Ultraviolet-visible (UV-Vis) spectroscopy is a technique that identifies chemicals based on the interaction of molecules with electromagnetic radiation in the ultraviolet-visible region (10,000-33,333cm-¹ or 300-1000 nm). Molecular absorbances of UV-Vis light cause electronic transitions within molecules. These transitions typically occur with the presence of a transition metal ion, or a conjugated organic molecule. Point analysis (“bench top”) systems are used for analyzing liquid phase materials, although a few systems are also capable of analyzing gases and solids. UV-Vis instrumentation has been scaled down to hand-held size for specific colorimetric applications, but most research-grade instruments are of larger size, and are often combined with NIR instrumentation. There are UV-Vis reference databases, but there is much less specificity in a UV-Vis spectrum compared to MIR data, making it a secondary verification technique with unknown chemicals.