Let us take a simple molecule, e.g. C2He. Draw three fragmentation pathways for the molecular ion. with each involving only G— H bond cleavage but which lead to the production of a neutral atom, a neutral radical and a neutra i mol ec u ie, respeeti;v ely.
I.i I i I
x 10
S
jjii
X 1
"i     I I—r*~i 1 i 11 i—r~r~i—i i I I m i i I I I 111 11 i 111 11' — 12     4   6   8 10        15    20    25    30 m/z
Mass spectra of methanol (CH,OH)
.:       I    " ,,, -~---:---— - -----------:—-
Draw up a fragmentation pattern for methanol based on the above assignments and underline the most intense ion in the spectrum;
The mass spectrum of ethartol, QH5OH, is shown in . Figure. Use this to carry out the following:
(a) write down the miz value of the molecular ion;
(b) write down the miz value of the base peak;
' - '      ' ' i
(c) the base peak is formed from the molecular ion j
via a single step—write down a pathway for this process;
I (d) write down two fragmentation pathways for the ! production of ions of miz 29 which may have j        different formulae;
(e) write down fragmentation pathways for the following stepwise decompositions:
miz 46 —■—> miz 45--» miz 43
(f) assign  a  formula  to miz  18 and give  a j fragmentation pathway for its direct formation from the molecular ion:
(g) combine the fragmentation pathways j mentioned above to give the fragmentation I pattern for ethanol. j
100				
				
j				
				
	I I	I	i	
	4   8   12 16 20 24 28 32 36 40 44 48 52 m/z Mass spectrum of ethanol (C3H5OH)