1

Mass Spectrometry (MS)

Measure mass of molecule

How?

2

Mass Spectrometry (MS)

Measure the degree of deflection

Light molecule

Large deflection

Heavy molecule

Small deflection

Measure mass of molecule

3

Cocaine

Molecular formula

C

17

H

21

NO

4

4

Cocaine

Molecular weight

12 x 17 = 204

1 x 21 = 21

14 x 1 = 14

16 x 4 = 64

Total = 303

Carbon

Hydrogen

Nitrogen

Oxygen

C

17

H

21

NO

4

5

Cocaine

Molecular weight = 303

Cocaine?

No

C

17

H

21

NO

4

Isomers

Same atoms can be

arranged in different ways

6

C

17

H

21

NO

4

Isomers

Cocaine

7

Mass Spectrum

Pattern of fragments at detector

8

Mass Spectrum

mass

amount of deflection

Molecular

ion (M

+

)

Fragments

9

Mass Spectrum

Highest weight

Lower weights

Always the same pattern

Pattern of fragments at detector

Molecular ion

Fragment ions

10

Mass Spectrum

Same

Cocaine?

Authentic sample of cocaine

Compare the 2 fragmentation patterns

Cocaine

11

Mass Spectrum

Molecular

ion (M

+

)

Cocaine

12

Mass Spectrum

Cocaine

Diamorphine

Molecular

ion (M

+

)

13

Techniques

Chromatography

Separation of mixtures

1

Spectroscopy and spectrometry

Identification of components

2

14

Techniques

Combining separation and identification

Gas chromatography -

Mass Spectrometry (GC-MS)

Hyphenated technique

15

GC-MS

GC output

Auto-

sampler

Goes to mass

spectrometer

MS

Detector

MS

GC

16

GC-MS

GC output

Retention time of components

MS output

Identification

Quantify amount

Combines separation and identification

17

Summary

Chromatography

Separation of mixtures

1

TLC, GC and HPLC

18

Summary

Infrared spectroscopy

Identification by molecular vibrations

2

Molecular stretching and bending

Chromatography

1

19

Summary

Mass spectrometry

Identification by fragmentation

3

Infrared spectroscopy

2

Chromatography

1