What is the role of a mass filter in mass spectrometry?

The role of a mass filter in mass spectrometry is to separate ions based on their mass-to-charge ratio (m/z). This is crucial because mass spectrometry is primarily concerned with identifying and quantifying molecules based on their mass. Ions produced from the sample are sorted by this mass-to-charge ratio as they pass through the mass filter, allowing for the detection of specific ions of interest.

This separation enables the mass spectrometer to produce a mass spectrum, which represents the intensity of detected ions as a function of their m/z ratios. Each peak in the mass spectrum corresponds to a different ion, providing insights into the molecular composition of the sample being analyzed.

While other options like ionizing the sample, storing ions, and cooling the ion stream are all relevant aspects of mass spectrometry, they do not describe the function of the mass filter specifically. Instead, they represent different stages or methods used in the overall process of mass spectrometry that contribute to preparing the sample or managing ion behavior before or after mass analysis.