17.1 Mass spectrometry
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What can mass spectra be used for
To identify the molecular mass of an organic compound and to gain further info about its structure
When an organic compound is placed in the mass spectrometer, it loses an electron and forms a ______ ion, the ______ ion. The mass spectrometer detects the mass-to-charge ratio (/) of the molecular ion which gives the ______ mass of the compound.
Positive Molecular m/z Molecular
What must be located to find the molecular mass
The molecular ion peak (M+ peak)
What is the molecular ion peak
M+ peak Clear peak at the highest m/z value on the right-hand side of the mass spectrum Eg. if peak m/z is 60, the molecular mass is 60
What is fragmentation
In the mass spectrometer, some molecular ions break down into smaller pieces known as fragments
What are the other peaks in a mass spectrum caused by
Fragment ions formed from the breakdown of the molecular ion
What does the simplest fragmentation break a molecular ion into
Two species A positively charged fragment ion And a radical Any positive ions formed will be detected by the mass spectrometer but the uncharged radicals are not detected
Main features of the mass spectrum of ethanol
Molecular ion peak at m/z=46 Small M+1 peak at m/z=47 A number of fragment ion peaks
Equation to find number of carbon atoms from mass spectrum
no. of carbon = height of M+1 peak x 100 / height of M peak
What is Clenbuterol
Believed to increase development of muscle Considered a performance enhancing drug Banned in athletic competitions