Mass spectrometers are very useful tools for identifying molecules because
they determine the masses of molecules and the masses of fragments of molecules.
Fifteen years ago these measurements were limited to compounds of low molecular
weight that could be easily placed in the gas phase. Since then, two new techniques
have been developed that allow mass spectrometry to analyze larger, non-volatile
molecules such as peptides and proteins. Half of the 2002 Nobel Prize in Chemistry
was awarded for using these techniques with proteins. In this Activity students
solve puzzles that are analogous to finding the amino acid sequence of a peptide
using mass spectrometry. Students are asked to identify words that have been broken
into letters or groups of letters. Puzzle 1 uses letter fragments from a word;
puzzles 2 and 3 use numbers that represent fragment “masses”, where
each letter of the alphabet is assigned a numerical “mass”.
Supplement
This Activity is based on the JCE article by Gary A. Mabbott, "An
Analogy for Teaching Interpretation of Mass Spectra" J. Chem. Educ.1988,65, 1052, which is available. A more advanced
version of the Activity will also be available soon.
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