addition won't help you as the matrix will react with the purposely added analyte as well. You'll never get a good feel for what extent the reaction proceeds and when/if the other reactant is depleted.

In what form is the API? Is it in water? Is it a dry powder?