Mass spectrum

[paresh]

Hello,

I am seeking help from you all regarding mass spectra I got.

I have MS spectra of my drug donepezil HCl from Electron Impact and also from Time of Flight analyzer with Electrospray.

But spectral pattern is different.

In EI spectrum i am getting fragmentation pattern while in Electrospary with TOF analyzer there is no such fragmentation pattern only a molecular ion peak was seen at m/z=380 (molecular wt of donepezil) and nothing else.

Plz help me in this regards,

[MG]

That is normal. Electrospray gives less fragmentation than EI, and sometimes no fragmentation at all. The idea of running the sample by ESI-TOF is to get accurate mass on the molecular ion, to confirm the molecular formula. On the other hand, with EI, you match the fragmentation pattern against a library.

The mass spec operator should be able to generate fragments in the ESI spectrum, if you really want to see them. But, the fragmentation pattern probably won't be the same as in EI.