Question about a stability-indicating method development

[Apple_insci]

I am about to develop a stability-indicating method for a new drug. The compound's pKa is 5. But it is not stable at low pHs. We knew one of the degradation product is ketone and it elutes very close to the parent peak. We dissolved the compound into 50/50 H2O/ACN.

Can anyone suggest what pH of mobile phase and what kind of RP-C18 column we can start with?

Thanks!

[amaryl]

I am about to develop a stability-indicating method for a new drug. The compound's pKa is 5. But it is not stable at low pHs. We knew one of the degradation product is ketone and it elutes very close to the parent peak. We dissolved the compound into 50/50 H2O/ACN.

Can anyone suggest what pH of mobile phase and what kind of RP-C18 column we can start with?

Thanks!

work at higher pH than the pKa of your analyte. u can work at pH 6.8. higher than this the column may be dissolved. If working with special columns that function well at high pH (see the pamphlet accompanying column must be showing the working pH range).

usually u should work at least 1.5 units away from the pka of drug.