Could anyone tell me how to develop Impurity analytical method development for organic acid/basic salt. It seems that we can not follow reverse phase method,because it is easy to hydrolysis.

You may need to look further at the degradation. Is is happening on column, or does the sample degrade upon sitting? Maybe a different diluent for sample. Light sensistivity? Maybe a using a cool column and chilled autosampler? Are you using an acidic mobile phase that might promote degradation? May have to go to a normal phase separation if you cannot find a way to eliminate or inhibit the problem