No sample fragments are found in negative ESI process, but a lot of fragments are almost presented in FAB process.Comparing these spectra,the fragments or molecular ion can be distinguished.

• 试样在负离子电喷雾电离（ESI）过程中不产生碎片峰，但是在FAB过程中产生许多碎片，比较这些谱图，就可以区别碎片峰和分子离子峰。