A mass spectrometer is an analytical instrument used to measure the mass-to-charge ratio of ions. It works by ionizing chemical compounds to generate charged molecules or molecule fragments and then sorting these ions based on their mass. This process allows scientists to identify and quantify different substances in a sample. Mass spectrometers are widely used in various fields, including chemistry, biology, and environmental science. They help in applications such as proteomics, metabolomics, and forensic analysis, providing valuable information about the composition and structure of complex mixtures.