Mass Spectrometry (LS)

Mass Spectrometry (LS) - m/z Relative Abundance Identity 17...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
14 Lecture Supplement: Mass Spectrometry Mass Spectrometry Fundamental principle: Determine mass of molecule by observing behavior of its ion (or fragments) in magnetic field Aston/Thomson Neon Experiment (1919) Ionization: Ne + e - Ne + + 2 e - sample introduction ionization ion sorting by m/z magnet accelerator plates electron gun to vacuum pump detector slit slits ion beam: radius of curvature controlled by ion mass only ions of specific m/z are on path to enter detector Sample : Neon gas, atomic weight = 20.20 amu Results : m/z Relative Abundance 20.0 90 % 20.20 no peak 22.0 10 % Weighted average: (90% x 20.0) + (10% x 22.0) = 20.20 Conclusion: Neon is made up of isotopes Drug Use Screening by Gas Chromatography/Mass Spectrometry N O O O O metabolism Cocaine (injested) CH 3 N OH O O O Benzoylecgonine (excreted) C 16 H 19 NO 4 M = m/z 289 H 3 C H 3 C
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Lecture Supplement: Mass Spectrometry 15 Features of a Typical Mass Spectrum: Methane Tabulated Spectrum:
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: m/z Relative Abundance Identity 17 1.1 % M+1 16 100.0 base peak M molecular ion 15 85.0 14 9.2 13 3.9 12 1.0 Natural Abundance of Important Isotopes Isotope Natural Abundance Isotope Natural Abundance Isotope Natural Abundance 1 H 99.985 % 2 H 0.015% 12 C 98.893 13 C 1.107 14 N 99.634 15 N 0.366 16 O 99.759 17 O 0.037 18 O 0.204 % 19 F 100 32 S 95.0 33 S 0.76 34 S 4.22 35 Cl 75.77 37 Cl 24.23 79 Br 50.69 81 Br 49.31 127 I 100 M contributors M+1 contributors M+2 contributors It is not necessary to memorize this table. The data will be given on an exam if needed. 16 Lecture Supplement: Mass Spectrometry Compounds with Chlorine and Bromine Have Strong M+2 Peaks Lecture Supplement: Mass Spectrometry 17 Fragmentation Yields Structural Information Example: Which C 5 H 12 Isomer? Example: Which Alcohol Isomer?...
View Full Document

Page1 / 4

Mass Spectrometry (LS) - m/z Relative Abundance Identity 17...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online