Topic overview

Start with the big picture

UV-Vis measures electronic transitions and can support quantitation through the Beer–Lambert relationship; its absorbance behavior and wavelength maximum depend on factors such as concentration, chromophore, and solvent. IR and FT-IR reveal molecular vibrations, with characteristic functional-group signals and a fingerprint region that support identification and purity assessment. NMR uses chemical shifts, signal areas, and coupling patterns to provide information about nuclei and molecular connectivity. MS ionizes molecules and measures mass-to-charge ratios; molecular ions and fragmentation patterns can inform molecular mass and structure. Across these methods, instrument design, sample preparation, and sources of error affect the results. The lesson compares their analytical strengths and limitations without treating any single technique as sufficient for every question.