To learn how mass spectrometry differentiates between different isotopes of an element, open the Mass Spectrometer Learning Tool and work through the following steps.
- Under the 'Options' menu, hover over the 'Select Elements' submenu, and select 'chlorine'.
- Leave the isotope ratios at the default settings (these are the ratios that are commonly found in nature) and click scan.
- When the scan is complete, click 'spectrum' (along the bottom). Note the very large peak at an m/z ratio of 35, which corresponds to the chlorine-35 isotope. The smaller peak at an m/z ratio of 37 corresponds to the chlorine-37 isotope.
- Click and drag the mouse over any area of the spectra you would like to zoom in on.
Your turn
Mass spectrometry measures which of the following?
- the mass of a sample of neutral atoms
- the mass-to-charge ratio of a sample of neutral atoms
- the mass of a sample of cations
- mass-to-charge ratio of a sample of cations
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The correct answer is D.
A mass spectrum for a sample of a given element shows only one peak. How many isotopes of that element were present in the sample?
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The mass spectrum only displayed one peak, so there was only one isotope of that element present in the sample.