I'm analyzing cortisol (standard) and methylprednisolon (Internal Standard) using HSF5 2.1mm, 15cm, 5 mic column, 0.25 ml/min, cannot get result, why?

Using isocratic mobile phase (73% water and 27% ACN). Only one small peak (4mAU) found. Please suggest me what to do.

12 December 2018 3,621 2 View