RSC org

An education video on Mass Spectrometry using a magnetic sector instrument from the Royal Society of Chemistry. From the Modern Instrumental Techniques for schools and colleges DVD. For more information on the Chemistry for our Future programme please visit http://www.rsc.org/CFOF (C) Royal Society of Chemistry

http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/Spectrpy/MassSpec/masspec1.htm

The Mass Spectrometer
In order to measure the characteristics of individual molecules, a mass spectrometer converts them to ions so that they can be moved about and manipulated by external electric and magnetic fields. The three essential functions of a mass spectrometer, and the associated components, are:

1. A small sample is ionized, usually to cations by loss of an electron. The Ion Source
2. The ions are sorted and separated according to their mass and charge. The Mass Analyzer
3. The separated ions are then measured, and the results displayed on a chart. The Detector


Ultraviolet/Visible Spectroscopy (UV-Vis)




An obvious difference between certain compounds is their color. Thus, quinone is yellow; chlorophyll is green; the 2,4-dinitrophenylhydrazone derivatives of aldehydes and ketones range in color from bright yellow to deep red, depending on double bond conjugation; and aspirin is colorless. In this respect the human eye is functioning as a spectrometer analyzing the light reflected from the surface of a solid or passing through a liquid. Although we see sunlight (or white light) as uniform or homogeneous in color, it is actually composed of a broad range of radiation wavelengths in the ultraviolet (UV), visible and infrared (IR) portions of the spectrum. As shown on the right, the component colors of the visible portion can be separated by passing sunlight through a prism, which acts to bend the light in differing degrees according to wavelength. Electromagnetic radiation such as visible light is commonly treated as a wave phenomenon, characterized by a wavelength or frequency. Wavelength is defined on the left below, as the distance between adjacent peaks (or troughs), and may be designated in meters, centimeters or nanometers (10-9 meters). Frequency is the number of wave cycles that travel past a fixed point per unit of time, and is usually given in cycles per second, or hertz (Hz). Visible wavelengths cover a range from approximately 400 to 800 nm. The longest visible wavelength is red and the shortest is violet. Other common colors of the spectrum, in order of decreasing wavelength, may be remembered by the mnemonic: ROY G BIV. The wavelengths of what we perceive as particular colors in the visible portion of the spectrum are displayed and listed below. In horizontal diagrams, such as the one on the bottom left, wavelength will increase on moving from left to right.



Proton Nuclear Magnetic Resonance (NMR)




1H NMR Intrepretation Tutorial

Proton Nuclear Magnetic Resonance (1H NMR) Spectroscopy is a powerful method used in the determination of the structure of unknown organic compounds.

During Chemistry 222 lab you will be using NMR extensively to help assign structures to two unknown organic compounds and this tutorial and exercises will hopefully help you solve your unknown.

To remind you of some things that you probably already know about the basic workings of an NMR and interpreting NMR spectra:

The 1H NMR spectrum of an organic compound provides information concerning:

the # of different types of hydrogens present in the molecule
the relative #'s of the different types of hydrogens
the electronic environment of the different types of hydrogens
the number of hydrogen "neighbor" a hydrogen has
Use the index on the left to choose which topic you want to go.
If you feel pretty good about your knowledge of NMR, you should go directly to the exercises. If not, maybe you could visit the tutorial pages and take the included quizzes to help you remember.