4 (10 pts) Consider the following mass spectrum generated for an using electron
ID: 696181 • Letter: 4
Question
4 (10 pts) Consider the following mass spectrum generated for an using electron ionization on a GC-MS instrument 74 87 41 143 171 183 214 101 115 129 | 157 40 60 80 100 120 140 160 180 200 220 240 m/z a) What is the most likely value of the molecular ion? b) What is the base peak in the spectrum? c) What information do the base peak and molecular ion peak provide for the chromatographic peak? Be specific )Describe what happens from sample to detection during a GC-MS experiment. What form is th analyte in during injection, and how is that changed during the chromatography, and mass analysis?Explanation / Answer
a) Most likely value of molecular ion peak is m/z 214
b) Base peak in the spectrum is m/z 74
c) Base peak corresponds to the stable ion formed during fragmentation
Molecular ion peak corresponds to heaviest ion that is with greatest m/z value of compound.
d) Liquid or Gas samples injected into to sample injector then with carrier gas it passes through the column.
If liquid samples are present then with high temperature it coverted to gases form and moves with carrier gas.
Then ionisation of molecules takes place in ionisation chamber ( by chemical ionisation or electron ionisation).
Then different Ions with varring m/z values travels towards detector.
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