HRMS stands for high-resolution mass spectrometry, a type of mass spectrometry that can measure the mass of ions with very high accuracy and precision, usually in the range of parts per million (ppm) or less. Scientists can use HRMS to determine the exact molecular formula and structure of unknown compounds and distinguish between isomers and isotopes. HRMS can also perform qualitative and quantitative analysis of complex mixtures, such as proteomics and metabolomics samples.