Liquid chromatography-mass spectrometry (LC-MS) is an analytical technique that combines the separation capabilities of liquid chromatography and the mass analysis capabilities of mass spectrometry, allowing for the analysis of a wide range of molecular species. LC-MS is useful for identifying proteins, peptides, and drugs, providing advantages such as compound identity, sensitive response, and structural information. This method has applications in drug discovery, clinical analysis, proteomics, and various other fields, with future potential in bioequivalence studies and blood analysis.