What is mass spectrometry primarily used for?

Mass spectrometry is primarily used for identifying chemical compositions. This analytical technique allows scientists to determine the mass-to-charge ratios of ions, which can be used to deduce the molecular weights of compounds and identify their structural composition. When a sample is ionized and its ions are accelerated through an electric field, they are separated based on their mass. The resulting mass spectrum provides information on the different ion species present in the sample, allowing for the identification of compounds, determination of molecular structures, and even quantification of components within a mixture.

The capability of mass spectrometry to provide detailed information about the molecular composition of substances makes it a crucial tool in various fields, including chemistry, biochemistry, and pharmaceuticals. By interpreting the data produced by mass spectrometry, chemists can confirm the identity of compounds, analyze complex mixtures, and study the properties of materials. This is why identifying chemical compositions is the correct answer in the context of what mass spectrometry is primarily used for.