I have generated a Mass Spectrum for PAracetamol extracted from a coproxamol tablet and analysed by GCMS.

 

I see major peaks at m/z 43, 80, 109, 151.

 

151 is clearly the parent ion and 109 and 43 the fragments formed by the cleavage of the CO-NH bond.

 

but I have no idea where the peak at m/z 80 comes from... can anyone help ?

 

Thanks in Advance

A

substract 80 from the M+ peak, you get 151-80=71. Now what you got to do is put on your thinking cap and manipulate between different atoms(which are involved in paracetamol) to arrive at the right fragment.

 

its quite basic and i assume if you have generated the mass spectrum yourself you already know this but thats all i can help now.