Serious peak tailing

[stdev]

Hello everyone,

I have been working on the determination of amisulpride in plasma with LC-MS and a C18 column, with a 0.1% HCOOH - Acetonitrile mobile phase. Up to now, I have observed some serious peak tailing. Can you tell me a couple of basics towards the optimisation of peak shape? For example, would the addition of an ammomium formate buffer help? I have attached the structural formula of amisulpride:



Thanks a lot

[Alp]

Increasing the ionic strength of the mobile phase may help.
Lowering the pH to below 3 may help.
Add a competing base (watch your mobile phase pH does not rise too much, buffer it to prevent dissolution of your silica).
These may likely change your retention times.

Using a C18 that has extensive endcapping would probably help a lot. Or try another type of column and redo the chromarographic conditions (phenyl, aminopropyl, cyano...).

Alp

[Rooke123]

increasing the formic acid % could help (eg. 1%), if the tailing is bcos of silanol interactions