My colleague is working on the GCMS to extract an analyte and its metabolite (she is derivatising in her method). The method has been working until a few weeks ago when just her peak metabolite started to look quite small and broad. She has trimmed the column, she baked it and then changed it, changed the liner, she checked the vials and changed it (just in case was related to the septa). The solution is regularly changed as well. However, the peak still looks the same. Is there something else she can try?