17.1 Mass spectrometry Flashcards

1
Q

What can mass spectra be used for

A

To identify the molecular mass of an organic compound and to gain further info about its structure

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2
Q

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.

A

Positive
Molecular
m/z
Molecular

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3
Q

What must be located to find the molecular mass

A

The molecular ion peak (M+ peak)

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4
Q

What is the molecular ion peak

A

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

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5
Q

What is fragmentation

A

In the mass spectrometer, some molecular ions break down into smaller pieces known as fragments

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6
Q

What are the other peaks in a mass spectrum caused by

A

Fragment ions formed from the breakdown of the molecular ion

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7
Q

What does the simplest fragmentation break a molecular ion into

A

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

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8
Q

Main features of the mass spectrum of ethanol

A

Molecular ion peak at m/z=46
Small M+1 peak at m/z=47
A number of fragment ion peaks

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9
Q

Equation to find number of carbon atoms from mass spectrum

A

no. of carbon = height of M+1 peak x 100 / height of M peak

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10
Q

What is Clenbuterol

A

Believed to increase development of muscle
Considered a performance enhancing drug
Banned in athletic competitions

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