Forced degradation on oil based soft gel capsule fill

[kimy]

Does anyone have any tips for acid and base forced degradation on oil based soft gel capsule fill. We are finding that under these conditions the active peak shifts by a few minutes. (Heat, hydrolysis and oxidation conditions are fine). Has anyone found a way to successfully stress this type of sample under acid and base?

[Mattias]

Are you neutralising the sample before analysis?

[kimy]

In the past we did neutralise, but our present way (following our current SOP), we add the degradant agent and take an aliquot at various time points. Another problem we are have with base degraded samples is that for some products we end up saponifying the oil and so are left with a solid mass.

[paulw]

Without neutralization, you are changing the pH of the diluent, which in turn can affect the initial ionization of the analyte of interest. I would expect this to shift retention time. In some instances you could even have the pH of the injected solution "fighting" with the pH of your mobile phase and cause the peak to split.

Paul