UV-Vis Spectrophotometers measure the absorption or transmission of ultraviolet and visible light through a sample. This technique is widely used in geochemistry for quantitative and qualitative analysis of various substances in solution. Key applications include determining the concentration of metal ions, studying metal speciation in aqueous solutions, identifying organic compounds, and analyzing mineral extracts. It can also be used for certain mineral identification in solid samples. The instrument provides information on electronic transitions within molecules, which is crucial for understanding the chemical behavior and properties of geological fluids and dissolved components.