[someonenew]

Hey

I'm doing a flavone synthesis experiment... and embarrassingly  I cant work out the fragments in the mass spec. the peaks are as following:

222
194
165
139
120
105
97
92
76
64
51

i know the total mass is 222, and then a removal of a CO group gives the 194 but then I'm lost

[someonenew]

i heard that CO2 and CH3 groups are normally broken off more easily but im trying to figure out where the ions make up the figures above

[MOTOBALL]

Basically, you continue what you did to interpret the m/z 194 ion.

So add a second column to your ion list, and write down the mass difference between sucessive ions.

A third column is then any reasonable combination of C, H, O to give that mass difference.

Be aware that, in general, not all fragments are formed directly from the next highest mass.

Thus, possibly m/z 120 => 105 by loss of CH3, BUT m/z 105 => 97 and 97 => 92 do not happen. So then does m/z 97 come directly from m/z 222 or from any one of 194, 165, 139 or 120 ?

A fourth column might be the empirical formula of the ions,
         
         m/z     Difference    C/H/O                   Formula
         222         ------      ------                    CxHyOz
         194         28              CO                    C(x-1)HyO(z-1)   

Good Luck !!         

[someonenew]

sorry for the late reply. Thank you for your help